Moisture and heat budgets of the south American monsoon system: climatological aspects
The climatology of the moisture and heat budget equation terms for subareas within the South American Monsoon System (SAMS) region is investigated for the 1958–2014 period considering the distinct phases of the Pacific Decadal Oscillation (PDO). These budget equations are applied to the data from the National Centers for Environmental Prediction (NCEP) Reanalysis project. Sources or sinks of moisture and heat are equation residues, referred to as residue and diabatic terms, respectively. Analyses are done for the Central Amazon Basin (CAM) and Western-Central Brazil (WCB) for three distinct periods, 1958–1976, 1977–1995, and 1996–2014, that correspond to the cold, warm, and undefined PDO phases. The differences among the PDO phases for each term are discussed. The CAM region acts dominantly as a moisture sink and heat source in all months during the three phases. On the other hand, in the WCB region, the monsoon characteristics are better defined, with a moisture sink (source) and a heat source (sink) during the wet (dry) season. The main result of the present analysis is the persistence of SAMS intensification signs in both CAM and WCB areas up to the last analyzed period (1996–2014), which is consistent with intense flooding in the Amazon Basin in 2008/2009, 2012, and 2014.
KeywordsPacific Decadal Oscillation Heat Budget South Atlantic Convergence Zone Adiabatic Expansion Pacific Decadal Oscillation Index
The authors were partial supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 472337/2010–6; CNPq 305529/2012-9; CNPq 302679/2013-8).
- Grimm AM, Vera CS, Mechoso CR (2005) The South American monsoon system. In: Chang C-P, Wang B and Lau N-C G (ed) The global monsoon system: research and forecast, WMO/TD n. 1266 – TMRP Report 70: p 219–238Google Scholar
- Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, White G, Woollen J, Zhu Y, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Leetmaa A, Reynolds R, Jenne R, Joseph D (1996) The NCEP/NCAR reanalysis project. Bull Am Meteorol Soc 77:437–471CrossRefGoogle Scholar
- Kousky VE (1988) Pentad outgoing longwave radiation climatology for the South American sector. Rev Bras Meteor 3:217–231Google Scholar
- Newell RE, Kidson JW, Vincent DJ, Boer GJ (1974) The general circulation of the tropical atmosphere. MIT Press, BostonGoogle Scholar
- Nogués-Paegle J, Mechoso CR, Fu R, Berbery EH, Chao WC, Chen T-C, Cook K, Diaz AFG, Enfield D, Ferreira R, Grimm AM, Kousky V, Liebmann B, Marengo J, Mo K, Neelin JD, Paegle J, Robertson AW, Seth A, Vera CS, Zhou J (2002) Progress in Pan American CLIVAR research: understanding the south American monsoon. Meteorologica 27:1–30Google Scholar
- Riehl H (1954) Tropical meteorology. McGraw-Hill, New York, 392Google Scholar