摘要
利用2020年中国气象局吉林云物理野外科学试验基地微波辐射计数据,结合小时降水量数据、ERA5(ECM-WF reanalysis version 5)再分析数据等对长白山麓东北冷涡降水云系进行统计分析,将东北冷涡降水划分为强降水、中等强度降水和弱降水3类.结果表明:在长白山麓东北冷涡降水发生前6 h首先出现中高云,水汽、云液态水含量对东北冷涡强降水的发生与维持至关重要.东北冷涡强降水发生前5 h,6 km高度以下水汽出现跃升,1.0 km高度以下水汽密度增加至12～14 g·m-3;5～6 km高度温度层结为-5 ℃至-10 ℃,云液态水含量为1.0～1.6 g·m-3,有助于冰雪晶的形成;在温度层结-6 ℃至-16 ℃内存在中高云,云底高度从5.5～7 km陡降至地面,出现干冷空气侵入现象,相对湿度急剧下降,这些特征一直持续至强降水发生;在东北冷涡中等强度降水和弱降水发生前6 h,云系为中云,5～6 km高度的云液态水含量为0.4～0.8 g·m-3,但并未出现水汽跃升、相对湿度下降的特征.
Abstract
Utilizing the microwave radiometer data and hourly rainfall data in Jilin Cloud Physics Field Scientific Test Base,CMA,the precipitation cloud system in Northeast China cold vortex at the Changbai Mountain foothills is analyzed.Rainfall events are divided into heavy precipitation,moderate intensity precipitation,and weak precipitation.Assisted by ERA5 reanalysis data,results show that the middle and high clouds appear first by 6 hours before the precipitation occurrence at the Changbai Mountain foothills.Water vapor and cloud water are both important for the occurrence and maintenance of heavy precipitation induced by Northeast China cold vortex.The cloud liquid water appears approximately with the height of 5-6 km by 4 hours before the precipitation induced by Northeast China cold vortex.Two hours before precipitation,the cloud descendes sharply.During one hour after the three types precipitation occurrence,the vapor den-sity respectively leap to 13-14 g·m-3,9-12 g·m-3,and 7-9 g·m-3below 1 km height.Integrated water vapor during three types of precipitation increase to 5.8 cm,4.2 cm,and 3.5 cm,respectively.The water vapor increases 5 hours before the occurrence of strong precipitation below 6 km height.The vapor density increases to 12-14 g·m-3 below 1 km height.There is cloud liquid water with 1.0-1.6 g·m-3 at the height of 5-6 km in the temperature layers of-5--10 ℃,which contributes to the formation of ice and snow crystals.Six hours before the heavy precipitation,moderate intensity precipitation,and weak precipitation,the integrated cloud liquid water are 4.2-4.8 mm,3.0 mm,2.3 mm,respectively.There are middle and high clouds in the temperature layers of-6 ℃ and-16 ℃.The height of cloud base drops sharply from 5.5-7 km to the ground,while the relative humidity drops sharply.These characteristics continue until the beginning of heavy rainfall.For moderate and weak precipitation induced by Northeast China cold vortex,there is middle cloud before the precipitation,and the cloud liquid water is 0.4-0.8 g·m-3 at the height of 5-6 km.However,there is no characteristic of water vapor jumping or relative hu-midity decreasing.Through the study of these physical quantity characteristics,indicators with indicative and predictive significance for precipitation induced by Northeast China cold vortex have been established.
基金项目
吉林省科技发展计划重点研发项目(20230203126SF)
国家自然科学基金(41775140)
维普
万方数据