Maritime continent coastlines controlling Earth’s climate
During the Monsoon Asian Hydro−Atmosphere Scientific Research and Prediction Initiative (MAHASRI; 2006–16), we carried out two projects over the Indonesian maritime continent (IMC), constructing the Hydrometeorological Array for Intraseasonal Variation−Monsoon Automonitoring (HARIMAU; 2005–10) radar network and setting up a prototype institute for climate studies, the Maritime Continent Center of Excellence (MCCOE; 2009–14). Here, we review the climatological features of the world’s largest “regional” rainfall over the IMC studied in these projects. The fundamental mode of atmospheric variability over the IMC is the diurnal cycle generated along coastlines by land−sea temperature contrast: afternoon land becomes hotter than sea by clear-sky insolation before noon, with the opposite contrast before sunrise caused by evening rainfall-induced “sprinkler”-like land cooling (different from the extratropical infrared cooling on clear nights). Thus, unlike the extratropics, the diurnal cycle over the IMC is more important in the rainy season. The intraseasonal, seasonal to annual, and interannual climate variabilities appear as amplitude modulations of the diurnal cycle. For example, in Jawa and Bali the rainy season is the southern hemispheric summer, because land heating in the clear morning and water vapor transport by afternoon sea breeze is strongest in the season of maximum insolation. During El Niño, cooler sea water surrounding the IMC makes morning maritime convection and rainfall weaker than normal. Because the diurnal cycle is almost the only mechanism generating convective clouds systematically near the equator with little cyclone activity, the local annual rainfall amount in the tropics is a steeply decreasing function of coastal distance (e-folding scale 100–300 km), and regional annual rainfall is an increasing function of “coastline density” (coastal length/land area) measured at a horizontal resolution of 100 km. The coastline density effect explains why rainfall and latent heating over the IMC are twice the global mean for an area that makes up only 4% of the Earth’s surface. The diurnal cycles appearing almost synchronously over the whole IMC generate teleconnections between the IMC convection and the global climate. Thus, high-resolution (<< 100 km; << 1 day) observations and models over the IMC are essential to improve both local disaster prevention and global climate prediction.
KeywordsIndonesian maritime continent Atmosphere–ocean–land interaction Convective clouds Multiple scales Diurnal cycle Sea−land breeze circulation
Ante meridiem (before noon)
Asian Monsoon Years
Asian Precipitation–Highly Resolved Observational Data Integration Towards Evaluation of Water Resources
Indonesian Agency for Meteorology, Climatology and Geophysics
Agency for the Assessment and Application of Technology
Community Climate System Model version 3
Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011
Conditional instability of the second kind
Coupling Processes in the Equatorial Atmosphere
Central Research Institute of Electric Power Industry
Equatorial Atmosphere Radar
Exclusive economic zone
El Niño southern oscillation
Earth observation system
Group of Twenty
Group on Earth Observations
Global Earth Observation System of Systems
Global Energy and Water Cycle Exchanges
Geostationary Meteorological Satellite
Hydrometeorological Array for ISV−Monsoon Automonitoring
Indonesian maritime continent
Indian Ocean Dipole mode
Indian Ocean Moored Network Initiative for Climate Studies
Intertropical convergence zone
Japan Agency for Marine−Earth Science and Technology
Japan EOS Promotion Program
Japan International Cooperation Agency
- JST (in Acknowledgement)
Japan Science and Technology Agency
- JST (in Fig. 6)
Japanese standard time (= Indonesian east standard time = UT + 9 h)
Indonesian National Institute of Aeronautics and Space
Local time (Sumatera, west/central Kalimantan and Jawa: West Indonesian standard time (WIB) = UT + 7 h; Bali, east Kalimantan and Sulawesi: Central Indonesian standard time (WIP) = UT + 8 h; Papua = East Indonesian standard time = UT + 9 h = JST)
Monsoon Asian Hydro−Atmosphere Scientific Research and Prediction Initiative
Maritime Continent Center of Excellence
Japanese Ministry of Education, Culture, Sports, Science and Technology
Mirai Indian Ocean Cruise for the Study of the MJO−Convection Onset in 2006
Japanese Ministry of Foreign Affairs
Post meridiem (after noontime)
Research Moored Array for African−Asian−Australian Monsoon Analysis and Prediction
Science and Technology Research Partnership for Sustainable Development
Sea surface temperature
Tropical Ocean Climate Study
Tropical Rainfall Measuring Mission
Universal time (see LT for further explanation)
Very high frequency
World Climate Research Programme
Wind-induced surface heat exchange
Years of the Maritime Continent
Tropical rainfall in the global climate
Köppen classified low latitude regions of South America and Africa and most of the “East Indies” as Af climate regions defined by a minimum monthly rainfall ≥ 60 mm/month (total annual rainfall >> 720 mm/year), but carefully excluded the inland areas of Sumatera, Kalimantan and Papua,1 as well as those of South America and Africa (except for the Amazon and Congo River Basins) so that his “idealized” land had Af along the equator including inland areas (see Fig. 1d). This view of the rainfall concentration in the equatorial coastal areas was still accepted after some revisions up to his updated version (Köppen and Geiger 1954),2 but is no longer consistent with recent descriptions (Peel et al. 2007).3 The smaller (Lesser Sunda) islands between Jawa and Papua were also excluded from Af, which was recognized as a west−east difference in the Indonesian maritime continent (IMC). At present, a detailed gridded rainfall distribution based on rain gage data (APHRODITE; Yatagai et al. 2012) shows differences between coastal and inland regions, although this is less clear than in the space-borne radar data to be mentioned later.
Köppen’s son-in-law Wegener (1929, after revisions of the first edition published in 1915) tried to use his father-in-law’s idealized climate distribution (1918) to estimate the geographical location of his proposed early-Mesozoic supercontinent before separation and drift, assuming the Af climate near the equator and the coastline. He also speculated on the origin of the East Indies by the association of northward movement of the Indian subcontinent followed by the Australian continent, which is essentially consistent with present-day plate tectonics after a long period of controversy (e.g., Frankel 2012). Köppen and Wegener (1924) evaluated the importance of theories of climate variability associated with insolation changes, developed by Milanković, a Serbian applied mathematician, who published a compilation of these theories (Milanković 1941), which concerned mainly long-term historical climate change (ice ages) but were based on the variation of insolation with the axis of the Earth’s rotation that will be described later in this article. The East Indies, that is the present-day Indonesian Archipelago, and surroundings were designated the maritime continent by Ramage (1968), based on the occurrence frequency of thunderstorms, which was the only database covering the whole equatorial region at that time. In the tropics, thunderstorms as well as rainfall are dependent on convective cloud activity, and the Indonesian maritime continent4 (hereafter referred to as IMC) is known as the world’s convection center or the region of maximum rainfall on Earth.
The IMC was one of the most important regions for hydroclimate studies during the Monsoon Asian Hydro−Atmosphere Scientific Research and Prediction Initiative (MAHASRI; 2006–2016) and the Asian Monsoon Years (AMY; 2007–2012)5 in the World Climate Research Programme (WCRP) (Matsumoto et al. 2016, 2017; Yamanaka et al. 2016). This is simply because the IMC is the region with the world’s largest regional rainfall but has no sufficiently reliable observation network. In the subsequent two subsections we summarize the scientific background and implementation of the two projects carried out over the IMC related to MAHASRI and AMY.
The global energy/water cycle and the maritime continent
Ten tropical regions specified in a basic study by the CRIEPI group (Maruyama et al. 2005) to check the reliability of a numerical climate model (CCSM3; Collins et al. 2006). Land areas and coastline lengths were estimated by calculating numbers of 1° longitude × 1° latitude (corresponding to 111 km × 111 km on the equator) grid points close to coastlines (within 0.5°). “IPCC07 Obs/Model” rainfall amounts are obtained from figures of the original paper. “TRMM Dec97−Jan11” is from Ogino et al. (2016)
On the other hand, the land is heated more easily than the sea (Fig. 4a), but convective clouds generated over the true continents (Africa and South America) are less active than those over the IMC. Therefore, another systematic mechanism is necessary to kick-off an initial updraft in the conditionally unstable tropical atmosphere, and it must work most actively over the IMC.
We have also noticed climatic variabilities of the IMC (cf. Yamanaka 2016): two systematic periodical (annual and diurnal) cycles that are forced astronomically and other components without fixed periodicity (ISVs and interannual variations). The annual cycles of rainy (monsoon) and dry seasons are less clear in the IMC than in adjacent regions such as Indochina (Murakami and Matsumoto 1994) and vary spatially: the seasonal march in the southern hemispheric part (Jawa and Bali) has a southern-hemispheric annual cycle (a clear rainfall maximum in southern summer) (e.g., Haylock and McBride 2001; Hamada et al. 2002; Aldrian and Susanto 2003; McBride et al. 2003; Chang et al. 2004, 2016). The equatorial and northern-hemispheric parts have either a semi-annual cycle (with double peaks near equinox seasons), a northern-hemispheric annual cycle (one peak in northern summer), or the cycle is unclear. The semi-annual cycle is reasonable if we consider that the sun passes the zenith, when the insolation becomes maximum, twice a year. So the rainfall over the IMC is sensitive to the insolation. However, why is the insolation stronger in the rainy and cloudy season? Why is the southern-hemispheric rainy season so dominant in low-latitude Jawa and Bali? We must answer these questions adequately, as well as establishing the mechanism to explain why the world’s largest regional rainfall falls over the IMC.
