Meteorological conditions and their effects on the relationship between aerosol optical depth and macro-physical properties of warm clouds over Shanghai based on MODIS

Many studies have shown that aerosols have an important effect on the cloud reflectance of solar radiation and cloud lifetime, however, the effect of aerosols on the cloud development might be over- or under-estimated without considering the meteorological conditions. In this study, the effect of aerosol optical depth (AOD) on low warm cloud development (cloud fraction (CF) and cloud top pressure (CTP) stood for the horizontal and vertical development of clouds) over Shanghai, were analyzed based on the water vapor (WV) and atmospheric stability (K index) with ten-year (2006-2015) data from Moderate Resolution Imaging Spectroradiometer (MODIS) observations. The AOD, CF, WV, and K index had similar monthly variations, and their maxima occurred in summer. The maximal AOD in summer might be a result of moisture absorption growth of fine aerosols when there was a large amount of water vapor in the atmosphere. The influence of the WV on the CF was greater than that of the AOD. The results of the satellite data showed that a negative relationship between AOD and CF, which might be caused by the absorptive aerosols. Furthermore, the WV and AOD promoted the vertical development of clouds, which increased the cloud top altitude (the CTP decreased). Besides, the effects of the atmospheric stability (K index) on the horizontal and vertical development of clouds due to AOD were different. When the K index was below 20 degrees C, the influence of AOD on the CF was significant; for a K index above 20 degrees C, the influence was greatly weakened. With the increasing K index, the influence of AOD on CTP increased.