Abstract
Nearly 30-year aerosol optical thickness (AOT) climate data record (CDR) derived from the operational satellite observations of National Ocean and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) is used to study the AOT trends over seventeen megacities in the coast zone (MCCZ). Linear trends are derived from monthly and seasonal mean AOT in the past three decades and used in the analysis. The results indicate the following: (1) AOT around a MCCZ in fast developing countries has relatively high value and a positive trend with a confidence level generally above 95%; (2) AOT around a MCCZ in industrialized countries has relatively low value and a negative trend with a confidence level generally above 95%; (3) AOT values and their trends show distinct seasonal variations in MCCZ, which can be explained somewhat by the seasonal variations of meteorological conditions. AOT trend is an effective index for examining the efficacy of air pollution control policies implemented for these megacities.
Highlights
About half of the world’s population lives in urban areas today due to convenient living facilities and the opportunity of a better quality of life, driving the formation of many rapidly growing urban centers or agglomerations, called megacities
Air and water pollutions associated with human activities have become one of the most imminent environmental issues of megacities in the coastal zone (MCCZ) in recent decades [3,4,5,6], especially in the developing countries where limited resources are available for addressing the pollution issues
The paper is arranged as follows: Section 2 introduces selected MCCZ and the Advanced Very High Resolution Radiometer (AVHRR) satellite aerosol optical thickness (AOT) data; trend analysis approach is briefly described in Section 3; variation of monthly mean AOT and its trend for the selected MCCZ are studied in Section 4; seasonal features of AOT and its trend are examined in Section 5; summary and conclusions are given in the close section
Summary
About half of the world’s population lives in urban areas today due to convenient living facilities and the opportunity of a better quality of life, driving the formation of many rapidly growing urban centers or agglomerations, called megacities. A megacity is defined as a large urban agglomeration with populations exceeding 10 million inhabitants The majority of these urban megacities are located in a coastal zone or a zone with distinct coastal influence [1], which are called megacities in the coastal zone (MCCZ) hereafter. One primary reason for monitoring ambient air pollutants is to provide information for estimating their potential effects, on environmental and human health. Long-term observation of AOT over MCCZ from satellite can provide information on the changes and trends of air pollution, which can be used to evaluate the efficiency of the measures and polices implemented for air pollution control and air quality improvement in MCCZ. The paper is arranged as follows: Section 2 introduces selected MCCZ and the AVHRR satellite AOT data; trend analysis approach is briefly described in Section 3; variation of monthly mean AOT and its trend for the selected MCCZ are studied in Section 4; seasonal features of AOT and its trend are examined in Section 5; summary and conclusions are given in the close section
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