JEPP−HARIMAU and SATREPS−MCCOE projects
Our observations have been outlined in Yamanaka et al. (2008, 2016) and Yamanaka (2016), and here, we give some details of the background (see also the map in Fig. 5b). The most important aspect in promoting a hydroclimate project over Southeast Asia in the present century is that both infrastructure and the need for observations have grown rapidly with economic growth. More complete understanding and more accurate predictability are requested strongly from industry and the public sectors that have graduated quickly from day-to-day business and a hand-to-mouth existence. The numbers of universities and their students are also increasing rapidly. These circumstances have encouraged governments to promote hydroclimatology with resolution better than annual or continental scale monsoons, as well as with interannual and global scope to maintain sustainable development by mitigating the effects of climate change. Therefore, scientific studies have been conducted in parallel with projects for societal applications (e.g., disaster prevention) and capacity building.
Projects related to MAHASRI and AMY over the IMC are most typical in view of their relevance to the criteria mentioned above. In particular, high-resolution radar observations were strongly requested by both hydroclimatological interest in the world’s strongest convective activity and the societal impacts such as frequent flood and landslide disasters. When we proposed a project related to MAHASRI over the IMC, the Japanese Government established the Japan Earth-Observation System Promotion Program (JEPP) contributing to the Global Earth Observation System of Systems (GEOSS; see GEO 2007), which emphasized societal benefits. Our proposal for the Hydrometeorological ARray for Intraseasonal variation−Monsoon AUtomonitoring (HARIMAU) (Yamanaka et al. 2008)8 was approved as a JEPP project and was conducted from August 2005 to March 2010 (see: http://www.jamstec.go.jp/iorgc/harimau/HARIMAU.html), in collaboration with the Japan Agency for Marine−Earth Science and Technology (JAMSTEC), Kyoto University, Hokkaido University, the Agency for the Assessment and Application of Technology (BPPT), the Indonesian National Institute of Aeronautics and Space (LAPAN), and the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG). HARIMAU consisted of a radar-profiler network with meteorological Doppler radars of X-band (at Padang; e.g., Kawashima et al. 2011; Mori et al. 2011; Sakurai et al. 2011; Kamimera et al. 2012) and C-band (at Serpong near Jakarta; e.g., Wu et al. 2013; Mori et al., 2018, personal communication), and wind profilers of L-band (at Pontianak, Manado, and Biak; e.g., Tabata et al. 2011a, 2011b). A large very high frequency (VHF) wind profiler called the Equatorial Atmosphere Radar (EAR) located at Kototabang (e.g., Fukao 2006; Shibagaki et al. 2006; Seto et al. 2009) was also included in the network. Rainfall and wind distribution data were displayed via the Internet in near real-time throughout the project.
Since 2005, the Indonesian Government has funded the BMKG’s efforts to install over 40 meteorological radars.9 The number of radiosonde stations was also increased to 22, which contributed to the improved accuracy of objective analyses at meteorological agencies worldwide (cf. Seto et al. 2009).10 In parallel with the measurements obtained by the radars and radiosondes, JAMSTEC and BPPT collaborated on buoy and shipboard observations over the Indonesian exclusive economic zone (EEZ) as part of the international network of the Tropical Ocean Climate Study (TOCS; Ando et al. 2010). Another JEPP project, the Indian Ocean Moored Network Initiative for Climate Studies (IOMICS), collected data during 2005–2010 as part of the Research Moored Array for African−Asian−Australian Monsoon Analysis and Prediction (RAMA; McPhaden et al. 2009). Ship-based sea water, surface weather, radar, and radiosonde observations on atmosphere−ocean interactions over the Indian Ocean were conducted by the Mirai Indian Ocean Cruise for the Study of the MJO−Convection Onset in 2006 (MISMO2006; Yoneyama et al. 2008).
In 2009, a follow-on project to HARIMAU and IOMICS was approved under the Science and Technology Research Partnership for Sustainable Development (SATREPS). This project established an international center of tropical climatology, meteorology, and oceanography, called the Maritime Continent Center of Excellence (MCCOE) under BPPT in November 2013 and included capacity building for radar operations and buoy manufacturing during February 2010–March 2014 (see http://www.jamstec.go.jp/rigc/tcvrp/satreps_id/ in Japanese). Some observations were conducted also in collaboration with the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY2011; Yoneyama et al. 2013). After MCCOE was established, the HARIMAU radars and profilers came under the responsibility of that center. Observational data have contributed to global reanalysis (e.g., Onogi et al. 2007; Kobayashi et al. 2015), as well as high-resolution numerical studies at both regional (e.g., Wu et al. 2008, 2009) and global (e.g., Sato et al. 2009) scales.
Intense observation periods (IOPs) of the HARIMAU project under MAHASRI
Intense observation area/period
Stations of major instruments
Sumatera Barat (incl. Siberut Island) 26 Oct–27 Nov 2006
MIA (XDR, AWS, SVC)
Tiku (XDR, AWS)
Tabing (RS, AWS, RIS)
Siberut (RS, AWS, GPS, RIS)
MAHASRI, CPEA, MISMO2006
Diurnal cycle at small island
14 Apr–25 May 2007
MIA (XDR, AWS, SVC)
Tiku (XDR, AWS)
Tabing (RS, AWS)
MAHASRI, AMY, PRIMO/Maldives
Details of diurnal cycles
21–27 Aug 2008, 20 Jan–7 Feb 2009, 20–26 Aug 2009,
Pontianak (WPR, RS, AWS, GPS)
Putussibau (AWS, GPS)
Balikpapan (AWS, GPS)
(Manado (WPR, RS, AWS),
Biak (WPR, RS, AWS))
Geographical differences of diurnal cycles
Local water cycles
(co-funded with SATREPS)
16 Jan–14 Feb 2010
Serpong (CDR, WPR, AWS, RSD)
Bogor (RS, AWS, RSD, RIS)
Pramuka (RS, AWS, RIS)
Serang (RS, AWS)
Cengkareng (RS, AWS)*
Details of diurnal cycles
River diurnal cycle
(funded by SATREPS)
(incl. Sipora Island)
1–31 Dec 2011
MIA (XDR, AWS), Pontiank (RSD)
Muara Putus (MPR, AWS)
Tabing (RS, AWS)
Tuapejat/Sipora (RS, AWS), Pariaman (AWS, RSD, ARG), Sicincin (AWS, RSD), Bawan, (AWS) Kapar, Maninjau, Kandang Empat, Limau Purut, Sungai Sarik, Sintuk, Buayan, Lubuk Minturun, UNAND (ARG)
MAHASRI, AMY, CINDY2011
Organization processes of coastal heavy rainbands
Examination for quantitative precipitation estimation
Experiment for quantitative precipitation forecasting
Many other projects over this important region have been carried out in collaboration with various countries and agencies, for example, ocean–atmosphere interaction studies with China (e.g., Yang et al. 2015), aerosol studies with the USA and others (e.g., Reid et al. 2016), a collaboration within Southeast Asia (e.g., Koh and Teo 2009), and a collaboration/capacity building for meteorological operations and database construction with Australia, the Netherlands, France, Germany, and others. Collaborations between projects are occurring, and contributions from Indonesian scientists are increasing (see the last paragraph of the “Conclusions” section of this article).
In this article, we review mainly our own observational studies on the mechanisms generating the world’s largest regional rainfall over the IMC under the JEPP−HARIMAU and SATREPS−MCCOE projects. The “Review” section is separated into five subsections. The “Diurnal cycle observed around the IMC coastlines” section concerns observational evidence of the diurnal cycle near coastlines, which is the most fundamental and dominant mode over the IMC. The “Local rainfall as a function of coastline length” section describes the general feature of tropical rainfall concentration near coastlines. The “Regional rainfall as a function of ‘coastline density’” section explains the largest regional rainfall over the IMC in terms of the concentration of coastal diurnal cycle rainfall. The “Consistency with the global water budget” section estimates the contribution of the IMC rainfall to the global water/energy cycle. The “Control of the global climate” section looks toward connections between the IMC rainfall and the global climate.
