根据SKYNET合肥站三年期间无云晴天4～50μm波段地表向上长波辐射R_lu和大气逆辐射R_ld的观测资料，定量分析了大气逆辐射对草地下垫面地表温度的影响。结果表明：大气逆辐射对地表温度日平均值的影响程度在夏季最大、秋季次之、冬季最小，当地表比辐射率ε=0．98时，地表视温度与地表温度日平均差值全年在0．96～1．41K之间，7、8月份在1．3K以上；任何季节，大气逆辐射对地表温度日分布的影响幅值均在夜间大、白天小、中午前后最小，冬季影响最为显著，地表视温度与地表温度的差值T_*－T_s均具有“V”型日分布特征；长波辐射比R_ld／R_lu越大，大气逆辐射对地表温度的影响程度越大，得出了T_*－T_s与长波辐射比以及地表比辐射率之间的定量统计关系。

The effect of downwelling atmospheric radiation(R_ld) on grass land surface temperature(T_s) is analyzed based on the three-year observations of upwelling surface long-wave radiation(R_lu) and R_ld in 4～50 μm band on clear days at SKYNET Hefei site. Results indicate that the effect of R_ld on mean daily T_s are stronger in summer than in fall and the weakest in winter. The mean daily difference between apparent surface. temperature T_* and T_s ranges from 0.96 K to 1.41 K through all year, with value larger than 1.3 K in July and August provided that land surface emissivity ε equals to 0.98. The effect of R_ld on diurnal variation of T_s is weakest at noon, greatest at night with the diurnal distribution of T_*－T_s showing“V”shape for each season and the effect is most remarkable in winter. The larger the ratio R_ld/R_lu, the greater the effect of R_ld on T_s and the quantitative statistical relationship between the ratio R_ld/R_lu, surface emissivity ε and T_*－T_s are obtained under different seasonal conditions.