【摘要】 选取西北地区均匀分布的85个地面测站1961—2001年冰雹资料,分析了降雹的空间分布和年、日变化及持续时间。结果表明,西北地区冰雹与地形、海拔高度有密切关系,具有明显的局地性。其自然正交函数分解(EOF),主要表现为干旱区、高原区等空间差异(LV)。旋转自然正交函数分解(REOF)表明,旋转载荷向量场(RLV)反映了8个主要降雹异常类型区。旋转主分量(RPC)揭示了近41年来西北地区冰雹日数时间演变特征:北疆、南疆和秦岭南部年冰雹日数总体呈多雹—少雹—多雹趋势;柴达木盆地和青藏高原东北侧总体呈少雹—多雹—少雹趋势;天山、青藏高原东南部、河套南部总体呈减少趋势。更多还原

【Abstract】 Using the hail data of 85 surface observation stations in Northwest China from 1961 to 2001, the spatialdistribution, annual and day changes, and duration of hail shooting were analyzed. Theresults showed that hail in Northwest China closely correlated with topography and sea level elevation, which have obviously the local and dispersive characters. The result of EOF indicatedthat there are actually spatial difference between arid, plateauand other areas. There 8 main anomaly patterns of hail shooting areas were partitioned respectively in RLV by the method of REOF. The results of RPC revealed the temporal evolution properties of the daily numbers of hail in Northwest China in recent 41 years were that: The daily numbers of annual hail stream was total more-less-more trends in Northern and Southern Xinjiang, and South Qinling Mountain; and one in Caidamu Basin and Northeastern Qingzang Plateau, for less-more-less trends, while graduallydecrease trend in Tianshan Mountain, Southeastern Qinghai-Xizang Plateauand Southern Hetao region.更多还原