Diurnal cycle observed around the IMC coastlines
The dominant periodicity of insolation is diurnal, and sea−land heat capacity contrasts enforce the local diurnal variations in wind, clouds, and rainfall that were known in Batavia (now Jakarta) a century ago (van Bemmelen 1922). These diurnal variations have been confirmed everywhere along the coastal zones of larger islands (Sumatera, Kalimantan, Jawa, Sulawesi, and Papua) of the IMC, based on wind profilers (including raindrop measurements) (e.g., Hashiguchi et al. 1995; Renggono et al. 2001; Hadi et al. 2002; Murata et al. 2002; Araki et al. 2006; Marzuki et al. 2009; Tabata et al. 2011b), precipitation radars (e.g., Kawashima et al. 2006, 2011; Wu et al. 2007, 2013; Sakurai et al. 2009, 2011; Mori et al. 2011; Kamimera et al. 2012), a space-borne precipitation radar (e.g., Sorooshian et al. 2002; Mori et al. 2004; Kikuchi and Wang 2008; Wu et al. 2008, 2009; Peatman et al. 2014), GPS radio occultation (precipitable water or moisture) sounding (e.g., Wu et al. 2003, 2008, 2009), and satellite observations of outgoing longwave (infrared) radiation (OLR) (cloud-top temperature or height) (e.g., Hendon and Woodberry 1993; Nitta and Sekine 1994; Ohsawa et al. 2001; Yang and Slingo 2001; Sakurai et al. 2005; Hamada et al. 2008). As categorized by Kikuchi and Wang (2008), the diurnal cycle over the IMC is different from that over the open ocean (e.g., Sui et al. 1997).
Usually the land surface, which has a smaller effective heat capacity, is heated or cooled by any thermal forcing more quickly and more largely than the sea surface with larger effective heat capacity, and the horizontal gradient (sea−land difference) of surface temperature (precisely, atmospheric bottom temperature) directly governs the amplitude of diurnal cycles (e.g., Kimura 1975; Rotunno 1983; Niino 1987; Niino et al. 2006). Figure 9d shows mean diurnal variations of the land−sea atmosphere temperature difference for the lowest 1 km obtained by radiosonde observations. Warmer land than sea is observed through the analyzed altitude range (especially strong below 500 m) during daytime (10−16 LT, with a downward phase delay), whereas sea is warmer than land by a greater amount and for longer (19−07 LT) but only below 200-m altitude. This asymmetric temperature cycle seems consistent with the diurnal cycle rainfall being heavier in the morning on the sea-side than in the evening on the land-side (contrary to the cloud top height shown in Fig. 6) as observed in various coastal areas (Sumatera, Jawa, and Kalimantan) over the IMC (Mori et al. 2004, 2011; Wu et al. 2008, 2009). For the case shown in Fig. 9, detailed features including those associated with an MJO landing are also shown elsewhere (Wu et al. 2017, 2018; Yokoi et al. 2017).
On land, these processes lead to rapid land/hydrosphere−atmosphere water exchange (Sulistyowati et al. 2014) and local air pollutant washout. The resulting clear sky over land from sunrise until around noon provides insolation dependent upon the solar angle, which gives more active convection or a rainy season in each hemispheric summer in spite of the very low latitudes (e.g., Jawa and Bali in southern hemispheric summer) or two (semi-annual) rainy seasons in the vicinity of the equator (Murakami and Matsumoto 1994; Hamada et al. 2002; Aldrian and Susanto 2003). Detailed observations and investigations are needed in future. Air pollution in a mega city such as Jakarta is becoming more serious with rapid development.
Over the open oceans, in the CISK mechanism (e.g., Ooyama 1971; Lindzen 1974; Hayashi and Sumi 1986), cyclonic or wavelike disturbances are generated as feedback that further enhances upward motion, that is the cumulus cloud. Energetically speaking, the kinetic energy is always dissipated in the boundary layer and supplied by the conversion of latent heat obtained by ocean surface evaporation, through the potential energy producing the meridional and zonal circulation. Several other feedback mechanisms have been proposed to explain tropical cyclones and ISVs/MJOs (see, e.g., Wang 2012). For example, in the wind-induced surface heat exchange (WISHE) mechanism (Emanuel 1987; Neelin et al. 1987), surface wind generates waves that enhance evaporation and latent heat supply. These feedback mechanisms may be suppressed, because the hydrologic and energy cycles close approximately on a diurnal time scale (including clear/dry land in the morning) over the IMC, and the standard features of ISVs/MJOs along the ITCZ over the Indian and Pacific Oceans (e.g., Madden and Julian 1971, 1994; Wheeler and Hendon 2004; Zhang 2005, 2013; Yoneyama et al. 2008, 2013) are greatly modified over the IMC. For example, passage of ISVs/MJOs over the IMC is shifted to the southern side of the equator, which gives a decrease in rainfall over the IMC from west to east (e.g., Nitta et al. 1992; Shibagaki et al. 2006; Hidayat and Kizu 2010; Fujita et al. 2011; Kamimera et al. 2012; Marzuki et al. 2013; Peatman et al. 2014; Zhang and Ling 2017).
Simultaneously, the ISVs/MJOs influence the amplitudes of local diurnal cycles in moisture, stratification stability, and wind over the IMC. The rainfall (particularly over the sea rather than the land) at various locations over the IMC increases during the active/wet phase of ISVs/MJOs (e.g., Hashiguchi et al. 1995; Widiyatmi et al. 2001; Murata et al. 2002; Sakurai et al. 2005, 2009, 2011; Shibagaki et al. 2006; Wu et al. 2007, 2013; Hidayat and Kizu 2010; Mori et al. 2011, (2018, personal communication); Kamimera et al. 2012; Marzuki et al. 2013; Peatman et al. 2014). As a result, the onset and total rainfall amount of the rainy season over the IMC (in particular over the southern hemispheric part) are governed by the passage of active phases of ISVs/MJOs (see Fig. 5a) (Hashiguchi et al. 1995; Renggono et al. 2001; Hamada et al. 2002; Sakurai et al. 2005; Araki et al. 2006; Xie et al. 2006). Interactions with monsoon surges over complex topography (e.g., Chan and Li 2004; Chang et al. 2004, 2016) may also affect the amplitude variations of diurnal cycle rainfall (Wu et al. 2007, 2013; Hattori et al. 2011; Matsumoto et al. 2017), and sometimes generate sub-synoptic scale Borneo (or cold surge) vortices (e.g., Yokoi and Matsumoto 2008; Chen et al. 2013, 2015). These features of rainfall distribution and variation are in general consistent with sea-side dominance of mainly diurnal cycle coastal rainfall (e.g., Mori et al. 2004; Wu et al. 2009; Ogino et al. 2016, 2017).
Correlations between the IMC rainfall and the sea surface temperature (SST) that vary with interannual atmosphere−ocean interactions such as El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole mode (IOD) have been noted in particular in the dry season, but are notably spatially incoherent in the rainy season (e.g., Haylock and McBride 2001; Hamada et al. 2002; Aldrian and Susanto 2003; McBride et al. 2003). More detailed correlation analyses of recent improved rainfall observations for West Jawa with SST over the Central Pacific and Western Indian Oceans (Hamada et al. 2012) and for the eastern IMC (Kubota et al. 2011; Lestari et al. 2016) are now being applied to the whole of Indonesia. SST variations may reduce or amplify the nighttime sea-to-land temperature gradient and control the morning coastal-sea rainfall in particular in the dry season. In major El Niño and positive IOD years, rainfall is often reduced, even in the rainy season, leading to serious drought and smog disasters over the IMC (e.g., Hashiguchi et al. 2006; As-syakur et al. 2016; Hidayat et al. 2016). In La Niña and negative IOD years, larger moisture transport from warmer sea water enhances diurnal cycle rainfall, which leads to a less clear dry season and flood disasters during cold surges and/or MJO active phases in the rainy season (e.g., Wu et al. 2007, 2013; Matsumoto et al. 2017). These results are essentially consistent with independent similar studies by Qian (2008) and Qian et al. (2013). Decadal or longer-scale rainfall trends (e.g., Endo et al. 2009; Villafuerte and Matsumoto 2015) should also appear through amplitude modulations of the diurnal cycles associated with variations of SST and moisture transport.
Local rainfall as a function of coastal distance
As mentioned already, we may consider a very rapid hydrologic cycle near the IMC coastline, unlike in the extratropics where the hydrologic cycle closes on an annual time scale. If so, liquid water transport by river from land to sea should be approximately balanced by water vapor transport by sea breeze from sea to land. We have confirmed that a major river in West Jawa has a diurnal cycle (Sulistyowati et al. 2014). The hydrologic cycle over the IMC has been revealed using isotopic analyses of sampled rain and land water (Kurita et al. 2009; Fudeyasu et al. 2011; Suwarman et al. 2013, 2017; Belgaman et al. 2016; Permana et al. 2016). Furthermore, we know diurnal cycles occur also in the biosphere and humanosphere, which are also concentrated near the coastline.
For an island smaller than this horizontal scale, the diurnal cycle of sea−land circulation along the coastline is suppressed, which is consistent with theoretical and numerical studies (cf. Niino et al. 2006; Takasuka et al. 2015, for local and global models, respectively, although the resolution of the latter is critical). In smaller islands within about 100 km of larger islands, such as Siberut near Sumatera (Wu et al. 2008; Kamimera et al. 2012) and Biak near Papua (Tabata et al. 2011b), there are two peaks due to the diurnal cycles of both islands (night and morning by small and large islands, respectively).
The predominance of the coastal diurnal cycle is characteristic in the equatorial tropics, and it disappears with the traveling cyclone activity in the subtropics and extratropics (appearing only on clear days in anticyclones). However, because of its perennial, stationary, and somewhat broader features, the tropical diurnal cycle generates much more rainfall in the annual or longer-period total than (sub)tropical and extratropical cyclones.
