春季晴天与阴天草原辐射和能量平衡特征的一次对比观测

Surface Heat and Radiation Budget over Semi-arid Grassland in a Clear Day and a Cloudy Day during Early Spring

利用2008年3月锡林浩特国家气候观象台通量观测系统获取的资料,对草原初春晴天和阴天地表能量和辐射平衡特征进行了对比。结果显示,初春典型晴天总辐射、反射辐射、向下和向上长波辐射的最大值分别为801W·m-2、203W·m-2、197W·m-2和390W·m-2;阴天总辐射与反射辐射明显减弱,峰值分别为595W·m-2、147W·m-2,向下、向上长波辐射最大值分别为290W·m-2和182W·m-2。晴天感热、潜热、土壤热通量和净辐射的日积分值分别是6.58MJ·m-2·d-1、1.05MJ·m-2·d-1、-0.25MJ·m-2·d-1和5.89MJ·m-2·d-1,阴天感热、潜热、土壤热通量和净辐射的日积分值分别是1.15MJ·m-2·d-1、0.49MJ·m-2·d-1、-0.08MJ·m-2·d-1和1.65MJ·m-2·d-1。典型晴天地表反照率早晚大,中午最小,最小值为0.26;而阴天受云的影响,最小值仅为0.22,且日变化不明显。

By using the micrometeorology data observed at Xilingol grassland on 12—13 March,2008,the characteristics of diurnal variations（in a clear day and a cloudy day）of surface radiation budget,heat budget and albedo over this semi-arid grassland were researched.On the clear day,the maximal value of total radiation,up-ward short radiation,down-ward long radiation and up-ward long radiation was 801 W·m-2,203 W·m-2,197 W·m-2and 390 W·m-2,respectively.On the cloudy day it was 595 W·m-2,147 W·m-2,290 W·m-2and182 W·m-2,respectively.As for the sensible heat fluxes,potential heat flux,soil heat flux and net radiation,the value was 6.58 MJ·m-2 ·d-1,1.05 MJ·m-2·d-1,-0.25 MJ·m-2·d-1 and 5.89 MJ·m-2·d-1 respectively on a clear day,but only 1.15 MJ·m-2·d-1,0.49 MJ·m-2·d-1,-0.08 MJ·m-2·d-1and 1.65 MJ·m-2·d-1 respectively on a cloudy day.In the diurnal curves,the albedo in the morning and afternoon is larger than that at noon on the clear day and the minimal value is 0.23;there is not obvious diurnal fluctuations on the cloudy day and the minimal value is 0.22.