Retrieval of biomass burning aerosols with combination of near-UV radiance and near -IR polarimetry I.Sano, S.Mukai, M. Nakata (Kinki University, Japan), B. Holben (NASA/GSFC, USA) and N. Kikuchi (NIES, Japan)

Objective Carbonaceous aerosol plays an important role not only in climate but also in aerosol study. It is difficult of modeling the biomass burning aerosols because their properties are widely varied. This work intends to develop an algorithm for retrieval of the biomass burning aerosols (BBA) based on combined use of near-UV radiance by GOSAT/CAI & near-IR polarization by PARASOL/POLDER.

TANSO - CAI on GOSAT CAI – Cloud Aerosol Imager a complimentary sensor for Fourier Transform Spectrometer (FTS) launched on 23rd January, Four observing wavelengths : 380, 670, 870, 1600 nm. Level 1 data provide us with the TOA reflectance of the Earth.

Time difference between GOSAT/CAI and PARASOL/POLDER ± 5 min ± 30 min Apr. 25, 2009

Retrieval flow for BBA

Estimation of ground reflectance 2nd minimum reflectance is chosen during a month at each pixel in order to reduce the cloud shadow effects. Furthermore, the cloud shadow effect on the neighbors is considered in detail. Rayleigh atmospheric correction is adopted with DEM data. R Ground : GOSAT / CAI (BGR: 380, 870, 670 nm)

GOSAT / CAI (BGR: 380, 870, 670 nm) Estimation of atmospheric light Satellite image2nd min imageAtmos. light image

Retrieval flow for BBA

Heterogeneous particles should be considered for carbonaceous aerosols. Heterogeneous particles is approximately interpreted by using the refractive index calculated by Maxwell-Garnett mixing rule. Matrix Inclusions f [%] : volume fraction of inclusions against matrix ex)Matrix : m= i Inclusions: m= i measurements value for carbon Aerosol model : carbonaceous aerosols

Refractive index (0.38 µm) from Maxwell-Garnett Single scattering albedo (0.38 µm) f : " SSA is decreasing according to the volume fraction of carbonaceous inclusions."

Retrieval flow for BBA

Vertical profile of biomass burning plume CALIPSO results show that the Biomass burning plume was concentrated under 3-5 km height. Aerosol vertical structure is considered based on the US std profile with plume concentration under 5 km. CALIPSO 532nm Backscatter, on Aug. 8, 2010

Retrieval flow for BBA

A set of  a,  and  is retrieved for each aerosol model based on POLDER Q U (670, 870) and GOSAT CAI I (380) R (380 nm) PR (670 nm) PR (870 nm) R (670 nm) R (380 nm) Retrieval process in practice

Aerosol properties over Central Russia on August 5, 2010

Aerosol properties over Central Russia on August 8, 2010

Validation of retrieved results aa Ångström exponent The AERONET AOT and Angstrom data are selected during the ± 30 min against the satellite overpass. Error bars : Min and max values of the measurements.

Summary It is found that combination use of near-UV radiance and polarized radiance in the near-IR has a potential to retrieve the carbonaceous aerosols. As results, aerosol optical thickness (  a ), Angstrom exponent (  ), and single scattering albedo (  ) are retrieved. The retrieved values of  a and  are partially validated with AERONET ground sun photometric data. It has been shown that optical properties of biomass burning aerosols present temporal variations over the plume. e.g., plume core (  a >5);   1.5,   0.85 surrounding (  a <5);  < 1.3,  < 0.8

Acknowledgement The authors thank to NIES GOSAT team, CNES PARASOL team, Dr. Natalia Chubarova, and NASA AERONET team for operations of their instrument and data distributions. This work was supported by the Greenhouse Gases Observing Satellite (GOSAT) Science Project of the National Institute of Environmental Studies (NIES), Tsukuba, Japan, and GCOM-C1 SGLI project by JAXA.

GCOM-C / SGLI Polarization (670, 870 nm) (2ch) with +/- 45 degrees along track tilting :1000m Near UV - N IR(11ch): 250 m Shortwave infrared(4ch) : 250 / 1000m Thermal infrared (2ch): 500 m (JAXA)

GCOM-C / SGLI Band c SW11050 SW21380 SW31630 SW42210 T110.8 T212.0 Band c VN1380 VN2412 VN3443 VN4490 VN5530 VN6565 VN VN VN9763 VN VN Band c P P VNIR Polarization TIR +/- 45 deg. along track tilting