Regional rainfall as a function of “coastline density”
The approximately linear relationship Eq. (2) and its variance as shown in Fig. 14 imply similarities and variations of precipitating convective clouds and their clusters. Deviations may be partly due to the arbitrary selection and boundary of each region. A systematic difference between the western and eastern coasts of meridionally elongated land areas such as Sumatera, Kalimatan, the Malay Peninsula, and the Indian Subcontinent (e.g., Ogura and Yoshizaki 1988; Murata et al. 2002; Chang et al. 2004, 2016; Xie et al. 2006; Wu et al. 2009) should possibly be included in the linearity factor 2000 mm/year/100 km.
Steep slopes between high mountain ranges and low swampy basins may also produce diurnal variations with mountain−valley breeze-like circulation. In the IMC, mountains of major islands reach significant heights (3000 m or higher) but are close to the coastlines, so that the mountain−valley breezes are not separated from the sea−land breezes (e.g., Yang and Slingo 2001). However, inland regions of the true continents may have diurnal cycles of the mountain−valley type completely separated from the coastlines. Thus, if we take such steep slope effects into account and replace the coastline length by the length of the contour line of an appropriate altitude (probably given by a midpoint between the lifting condensation levels in the morning and evening), we may obtain a corrected result in which the data plots for Central Africa (Fig. 8a, d) and Amazonia (Fig. 8c, f) also approach the linear relationship. This is only a secondary effect because, as shown in the previous subsection and Figs. 12 and 13, the local rainfall distribution is primarily a function of the coastal distance (Ogino et al. 2016, 2017).
Detailed studies of the local rainfall variability due to orography over the IMC have started with a dense mesoscale rain gage network of daily-pentad (so the diurnal cycle is not resolvable) sampling (Hamada et al. 2008), and with raindrop size disdrometers (Marzuki et al. 2013) and wind profilers (Tabata et al. 2011a, 2011b) with high time resolution at almost isolated stations. For local orographic effects on the diurnal cycle rainfall (and wind), we need to analyze meteorological Doppler radar data more precisely in the next step.
In particular, west−east differences of the IMC have been found in climatological (e.g., Köppen 1918; Murakami and Matsumoto 1994; Kubota et al. 2011; Hidayat et al. 2016; Lestari et al. 2016), and cloud-physical (e.g., Marzuki et al. 2013; As-syakur et al. 2016) and water isotope (Suwarman et al. 2013, 2017; Belgaman et al. 2016; Permana et al. 2016) observations. The western part has relatively greater rainfall, a more continental-like raindrop size distribution, and more Indian Ocean monsoon-like origin than the eastern part. The border is roughly the Makassar and Lombok Straits, and a similar separation was noted much earlier in zoology/ecology (e.g., the famous line discovered first by Wallace 1869), geology/geophysics (e.g., Wegener 1929; Frankel 2012), and oceanography (e.g., Lukas et al. 1996; Gordon 2005). The western part consists of three large islands (Kalimantan, Sumatera, and Jawa; the world’s 3rd, 6th, and 11th largest) and the Malay Peninsula, which have longer coastlines than the eastern side with two large (the 2nd and 9th; Papua and Sulawesi) and many much smaller islands. This is consistent with the greater rainfall in the western part.
The results described here suggest that a numerical model needs to resolve the equatorial coastlines with sufficiently high resolution (<< 100 km). The importance of the diurnal cycle over the IMC not only in this region but also for the global climate has been suggested by modelers (e.g., Neale and Slingo 2003). Results from a high-resolution model (20 km mesh) indicate that the diurnal cycles over the IMC will be weakened in future mainly due to nighttime land temperature increase associated with global warming (Kitoh and Arakawa 2005), although at present, even megacities (such as Jakarta) in the IMC do not have notable local heat island effects. Much higher resolution models (7 and 3.5 km grids) have simulated local clouds activated by an MJO causing a flood in the Malay Peninsula (Miura et al. 2007) and rainfall coupled with convergence of sea−land breeze circulations over the IMC (Sato et al. 2009). However, the effects of the resolution improvement on the accuracy of the simulation do not seem to be so simple (e.g., Wang et al. 2012). Numerical studies for different coastline features will also be useful for the study of paleoclimate; these will be mentioned later.
Consistency with the global water budget
As shown in Table 1, the IMC coastline is longer than half the 10-region total, and longer than 20% of the total coastline length of 150,000 km within latitudes < 37°. This is why the IMC (both land and sea) occupying only 4% of the Earth’s surface generates such a large fraction of the global latent heating. We may imagine that we replace clouds distributed along the ITCZ (Fig. 2a) by clouds along the IMC coastline, which has length comparable to the equatorial circumference (Fig. 2c). The IMC produced tectonically as suggested by Wegener (1929) is now experiencing equatorial climate that will be recorded as fossils of tropical organisms in future, and here we may say in addition that the present climate itself is also dependent on the geomorphology of the IMC! A new climatological classification including the diurnal cycle amplitude may be necessary to replace Köppen’s that only considers the annual cycle.
Control of the global climate
Another process controlling the global climate may be through the modification of MJOs (cf. Zhang 2005, 2013), which are regarded as an important factor governing the medium-range variability of global weather and climate. A recent study by Zhang and Ling (2017) shows a “barrier effect” of the IMC on more than 75% of MJOs. More detailed observational and theoretical studies may be necessary to identify the mechanisms weakening MJOs, but the synchronous diurnal cycle noted above may play an important role.
In addition, a convection cell such as the sea or land breeze circulation consists dynamically of a pair of internal gravity waves propagating upward and downward, and their diurnal cycle migrations both seaward and landward imply generation of waves with phase velocities and momenta of two opposite directions (e.g., Rotunno 1983; Niino 1987). This feature is important for considering the horizontal propagation of the diurnal cycle generated at a coastline, as well as interaction with other diurnal cycles (e.g., Niino et al. 2006), and to study upward propagation (e.g., Ogino et al. 1995; Tsuda et al. 1995, 2000) and stratospheric mean-flow acceleration in two opposite directions (such as the quasi-biennial oscillation (QBO), which has become somewhat controversial very recently, see e.g., Osprey et al. 2016). This issue will be discussed as a case study based on recent radiosonde campaign observations in a subsequent paper. The contributions of the 11-year solar-cycle variation of insolation to climate are still controversial and do not look so clear in recent studies (e.g., Lean et al. 2005).
For longer time scales (102–106 years) several studies (such as those cited in Randall et al. 2007) suggest increasing occurrence of El Niño (La Niña) in a globally warmer (colder) climate. If so, the rainy (dry) season is dominant over the IMC in glacial (interglacial) periods (with time scales of a few 105 years called the Milanković (1941) cycle). However, in a glacial period the sea level falls, and the IMC became part of real continents (Sunda and Sahul subcontinents) connected to Eurasia and Australia (e.g., Voris 2000), and the IMC “dam” was almost closed, although the Makassar Strait transporting warm water from the Pacific to Indian Ocean (e.g., Lukas et al. 1996; Gordon 2005) still existed. The coastlines were much shorter around the Indonesia throughflow region and around the whole subcontinents, which means broader drier areas inland and less regional rainfall. Therefore, the active water cycle occurs in a much more limited coastal area, and a smaller amount of water is circulated (consistent with a larger amount of water frozen over land). Results from a model run with changing sea level (Braconnot et al. 2007a, 2007b) gave less tropical rainfall in particular over the IMC than from a run without the change (Kitoh and Murakami 2002), although the authors considered that the sea level change in the former is model-dependent and the rainfall decrease is due to atmospheric water vapor decrease with cooling. On much longer scales (≳ 107 years), the continents and oceans may be aggregated or separated (with a period of a few 108 years called the Wilson (1963) cycle), and the results are not so simple, because other conditions (such as land orography, ocean circulation, and atmospheric composition) are not fixed. In general, the inland of a supercontinent is very dry, and a stronger monsoon is expected to or from the surrounding superocean (e.g., Parrish 1993), which is not inconsistent with our idea on the diurnal cycle coastal rainfall in the tropics.
The cloud−precipitation observation system over the IMC has been improved by the JEPP−HARIMAU and SATREPS−MCCOE projects that have produced scientific results as listed below.
The diurnal cycle has been established by (i) as the fundamental phenomenon in particular near the coastlines over the IMC. It is forced by the land–sea temperature difference mainly due to the daytime insolation (dependent on latitude and season) and the nighttime sprinkler-like rainfall itself and partly by interannual SST variations. It is synchronized over almost the whole IMC and forces cloud convection systems from meso to synoptic scales.
Analyses of the TRMM−PR observation data and the JRA-55 objective reanalysis data have shown that the local rainfall in the tropics is found to be a steeply decreasing function of the coastline length, which results mainly from rainfall concentrated near the IMC coastline (ii).
The regional rainfall as summarized by the IPCC can be expressed by a roughly linear function of the “coastal density” defined as the coastline length divided by the enclosed land area. The world’s largest regional rainfall over the IMC is explained by the long coastlines, which is consistent with (ii) and (iii).
