基于ERA5再分析资料的冬季南海北部低云日变化研究  

Study on Diurnal Variation Characteristics of Low Clouds in the South China Sea in Winter based on ERA5 Reanalysis Data

作　　者：姚海兰 龙景超 谢丹惠 何维帅 李钟锐 薛宇峰[1,2,3] Yao Hai-lan(College of ocean and meteorology/South China Sea institute of marine meteorology(SIMM),Guangdong Ocean University,Zhanjiang,Guangdong 524088)

机构地区：[1]广东海洋大学海洋与气象学院/南海海洋气象研究院,广东湛江524088 [2]中国气象局广东海洋大学气象联合实验室,广东湛江524088 [3]广东省高等学校陆架及深远海气候、资源与环境重点实验室,广东湛江524088

出　　处：《农业灾害研究》2023年第7期144-147,共4页Journal of Agricultural Catastrophology

基　　金：国家自然科学基金项目(41905006);广东海洋大学大学生创新创业项目(580520154);广东海洋大学博士启动金(R19018)。

摘　　要：低云对区域辐射能量平衡和天气、气候具有重要意义。利用ERA5再分析数据和中国香港探空站资料研究了冬季南海北部低云日变化机理。主要结论如下:(1)南海低云量呈现西北多东南少、夜多昼少,低云高度呈夜高昼低,低云厚度呈夜厚昼薄的特征。(2)冬季南海北部低层大气稳定性强,海气界面稳定性弱,云层下方边界层混合均匀,有利于低云形成。(3)夜间,陆风环流系统改变海洋风场和湿度场的分配,异常南风使近海水汽辐合抬升,为云层发展提供水汽。(4)夜间逆温层强度虽弱但发生频率更高,且云底以下边界层退耦减弱,边界层混合加强,云顶短波辐射加热作用消失,促使低云的产生。这都将有利于提高人们对南海低云日变化的理解和数值模拟能力。Low cloud was of great significance to regional radiative energy balance,weather and climate.ERA5 reanalysis data and Hong Kong sounding station data were used to study the diurnal variation characteristics of low clouds in the South China Sea(SCS)in winter.The main conclusion was as follows:(1)The low cloud cover in the SCS was characterized by“more northwest than southeast”,“more night than day”,the low cloud height was“higher night than day”and the low cloud thickness was“thick night and thin day”.(2)In the northern of SCS in winter,the lower tropospheric stability was high,the air-sea interface stability was weak,the boundary layer below the clouds was homogeneously mixing.All of above promotes low-cloud formation.(3)At night,the land breeze circulation system changes the distribution of wind and humidity fields on the ocean,abnormal southerly make the near-sea vapor converge and uplift,which provides water vapor for cloud development.(4)The thermal inversion layer was weak in strength but high in frequency of occurrence at night.Meanwhile,under the cloud bottom,the decoupling degree in the boundary layer was little,the boundary layer mixing was strengthened,and on the cloud top,the heating effect of shortwave radiation disappears,which has contributed to the creation of low clouds.This study was helpful to enhance the understanding of diurnal variation of low cloud in the SCS and improve the ability of numerical simulation.

关 键 词：低云 南海北部 日变化 海陆风环流 

分 类 号：P732[天文地球—海洋科学]