Abstract: Sanjiang Plain is an important base of commodity grains and the largestswamp region in China.This paper established the equations of total radiation and of the equation ofground albedo in winter based on solar rediation data and sunshine data in Jiamusifrom 1961 to 1979. The deduced equations for total radiation are:Spring (Mar.—Apr.) Q=Q_A(0.23+0.472S)Summer (Tune—Aug.) Q=Q_A(0.125+0.625S)Autumn (Sept.—Oct.) Q=Q_A(0.155+0.556S)Winter (Nov.—Mar.) Q=Q_A(0.232+0.52S)Where all the terms are on monthly basis;Q,the total radiation;Q_A,theastronomical radiation;S,the relative sunshine.The correlation coefficient for linear equations are 0.62,0.81,0.80,0.62.The equation for ground albedo is:
A=0.196+0.272D (in winter)
Where D,days of snow cover.The correlation coefficient between A and D is 0.81.This paper has computed and analyzed the annual and the monthly values oftotal radiation,effective radiation and net radiation for 19 stations of sanjiangPlain.Some characteristics have been discussed with regard to the distribution intime and space of total radiation,effective radiation and net radiation.The results indicate that the Sanjiang Plain is rich in solar radiation resources.The total annual amount of global radiation is 99-112 kcal./cm² and that ofradiation balance,33-42.5 kcal./cm².In respect to the spatial distribution fromsouthwest to northeast,the total radiation and net radiation have a decreasingtendency.In respect to the annual variation,the monthly values of total radiationand net radiation are the smallest in December and the largest in June.All va-lues of net radiation from February to October stand positive;that from Novem-ber to January negative.Comparing the values of R/Lr and the distribution area of swamp andswampy-meadow,it can be seen that in regions with smaller R/Lr values thereare larger area of swamp and swampy meadow;and in those with larger R/Lrvalues,there are less area of swamp and swampy meadow.Comparing the R/Lr and other moisture index,it is considered that theclimate of the west part of this region belongs to semi-moist climate.On the basis of studies of the characteristics of radiation climate in SanjiangPlain,the photosynthesis potential has been computed.This region should bringthe superiority of radiation resources and photo-synthesis potential into full play,a modernized base of agriculture should be established.