The IMC coastline rainfall as mentioned in (ii)−(iv) produces the largest part (roughly 20% or more) of the global latent heating, which is about 22% of the magnitude of the global infrared radiation (see Fig. 1a). Thus, its variations may affect the global climate considerably. This is consistent with the rainfall itself enhancing the diurnal cycle as mentioned in (ii).
The larger-scale forcing as mentioned in (ii) by the IMC coastline diurnal cycle convection of the intensity mentioned in (v) may generate teleconnections controlling the global climate.
There are several issues which must be clarified. For example, the regional rainfall–coastline density relation (iv) must be improved, using the local rainfall–coastal distance relation (iii). Understanding tropical and global characteristics including the impacts of IMC-like complex land distributions is also quite important for considering the future climate. We now understand that high-resolution observations and models that can detect or reproduce the diurnal cycle and cloud convection over the IMC are necessary in order to improve both local disaster prevention and global climate prediction. In the next step called Years of the Maritime Continent (YMC; 2017−9), Indonesia as a G20 country should take observations under a more completely multinational framework (see YMC (Years of the Maritime Continent) 2017). As a preliminary activity, pre-YMC campaign observations have been carried out in and off Bengkulu (Wu et al. 2017, 2018; Yokoi et al. 2017), which is located about 400 km south of Padang (Sumatera Barat area in Table 2). The Bengkulu area has not yet been observed well and is almost free from small islands distributed off Padang. Also, the long historical meteorological records of Indonesia are starting to be analyzed by Indonesian scientists (e.g., Siswanto et al. 2016; Yanto et al. 2016; Supari et al. 2016), which will clarify features and mechanisms of the multi-scale interactions. Agricultural applications of climatological studies (Hidayat et al. 2016; Marjuki et al. 2016) are requested strongly by the Indonesian government and society. Interdisciplinary studies with hydrology and oceanography are also developing, although they are out of the scope of this article.
We use Indonesian names for islands of the IMC: Sumatera, Kalimantan, Jawa, Sulawesi and Papua for English names of Sumatra, Borneo, Java, Celebes, and New Guinea, respectively.
A major revision separated Am (meaning originally medium and later monsoonal) from Aw, dependent on whether the minimum monthly rainfall (< 60 mm/month) is greater than 4% of the annual rainfall or not.
A spline interpolation might smooth variations within the scale of coastal regions (102 km).
In the Paleogene (66–23 Ma) the Americas were separated like the present-day Asia–Australia, which was another example of maritime continent.
The AMY program is a cross-cutting coordinated observation and modeling initiative under the International Monsoon Study (IMS) of WCRP, which nearly overlapped with and was promoted together with MAHASRI (see Matsumoto et al. (2017)).
Rainfall estimates from cloud observations differ from direct measurements, but have merits such as temporal and horizontal continuity (see, e.g., Xie and Arkin 1997).
At this initial stage, ISVs and monsoons were specified as the most important targets; although, the diurnal cycle became the most important target by the end of the period.
As of March 2017, 36 C-band and 4 X-band radars are in operation, and one more radar is being installed in 2017.
Radiosonde observations (originally at 12 stations) reported to the global telecommunication system (GTS) were increased to more than once per day since mid-2005 (approaching twice a day during 2007); their impact on objective analysis has been shown by Seto et al. (2009), and the number of stations has been increased to 22 (in addition to 2 wind-profiler and 73 pilot balloon stations) as of March 2017.
A “tropical night” is defined by the Japan Meteorological Agency as having the daily minimum temperature higher than 25 °C, although another criterion, for example, in Germany (20 °C), is somewhat lower than the Japanese definition and also lower than the usual daily minimum temperature in the IMC.
The typical values are observationally less than 102 km in the extratropics and theoretically given as the half horizontal wavelength using the gravity-wave dispersion relation, substituting the height of the sea–land breeze circulation cell as the half vertical wavelength (internal case, latitude < 30°) (e.g., Rotunno 1983; Niino 1987).
The coastal density is 2/radius for a circular land area, and 4/side length for a square land area.
As mentioned in the text, the contents overviewed in this article were obtained under the two projects, JEPP−HARIMAU and SATREPS−MCCOE. We would like to acknowledge the Japanese and Indonesian Governments, JST, JICA, JAMSTEC, Kyoto University, Hokkaido University, BPPT, LAPAN, and BMKG for their support and collaboration. In completing this article, we thank Dr. Kunio Yoneyama, Director of the Department of Coupled Ocean−Atmosphere−Land Processes Research of JAMSTEC for his supervision and encouragement concerning research toward the YMC and on our submission of an earlier version of this paper to the international seminar at Bengkulu on October 19−20, 2016. The YMC websites at BMKG and JAMSTEC are maintained/updated by Ms. Nurhayati and Dr. Yoneyama, respectively. We also thank Dr. Dawn P. Erlich and other editors of GEWEX NEWS for their comments on a summary of MAHASRI, JEPP−HARIMAU, and SATREPS−MCCOE projects related partly to this article. Comments from Profs. Mike Chen, Masahito Ishihara and Shigeo Yoden, on the authors’ presentations related to this article are also greatly acknowledged. The authors wish to thank sincerely Prof. Susumu Kato and the late Prof. Shoichiro Fukao for much important advice and encouragement since the beginning of observational studies over the IMC. Lastly, the authors would like to acknowledge the journal General Chief Editor (Prof. Yasufumi Iryu), an Editor (Prof. Jonny Chan), and two anonymous reviewers for their constructive comments and positive evaluations.
This study was mainly supported by JEPP and SATREPS.
JEPP was a Japanese Government program operated directly by Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).
SATREPS is a Japanese Government program operated jointly by JST and JICA under supervisions of MEXT and MOFA.
All authors read and approved the final manuscript. MDY proposed and summarized this article, based on the contents first-authored by the other authors, and contributed mainly to the first subsection of the “Introduction” section, the “Regional rainfall as a function of ‘coastline density’” section of the “Review” section, and the “Conclusions” section. SM and HJI carried out the radar and radiosonde observations and operational data collections in Indonesia, as well as data analysis and paper publication in Japan and contributed mainly to the “JEPP−HARIMAU and SATREPS−MCCOE projects” section of the “Introduction” and the “Tropical rainfall in the global climate” section of the “Review”. PMW and SYO carried out observations including outside the Indonesian territory, regional numerical modeling, and global data analysis and contributed mainly to the “Local rainfall as a function of coastline length” and “Regional rainfall as a function of ‘coastline density’” sections of the “Review” section. JM and FS combined our results with the whole international collaborative studies and contributed mainly to the “The global energy/water cycle and the maritime continent” of the “Introduction” section and the “Control of the global climate” section of the “Review” section.
MDY was the Principal Investigator of the JEPP-HARIMAU (2005–2010) and STREPS-MCCOE (2009–2014) projects in which all authors were involved. SM was the Leader of JAMSTEC Maritime Continent Research Group (2005–2014), of which HJI is a member. JM was the Leader of JAMSTEC Monsoon Meteorology Research Group (2005–2014), of which PMW and SYO are members. JM was also the Chairman of the Steering Committee for the MAHASRI project (2005–2016), which also involved all the authors. FS was the Head of the Climate Dynamics Laboratory (2005–2015) of BPPT, the Principal Investigator of the Indonesian Team for JEPP-HARIMAU and SATREPS-MCCOE projects, and the Indonesian representative for MAHASRI.
