河西走廊东部西北气流型沙尘暴的大气物理特征
Atmospheric Physical Characteristics of Northwest Airflow Type Sandstorm in the East of Hexi Corridor
杨梅 1李岩瑛 2罗晓玲 1杨吉萍 3聂羽彗 3聂鑫4
作者信息
- 1. 武威市气象局,甘肃 武威 733000;武威国家气候观象台,甘肃 武威 733000
- 2. 武威市气象局,甘肃 武威 733000;中国气象局兰州干旱气象研究所,甘肃 兰州 730020
- 3. 民勤县气象局,甘肃 民勤 733300
- 4. 中国气象局兰州干旱气象研究所,甘肃 兰州 730020
- 折叠
摘要
利用2006-2022年河西走廊东部常规高空地面观测资料、民勤探空站8时和20时间隔50m高空加密观测资料,分析冬季和春季西北气流型沙尘暴气象要素时间、垂直结构变化及大气层结特征.结果表明:(1)研究区西北气流型沙尘暴出现在地气温度和温差最大、相对湿度最小、地面气压和风速陡增时,春季,沙尘暴发生时,风速大、地表干且近地层热力对流最强.(2)垂直结构特征是早干晚湿、风速随高度递增,风向先顺转后逆转,低层暖高层冷;春季低层气温较高,垂直温度梯度增幅大,温度露点差大,冷暖空气强度强且交汇高度较低(1km附近),层结不稳定,易发生沙尘暴.(3)春季8时和冬季20时位温随不稳定层结高度变化梯度较大,即沙尘暴春季出现早于冬季.春季20时和冬季8时不稳定高度厚而低,因而春季下午到夜间和冬季中午沙尘暴较强.(4)500hPa冷平流中心强度(≥-34℃)和西北急流(≥26m/s)越强,对应700hPa河西风速＞20m/s及低层暖区范围越大,沙尘暴强度越强,持续时间越长.
Abstract
Based on the conventional high altitude,ground observation data and encrypted observation data with interval of 50 m at 08:00 and 20:00 of Minqin station in the east of Hexi Corridor from 2006 to 2022,the surface time variations of meteorological elements,characteristics of vertical structure and atmospheric stratification were analyzed.The results showed that:(1)The northwest airflow type sandstorm occurred when ground-air temperature and temperature difference were maximum,relative humidity was minimum,surface air pressure and wind speed increased sharply.Especially in spring,the sandstorm occurred with big wind,dry surface and strong thermal convection near surface layer.(2)The vertical structure was dry in the morning but wet in the evening,the wind speed increased with height,the wind direction turned clockwise and then reversed,the lower layer was warm and the upper layer was cold.The lower layer air temperature was higher,vertical gradient increased greatly,T-Td was bigger,intensity of cold-warm air was stronger and intersection height(near 1 km)in spring,the stratification was more unstable and sandstorms were prone to occur.(3)The bigger vertical gradient of potential temperature resulted more unstable atmosphere at 08:00 in spring and 20:00 in winter,so sandstorm appeared earlier in the day in spring.There were deeper and lower unstable stratification heights at 20:00 in spring and 08:00 in winter,so the strong sandstorm often concentrated from afternoon to night in spring and noon in winter.(4)When the center strength of cold advection(≥-34℃)and northwest jet stream(≥26 m/s)were stronger at 500 hPa,and the corresponding wind speed was greater than 20.0 m/s at 700 hPa over Hexi and the larger area of lower warm zone,the stronger the intensity and the longer the duration of the sandstorm.
关键词
西北气流型沙尘暴/地面要素/垂直结构/大气层结Key words
morthwest airflow type sandstorm/ground elements/vertical structurel/atmospheric stratification引用本文复制引用
基金项目
国家自然科学基金面上项目(41975015)
武威市市列科技项目(WW2101101)
出版年
2024
国家科技期刊平台
NSTL
万方数据