Assessment of the temperature regime in Agro Ecological Regions of Sri Lanka

Sri Lanka exemplifies a variety of climatic conditions depending on the geographical settings of respective locations. Considering the high heterogeneity of climatic factors, different soil types, terrain, vegetation and land use of the island, Sri Lanka has been delineated in to 46 Agro Ecological Regions (AERs). In the absence of adequate spatial coverage of temperature data to assess the temperature regime of different geographical settings of the country in delineating aforesaid AERs, elevation differences have been taken in to account to capture the spatial variation of temperature as a proxy parameter to identify different AERs. However, it has been observed that there are significant differences exist in temperature regime among different AERs of the country which have not quantified yet due to lack of meteorological observatories representing each AER. It has led to limit the use of the AER map, especially in recommending crops where temperature regime should also be taken in to account. Thus, a study was undertaken to assess the temperature regime of all 46 AERs of Sri Lanka using available daily minimum and maximum temperature data covering 23 AERs. Using spatial interpolation technique of Geographic Information System (GIS), the maximum and minimum temperature values were interpolated for the rest of AERs. There is an apparent increasing trend of all temperature parameters from Wet zone to Dry zone while decreasing trend with increasing altitude as expected. However, there was hardly any discernible trend in temperature parameters with respect to expected quantum of rainfall in each AER. These values can be used for agricultural and other weather related decision making and research purposes with a least margin of error in the absence of point data of temperature for each AER.