Analysis of the net radiation on paddy fields in red earth hilly region of China

This study was conducted in Qianyanzhou Experiment Station of the Chinese Academy of Sciences,which is located in typical red earth hilly region of south China.The net radiation and the global solar radiation on the paddy fields and the meteorological observation site in the station have been respectively measured every one hour by using the automatic meteorological observing system.The results show that both the net radiation and the global radiation for the paddy fields reach the peak point at 11:00～13:00 in local time normally,and pass the zero point separately at the time of about one hour behind sunrise and ahead of sundown,and that the global radiation is zero during night,and the net radiation varies between 0～-100W/m².It is evident from the data analysis that there exist obvious linear correlation between the net radiation and the total radiation on the paddy fields and the meteorological observation site.Accordingly we can employ the global radiation and the net radiation of the meteorological station for simulating the corresponding data of the paddy fields.And it was also found that there was an obvious annual variation for the net radiation on the paddy fields and the meteorological observation site.The variation is in keeping with the annual change of solar radiation,the maximum value emerges in July,the minimum in December at the paddy fields and in January at the meteorological observation site ,and the net radiation is positive value at both the two test sites.