Linggo, Agosto 19, 2012

Comparison of Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR) Aerosol Optical Depth Correlation with Particulate Matter (PM¬2.5) Concentrations at the Manila Observatory (14.635 N, 121.078 E)


HANZ VLADIMIR CABANES1*, IRWIN ANGELO AMAGO1, and NOFEL LAGROSAS1,2
1Physics Department, Ateneo de Manila University, Loyola Heights, Quezon City, Philippines

2Manila Observatory, Ateneo de Manila University, Loyola Heights, Quezon City, Philippines
hanzcabanes@yahoo.com




In this paper, a correlation analysis for both Moderate Resolution Imaging Spectroradiometer aerosol optical depth and Multiangle Imaging Spectroradiometer aerosol optical depth with ground-based PM2.5 concentration measurements at the Manila Observatory for January to December 2011. The resulting analysis showed that MISR AOD had a better correlation (R2=0.7360) than MODIS AOD (R2=0.6793). Using this analysis, it was observed that the MISR AOD readings have a tendency to overestimate the ground-measured PM2.5 concentration values while the MODIS AOD underestimates the PM2.5 ground-measured data. Moreover, given the higher R2 value, the results affirm those of previous studies, which say that MISR AOD is more accurate in determining PM2.5 concentrations than MODIS AOD [1]. However, MODIS is known to have a better temporal resolution because it is onboard both TERRA and AQUA satellites whereas MISR is only onboard the TERRA satellite. To couple the individual advantages of these two data sets, the multivariate regression approach was used with the MODIS and MISR AOD values as predictors to the ground-measured PM2.5 values. The resulting equation from the analysis was PM2.5c=52.94MISR+37.10MODIS+15.33 where the PM­2.5c is the computed PM2.5 value, and MISR and MODIS represent the corresponding MISR AOD and MODIS AOD values, respectively. The computed PM2.5 values from this equation yielded an absolute error of 21.85% and an R2 of 0.7249 compared to the actual values. The resulting error value is lower than the 30-40% range often reported in literature, which affirms the utility of the multivariate regression method in relating satellite-derived data with ground-measured data [1, 2]. The analysis presented in this paper foregrounds further work geared towards the utilization of satellite data as a surrogate for ground-measured data.

References

[1]     Engel-Cox, J.A.; Hoff, R.M.; Haymet, A.D.J., “Recommendations on the Use of Satellite Remote-Sensing Data for Urban Air Quality,” Journal of Air & Waste Management Association. 54, 1360-1371, 2004.
[2]     Gupta, P., et al, “Satellite remote sensing of particulate matter and air quality assessment over global cities.” Atmospheric Environment 40, 5880-5892, 2006.


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