東亞冬春季海洋暖雲對氣膠敏感性之探討

A Study of the Susceptibility of East Asian Marine Warm Clouds to Aerosol Index in Winter and Spring

張巧薇(Chiao-Wei Chang) ； 陳怡均(Yi-Chun Chen) ； 陳維婷(Wei-Ting Chen)

《大氣科學》 49卷2期 (2021/12) Pp. 176-202

https://doi.org/10.53106/025400022021124902003

摘要

氣膠透過氣膠間接效應影響雲輻射力，同時氣膠與雲的交互作用也會受到大氣環境條件影響。本研究使用2006－2010年A-Train衛星序列的共同定位資料探討冬季與春季時東亞地區氣膠與海洋性暖雲的交互作用，依據環境特性，我們以近地表穩定度（Near Surface Stability, NSS）和估計逆溫強度（Estimated Inversion Strength, EIS）進一步分類雲的樣本，探討不同環境條件下雲敏感性的變化。雲敏感性分析的結果顯示，近地面穩定度、逆溫強度以及雲的降水狀態均會影響氣膠與雲的交互作用，本研究分別針對不降水雲與降水雲在不同環境條件下的型態與敏感性進行分析。在穩定的海洋邊界層中，由於氣膠增加有利蒸發逸入回饋增強，不降水雲的雲水含量隨著氣膠增加而減少，然而降水雲則因為氣膠增加抑制了碰撞合併成長過程，雲中的液態水含量因此增加。在強沉降逆溫的環境下，蒸發逸入回饋作用會進一步使得不降水雲中的液態水含量降低，而降水雲的雲水含量、雲光學厚度與雲反照率則具有顯著的正敏感性。在弱沉降逆溫的環境下，雲與氣膠之間的交互作用並不顯著。比較不降水雲與降水雲，降水雲的敏感性比不降水雲更高。

關鍵字

氣膠與雲交互作用 ； 氣膠間接效應 ； 雲敏感性 ； 衛星共同定位

並列摘要

Aerosols can affect the cloud radiative forcing by acting as the cloud condensation nuclei and subsequently changing the micro- and macro-physical properties of clouds. Recent studies suggested that the interaction between the shallow clouds and aerosols can be affected by the condition of atmospheric environment. In this study, we applied the datasets from A-train constellation of Earth-observing satellites to investigate the aerosol-cloud interaction in East Asia in winter and spring, the seasons in which the low-level marine clouds and high aerosol pollution coexist most frequently. It is found that the environmental condition in East Asian winter and spring is controlled by the monsoonal circulation and the warm sea surface temperature associated with the Kuroshio current. The clouds are then classified based on the near-surface stability (NSS) and estimated inversion strength (EIS) to explore the variation of the susceptibility of cloud properties under different environmental conditions. The analysis of cloud susceptibility showed that under the stable marine boundary layer, the increase in aerosol particles would enhance the evaporation-entrainment feedback and reduce the liquid water path in the non-precipitating clouds, while the liquid water path in the precipitating clouds would increase due to the inhibited collision-coalescence and the suppressed precipitation. Under strong inversion condition, the liquid water path in the non-precipitating clouds is reduced through enhanced entrainment, while the susceptibility of the liquid water path, cloud optical depth, and cloud albedo were positive for precipitating clouds. Under weak inversion, the aerosol-cloud interaction is not significant. Comparing non-precipitating and precipitating clouds, the susceptibility of the precipitating clouds is higher.

並列關鍵字

Aerosol-cloud interaction ； cloud susceptibility ； co-located