Correlation between Temperatures and Solar Irradiation in Botswana: Bivariate Models

P.K. Jain, J. Prakash, and E.M. Lungu (Botswana)


Extremum temperatures, solar irradiation, correlation analysis, bivariate models, Botswana.


The Republic of Botswana in Southern Africa is a sunniest country with very little cloud cover, and the daily extremum temperatures appear to be very much related to solar irradiation. From the correlation analysis, the mean monthly maximum and minimum temperatures are found to be corelated to the mean monthly solar irradiation by a factor of 0.84 and 0.78 respectively. This paper presents bivariate models that corelate solar irradiation (as input) to extremum temperatures (as output) for Sebele, Botswana. Autocorrelation analysis revealed that there is a lag of three months between the peaks of the differenced series of solar irradiation and maximum temperatures, whereas the lag between the differenced series of solar irradiation and minimum temperatures is at most one month. Analysis of the noise component showed that the bivariate processes under consideration behaved either as ARIMA processes of order (0, 1, 1) × (0, 1, 1)12 or as MA processes of order (0, 1, 1)12. However, where non seasonal influences are present, i.e., in the case of model (0, 1, 1) × (0, 1, 1)12, these effects exhibit month to month memory only. We claim that the relationships found for Sebele can be applied to estimate extremum temperatures at other locations in the region, where similar climatic conditions prevail.

Important Links:

Go Back