MODIS 3 km aerosol product: algorithm and global perspective

Abstract

After more than a decade of producing a nominal 10 km aerosol product based on the dark target method, the MODerate resolution Imaging Spectroradiometer (MODIS) aerosol team will be releasing a nominal 3 km product as part of their Collection 6 release. The new product differs from the original 10 km product only in the manner in which reflectance pixels are ingested, organized and selected by the aerosol algorithm. Overall, the 3 km product closely mirrors the 10 km product. However, the finer resolution product is able to retrieve over the ocean closer to islands and coastlines, and is better able to resolve fine aerosol features such as smoke plumes over both ocean and land. In some situations, it provides retrievals over entire regions that the 10 km product barely samples. In situations traditionally difficult for the dark target algorithm such as over bright or urban surfaces, the 3 km product introduces isolated spikes of artificially high aerosol optical depth (AOD) that the 10 km algorithm avoids. Over land, globally, the 3 km product appears to be 0.01 to 0.02 higher than the 10 km product, while over ocean, the 3 km algorithm is retrieving a proportionally greater number of very low aerosol loading situations. Based on collocations with ground-based observations for only six months, expected errors associated with the 3 km land product are determined to be greater than that of the 10 km product: ± 0.05 ± 0.20 AOD. Over ocean, the suggestion is for expected errors to be the same as the 10 km product: ± 0.03 ± 0.05 AOD, but slightly less accurate in the coastal zone. The advantage of the product is on the local scale, which will require continued evaluation not addressed here. Nevertheless, the new 3 km product is expected to provide important information complementary to existing satellite-derived products and become an important tool for the aerosol community

The effect of atmospheric aerosol particles and clouds on net ecosystem exchange in the Amazon

“…The regression analysis presented in Fig. 5b and d shows that MODIS can be used to derive AOD, taking AERONET values as a reference (Remer et al, 2013).…”

A surface reflectance scheme for retrieving aerosol optical depth over urban surfaces in MODIS Dark Target retrieval algorithm

“…In the recent release of MODIS Collection 6 (C6) data version, there is also a MxD04_3K product, which is at 3 km spatial resolution (nadir) and available globally. The standard C6 products have gone through initial validation (e.g., Levy et al, 2013;Munchak et al, 2013;Remer et al, 2013).…”

“…As retrievals of AOD are increasing in their spatial resolution, coverage and accuracy, environmental monitoring agencies are increasingly looking to satellites to cover the gaps in aerosol monitoring. Although it is not straightforward, many studies (Wang and Christopher 2003;Gupta et al, 2006;Gupta and Christopher, 2009;Hoff and Christopher, 2009;van Donkelaar et al, 2010van Donkelaar et al, , 2015Liu et al, 2010) are trying to link satellites retrievals of AOD to surface concentrations of PM 2.5 or PM 10 (PM having aerodynamic diameters of 2.5 or 10 micrometers, respectively).…”

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe – Part 1: AERONET, MODIS and lidar observations

“…MODIS aboard the NASA Terra and Aqua satellites have been in operation since 2000 and 2002, respectively, providing retrieval products of aerosol and cloud properties with nearly daily global coverage (Remer et al, 2013). The MODIS dark target algorithms over land (with spatial resolution of 10 km and 3 km) perform a simultaneous inversion of the measured top 15 of the atmosphere reflectance in three channels (centered at wavelengths of 466, 645, and 2113 nm) to retrieve total spectral AOT, fine model weighting parameter, and surface reflectance at 2113 nm (Remer et al, 2013) from the MODIS data.…”

“…The MODIS dark target algorithms over land (with spatial resolution of 10 km and 3 km) perform a simultaneous inversion of the measured top 15 of the atmosphere reflectance in three channels (centered at wavelengths of 466, 645, and 2113 nm) to retrieve total spectral AOT, fine model weighting parameter, and surface reflectance at 2113 nm (Remer et al, 2013) from the MODIS data. The most recently released MODIS Collection 6 product MOD04_3K (for Terra) and MYD04_3K (for Aqua) contains AOT at a 3 km horizontal resolution in addition to the L2 10 km product (Remer et al, 2013;Levy et al, 2015). The retrieval algorithm of the higher resolution product is similar to that of the 10 km standard product with several exceptions (for more details, see observations because this lidar was continuously running on these days, while the Polly at Leipzig was sporadically operated only, e.g., not continuously on 21 and 23 August 2013.…”