Improving Remote Sensing of Aerosol Optical Depth over Land by Polarimetric Measurements at 1640 nm: Airborne Test in North China

Abstract

An improved aerosol retrieval algorithm based on the Advanced Multi-angular Polarized Radiometer (AMPR) is presented to illustrate the utility of additional 1640-nm observations for measuring aerosol optical depth (AOD) over land using look-up table approaches. Spectral neutrality of the polarized surface reflectance over visible to short-wavelength infrared bands is verified, and the 1640-nm measurements corrected for atmospheric effects are used to estimate the polarized surface reflectance at shorter wavelengths. The AMPR measurements over the Beijing-Tianjin-Hebei region in north China reveal that the polarized surface reflectance of 670, 865 and 1640 nm are highly correlated with correlation slopes close to one (0.985 and 1.03) when the scattering angle is OPEN ACCESS Remote Sens. 2015, 7 6241 less than 145°. The 1640-nm measurements are then employed to estimate polarized surface reflectance at shorter wavelengths for each single viewing direction, which are then used to improve the retrieval of AOD over land. The comparison between AMPR retrievals and ground-based Sun-sky radiometer measurements during three experimental flights illustrates that this approach retrieves AOD at 865 nm with uncertainties ranging from 0.01 to 0.06, while AOD varies from 0.05 to 0.17.

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

“…Guo et al [33] revealed the spatial and temporal characteristics of AOD values during 1980-2008 over mainland China using the TOMS AOD and MODIS AOD products (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008). Meanwhile, many studies on the spatial and temporal variations of AOD values in regional scale in Chinawere conducted using meteorological measurement and satellite signals [10,26,[34][35][36][37][38][39][40]. However, few studies have been made for analyzing the characteristics and driving factors of AOD values in different climate zones and terrain features over mainland China, due to the relative sparse AOD and meteorological measurements.…”

Improving Remote Sensing of Aerosol Microphysical Properties by Near‐Infrared Polarimetric Measurements Over Vegetated Land: Information Content Analysis

“…In the first scenario (P1), we consider only the polarized radiances Q and U at 490, 670, and 870 nm corresponding to the POLDER/Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar instrument (Deuzé et al, , ), and the 490 nm band is used instead of 443 nm (Tanré et al, ). Polarimetric measurements at 1,610 nm are added to the second scenario (P2) to represent the airborne Advanced Atmosphere Multiangle Polarization Radiometer instrument (Qie et al, ). Next, the third scenario (P3) is defined identical to scenario P2 in addition to polarimetric measurements at 2,250 nm to represent the MICROPOL instrument (Goloub et al, ; Waquet et al, ; Waquet, Cairns, et al, ).…”

“…Recently, another new spaceborne instrument known as the Polarized Scanning Atmospheric Corrector (PSAC), which was designed with multispectral single‐viewing polarimetric measurements, was also developed in China to provide aerosol properties for the atmospheric corrections of other sensors onboard the same satellite. The airborne prototype of PSAC, namely, the Advanced Atmosphere Multiangle Polarization Radiometer, has been employed for some aerosol retrieval tests (Hou et al, ; Qie et al, ; Wang, Sun, et al, ; Wang et al, ).…”

The Normalized Difference Vegetation Index and Angular Variation of Surface Spectral Polarized Reflectance Relationships: Improvements on Aerosol Remote Sensing Over Land

“…The spectral sensitivities of the polarized reflectances obtained from research scanning polarimeter and micropolarimeter measurements over vegetated surfaces were studied previously Waquet, Léon, et al, 2009), and the offsets of the regression lines were determined as small with slopes close to 1. This conclusion has been applied to aerosol retrieval for a number of airborne polarimetric instruments, such as the research scanning polarimeter and the advanced multi-angle polarization radiometer (Qie et al, 2015;Wang et al, 2014Wang et al, , 2017). This conclusion has been applied to aerosol retrieval for a number of airborne polarimetric instruments, such as the research scanning polarimeter and the advanced multi-angle polarization radiometer (Qie et al, 2015;Wang et al, 2014Wang et al, , 2017).…”