那曲地区不同季节陆面过程与大气边界层演变耦合关系的对比分析

Comparative Analysis of Coupling Relationship Between Land Surface Processes and Atmospheric Boundary Layer Evolution in Nagqu Area in Different Seasons

陆面过程与大气边界层之间耦合关系是理解青藏高原热力效应的关键环节和难点之一。本文基于那曲高寒气候环境观测研究站2019年5月、7月和10月地面及探空观测数据分析了青藏高原那曲地区地表能量收支及大气温湿垂直廓线的日变化和季节差异,探讨了该地区干湿季大气边界层高度的演变规律。结果表明,在5月观测期间内受日间净辐射强度变化的影响,对流边界层在晴天较高,为2842 m;阴天较低,为1481 m,强对流天气也可能使其在低层转变成稳定边界层。同时,位于近地层大气的感热和潜热交换为大气边界层的维持和发展提供了能量支持,位温和比湿垂直廓线能够正确反映出那曲地区大气边界层高度的季节性差异,对流边界层高度在5月最高、10月次之、7月最低,而稳定边界层在7月最高、5月次之、10月最低。

The coupling relationship between land surface processes and atmospheric boundary layer is one of the key links and difficulties in understanding the thermal effect over the Qinghai-Xizang Plateau.Based on the surface and radiosonde observation data of Nagqu Plateau Climate and Environment Observation and Research Station in May,July and October 2019,this paper analyzes the surface energy budget,the daily and seasonal variations of vertical profile of atmospheric temperature and humidity,in Nagqu Area of the Qinghai-Xizang Plateau,and discusses the evolution law of the atmospheric boundary layer height in different seasons in this region.The results show that the convective boundary layer is 2842 m high in sunny days due to the influence of diurnal net radiation intensity during the observation period in May.It is 1481 m high in cloudy day,which is relatively low,and the strong convective weather may change it into a stable boundary layer.In the meanwhile,the exchange between the sensible heat and the latent heat in the near surface atmosphere provides energy support for the maintenance and development of the atmospheric boundary layer.The vertical profile of potential temperature and specific humidity can correctly reflect the seasonal difference of atmospheric boundary layer height in gqu Area.The height of the convective boundary layer is highest in May,less high in October and the lowest in July while the stable boundary layer is highest in July,less high in May and lowest in October.