Browsing by Autor "Nurmohamed, Riad"

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Development of scenarios for future climate change in Suriname
(RevActaNova., 2006) Nurmohamed, Riad; Naipal, Sieuwnath
This paper describes one way of developing climate change scenarios for temperature and precipitation, using results of five atmospheric-ocean global circulation models (AO-GCMs). The scenarios are developed using the MAGICC/SCENGEN model and the GCMs, having a spatial resolution of 0.5° x 0.5° longitude/latitude. Four global emission scenarios, SRES A1, A2, B1, B2, and three time horizons, year 2020, 2050 and 2080, are used. The results shows that there is a relative high correlation (0.66 to 0.86) between the monthly observed temperature data and the modeled baseline data by the GCMs, while weak correlation (0.02 to 0.47) is found between the monthly observed precipitation and modeled baseline data by the CSI296, GFDL90 and ECH498 model, and a relative high correlation (0.66 to 0.85) by the HAD300 and CCSR96 model. Most of the GCMs follow the seasonal pattern of the temperature and precipitation in Suriname well. The model outputs show that for both temperature and precipitation, the A1, B1 and B2 scenarios give similar results, which differ significantly from the A2 scenario. The climate change scenarios for Suriname lead to an annual increase in mean temperature up to 2.9°C in 2080 for SRES A2, and 2.6°C for SRES A1, B1, B2, reference to 1961-1990. For the annual precipitation, an increase is expected up to 342.3 mm (16%) in 2080 for SRES A2 and a decrease in annual precipitation up to 102.6 mm (5%) in 2080 for SRES A1, B1, B2, reference to 1981-2000. The outputs of the SRES A1, B1, B2 indicate an increase in mean precipitation up till 2080 during January and April, and a decrease in mean precipitation during May and December. The SRES A2 output indicates however an increase in mean precipitation from December till March, and from July till October, and a decrease from April till June, and in November. The future increase in mean temperature will lead to an increase in evaporation/evapotranspiration and correspondingly changes in future precipitation. Wet and dry seasons in Suriname will be affected, resulting in an overall increase or decrease of water resources. There is therefore a need to develop high resolution scenarios (scale of about 25-50 km), using regional climate models (RCMs) in order to assess the impact of climate change on smaller scales.
Rainfall variability in Suriname and its relationship with the Tropical Pacific ENSO SST anomalies and the Atlantic SST anomalies
(RevActaNova., 2006) Nurmohamed, Riad; Naipal, Sieuwnath; Becker, Cor
Spatial correlations (r) in the annual rainfall anomalies are analyzed using principle component analyses (PCA). Cross correlation analysis and composites are used to measure the influence of sea surface temperatures anomalies (SSTAs) in the tropical Atlantic and tropical Pacific Ocean with the seasonal rainfall in Suriname. It is shown that the spatial and time variability in rainfall is mainly determined by the meridional movement of the Inter-tropical Convergence Zone (ITCZ). It occurs that the rainfall anomalies are fairly uniformly over the whole country. The strongest correlation between the December-January rainfall (short wet season) at station Cultuurtuin is found with the SSTAs in the Pacific region and is about c k Nino 1+2 = 0.59 at lag 1 month. In March-May rainfall (beginning long wet season) there is a lagged correlation with the SSTAs in the Pacific region (c lag 3 Nino 1+2 = 0.59). The June-August rainfall (end part of long wet season) shows the highest correlation with SSTAs in the TSA region and is about c = -0.52 for lag 0. In the September-November long dry season there is also a lagged correlation with the TSA SSTAs of about c lag 3 = 0.66. The different correlations and predictors can be used for seasonal rainfall predictions.