THE CHARACTERISTICS OF RADIATION CLIMATE OF SANJIANG PLAIN
Liu Xingtu (Changchun Institute of Geography,Academia Sinica)
Sanjiang Plain is an important base of commodity grains and the largest swamp region in China. This paper established the equations of total radiation and of the equation of ground albedo in winter based on solar rediation data and sunshine data in Jiamusi from 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,the astronomical 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 of total radiation,effective radiation and net radiation for 19 stations of sanjiang Plain.Some characteristics have been discussed with regard to the distribution in time and space of total radiation,effective radiation and net radiation. The results indicate that the Sanjiang Plain is rich in solar radiation resour- ces.The total annual amount of global radiation is 99-112 kcal./cm~2 and that of radiation balance,33-42.5 kcal./cm~2.In respect to the spatial distribution from southwest to northeast,the total radiation and net radiation have a decreasing tendency.In respect to the annual variation,the monthly values of total radiation and 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 and swampy-meadow,it can be seen that in regions with smaller R/Lr values there are larger area of swamp and swampy meadow;and in those with larger R/Lr values,there are less area of swamp and swampy meadow. Comparing the R/Lr and other moisture index,it is considered that the climate of the west part of this region belongs to semi-moist climate. On the basis of studies of the characteristics of radiation climate in Sanjiang Plain,the photosynthesis potential has been computed.This region should bring the superiority of radiation resources and photo-synthesis potential into full play, a modernized base of agriculture should be established.