青藏高原地区NCEP新再分析地面通量资料的检验

Evaluation of NCEP/DOE Surface Flux Data over Qinghai-Xizang Plateau

利用1979—1998年地面气象站温度观测资料和1982年8月—1983年7月高原热源观测资料,检验了NCEP DOE新再分析地面气温和地面辐射收支在青藏高原地区的偏差。比较表明,气温和地面辐射量新再分析值能反映实际年变化特征,但其温度值系统性偏低,偏低幅度随地区和季节而变化。由于其气温和地表温度偏低造成地表长波辐射和大气逆辐射系统性偏低;冬季积雪地区的地表吸收太阳辐射和净辐射新再分析值偏小;地面净长波、净短波和总的净辐射与实测的偏差比较小。分析发现,同化模式地形高度与地面气象站海拔高度的差异是造成气温新再分析与实测偏差的主要原因,冬季积雪区地表反照率新再分析值偏大是造成冬季地面净辐射偏小的因素,并加剧了冬季气温新再分析的偏差。其研究对改进气候模拟结果分析有一定的启发。

The monthly mean surface flux of NCEP/DOE reanalysis data were evaluated by comparing with the surface air temperature at meteorological stations and the surface radiation data observed during the period of August 1982 to July 1983. The results show that the annual variations of the reanalyzed temperature and radiation fluxes are very well agreed with the observations. The reanalyzed temperature are, however, systematically lower than the observation over Plateau. And it causes the reanalyzed surface downward and upward long\|wave radiation flux much lower than the observations. The reanalyzed surface albedo is higher, and it causes the net solar radiation flux and total net radiation flux lower than the observation on the areas where snow is covered in winter. The deviation of temperature is mainly resulted from the difference of the reanalysis model orography and the height of station in snow\|free area and seasons. The other part of deviation of temperature is resulted from the reanalysis lower net radiation flux by using higher albedos on snow\|cover plateau in winter