The Aerosol Characterization from Polarimeter and Lidar (ACEPOL) airborne field campaign

Abstract

Abstract. In the fall of 2017, an airborne field campaign was conducted from the NASA Armstrong Flight Research Center in Palmdale, California, to advance the remote sensing of aerosols and clouds with multi-angle polarimeters (MAP) and lidars. The Aerosol Characterization from Polarimeter and Lidar (ACEPOL) campaign was jointly sponsored by NASA and the Netherlands Institute for Space Research (SRON). Six instruments were deployed on the ER-2 high-altitude aircraft. Four were MAPs: the Airborne Hyper Angular Rainbow Polarimeter (AirHARP), the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI), the Airborne Spectrometer for Planetary EXploration (SPEX airborne), and the Research Scanning Polarimeter (RSP). The remainder were lidars, including the Cloud Physics Lidar (CPL) and the High Spectral Resolution Lidar 2 (HSRL-2). The southern California base of ACEPOL enabled observation of a wide variety of scene types, including urban, desert, forest, coastal ocean, and agricultural areas, with clear, cloudy, polluted, and pristine atmospheric conditions. Flights were performed in coordination with satellite overpasses and ground-based observations, including the Ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI), sun photometers, and a surface reflectance spectrometer. ACEPOL is a resource for remote sensing communities as they prepare for the next generation of spaceborne MAP and lidar missions. Data are appropriate for algorithm development and testing, instrument intercomparison, and investigations of active and passive instrument data fusion. They are freely available to the public. The DOI for the primary database is https://doi.org/10.5067/SUBORBITAL/ACEPOL2017/DATA001 (ACEPOL Science Team, 2017), while for AirMSPI it is https://doi.org/10.5067/AIRCRAFT/AIRMSPI/ACEPOL/RADIANCE/ELLIPSOID_V006 and https://doi.org/10.5067/AIRCRAFT/AIRMSPI/ACEPOL/RADIANCE/TERRAIN_V006 (ACEPOL AirMSPI 75 Science Team, 2017a, b). GroundMSPI data are at https://doi.org/10.5067/GROUND/GROUNDMSPI/ACEPOL/RADIANCE_v009 (GroundMSPI Science Team, 2017). Table 3 lists further details of these archives. This paper describes ACEPOL for potential data users and also provides an outline of requirements for future field missions with similar objectives.

Validation of GRASP algorithm product from POLDER/PARASOL data and assessment of multi-angular polarimetry potential for aerosol monitoring

“…Nevertheless, aerosol effects remain the largest contributor to forcing uncertainty according to the Intergovernmental Panel on Climate Change (IPCC) assessments (Boucher et al, 2013); the aerosol effective radiative forcing has been recently assessed to be between −2.0 and −0.4 W/m 2 with a 90 % likelihood (Bellouin et al, 2020). Over the past few decades, satellite remote sensing techniques have developed rapidly and extensively, and various (primarily photometric) instruments have been developed and deployed to monitor atmospheric aerosols from space (Bréon et al, 2011;Dubovik et al, 2019;King et al, 1999;Kokhanovsky et al, 2015;Li et al, 2009;Tanré et al, 2011). While the design and capabilities of the photometric observations are constantly evolving, the greatest improvement has been in the form of multi-angular multi-spectral polarimetry (MAP) measurements (Hansen et al, 1995;Hasekamp and Landgraf, 2007;Knobelspiesse et al, 2012;Mishchenko and Travis, 1997;Mishchenko et al, 2004;Waquet et al, 2009;Tanré et al, 2011).…”

Efficient multi-angle polarimetric inversion of aerosols and ocean color powered by a deep neural network forward model

“…To retrieve the aerosol information from polarimetric measurements over oceans, several advanced aerosol retrieval algorithms have been developed for both airborne and spaceborne MAPs, such as POLDER/PARASOL (Hasekamp et al, 2011;Dubovik et al, 2011Dubovik et al, , 2014Li et al, 2019;Hasekamp et al, 2019b;Chen et al, 2020), the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) (Xu et al, 2016(Xu et al, , 2019, SPEX airborne (the airborne version of SPEXone) (Fu and Hasekamp, 2018;Fu et al, 2020;Fan et al, 2019), the Research Scanning Polarimeter (RSP) (Chowdhary et al, 2005;Wu et al, 2015;Stamnes et al, 2018;Gao et al, 2018Gao et al, , 2019Gao et al, , 2020, and the Directional Polarimetric Camera (DPC) on board Gaofen-5 (Wang et al, 2014;Li et al, 2018). The retrieval algorithms are mostly based on iterative optimization approaches that utilize vector radiative transfer (RT) models as the forward model.…”

Retrieval of aerosol properties from Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) observations during ACEPOL 2017

“…It is open-source software and is available free to noncommercial users for downloading from the website https: //www.grasp-open.com/ (last access: 8 September 2020). GRASP first demonstrated its overall capability in an aerosol retrieval test study (Kokhanovsky et al, 2010). It has gone on to prove itself in a variety of real-world applications (Chen et al, 2018(Chen et al, , 2019Frouin et al, 2019;Li et al, 2019;Schuster et al, 2019;Torres et al, 2017).…”

“…There are several aerosol retrieval algorithms specifically optimized for MAPs, which include the SRON multi-mode inversion algorithm for SPEX airborne (Fu et al, 2020;Fu and Hasekamp, 2018); Microphysical Aerosol Property from Polarimeters (MAPP) (Stamnes et al, 2018) and GISS/RSP algorithm (Knobelspiesse et al, 2011;Waquet et al, 2009) for RSP; and correlated multi-pixel and joint retrieval algorithm for AirM-SPI developed at Jet Propulsion Laboratory (JPL) (Xu et al, 2017. This list is not complete, and for a comprehensive review of the polarimetric remote sensing of atmospheric aerosols based on MAPs, we encourage the readers to refer to several reviews in the literature (Dubovik et al, 2019;Kokhanovsky et al, 2010Kokhanovsky et al, , 2015Remer et al, 2019). In this work, we focus on retrieval of aerosol properties using Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) data, the airborne version of HARP, from the NASA aircraft campaign Aerosol Characterization from Polarimeter and Lidar (ACEPOL).…”