2001-2020年江西省主汛期降水日变化分布特征

Diurnal Variation Characteristics of Precipitation in Jiangxi Province During the Main Rainy Season from 2001 to 2020

【目的】为了分析江西主汛期(4-7月)降水日变化特征。【方法】利用2001-2020年江西省87个国家气象观测站和2011-2020年江西省736个区域气象监测站逐小时降水数据,采用气候统计方法进行分析研究。【结果】(1)江西省主汛期降水量、降水频次的日变化总体为双峰结构特征,降水量的主峰值出现在18时前后,降水频次的主峰值在20时前后。(2)降水日变化有明显的区域差异,赣北沿江地区和赣北其他地区的降水量、降水强度主峰值多出现在清晨到上午,赣中和赣南的降水量、降水频次、降水强度主峰值多出现在午后到傍晚。(3)不同持续时间降水事件,降水日变化也不同,并且不同区域不同月份降水日变化还有差异,≥6 h持续性降水事件的降水量峰值易出现在清晨到上午,这一特征在6月更为显著;而<6 h降水事件的降水量峰值则易出现在午后到傍晚,这一特征在7月份最为明显。(4)一般性降水(<20 mm·h^(-1))、短时强降水(≥20 mm·h^(-1))和5 a一遇的小时极端降水,有双峰特征,一般性降水量主峰出现在16时前后,而短时强降水和5 a一遇的小时极端降水主峰在18时前后。(5)纬度接近的河谷、平原测站降水日变化存在差异,鄱阳湖平原的观测站降水量日内大部分时段较信江、昌江河谷偏少;海拔高度不同的观测站降水日变化存在差异,赣南山区海拔偏高的观测站降水量较海拔偏低的观测站在白天各时段都要大,差异最大时段出现在16-18时。【结论】通过以上分析结果,进一步提高了对江西主汛期复杂降水过程的认识,为数值模式降水产品的订正和应用提供了科学依据。

In this article,we use the hourly precipitation data from 87 national meteorological observation stations from 2001-2020 and 736 regional stations in Jiangxi Province from 2011 to 2020,as well as the climate statistical methods to analyze the daily variation characteristics of precipitation during the rainy season(April to July)in Jiangxi Province.The results show that:(1)The daily variation of rainfall amount and frequency during the main rainy season in Jiangxi Province is generally featured with bimodal structures,with the main peak of rainfall amount appearing around 18∶00 and the main peak of precipitation frequency around 20∶00.(2)There are obvious regional differences in the daily variation of precipitation.The peaks of rainfall amount and intensity in the northern Jiangxi region along the Yangtze River and other areas of northern Jiangxi mostly appear from early morning to morning,while the peaks of rainfall amount,frequency and intensity in central and southern Jiangxi mostly occur from afternoon to evening.(3)The daily variation of precipitation varies with different durations of precipitation events,and discrepancies also exist in the daily variation of precipitation in different regions and months.The peak rainfall amount of precipitation events with the duration longer than 6 h is more likely to occur from early morning to morning,especially in June.However,the peak rainfall amount of precipitation events lasting less than 6 h is mostly seen from afternoon to evening,which is most obvious in July.(4)General precipitation(<20 mm·h^(-1)),short-time severe precipitation(≥20 mm·h^(-1)),and hourly extreme precipitation with a 5-year return period all have the features of bimodal peaks.The rainfall peak of general precipitation usually occurs around 16∶00,while the rainfall peaks of short-time severe precipitation and hourly extreme precipitation with a 5-year return period tend to appear around 18∶00.(5)The observation stations in valleys and plains with similar latitudes have differences in the daily variation of precipitation.The precipitation at the stations in the Poyang Lake Plain is mostly less than that in the Xinjiang and Changjiang valleys in the most time of the day.There are differences in the daily variation of precipitation at different stations with different altitudes.The precipitation at stations with higher altitudes in the mountainous areas of southern Jiangxi is more than that at stations with lower altitudes during all daytime periods,with the maximum difference seen from 16∶00 to 18∶00.The above analysis results would help improve the understanding of the complex precipitation process during the main rainy season in Jiangxi and provide a scientific basis for the correction and application of numerical model precipitation products.