The authors declare that they have no competing interest.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- Ando K, Syamsudin F, Ishihara Y, Pandoe W, Yamanaka MD, Masumoto Y, Mizuno K (2010) Development of new international research laboratory for maritime-continent seas climate research and contributions to global surface moored buoy array. Hal J, Harrison DE, Stammer D Proceedings of OceanObs’09: Sustained Ocean Observations and Information for Society (Annex), Venice, Italy, 21–25 September 2009, ESA publication WPP-306. https://doi.org/10.5270/OceanObs09
- Araki R, Yamanaka MD, Murata F, Hashiguchi H, Oku Y, Sribimawati T, Kudsy M, Renggono F (2006) Seasonal and interannual variations of diurnal cycles of wind and cloud activity observed at Serpong, West Jawa, Indonesia. J Meteor Soc Japan 84A:171–194. https://doi.org/10.2151/jmsj.84A.171 Google Scholar
- As-syakur AR, Osawa T, Miura F, Nuarsa IW, Ekayanti NW, Dharma IGBS, Adnyana IWS, Arthana IW, Tanaka T (2016) Maritime continent rainfall variability during the TRMM era: the role of monsoon, topography and El Niño Modoki. Dyn Atmos Oceans 75:58–77. https://doi.org/10.1016/j.dynatmoce.2016.05.004 Google Scholar
- Baumgartner A, Reichel E (1975) The World Water Balance: Mean Annual Global, Continental and Maritime Precipitation, Evaporation and Run-Off. Elsevier, AmsterdamGoogle Scholar
- Belgaman HA, Ichiyanagi K, Tanoue M, Suwarman R, Yoshimura K, Mori S, Kurita N, Yamanaka MD, Syamsudin F (2016) Intraseasonal variability of δ18O of precipitation over the Indonesian maritime continent related to the Madden−Julian oscillation. SOLA 12:192–197. https://doi.org/10.2151/sola.2016-039 Google Scholar
- Braconnot P, Otto-Bliesner B, Harrison S, Joussaume S, Peterchmitt JY, Abe-Ouchi A, Crucifix M, Driesschaert E, Fichefet T, Hewitt CD, Kageyama M, Kitoh A, Laîné A, Loutre MF, Marti O, Merkel U, Ramstein G, Valdes P, Weber SL, Yu Y, Zhao Y (2007a) Results of PMIP2 coupled simulations of the mid-Holocene and last glacial maximum, part 1: experiments and large-scale features. Clim Past 3:261–277. https://doi.org/10.5194/cp-3-261-2007 Google Scholar
- Braconnot P, Otto-Bliesner B, Harrison S, Joussaume S, Peterchmitt JY, Abe-Ouchi A, Crucifix M, Driesschaert E, Fichefet T, Hewitt CD, Kageyama M, Kitoh A, Loutre MF, Marti O, Merkel U, Ramstein G, Valdes P, Weber SL, Yu Y, Zhao Y (2007b) Results of PMIP2 coupled simulations of the mid-Holocene and last glacial maximum, part 2: feedbacks with emphasis on the location of the ITCZ and mid- and high latitudes heat budget. Clim Past 3:279–296. https://doi.org/10.5194/cp-3-279-2007 Google Scholar
- Chan JCL, Li C (2004) The east Asia winter monsoon. In: East Asian Monsoon, Chang CP (eds) World scientific series on Asia−Pacific weather and climate, vol 2. World Scientific Publication Company, pp 54–106. https://doi.org/10.1142/9789812701411_0002
- Chang CP, Harr PA, McBride JC, Hsu HH (2004) Maritime continent monsoon: annual cycle and boreal winter variability. In: East Asian Monsoon, Chang CP (eds) World scientific series on Asia−Pacific weather and climate, vol 2. World Scientific Publication Company, pp 107–152. https://doi.org/10.1142/9789812701411_0003
- Chang CP, Lu MM, Lim H (2016) Monsoon convection in the maritime continent: interaction of large-scale motion and complex terrain. In: Multiscale convection-coupled Systems in the Tropics: a tribute to Dr. Michio Yanai, Meteorological Monograph, vol 56, pp 6.1–6.29. https://doi.org/10.1175/AMSMONOGRAPHS-D-15-0011.1 Google Scholar
- Chen TC (2002) A North Pacific short-wave train during the extreme phases of ENSO. J Clim 15:2359–2376. https://doi.org/10.1175/1520-0442(2002)015<2359:ANPSWT>2.0.CO;2 Google Scholar
- Emanuel KA (1987) An air-sea interaction model of intraseasonal oscillations in the tropics. J Atmos Sci 44:2324–2430. https://doi.org/10.1175/1520-0469(1987)044<2324:AASIMO>2.0.CO;2 Google Scholar
- Frankel HR (2012) The continental drift controversy, Vol 1: Wegener and the early debate. Cambridge University Press, Cambridge. https://books.google.co.jp/books?isbn=1316616045
- Fudeyasu H, Ichiyanagi K, Yoshimura K, Mori S, Hamada JI, Sakurai N, Yamanaka MD, Matsumoto J, Syamsudin F (2011) Effects of large-scale moisture transport and mesoscale processes on precipitation isotope ratios observed at Sumatera, Indonesia. J Meteor Soc Japan 89A:49–59. https://doi.org/10.2151/jmsj.2011-A03 Google Scholar
- Gage KS, Nastrom GD (1986) Theoretical interpretation of atmospheric wavenumber spectra of wind and temperature observed by commercial aircraft during GASP. J Atmos Sci 43:729–740. https://doi.org/10.1175/1520-0469(1986)043<0729:TIOAWS>2.0.CO;2 Google Scholar
- GEO (Group on Earth Observations) (2007) The First 100 Steps to GEOSS, Annex of Early Achievements to the Report on Progress, 2007 Cape Town Ministerial Summit: Earth Observations for Sustainable Growth and Development, 30 November 2007, GEO Secretariat, p. 212. https://www.earthobservations.org/documents/the_first_100_steps_to_geoss.pdf. Accessed 20 Feb 2018
- Hadi TW, Horinouchi T, Tsuda T, Hashiguchi H, Fukao S (2002) Sea-breeze circulation over Jakarta, Indonesia: a climatology based on boundary layer radar observations. Mon Wea Rev 130:2153–2166. https://doi.org/10.1175/1520-0493(2002)130<2153:SBCOJI>2.0.CO;2 Google Scholar
- Hartmann DL (1994) Global physical climatology. Academic Press, San DiegoGoogle Scholar
- Hashiguchi H, Fukao S, Tsuda T, Yamanaka MD, Tobing DL, Sribimawati T, Harijono SWB, Wiryosumarto H (1995) Observations of the planetary boundary layer over equatorial Indonesia with an L-band clear-air Doppler radar: initial results. Radio Sci 30:1043–1054. https://doi.org/10.1029/95RS00653 Google Scholar
- Hashiguchi NO, Yamanaka MD, Ogino SY, Shiotani M, Sribimawati T (2006) Seasonal and interannual variations of temperature in tropical tropopause layer (TTL) over Indonesia based on operational rawinsonde data during 1992−1999. J Geophys Res 111:D15110. https://doi.org/10.1029/2005JD006501 Google Scholar
- Hayashi YY, Sumi A (1986) The 30–40 day oscillations simulated in an “aqua planet” model. J Meteor Soc Japan 64:451–467. https://doi.org/10.2151/jmsj1965.64.4_451
- Haylock M, McBride J (2001) Spatial coherence and predictability of Indonesian wet season rainfall. J Clim 4:3882–3887. https://doi.org/10.1175/1520-0442(2001)014<3882:SCAPOI>2.0.CO;2 Google Scholar
- Jaeger L (1983) Monthly and areal patterns of mean global precipitation. In: Street-Perrott A, Beran M, Ratcliffe R (eds) Variations in the global water budget. Springer, pp 129–140. https://doi.org/10.1007/978-94-009-6954-4_9
- Kawashima M, Fujiyoshi Y, Ohi M, Honda T, Mori S, Sakurai N, Abe Y, Harjupa W, Syamsudin F, Yamanaka MD (2011) Case study of an intense wind event associated with a mesoscale convective system in west Sumatera during the HARIMAU2006 campaign. J Meteor Soc Japan 89A:239–257. https://doi.org/10.2151/jmsj.2011-A15 Google Scholar
- Kimura R (1975) Dynamics of steady convections over heat and cool islands. J Meteor Soc Japan 53:440–457 https://doi.org/10.2151/jmsj1965.53.6_440
- Köppen W (1918) Klassifikation der Klimate nach Temperatur, Niederschlag und Jahresablauf (classification of climates according to temperature, precipitation and seasonal cycle). Petermanns Geogr Mitt 64:193–203 243−248. http://koeppen-geiger.vu-wien.ac.at/pdf/Koppen_1918.pdf. Accessed 20 Feb 2018
- Köppen W, Geiger R (1954) Klima der Erde (climate of the earth). Wall map 1:16 mill. Klett-Perthes, Gotha http://koeppen-geiger.vu-wien.ac.at/pics/Geiger_1954_Map.jpg. Accessed 20 Feb 2018
- Köppen W, Wegener A (1924) Die Klimate der geologischen Vorzeit, Gebriider Borntraeger, p 256 [Thiede J, Lochte, K., Dummermuth, A (eds); translated by Oelkers B (2015) The Climates of the Geological Past, Schweizerbart Science Publishers, pp. 657 http://www.schweizerbart.de/publications/detail/isbn/9783443010881. Accessed 20 Feb 2018]
