Aerosol optical depth (AOD) retrieval using simultaneous GOES-East and GOES-West reflected radiances over the western United States

Abstract

Abstract. Aerosol optical depth (AOD) in the western United States is observed independently by both the (Geostationary Operational Environmental Satellites) GOES-East and GOES-West imagers. The GASP (GOES Aerosol/Smoke Product) aerosol optical depth retrieval algorithm treats each satellite as a unique sensor and thus obtains two separate aerosol optical depth values at the same time for the same location. The TOA (the top of the atmosphere) radiances and the associated derived optical depths can be quite different due to the different viewing geometries with large difference in solar-scattering angles. In order to fully exploit the simultaneous observations and generate consistent AOD retrievals from the two satellites, the authors develop a new "hybrid" aerosol optical depth retrieval algorithm that uses data from both satellites. The algorithm uses both GOES-East and GOES-West visible channel TOA reflectance and daily average AOD from GOES Multi-Angle Implementation of Atmospheric Correction (GOES-MAIAC) on low AOD days (AOD less than 0.3), when diurnal variation of AOD is low, to retrieve surface BRDF (Bidirectional Reflectance Distribution Function). The known BRDF shape is applied on subsequent days to retrieve BRDF and AOD. The algorithm is validated at three AERONET sites over the western US. The AOD retrieval accuracy from the "hybrid" technique using the two satellites is similar to that from one satellite over UCSB (University of California Santa Barbara) and Railroad Valley, Nevada. Improvement of the accuracy is observed at Boulder, Colorado. The correlation coefficients between the GOES AOD and AERONET AOD are in the range of 0.67 to 0.81. More than 74% of AOD retrievals are within the error of ±(0.05 + 0.15 τ) compared to AERONET AOD. The hybrid algorithm has more data coverage compared to the single satellite retrievals over surfaces with high surface reflectance. For single observation areas the number of valid AOD data increases from the use of two-single satellite algorithms by 5–80% for the three sites. With the application of the new algorithm, consistent AOD retrievals and better retrieval coverages can be obtained using the data from the two GOES satellite imagers.

Tropospheric emissions: Monitoring of pollution (TEMPO)

“…The improvement of AOD is in part due to the much lower surface reflectance in the near-UV (where TEMPO measures) and is especially evident when TEMPO is located in the zenith direction of the sun, the direction for which the surface bidirectional reflectance distribution function (BRDF) is largest (J. [116,123]). Multiple measurements taken for the same pixel (from same viewing angle but multiple solar zenith angle and therefore scattering angles) can provide information on aerosol shape [118].…”

A Dark Target Algorithm for the GOSAT TANSO-CAI Sensor in Aerosol Optical Depth Retrieval over Land

“…After several studies suggested that the surface reflectance relationships in the VIS and 2.1 µm bands were angle (4). NDVI SWIR is an aerosol resistant measure of vegetation "greenness," defined in Equation (5).…”

“…Aerosols can absorb or scatter the incoming solar radiation and affect the Earth's radiation budget, thus modulating the warming or cooling of the Earth [2,3]. Ground-level aerosols, also known as particulate matter (PM), are associated with human health and as such are regulated as a priority air quality pollutant [4,5]. Aerosol monitoring contributes significantly to the understanding of the Earth's environmental systems.…”

“…Spectral aerosol optical depth (AOD) is the most frequently used aerosol optical property, because it is directly related to PM loading. AOD derived from satellite observations has thus been used as a proxy for surface PM [5,7]. AOD is a dimensionless measure of aerosol abundance and the amount of solar light extinction (scattering and absorption) caused by aerosol particles passing through a column of the atmosphere [7,8].…”

Retrieval of Aerosol Optical Depth from Optimal Interpolation Approach Applied to SEVIRI Data

“…In the case of another Asian geostationary satellite, the Multi-functional Transport Satellite (MTSAT-1R), visible and mid-IR channels were used in the AOD retrieval [12]. For the western hemisphere, measurements are made by the Geostationary Operational Environmental Satellite (GOES), for which an AOD retrieval algorithm was presented by Zhang et al [13], and recently a new version of the algorithm that uses data from two geostationary satellites, GOES-West and GOES-East [14], was developed.…”