Trends in Intra- and Inter-Annual Temperature Variabilities Across Sudan
- 149 Downloads
Four mean temperature variables, namely maximum (MAX), minimum (MIN), mean (MEAN) and diurnal temperature range (DTR), were considered for 14 selected observational stations throughout Sudan. The objectives were to investigate the seasonal and annual regimes, the seasonal and annual trends, the intra-annual variability (IAV) by the coefficient of variation (CV), and the inter-relationships between the temperature variables and percent of possible sunshine. A mounting evidence of daytime and nighttime warming since the 1940s until 2005 is presented. The exception is the dry season which is dominated by daytime cooling attributable to the damping effect of dust haze/storms. Apparently, the progressive drought across inland locations has raised the MAXs, and to a lesser extent the MINs, of the wet season over those for the hot season. Accordingly, maximum rates of 0.451 and 0.336°C decade−1 were found for the nighttime and daytime temperatures, respectively. The extreme eastern and western locations have been frequently dominated by the warmest trend rates obtained nationwide. The prevalence of significant decreases (increases) of DTR is more apparent in the dry, hot and annual series (wet series). Depending on the temperature variable under consideration, many stations possessed significant trends toward either increased or decreased variability of the within-year monthly values, i.e. IAV. The correlation between the time series of annual CV and extreme values for each of the four temperature variables shows generally that warmer climate in Sudan is associated with higher intra-annual temperature variability and vise versa, i.e. the CV is directly correlated with the highest value within the year, but inversely correlated with the lowest one. The findings of this investigation also indicate that the DTR is directly related to percent of possible sunshine, but the relationship of the latter parameter is not so clear with MAX, MIN and MEAN.
KeywordsTemperature variables Climate variability Climate change Sunshine Sudan
I am grateful for the very helpful review of the manuscript. Special thanks go to Dr. Muna Elhag for her assistance in the preparation of Fig. 7.
- Aguilar, E., A.A. Barry, M. Brunet, L. Ekang, A. Fernandes, M. Massoukina, J. Mbah, A. Mhanda, D.J. do Nascimento, T.C. Peterson, O.T. Umba, M. Tomou, and X. Zhang. 2009. Changes in temperature and precipitation extremes in western central Africa, Guinea Conakry, and Zimbabwea, 1955–2006. Journal of Geophysical Research 114: D02115. doi: 10.1029/2008JD011010.CrossRefGoogle Scholar
- Elagib, N.A., A.S.A Abdu. 2009. Development of temperatures in the Kingdom of Bahrain from 1947 to 2005. Theoretical and Applied Climatology. doi: 10.1007/s00704-009-0205-y.
- Elagib, N.A., S.H. Alvi, and M.G. Mansell. 1999. Day-length and extraterrestrial radiation for Sudan: a comparative study. International Journal of Solar Energy 20(2): 93–109.Google Scholar
- Jones, P.D., and K.R. Briffa. 1992. Global surface air temperature variations during the twentieth century: part 1. Spatial, temporal and seasonal details. Holocene 2(2): 165–179.Google Scholar
- Kanji, G.K. 1997. 100 statistical tests. London: SAGE Publications.Google Scholar
- Karl, T.R., P.D. Jones, R.W. Knight, D. Kukla, N. Plummer, V. Razuvayev, K.P. Gallo, J. Lindseay, R.J. Charlson, and T.C. Peterson. 1993. A new perspective on recent global warming: asymmetric trends of daily maximum and minimum temperature. Bulletin of the American Meteorological Society 74(6): 1007–1023.CrossRefGoogle Scholar
- Kunkel, K. E., P.D. Bromirski, H.E. Brooks, T. Cavazos, A.V. Douglas, D.R. Easterling, K.A. Emanuel, P.Ya. Groisman, G.J. Holland, T.R. Knutson, J.P. Kossin, P.D. Komar, D.H. Levinson, R.L. Smith. 2008. Observed weather and climate extremes. In: Weather and climate extremes in a changing climate. Regions of focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands, eds. T.R. Karl, G.A. Meehl, C.D. Miller, S.J. Hassol, A.M. Waple, W.L. Murray. A report by the U.S. Climate Science Program and Subcommittee on Global Change Research, Washington, DC.Google Scholar
- Lockwood, J.G. 1998. Future trends in daytime and night-time temperatures. Weather 53(3): 72–78.Google Scholar
- New, M., B. Hewitson, D.B. Stephenson, A. Tsiga, A. Kruger, A. Manhique, B. Gomez, C.A.S. Coelho, D.N. Masisi, E. Kululanga, E. Mbambalala, F. Adesina, H. Saleh, J. Kanyanga, J. Adosi, L. Bulane, L. Fortunata, M.L. Mdoka, and R. Lajoie. 2006. Evidence of trends in daily climate extremes over Southern and West Africa. Journal of Geophysical Research 111: D14102. doi: 10.1029/2005JD006289.CrossRefGoogle Scholar
- Pal, I., and A. Al-Tabbaa. 2009. Long-term changes and variability of monthly extreme temperatures in India. Theoretical and Applied Climatology. doi: 10.1007/s00704-009-0167-0.
- Qureshi, S., and N. Khan. 1994. Estimation of climatic transition in Riyadh (Saudi Arabia) in global warming perspectives. GeoJournal 33(4): 423–432.Google Scholar
- Trenberth, K. E., P.D. Jones, P. Ambenge, R. Bojariu, D. Easterling, A. Klein Tank, D. Parker, F. Rahimzadeh, J.E. Renwick, M. Rusticucci, B. Soden, P. Zahi. 2007. Observations: surface and atmospheric climate change. In: Climate change 2007: the physical science basis, eds. S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, H.L. Miller. Contribution of Working Group I to the Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press.Google Scholar