冷季黑龙江省温带气旋影响下中尺度降水带特征

Characteristics of the Mesoscale Precipitation Bands under the influence of Extratropical Cyclones in Heilongjiang Province during Cold Seasons

基于2010-2021年黑龙江省9部C波段多普勒雷达观测和常规资料,结合欧洲中期天气预报中心(European Center for Medium-RangeWeather Forecasts,ECMWF)0.25°×0.25°的1 h间隔的ERA5再分析资料,统计分析了黑龙江省温带气旋暴雪过程中尺度降水带的类型和活动特征,基于典型个例对比分析了两种主要中尺度降水带的环境场异同。结果表明:(1)中尺度降水带主要分为单带状、多带状、短暂带状和非带状;中尺度降水带主要分布在黑龙江南部和东北部,位于地面气旋的西北和东北象限,距离气旋中心900 km范围内,且主要发生在气旋的锢囚阶段;运动方式主要是横向平移与混合。(2)不同类型中尺度降水带降水强度的差异可以很好地从物理量的垂直廓线上体现出来,单带状低层比湿最大,低层锋生最强,造成的降水最强;而非带状低层锋生弱于单带状,最强比湿在800hPa附近,降水范围大,强度弱于单带状。(3)个例分析表明,单带状和多带状中尺度降水带均位于850hPa强暖平流的北侧和地面气旋的东北象限、处于弱的湿对称稳定或湿对称不稳定环境中,中尺度降水带的走向与锋生区平行。不同之处为单带状的形成伴随着低层低涡和地面气旋的快速发展和移动,变形场导致强锋生,上升运动集中在小范围,而多带状低层低涡和地面气旋少动、强度变化不大,变形场较弱,锋生较为浅薄,但高空辐散和低层暖平流更强,造成的上升运动范围更大,出现多个上升运动中心,对应多个小带。

Based on nine C-band Doppler radar observations of Heilongjiang Province and conventional data from 2010 to 2021,combined with 1-h interval ERA5 reanalysis data of 0.25°×0.25°from the European Center for Medium-Range Weather Forecasts,the types and activity characteristics of mesoscale precipitation bands associated with extratropical cyclones in Heilongjiang Province are statistically analyzed,and the similarities and differences in the environment fields of two types of mesoscale precipitation bands are compared through typical cases.The main results are:(1)Mesoscale precipitation bands are primarily divided into single,multi,transitory,and nonbanded.Precipitation bands are mainly located in southern and northeastern Heilongjiang and the northwest and northeast quadrants of surface cyclones,within 900 km from the cyclone centers,and occur in the mature stage of cyclones.The main movement types of mesoscale precipitation bands are laterally translating and hybrid.(2)Vertical profiles of physical quantities can well reflect differences in precipitation intensity of different precipitation bands.Single-banded bands have the most excellent low-level specific humidity and frontogenesis,causing the heaviest precipitation.Non-banded bands have extensively weaker low-level frontogenesis than single-banded bands,with maximum specific humidity near 800 hPa,causing a wide range of precipitation and a weaker precipitation intensity than single-banded bands.(3)The analysis of cases shows that both single-banded and multi-banded bands are located on the north side of the intense 850-hPa warm advection,the northeast quadrant of the surface cyclone,in a small moist symmetric stable or moist symmetric unstable environment.The direction of the mesoscale precipitation band is parallel to the frontogenesis.The differences between them are as follows:for the single-banded band,deformation leads to strong frontogenesis and the upward movement concentrated on a small area,accompanying the development and movement of the low-level low and the surface cyclone,while for the multi-banded,weak deformation and shallow frontogenesis accompanying little movement and intensity change,intense upper-level divergence and low-level warm advection caused more extensive upward motion with multiple upward centers,corresponding to multi bands.