Long-term trends of zonally averaged aerosol optical thickness observed from operational satellite AVHRR instrument

Abstract

Atmospheric aerosols are solid and liquid particles suspended in air. Aerosols have important consequences for global climate, ecosystem processes and human health due to their various sizes and chemical compositions. In this paper, nearly 23 years of aerosol optical thickness (AOT) data from operational satellite AVHRR observations over the global ocean have been used to study the latitudinal variations of the linear long-term trends (LLT) of zonal mean AOT. For the LLT of zonally averaged AOT over the global ocean, their significance generally falls below the 95% confidence level. However, the LLT of zonal mean AOT for the individual oceans, such as the Atlantic Ocean (AO), Indian Ocean (IO), and West Pacific Ocean (WPO), can easily pass 95% confidence level in some latitude belts (e.g. 5-25°N for IO, 33-40°N for WPO, 30-50°N for AO) and may produce zonally averaged solar dimming/brightening accordingly in cloudless conditions. The results will help us to understand the latitudinal features of the decadal changes in aerosol loadings, as well as surface solar radiation, better. © 2011.