Modelling photosynthetically active radiation in Belarus

Abstract

This research considers indirect methods for modelling values of photosynthetically active radiation (PAR) from shortwave radiation data in theRepublic of Belarus. The authors performed calculation and modelling in three models. Model 1 (the Ross and Tooming formula) is a universal one and does not take into account the area latitude. The PAR coefficient (qf) here is 52 % of the shortwave radiation. Models 2 and 3 were proposed by theMeteorological Observatory of Moscow State University and applied to the territory of Belarus. One of them was adjusted for Belarus area particularly. The results of calculation by model 2 show that the PAR coefficient (qf) for Belarus is 46–47 % of the shortwave radiation at different times of the year. Thus, PAR ranges from 1500 MJ/m2to 1600 MJ/m2around Belarus in the vegetation period. The PAR values calculated in the third model range from 1540 MJ/m2in Vitebsk and Braslav to 1630 MJ/m2in the area of the Polesskaya station. In central Belarus, PAR is 1560–1580 MJ/m2. Thecomparison analysis of the modelling results with each other and the results of similar research in the neighboring countriesshows advantages and drawbacks of the models under consideration. The calculation resultsare visualized on the maps created by the authors to show the distribution ofphotosynthetically active radiation over the territory of Belarus. The spatial distribution of PAR across the territory of Belarus goes in the direction from northwest to southeast.