两种高寒植被长波辐射的气候学特征及比较

摘要

地球边界层热量来源是地表吸收太阳短波辐射后再以长波辐射形式加热的结果,而边界层生物活动与近地表热量息息相关,讨论长波辐射的变化特征对生态系统的物质流动及能量交换具有重要意义.以2003年对高寒矮嵩草草甸、金露梅灌丛两种植被类型观测的资料,比较分析了两种植被类型地面长波辐射(ULR)、大气逆辐射(DLR)以及地面有效长波辐射(ELR)的变化特征.结果表明,高寒矮嵩草草甸、金露梅灌丛ULR、DLR以及ELR均具有明显的日、月变化.其中矮嵩草草甸、金露梅灌丛的ULR月平均日变化在北京时间14:00最高,凌晨最低;DLR在16:00-18:00最高,凌晨最低;ELR在8:00最低,14:00最高.月变化中,两种植被类型区ULR、DLR的最低值出现在1-2月,较高值出现在7-9月,而ELR变化趋势比较复杂.总体而言,金露梅灌丛的DLR、ULR变化值明显比矮嵩草草甸的高.%The earth's boundary layer heat source is the result of downward short-wave solar radiation and upward long-wave surface radiation, which are closely correlated with the organism's activities in the boundary.Therefore it is important to study the long-wave radiation variations for understanding ecosystem matter and energy fluxes.By analyzing the observation data measured by flux covariance system of alpine Kobresia humilis meadow and Potentilla fruticosa shrubland on the northeast of Qinghai-Tibetan Plateau in 2003, the variations and comparisons of upward long-wave radiation (ULR), downward long-wave radiation (DLR) and surface effective long-wave radiation (ELR) on the two vegetation types were discussed.The results showed that there were obvious diurnal and monthly variations of ULR,DLR and ELR on the two vegetation types.The peak value of monthly mean diurnal variations of ULR and DLR on the alpine meadow and shrubland appeared at 14:00 and 16: 00- 18:00 (Beijing time) and the lowest both appeared in the morning, respectively.Moreover, the maximum of ELR occurred at 14:00 and the minimum happened at 8: 00.The highest value of monthly DLR and ULR occurred from July to September and the lowest in January and February;while ELR showed a complex change tendency.Overall, ULR and DLR of Potentilla fruticosa shrnbland was much higher than that of Kobresia humilis meadow.