Studies on water balance in the northern area of Okinawa Island

利用红外成像仪对冲绳岛北部地区的地表温度进行了3个季节的观测，第一个季节是1999年2月7日（冬季），第二个季节是1999年7月13日（夏季），最后一个季节是1999年12月10日。未校正的地表温度实测面积平均值分别为18.0、30.4和19.5℃，变化范围分别为6.3、8.3和7.6℃。由于空气透过率和飞机下面的地球表面覆盖物的发射率的影响，上述未校正值应作3至4度的修正。以1997年的水平衡为例，同一北部地区的年平均降雨量和蒸散量分别为2220mm和1070mm，导致水量约占降雨量的50%。

Measurements of the surface temperature of the northern area of Okinawa Island was made with the air borne INFRA IMAGER observation in three seasons, the first on 7 Feb.(Winter), on the second 13 July(Summer) and the last on 10 Dec., 1999. The area averaged uncorrected measured values of the earth surface temperature are 18.0, 30.4 and 19.5 and changes in the range of 6.3, 8.3 and 7.6 degree in centigrade, respectively.Correction that should be made to the above uncorrected values due to the effects of the air transmissivity and the emissivity of the earth surface coverint substances underlying the aircraft is found to be an addition of 3 to 4 degree.Water balance for an example case of 1997 showed for the same northern area showed that the averaged annual rainfall and evapotranspiration amount, respectively, to 2220mm and 1070mm, resulting in the discharge of water being about 50% of the rainfall.