- Lindzen RS (1974) Wave CISK in tropics. J Atmos Sci 31:156–179. https://doi.org/10.1175/1520-0469(1974)031<0156:WCITT>2.0.CO;2 Google Scholar
- Madden RA, Julian PR (1971) Detection of a 40−50 day oscillation in the zonal wind in the tropical Pacific. J Atmos Sci 28:702–708. https://doi.org/10.1175/1520-0469(1971)028<0702:DOADOI>2.0.CO;2 Google Scholar
- Madden RA, Julian PR (1994) Observations of the 40–50-day tropical oscillation: a review. Mon Wea Rev 122:814–837. https://doi.org/10.1175/1520-0493(1994)122<0814:OOTDTO>2.0.CO;2 Google Scholar
- Marzuki, Hashiguchi H, Yamamoto MK, Yamamoto M, Mori S, Yamanaka MD, Carbone RE, Tuttle JD (2013) Cloud episode propagation over the Indonesian maritime continent from 10 years of infrared brightness temperature observations. Atmos Res 120−121:268–286. https://doi.org/10.1016/j.atmosres.2012.09.004 Google Scholar
- Matsumoto J, Oki T, Yamanaka MD, Hayashi T, Asanuma J (2016) 10 years of MAHASRI: accomplishments and the international science conference wrap-up. GEWEX NEWS 26(4):10–15 http://www.gewex.org/gewex-content/files_mf/1480533350Nov2016_final_opt.pdf. Accessed 20 Feb 2018
- Matsumoto J, Wang B, Wu GX, Li JP, Wu PM, Hattori M, Mori S, Yamanaka MD, Hamada JI, Syamsudin F, Koike T, Tamagawa K, Ikoma E, Kinutani H, Kamahori H, Kamiguchi K, Harada Y (2017) An overview of the Asian monsoon years 2007−2012 (AMY) and multi-scale interactions in the extreme rainfall events over the Indonesian maritime continent. Chang CP, Kuo HC, Lau NC, Johnson RH, Wang B, Wheeler MC, The global monsoon system: research and forecast, 3rd edn., world scientific series on Asia−Pacific weather and climate: Vol. 9, World Scientific Publication Company: 365–386. https://doi.org/10.1142/9789813200913_0029
- Matsuno T (1966) Quasi-geostrophic motions in the equatorial area. J Meteor Soc Japan 44:25–43. https://doi.org/10.2151/jmsj1965.44.1_25
- McBride JL, Haylock MR, Nicholls N (2003) Relationships between the maritime continent heat source and the El Nino−southern oscillation phenomenon. J Clim 16:2905–2914. https://doi.org/10.1175/1520-0442(2003)016<2905:RBTMCH>2.0.CO;2 Google Scholar
- Milanković M (1941) Kanon der Erdbestrahlung und seine Anwendung auf das Eiszeitenproblem (canon of insolation and the ice-age problem), Poseńa izdanja Srpska akademija nauka (Royal Serbian Academy special publications, section of mathematical and natural sciences), p 633 [Israel Program for Scientific Translations; (available from U.S. Dept. of Commerce, Clearinghouse for Federal Scientific and Technical Information, Springfield, Va.) (1969), 484pp]Google Scholar
- Mori S, Hamada JI, Sakurai N, Fudeyasu H, Kawashima M, Hashiguchi H, Syamsudin F, Arbain AA, Sulistyowati R, Matsumoto J, Yamanaka MD (2011) Convective systems developed along the coastline of Sumatera Island, Indonesia observed with an X-band Doppler radar during the HARIMAU2006 campaign. J Meteor Soc Japan 89A:61–81. https://doi.org/10.2151/jmsj.2011-A04 Google Scholar
- Mori S, Hamada JI, Tauhid YI, Yamanaka MD, Okamoto N, Murata F, Sakurai N, Sribimawati T (2004) Diurnal rainfall peak migrations around Sumatera Island, Indonesian maritime continent observed by TRMM satellite and intensive rawinsonde soundings. Mon Wea Rev 132:2021–2039. https://doi.org/10.1175/1520-0493(2004)132<2021:DLRPMO>2.0.CO;2 Google Scholar
- Murakami T, Matsumoto J (1994) Summer monsoon over the Asian continent and western North Pacific. J Meteor Soc Japan 72:719–745. https://doi.org/10.2151/jmsj1965.72.5_719
- Murata F, Yamanaka MD, Fujiwara M, Ogino SY, Hashiguchi H, Fukao S, Kudsy M, Sribimawati T, Harijono SWB, Kelana E (2002) Relationship between wind and precipitation observed with a UHF radar, GPS rawinsonde and surface meteorological instruments at Kototabang, West Sumatera during September−October 1998. J Meteor Soc Japan 80:347–360. https://doi.org/10.2151/jmsj.80.347 Google Scholar
- Nakazawa T (1988) Tropical super clusters within intraseasonal variations over the western Pacific. J Meteor Soc Japan 66:823–839. https://doi.org/10.2151/jmsj1965.66.6_823
- Neale R, Slingo J (2003) The maritime continent and its role in the global climate: a GCM study. J Clim 16:834–848. https://doi.org/10.1175/1520-0442(2003)016<0834:TMCAIR>2.0.CO;2 Google Scholar
- Neelin JD, Held IM, Cook KH (1987) Evaporation-wind feedback and low-frequency variability in the tropical atmosphere. J Atmos Sci 44:2341–2348. https://doi.org/10.1175/1520-0469(1987)044<2341:EWFALF>2.0.CO;2 Google Scholar
- Niino H (1987) The linear theory of sea−land breeze circulation. J Meteor Soc Japan 65:901–921. https://doi.org/10.2151/jmsj1965.65.6_901
- Nitta TS, Mizuno T, Takahashi K (1992) Multi-scale convective systems during the initial phase of the 1986/87 El Niño. J Meteor Soc Japan 70:447–466. https://doi.org/10.2151/jmsj1965.70.1B_447
- Nitta TS, Sekine S (1994) Diurnal variation of convective activity over the tropical western Pacific. J Meteor Soc Japan 72:627–641. https://doi.org/10.2151/jmsj1965.72.5_627
- Ogino SY, Yamanaka MD, Fukao S (1995) Meridional variation of lower stratospheric gravity wave activity: a quick look at Hakuho-Maru J−COARE cruise rawinsonde data. J Meteor Soc Japan 73:407–413. https://doi.org/10.2151/jmsj1965.73.2B_407
- Ogura Y, Yoshizaki M (1988) Numerical study of orographic−convective precipitation over the eastern Arabian Sea and the Ghat Mountains during the summer monsoon. J Atmos Sci 45:2097–2122. https://doi.org/10.1175/1520-0469(1988)045<2097:NSOOCP>2.0.CO;2 Google Scholar
- Ooyama K (1971) A theory on parameterization of cumulus convection. J Meteor Soc Japan 49A:744–756. https://doi.org/10.2151/jmsj1965.49A.0_744
- Parrish JT (1993) Climate of the supercontinent Pangea. J Geol 101:215–233. http://www.jstor.org/stable/30081148. Accessed 20 Feb 2018
- Ramage CS (1968) Role of a tropical “maritime continent” in the atmospheric circulation. Mon Wea Rev 96:365–369. https://doi.org/10.1175/1520-0493(1968)096<0365:ROATMC>2.0.CO;2 Google Scholar
- Randall DA, Wood RA, Bony S, Colman R, Fichefet T, Fyfe J, Kattsov V, Pitman A, Shukla J, Srinivasan J, Stouffer RJ, Sumi A, Taylor KE (2007) Climate models and their evaluation. Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL, Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Chapter 8. p. 589–662. https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8.html. Accessed 20 Feb 2018
- Reid JS, Xian P, Holben BN, Hyer EJ, Reid EA, Salinas SV, Zhang J, Campbell JR, Chew BN, Holz RE, Kuciauskas AP, Lagrosas N, Posselt DJ, Sampson CR, Walker AL, Welton EJ, Zhang C (2016) Aerosol meteorology of the maritime continent for the 2012 7SEAS southwest monsoon intensive study, part 1: regional-scale phenomena. Atmos Chem Phys 16:14041–14056. https://doi.org/10.5194/acp-16-14041-2016 Google Scholar
- Renggono F, Hashiguchi H, Fukao S, Yamanaka MD, Ogino SY, Okamoto N, Murata F, Sitorus BP, Kudsy M, Kartasasmita M, Ibrahim G (2001) Precipitating clouds observed by 1.3-GHz boundary layer radars in equatorial Indonesia. Ann Geophys 19:889–897. https://doi.org/10.5194/angeo-19-889-2001 Google Scholar
- Rotunno R (1983) On the linear theory of the land and sea breeze. J Atmos Sci 40:1999–2009. https://doi.org/10.1175/1520-0469(1983)040<1999:OTLTOT>2.0.CO;2 Google Scholar
- Sakurai N, Kawashima M, Fujiyoshi Y, Hashiguchi H, Shimomai T, Mori S, Hamada JI, Murata F, Yamanaka MD, Tauhid YI, Sribimawati T, Suhardi B (2009) Internal structures of migratory cloud systems with diurnal cycle over Sumatera Island during CPEA−I campaign. J Meteor Soc Japan 87:157–170. https://doi.org/10.2151/jmsj.87.157 Google Scholar
- Sakurai N, Mori S, Kawashima M, Fujiyoshi Y, Hamada JI, Shimizu S, Fudeyasu H, Tabata Y, Harjupa W, Hashiguchi H, Yamanaka MD, Matsumoto J, Emrizal, Syamsudin F (2011) Migration process and 3D wind field of precipitation systems associated with a diurnal cycle in west Sumatera: dual Doppler radar analysis during the HARIMAU2006 campaign. J Meteor Soc Japan 89:341–361. https://doi.org/10.2151/jmsj.2011-404 Google Scholar
