China

A study of the impact of synoptic weather conditions and water vapor on aerosol-cloud relationships over major urban clusters of China

 
Atmospheric Chemistry and Physics 05/2015; 15(10):14007-14026.
doi:10.5194/acpd-15-14007-2015 ·
 
A study of the impact of synoptic weather conditions and water vapor on aerosol-cloud relationships over major urban clusters of China
 
K. Kourtidis · S. Stathopoulos · A. K. Georgoulias · G. Alexandri · S. Rapsomanikis
 

ABSTRACT: The relationships between Aerosol Optical Depth (AOD) and Cloud Cover (CC) over 3 major urban clusters in China are studied under different Sea Level Pressure (SLP) and Water Vapor (WV) regimes using a decade (2003–2013) of MODIS observations. Over all urban clusters, for all SLP regimes, CC is found to increase with AOD, thus pointing out that the CC dependence on AOD is not solely due to meteorological co-variability. WV is found to have a stronger impact on CC than AOD. This impact is more pronounced at high aerosol load than at low aerosol load. Hence, studies of AOD-CC relationships based on satellite data, might greatly overestimate or underestimate the AOD impact on CC in regions where AOD and WV have similar or opposite seasonal variations, respectively. Further, this impact shows that the hydrological cycle interferes with the aerosol climatic impact and we need to improve our understanding of this interference. Our results also suggest that studies attributing Cloud Top Pressure (CTP) long-term changes to changes in aerosol load might have a WV bias.