近46年辽宁省降水集中程度研究

利用辽宁省25个台站1960—2005年逐候的降水资料，运用降水集中度和集中期分别讨论了辽宁省降水时空分布特征和变化规律，同时对多水年和少水年的集中度进行了比较。结果表明降水集中度和集中期能够定量地表征降水量在时空场上的非均一性，降水集中度平均为0．655，最大为0．749，最小为0．509；集中期平均为40．953候，最大值为45．221候，最小值为37．697候。年降水集中度和汛期降水集中度均呈减小趋势，汛期降水集中度减小的趋势明显。降水集中度的EOF分析显示取前3个特征值对应的特征向量可解释70％以上的方差。第一特征向量表现为全省一致性，而第二特征向量表征为东南与西北地区的反相，第三特征向量表征为东部山区与西部和沿海地区的反相。多水年的降水集中度明显比少水年的偏大且多水年的降水集中度分布较少水年复杂。

Research of Precipitation Concentration Degree in Liaoning Province for the Last 46 Years

By use pentad precipitation data at 25 stations in Liaoning Province from 1960 to 2005, the characteristics of the spatial-temporal distribution and variation of the precipitation are analyzed,in terms of the precipitation concentration degree (PCD) and precipitation concentration period (PCP). Meanwhile, the comparison of the PCD is also made between rainy years and dry years. The results show that the PCD and PCP can demonstrate the inhomogeneity of quantitative precipitation in spatial-temporal distribution. The mean PCD in all stations is 0.655, with the maximum of 0.749, and the minimum of 0.509. The mean of PCP is 40.953 pentad, with the maximum of 45.221 pentads, the minimum of 37.697 pentads. The trend of both annual PCD and the PCD in flood season diminishes. The diminishing trend of the PCD in flood season is obvious. The EOF of normalized anomaly fields of the PCD shows that the three EOF modes can depict the spatial distribution. The first principal component exhibits all the stations inphase. The second principal component takes on seesaw between the southeast and northwest areas. The synthetic analysis of more and less precipitation showed that PCD in years with more precipitation is obviously larger than that of less precipitation, besides, the distribution of the PCD is more complicated in rainy years than in dry years.