- Seto TH, Tabata Y, Yamamoto MK, Hashiguchi H, Mega T, Kudsy M, Yamanaka MD, Fukao S (2009) Comparison study of lower-tropospheric horizontal wind over Sumatera, Indonesia using NCEP/NCAR reanalysis, operational radiosonde, and the equatorial atmosphere radar. SOLA 5:21–24. https://doi.org/10.2151/sola.2009-006 Google Scholar
- Shibagaki Y, Shimomai T, Kozu T, Mori S, Fujiyoshi Y, Hashiguchi H, Yamamoto MK, Fukao S, Yamanaka MD (2006) Multi-scale convective systems associated with an intraseasonal oscillation over the Indonesian maritime continent. Mon Wea Rev 134:1682–1696. https://doi.org/10.1175/MWR3152.1 Google Scholar
- Simpson RH (1947) Synoptic aspects of the intertropical convergence near Central and South America. Bull Amer Meteor Soc 28:335–346. http://www.jstor.org/stable/26257787. Accessed 20 Feb 2018
- Slingo J, Belcher S, Scaife A, McCarthy M, Saulter A, McBeath K, Jenkins A, Huntingford C, Marsh T, Hannaford J, Parry S (2014) The recent storms and floods in the UK. UK Met Office, p 27. http://nora.nerc.ac.uk/505192/. Accessed 20 Feb 2018
- Sorooshian S, Gao X, Hsu K, Maddox RA, Hong Y, Gupta HV, Imam B (2002) Diurnal variability of tropical rainfall retrieved from combined GOES and TRMM satellite information. J Clim 15:983–1001. https://doi.org/10.1175/1520-0442(2002)015<0983:DVOTRR>2.0.CO;2 Google Scholar
- Stull RB (1988) An introduction to boundary layer meteorology. Kluwer Academic, DordrechtGoogle Scholar
- Sui CH, Lau KM, Takayabu YN, Short DA (1997) Diurnal variations in tropical oceanic cumulus convection during TOGA COARE. J Atmos Sci 54:639–655. https://doi.org/10.1175/1520-0469(1997)054<0639:DVITOC>2.0.CO;2 Google Scholar
- Supari, Tangang F, Juneng L, Aldrian E (2016) Observed changes in extreme temperature and precipitation over Indonesia. Int J Climatol 37:1979–97. https://doi.org/10.1002/joc.4829
- Suwarman R, Ichiyanagi K, Tanoue M, Yoshimura K, Mori S, Yamanaka MD, Kurita N, Belgaman HA, Syamsudin F (2017) El Niño southern oscillation signature in atmospheric water stable isotopes over maritime continent during wet season. J Meteor Soc Japan 95:49–66. https://doi.org/10.2151/jmsj.2017-003
- Tabata Y, Hashiguchi H, Yamamoto MK, Yamamoto M, Yamanaka MD, Mori S, Syamsudin F, Manik T (2011a) Lower tropospheric horizontal wind over Indonesia: a comparison of wind-profiler network observations with global reanalyses. J Atmos Solar Terr Phys 73:986–995. https://doi.org/10.1016/j.jastp.2010.09.016 Google Scholar
- Tabata Y, Hashiguchi H, Yamamoto MK, Yamamoto M, Yamanaka MD, Mori S, Syamsudin F, Manik T (2011b) Observational study on diurnal precipitation cycle in equatorial Indonesia using 1.3-GHz wind profiling radar network and TRMM precipitation radar. J Atmos Solar Terr Phys 73:1031–1042. https://doi.org/10.1016/j.jastp.2010.10.003 Google Scholar
- Tsuda T, Fukao S, Yamamoto M, Nakamura T, Yamanaka MD, Adachi T, Hashiguchi H, Fujioka N, Tsutsumi M, Kato S, Harijono SWB, Sribimawati T, Sitorus BP, Yahya RB, Karmini M, Renggono F, Parapat BL, Djojonegoro W, Mardio P, Adikusumah N, Endi HT, Wiryosumarto H (1995) A preliminary report on observations of equatorial atmosphere dynamics in Indonesia with radars and radiosondes. J Meteor Soc Japan 73:393–406. https://doi.org/10.2151/jmsj1965.73.2B_393 Google Scholar
- van Bemmelen W (1922) Land- und seebrise in Batavia. Beitr Phys Frei Atmos 10:169–177Google Scholar
- Wallace AR (1869) The Malay archipelago: the land of the orang-Utan, and the bird of paradise, A narrative of travel, with studies of man and nature, vol 1. Macmillan and Co. http://darwin-online.org.uk/converted/Ancillary/1869_MalayArchipelago_A1013.1/1869_MalayArchipelago_A1013.1.1.html. Accessed 20 Feb 2018
- Wallace JM, Hobbs PV (2006) Atmospheric science: an introductory survey, 2nd edn. Academic Press, San Diego. https://www.sciencedirect.com/science/book/9780127329512. Accessed 20 Feb 2018
- Wang B (2012) Theories. Lau WKM, Waliser DE, Intraseasonal variability in the Atmosphere–Ocean climate system, 2nd edn, Springer-Verlag: 335–398. doi: https://doi.org/10.1007/978-3-642-13914-7_10
- Wegener A (1929) Die Entstehung der Kontinente und Ozeane, Verte umgearbeitete Auflage. https://archive.org/details/Entstehung1929. Accessed 20 Feb 2018. [Translated by Biram J (1966) The Origin of Continents and Oceans, 4th Ed.]
- Wheeler MC, Hendon HH (2004) An all-season real-time multivariate MJO index: development of an index for monitoring and prediction. Mon Wea Rev 132:1917–1932. https://doi.org/10.1175/1520-0493(2004)132<1917:AARMMI>2.0.CO;2 Google Scholar
- Widiyatmi I, Hashiguchi H, Fukao S, Yamanaka MD, Ogino SY, Gage KS, Harijono SWB, Diharto S, Djojodihardjo H (2001) Examination of 3−6 day disturbances over equatorial Indonesia based on boundary layer radar observations during 1996−1999 at Serpong, Biak and Bukittinggi. J Meteor Soc Japan 79:317–331. https://doi.org/10.2151/jmsj.79.317 Google Scholar
- Wu PM, Hamada JI, Mori S, Tauhid YI, Yamanaka MD, Kimura F (2003) Diurnal variation of precipitable water over a mountainous area in Sumatera Island. J Appl Meteorol 42:1107–1115. https://doi.org/10.1175/1520-0450(2003)042<1107:DVOPWO>2.0.CO;2 Google Scholar
- Xie P, Arkin PA (1997) Global precipitation: a 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull Amer Meteor Soc 78:2539–2558. https://doi.org/10.1175/1520-0477(1997)078<2539:GPAYMA>2.0.CO;2 Google Scholar
- Yamanaka MD, Mori S, Syamsudin F (2016) MAHASRI activities related to the Indonesian maritime continent. GEWEX NEWS 26(4):18–22. http://www.gewex.org/gewex-content/files_mf/1480533350Nov2016_final_opt.pdf. Accessed 20 Feb 2018
- Yamanaka MD, Mori S, Wu PM, Hamada JI, Sakurai N, Hashiguchi H, Yamamoto MK, Shibagaki Y, Kawashima M, Fujiyoshi Y, Shimomai T, Manik T, Erlansyah, Setiawan W, Tejasukmana B, Syamsudin F, Djajadihardia YS, Anggadiredja JT (2008) HARIMAU radar−profiler network over Indonesian maritime continent: a GEOSS early achievement for hydrological cycle and disaster prevention. J Disaster Res 3:78–88. https://doi.org/10.20965/jdr.2008.p0078 Google Scholar
- Yang GY, Slingo J (2001) The diurnal cycle in the tropics. Mon Wea Rev 129:784–801. https://doi.org/10.1175/1520-0493(2001)129<0784:TDCITT>2.0.CO;2 Google Scholar
- Yang L, Wang DX, Huang J, Wang X, Zeng L, Shi R, He Y, Xie Q, Wang SG, Chen R, Jinnan Yuan J, Wang Q, Chen J, Zu T, Li J, Sui D, Peng S (2015) Toward a mesoscale hydrological and marine meteorological observation network in the South China Sea. Bull Amer Meteor Soc 96:1117–1135. https://doi.org/10.1175/BAMS-D-14-00159.1 Google Scholar
- Yokoi S, Mori S, Katsumata M, Geng B, Yasunaga K, Syamsudin F, Nurhayati, Yoneyama K (2017) Diurnal cycle of precipitation observed in the western coastal area of Sumatra Island: offshore preconditioning by gravity waves. Mon Wea Rev 145:3745–3761. https://doi.org/10.1175/MWR-D-16-0468.1 Google Scholar
- Yoneyama K, Masumoto Y, Kuroda Y, Katsumata M, Mizuno K, Takayabu YN, Yoshizaki M, Shareef A, Fujiyoshi Y, McPhaden MJ, Murty VSN, Shirooka R, Yasunaga K, Yamada H, Sato N, Ushiyama T, Moteki Q, Seiki A, Fujita M, Ando K, Hase H, Ueki I, Horii T, Yokoyama C, Miyakawa T (2008) MISMO field experiment in the equatorial Indian Ocean. Bull Amer Meteor Soc 89:1889–1903. https://doi.org/10.1175/2008BAMS2519.1 Google Scholar
- Yoshida Y, Maruyama K, Tsutsui J, Nakashiki N, Bryan FO, Blackmon M, Boville BA, Smith RD (2005) Multi-century ensemble global warming projections using the Community Climate System Model (CCSM3). J Earth Simulator 3:2–10. http://www.jamstec.go.jp/esc/publication/journal/jes_vol.3/pdf/JES3-21yoshida.pdf. Accessed 20 Feb 2018Google Scholar
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