Development of a Database of Gridded Daily Temperatures for Southern Africa
Report No 1156/2/04

Dec 2004



Temperature is a basic climatological parameter used frequently as an index of the energy status of the environment.

Because temperature measurement is a simple procedure and because long term temperature data are relatively abundant, it is not surprising that temperature parameters have been used as input variables in a wide range of climatological, hydrological and agricultural applications, from the estimation of solar radiation, relative humidity or potential evaporation to the concepts of heat and chill units or the delimitation of frost zones and agroclimatically optimum growth areas of crops.

In light of its importance, as highlighted above, temperature was selected as the one multiple-use hydroclimatic variable, other than rainfall, for detailed study in the Water Research Commission (WRC) Project K5/1156 titled

“Development of a Revised Spatial Database of Annual, Monthly and Daily Rainfall and Other Hydroclimatic Variables for South Africa”.

More specifically, this temperature related component of Project K5/1156, which is reported separately from the rainfall component, sought to

In order to achieve these two objectives

The specific objectives of this study relate clearly to daily temperature estimates. Why?

In a previous publication by the senior author (the “South African Atlas of Agrohydrology and -Climatology”, WRC 1997), long term monthly means of temperature parameters were used in developing equations for computations of solar radiation, relative humidity, potential evaporation and crop yields. However, neither inter-annual nor intra-seasonal variabilities, nor probabilities of occurrence could be computed, neither could any trends over time be evaluated, because only long term monthly means were used as forcing functions. The generation of daily temperature time series at any location in southern Africa would, however, facilitate computation of all these higher order statistics.