2.2.1 Development of database
A spatial database consisting of data for the last 15 years (1998 and onward) for various
variables responsible for change in crop yield was developed. These include district wise crop
statistics, agro meteorological data for 36 stations covering min/max temperature, rainfall and
relative humidity. The sunshine duration data was available for 8 stations. The sunshine duration
data deemed to be very useful above all in the crop yield forecast as the radiation is an important
limiting factor of crop production after soil moisture availability. Daily maximum and minimum
temperatures were applied in the Hargreaves formula to fill the gaps in the calculated global
radiation time-series. The minimum and maximum temperature was applied through the
Hargreaves formula to complete the days with missing data. Hargreaves formula estimates the
global radiation on the basis of daily temperature range using the maximum (Tmax) and
minimum (Tmin) temperatures:
Where Hargreaves coefficient kRS which is between 0.16 (inland stations far from the sea) and
0.19 for stations at the sea-side. The (Tmax - Tmin) difference is the daily temperature
amplitude