摘要
九龙站位于青藏高原主体和成都平原之间的过渡带,地理位置、地形分布、天气气候都独具区域特色,基于中国气象局成都高原气象研究所连续9年夏季在九龙站开展的西南涡加密观测探空试验资料,对比分析了该站边界层大气的日变化和年际变化特征。结果表明:(1)九龙站边界层大气温度08:00(北京时,下同)最低,其次是02:00,而14:00最高。比湿与温度位相相反,14:00最小,20:00和02:00皆较大。近地层大气温度/比湿日变幅大,而离地2 km高度处日变幅小。地面温度/比湿较高时次对应的垂直梯度也大,以上观测结果符合普遍大气边界层特性。14:00的地表平均温度的年际差低于08:00,离地2 km高度处平均温度的年际差与地表相当。低层大气的温度/比湿年际差偏差幅度比高层大,但最大偏差并非出现在最接近地表的大气层。(2)九龙站边界层风场在垂直方向上存在风切变,20:00风速最大,14:00次之,08:00最小;在02:00和08:00以偏西风为主,14:00和20:00则是偏东风为主。平均风速极大值出现高度的波动范围在14:00最小,08:00最大,平均风速极大值之差则是08:00最小,20:00最大。(3)九龙站08:00边界层高度最低,14:00混合程度最强,20:00最高。(4)九龙站地面平均温度日较差在6.7~9.3 K,最大年际差为1.6 K。地面大气平均比湿日较差在0.6~1.13 g·kg^-1,最大年际差为2.66 g·kg^-1。地面平均气压在02:00最大,20:00最低,日变幅在2~2.5 hPa,最大年际差为3.19 hPa。14:00地面平均风速最大,02:00和08:00皆较小,日变幅在1.9~2.9 m·s^-1。降水与地面温度/比湿之间存在正相关关系,与地面气压/风速之间存在负相关关系。
Jiulong station located in the slope transition zone between Qinghai-Tibetan Plateau and Chengdu Plain,has regional characteristics in weather and climate because of terrain undulation and special geographical position.Based on the analysis of intensive sounding data in summer from 2010 to 2018,we obtained the following results:(1)The temperature of atmospheric boundary layer is the lowest at 08:00(Beijing Time,the same as after),then at 02:00,and the highest at 14:00.On the contrary,the smallest specific humidity appears at 14:00 and bigger at 20:00 and 02:00.The diurnal variation amplitudes of temperature and specific humidity are large near surface layer,while small at 2 km above the ground.The corresponding vertical gradient is also large when surface temperature/specific humidity is high.The inter-annual variation of mean surface temperature is smaller at 14:00 than at 08:00,but annual variation at 2 km height is similar at surface layer,and is little fluctuation.The deviation of temperature/specific humidity in lower atmosphere is larger than that in the upper atmosphere,but the maximum deviation does not occur in the atmosphere closest to the surface.(2)The vertical wind shear appears in the boundary layer.The wind speed is the biggest at 20:00,then at 14:00,and the smallest at 08:00.The westward wind is dominant at 02:00 and 08:00,but the eastward wind at 14:00 and 20:00 in the boundary layer.The fluctuation range of maximum wind speed is the smallest at 14:00,and the biggest at 08:00;the difference of maximum wind speed is the smallest at 08:00,and the biggest at 20:00.(3)The boundary layer height is the lowest at 08:00 and the highest at 20:00.It mixes most fully at 14:00.(4)The maximum difference of mean surface temperature is 1.6 K,and its diurnal range is 6.7~9.3 K.The maximum difference of mean surface specific humidity is 2.66 g·kg^-1,and its diurnal range is 0.6~1.13 g·kg^-1.The mean surface pressure is the highest at 02:00 and the lowest at 20:00.Its diurnal range is 2~2.5 hPa,and the maximum d
作者
卢萍
李跃清
LU Ping;LI Yueqing(Institute of Plateau Meteorology,China Meteorological Administration(CMA),Chengdu 610072,Sichuan,China;Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,Sichuan,China)
出处
《高原气象》
CSCD
北大核心
2020年第5期1058-1069,共12页
Plateau Meteorology
基金
国家自然科学基金项目(41405145)
成都高原气象研究所开放实验室基金项目(BROP201914)
四川省应用基础研究计划重点项目(2016JY0046)。
关键词
边界层
加密探空
日变化
年际变化
Atmospheric boundary layer
intensive sounding
diurnal variation
inter-annual variation
