基于卫星数据的2009~2023年西北太平洋多层云时空分布特征

Spatiotemporal Distribution Characteristics of Multilayer Clouds in the Northwestern Pacific Based on Satellite Data (2009~2023)

摘要: 本研究基于2009至2023年CALIPSO卫星数据，分析了西北太平洋中高纬度海域多层云及其下层低云的空间分布与季节变化特征，并探讨了大气环流、海面温度以及低层对流层稳定度等环境因子的影响。研究表明，多层云在该区域具有较高的发生频率，年均云频大部分海域超过0.4，且远离大陆的洋面上空存在较高比例的厚多层云。多层云下低云的发生频率较低，主要集中在沿岸海域，尤其是黄渤海区域，季节性差异显著。夏季多层云分布广泛且云顶高度增高，云下低云的多层云类型则主要出现在春夏季。气象分析表明，大气环流、低空风场及海面温度的季节性变化能够调控多层云及下层低云的分布。低层对流层稳定度(LTS)的季节差异也影响了云顶高度和低云发展。辐射传输模拟结果显示，多层云中不同光学厚度的上层云能不同程度遮盖下层低云的辐射特性，体现了多层云垂直结构对辐射传输的影响。

Abstract: This study analyzes the spatiotemporal distribution and seasonal variation characteristics of multilayer clouds and their lower-level clouds in the mid- to high-latitude regions of the northwestern Pacific, based on CALIPSO satellite data from 2009 to 2023. It also explores the influence of environmental factors such as atmospheric circulation, sea surface temperature, and lower-tropospheric stability. The results show that multilayer clouds occur with high frequency in this region, with the annual mean cloud frequency exceeding 0.4 in most of the sea areas. Additionally, there is a higher proportion of thick multilayer clouds over the open ocean, far from the continents. The occurrence frequency of lower-level clouds beneath multilayer clouds is relatively low, mainly concentrated in the coastal regions, especially in the Yellow and Bohai Seas, with significant seasonal differences. In summer, multilayer clouds are widely distributed, and cloud top heights increase, while lower-level clouds predominantly occur in the spring and summer. Meteorological analysis indicates that seasonal changes in atmospheric circulation, low-level wind fields, and sea surface temperature significantly regulate the distribution of multilayer clouds and lower-level clouds. The seasonal variations in lower-tropospheric stability (LTS) also affect cloud top heights and the development of low clouds. Radiation transfer simulation results show that upper clouds with varying optical thicknesses in multilayer clouds can partially obscure the radiative properties of lower-level clouds, reflecting the impact of the vertical structure of multilayer clouds on radiation transfer.