夏季青藏高原下垫面感热异常的诊断研究

A DIAGNOSTIC STUDY ON SURFACE SENSIBLE HEAT FLUX ANOMALY IN SUMMER OVER THE QINGHAI-XIZANG PLATEAU

利用青藏高原主体６０个地面站１９６１～１９９０年历年夏季各月资料计算了高原地面感热通量，并通过主成分分析、主值函数和功率谱等方法，对夏季高原地面感热通量的基本气候特征、异常变化的空间结构和时间演变趋势作了较系统的诊断研究。结果表明：夏季青藏高原地面感热通量表现为较大的正值，通常感热大的地方其年际变化也大，年际异常的空间型主要是南北差异。近３０年来，夏季高原主体及东部平均地面感热通量有增大现象，柴达木盆地、青海东部、西藏西部随时间呈减弱趋势。这种时间演变表现出明显的准３年。

In this paper,the monthly mean surface sensible heat flux for 60 stations during period from 1961 to 1990 over the Qinghai-Xizang Plateau was calculated,and the basic climatic features and the space anomaly structure and time evolution tendency have been diagnosed systematically by principal component analysis,a periodic function and a random function and power spectral analysis methods. The result shows that the surface sensible heat flux is remarkably positive in summer,usually the sensible heat flux interannual change is large too. The first space pattern of interannual anomaly of the surface sensible heat flux over the Qinghai-Xizang Plateau is south-north discrepancy. The surface sensible heat flux increases constantly in main body and east of the Qinghai-Xizang Plateau and has a decrease tendency in the Qaidam Basin,eastern Qinghai province,and western Xizang in summer, and there are quasi-three,-seven and -thirteen years periodic oscillation for the interannual variation.