Analysis and Forecast Points of Five Snowfall Events in 2022
李进 1陈光宇 1周娟 1郝世峰 2徐娟1
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作者信息
1. 杭州市气象局,杭州 310051
2. 浙江省气象台,杭州 310017
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摘要
本文采用ECMWF(European Centre for Medium-Range Weather Forecasts)细网格和NCEP(National Centers for Environmental Prediction)模式数据、NCEP 1°×1°再分析资料、降雪加密观测和常规资料,对2022年初的5次降雪过程进行对比分析,发现5次降雪过程均为雨转雪过程,且持续时间相对较短,平原为雨夹雪或小雪到中雪,山区中到大雪,局部暴雪,数值模式预报的积雪深度与实况相差甚远;大尺度环流形势为500 hPa中低纬南支槽或弱波动配合700 hPa上的暖湿气流和中低层冷空气,造成边界层浅薄的冷垫上温度骤降而在短时间内形成降雪;相较于平原地区,高山区上空温度层结与最大上升运动中心的配置,有利于降雪粒子较长时间维持在有利于枝状雪花的形成区域,且高山区云底云水含量显著偏低、整层温度足够低,故高山区更利于暴雪的形成.
Abstract
Based on the ECMWF(European Centre for Medium-Range Weather Forecasts)fine grid model and NCEP(National Centers for Environmental Prediction)model products,the NCEP reanalysis data with resolutions of 1°×1°,conventional meteorological data,as well as intensive snowfall observations,the five snowfall events in 2022 were analyzed.It was discovered that the five snowfall events were all weather processes of rain to snow with relatively short duration which predicted by the numerical models were far from the actual situations on snow depth.There were sleet or light to moderate snows in the plains and moderate to heavy snows,even partial snowstorms in the mountains;The large-scale circulation forms consisted of southern trough or weak fluctuation in middle and low latitudes at 500 hPa and warm moist current at 700 hPa as well as cold air at the middle and low levels causing a sudden drop in tem-perature on the shallow cold pad of the boundary layer which contributed to snowfalls in a short time.Compared with plain areas,snowstorms are more likely to occur in alpine regions where the configuration of temperature stratification and maximum ascending motion center was conducive to the snowfall particles staying in the area suitable for the forma-tion of branched snowflakes for a long time,furthermore,the water content of cloud bottom was significantly lower and the temperature of the whole layer was low enough in the mountains.
关键词
降雪过程/雪水比/高山区/暴雪/杭州
Key words
snowfall events/snow to liquid ratio/alpine region/snow storms/Hangzhou
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