Assesment and comparison of modis aod and ae product over Ilorin Aeronet station using the statistical analysis of empirical orthogonal function (EOF)

Abstract

In this Paper, Empirical Orthogonal Function (EOF) was used to assess the MODIS C006 LV2 aerosol AOD and AE products, and compared the data with AERONET AOD and AE observations. The data were taken from an AERONET station at Ilorin, Nigeria which were obtained from (MAPSS) and were averaged monthly using Microsoft excel spread sheets. The data period for the two satellite data were from Dec 2004 to May 2015 It was observed from the graphical representation that the seasonal variation of AOD peaks during the dry season from Dec to Feb and reaches minimum during summer in August 2008.The comparisons showed both underestimations in MODIS AOD and considerable overestimations in the AE. On the EOF analysis it was observed that a good correlation between MODIS & AERONET AOD are observed on the correlation matrices in all the data. Lower correlation is only observed at Ilorin AERONET wavelength at 470nm (ILA470) with Ilorin 660nm (ILM660).On the total variance explained table for MODIS and AERONET AOD, it was observed that out of the 6 components put into the EOF, only one component was extracted with a very high percentage of 81.57% For MODIS and AERONET AE,two components were observed with a percentage of 83.95% These show that the level of similarities is very high for MODIS and AERONET AOD,and little variation was observed for MODIS and AERONET AE.

Keywords: Aerosol optical depth, Angstrom exponent, Empirical orthogonal function,
AERONET nd MODIS Satellite data.