近40 a安顺市汛期降水的气候特征分析

Climate Characteristics of Precipitation in Anshun City During the Rainy Season in the Recent 40 Years

【目的】为探索安顺市汛期降水的气候特征。【方法】利用1984-2023年4-9月安顺市6个国家气象站的逐日降水资料、NCEP/NCAR第二套再分析资料,运用合成分析、统计分析、Mann-Kendall非参数统计检验及Morlet小波分析等方法,对安顺市汛期降水进行分析。【结果】安顺市汛期降水呈现明显的年代际变化特征,具有6~8 a长周期和准2 a的短周期变化特征,其汛期多年平均总降水量呈现西多东少的特征,降水量高值中心位于镇宁县,低值中心位于平坝区,降水异常偏多年的总降水量空间分布特征与多年平均基本一致,降水异常偏少年的总降水量的高值中心转移到普定县,低值中心转移到西秀区,呈现西北多、东北少的特征。汛期安顺市国家气象站的降水量级以小雨为主,其占比达70.26%,暴雨及以上量级的降水占比仅为3.92%。降水异常偏多年500 hPa位势高度距平场上乌拉尔山附近为负距平中心,西伯利亚地区为正距平,亚洲中高纬地区主要表现为“+、-、+”的南北结构特征,中国大部分地区为负距平,西太平洋副热带高压西伸脊点位于135°E左右,且位于正距平区,汛期降水异常偏少年的500 hPa位势高度距平场与异常偏多年基本相反,且西太平洋副热带高压较弱,西脊点位于142°E以东,位于负距平区。【结论】研究成果可为生产建设、洪涝灾害防御及提高汛期降水预报能力提供一定的参考。

By using the daily precipitation data from six national meteorological stations in Anshun City from April to September 1984 to 2023 and the second set of NCEP/NCAR reanalysis data,as well as the methods of synthetic analysis,statistical analysis,Mann-Kendall non-parametric statistical test and Morlet wavelet analysis,this article analyzes the precipitation during the flash flood season in Anshun City so as to explore the climate characteristics of precipitation during the rainy season in Anshun City.The results show that the precipitation during the rainy season in Anshun City exhibits obvious interdecadal variation characteristics,with a long period of 6-8 years and a short period of quasi-two years.The average annual total precipitation during the rainy season is featured with"more in the west and less in the east".The high-value center of precipitation is located in Zhenning County,while the low-value center of precipitation is found in Pingba District.The spatial distribution characteristics of the total precipitation in the years with more rain are basically consistent with those of the average total precipitation during the rainy season.The high-value center of total precipitation in the abnormally less precipitation years shifts to Puding County,while the low-value center moves to Xixiu District,thus the total precipitation shows the feature of"more in the northwest and less in the northeast".The precipitation of six national meteorological stations in Anshun City in rainy season is dominated by light rain,accounting for 70.26%,while the precipitation of rainstorm and above only accounts for 3.92%.In the excessive precipitation years,the area near Ural Mountains is the center of negative anomaly of the 500 hPa geopotential height,and Siberia is its positive anomaly center.Thus,the 500 hPa geopotential height in the mid-to-high latitudes in Asia mainly exhibits a north-south structural feature of"positive-negative-positive".Under such a situation,most parts of China have a negative anomaly of geopotential height at 500 hPa,while the western ridge point of the western Pacific subtropical high is located around 135°E in the positive anomaly area of the geopotential height.In the years with precipitation abnormally below normal,the 500hPa geopotential height anomaly field is basically opposite to that in the abnormally more rainfall year.In addition,the western Pacific subtropical high pressure is relatively weak with its western ridge point located east of 142°E in the negative anomaly area of the 500 hPa geopotential height.In a word,the results could provide a certain reference basis for preventing flood disaster,and improving the forecasting capability of precipitation during rainy season.