Hongqing Liu

Preliminary evaluation of S‐NPP VIIRS aerosol optical thickness

The Visible Infrared Imaging Radiometer Suite (VIIRS) is the next-generation polar-orbiting operational environmental sensor with a capability for global aerosol observations. The VIIRS aerosol Environmental Data Record (EDR) is expected to continue the decade-long successful multispectral aerosol retrieval from the NASAs Earth Observing System Moderate Resolution Imaging Spectroradiometer (MODIS) for scientific research and applications. Since the launch of the Suomi National Polar-orbiting Partnership (S-NPP), the VIIRS aerosol calibration/validation team has been continuously monitoring, evaluating, and improving the performance of VIIRS aerosol retrievals. In this study, the VIIRS aerosol optical thickness (AOT) at 550 nm EDR at current Provisional maturity level is evaluated by comparing it with MODIS retrievals and measurements from the Aerosol Robotic Network (AERONET) and the Maritime Aerosol Network (MAN). The VIIRS global mean AOT at 550 nm differs from that of MODIS by approximately −0.01 over ocean and 0.03 over land (0.00 and −0.01 for the collocated retrievals) but shows larger regional biases. Global validation with AERONET and with MAN measurements shows biases of 0.01 over ocean and −0.01 over land, with about 64% and 71% of retrievals falling within the expected uncertainty range established by MODIS over ocean (±(0.03 + 0.05AOT)) and over land (±(0.05 + 0.15AOT)), respectively. The VIIRS retrievals over land exhibit slight overestimation over vegetated surfaces and underestimation over soil-dominated surfaces. These results show that the VIIRS AOT at 550 nm product provides a solid global data set for quantitative scientific investigations and environmental monitoring.

An Evaluation of the GOES-R ABI Aerosol Retrieval Algorithm

A multi-channel aerosol retrieval algorithm has been developed for the Advanced Baseline Imager (ABI) onboard the next generation US Geostationary Operational Environmental Satellite (GOES-R series). Testing and evaluation of this algorithm is carried out with model simulated and satellite-observed multi-spectral reflectance. Sensitivity tests with synthetic reflectance show that ABI retrieved aerosol optical depth at 0.55 mum (tau0.55 mum) is expected to change by 5% and 9% (14% and 24%) on average over water (land) corresponding to 3% and 5% uncertainties in calibration. Model identification is expected to have a 50%-60% success rate for a 3%-5% calibration uncertainty. Performance of ABI aerosol retrieval is evaluated with MODIS observations. Compared with AERONET ground measurements, on average, retrieved tau0.55 mum differs from AERONET measurements by -0.02plusmn0.05 over water and 0.05plusmn0.17 over land. The effect of sensor polarization sensitivity on ABI aerosol retrievals is also estimated as a bias of -0.01 over water and -0.05 over land for the retrieved tau0.55 mum.