Comparison of MODIS and AERONET derived aerosol optical depth over the Ganga Basin, India

Abstract

Abstract. The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard EOS Terra measures global aerosol optical depth and optical properties since 2000. MODIS aerosol products are freely available and are being used for numerous studies. In this paper, we present a comparison of aerosol optical depth (AOD) retrieved from MODIS with Aerosol Robotic Network (AERONET) data for the year 2004 over Kanpur, an industrial city lying in the Ganga Basin in the northern part of India. AOD retrieved from MODIS (τ aMODI S ) at 0.55µm wavelength has been compared with the AERONET derived AOD (τ aAERON ET ), within an optimum space-time window. Although the correlation between τ aMODI S and τ aAERONET during the post-monsoon and winter seasons (R 2 ∼ 0.71) is almost equal to that during the pre-monsoon and monsoon seasons (R 2 ∼0.72), MODIS is found to overestimate AOD during the pre-monsoon and monsoon period (characterized by severe dust loading) and underestimate during the post-monsoon and winter seasons. The absolute difference between τ aMODI S and τ aAERON ET is found to be low (0.12±0.11) during the non-dust loading season and much higher (0.4±0.2) during dust-loading seasons. The absolute error in τ aMODI S is found to be about ∼25% of the absolute values of τ aMODI S . Our comparison shows the importance of modifying the existing MODIS algorithm during the dustloading seasons, especially in the Ganga Basin in northern part of India.

Quantitative assessment of AOD from 17 CMIP5 models based on satellite-derived AOD over India

“…Satellite-derived AOD has been extensively validated over different regions of India using ground-based observations (for example, Tripathi et al (2005), Prasad and Singh (2007), Jethva et al (2007a, b), Choudhry et al (2012), Misra et al (2008Misra et al ( , 2014b have validated different versions of the MODIS aerosol product). Hence, the accuracy of MODIS-derived AOD is understood over several, though not all, locations of India.…”

Retrieval of Aerosol Optical Depth Over Ecologically Stressed East African Land Surfaces from Top of Atmosphere Radiance Utilizing the Aerosol Free Vegetation Index

“…The correlation coefficients between retrieved AOD for developed algorithm and AERONET were higher as compared to that of MODIS collection 5 and AERONET over each study site and season. This was attributed to improper assumptions of surface reflectance and selection of aerosol type (Jethva et al, 2005;, Tripathi et al, 2005, More et al, 2013 that were addressed by the developed algorithm. Details of the correlation coefficients between (MODIS, developed algorithm) and AERONET retrieved AOD for each season except Mount Kilimanjaro as a result of luck of AERONET data over any of the three AERONET site during the dry season are shown in Table 2.…”

Role of Coarse and Fine Mode Aerosols in MODIS AOD Retrieval: a case study over southern India

“…Values of skyradiometer AODs at 550 nm are estimated by linear interpolation of log of AODs at 500 nm and 675 nm on log of wavelengths. There have been several validation exercises worldwide using ground-based data including our own (Ichoku et al, 2002;Hauser et al, 2005;Remer et al, 2005;Tripathi et al, 2005;Jethva et al, 2007Jethva et al, , 2010Misra et al, 2008;El-Metwally et al, 2010;Levy et al, 2010;Kharol et al, 2011;Kiran Kumar et al, 2013) and majority of them report that the MODIS AOD compares with ground-based data within the above-stated expected error. However, Kharol et al (2011) and we (Kiran Kumar et al, 2013) have reported a significant underestimation of AOD over the southern part of India by MODIS.…”