A COMPARATIVE STUDY OF AEROSOL OPTICAL DEPTH OVER SINGAPORE FROM 2007 - 2014: RESULTS FROM AERONET AND MODIS DATA ANALYSIS

摘要

South East Asia (SEA) is heavily dependent on satellite remote sensing given its vast geographical distribution as well as its complex surface, sea and atmospheric environment. In recent years, trans-boundary smoke, mainly caused by forest and agriculture burning in Sumatra and Borneo has become a recurring event affecting the SEA region. Haze/smoke events are occurring particularly between the dry months of August and October of every year. In a previous work, we examined aerosol optical depth (AOD) trend over Singapore over a period of eight years spanning from 2007-2014. AOD values, at 550nm, were obtained from our existing AERONET site. Smoke/non-smoke periods were analyzed and a multi-year trend showed a positive slope increase of average monthly AOD. In this work, and as a complement to our previous results, we have added AOD retrievals from the Moderate Resolution Imaging Spectro-radiometer (MODIS) sensor on board NASA's Terra and Aqua satellites for the same period of time. Monthly and seasonal variations of AOD are investigated and reanalyzed concurrently for both AERONET and MODIS data sets. In this study, we try to answer two questions; Does Terra/Aqua MODIS AOD values exhibit similar temporal variation patterns as those inferred from AERONET and whether there are common inter-annual or seasonal patterns noticeable in the AOD time series over the last 8 years. Monthly averaged level 3 MODIS gridded atmosphere global joint products and AERONET level 1.5/2.0 data sets (further processed for cloud contamination by the Spectral Deconvolution Algorithm) are exclusively used for this work.