Meteorological observations and penman estimates along a 17-km transect in the Sudan Gezira

Abstract

Daily measurements of maximum and minimum temperature, wind velocity, and vapour pressure were made at windward and leeward edges of selected cotton fields, interspersed amongst uncropped fields, in the Sudan Gezira. Mean temperature, vapour pressure deficit and wind run were lower at the leeward than windward edges of the cotton. At comparable windward sites, wind run per day and mean daily temperature decreased as the downwind distance from the most windward edge of the 17-km transect increased. Values of evaporation, calculated by the Penman formula from meteorological data at various sites, were reduced by the presence of upwind stretches of cotton. Negative Bowen ratios indicated that advective conditions existed.