Coupled Interface Atmosphere - Ocean (CIAO) code to account for polarization effects in space- based observations of greenhouse gases
Abstract
Over the past two centuries, anthropogenic emissions of greenhouse gases have increased to an alarming situation. The Greenhouse Gases Observing Satellite (GOSAT), which is in orbit since 23 January 2009, has considerable promise to improve surface flux inverse modeling. Algorithms for the operational satellite data processing must accurately account for atmospheric light scattering caused by aerosols and thin upper tropospheric clouds. Near-infrared Sensor for Carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) in short wavelength infrared (SWIR) region measures two polarized components spectra for both P- and S- polarization states. The current versions of the operational algorithms for GOSAT data processing utilize scalar radiance that is produced from combination of the polarized signals. To process both polarization states within the full physics algorithms, that utilized the solution of vectorial radiative transfer calculations, is still time consuming when utilizing the radiative transfer codes such as DISORT, P-star, RT3, SCIATRAN. In this paper we report an improved rapid code for spectral radiative transfer calculations that is refereed to as Coupled Interface Atmosphere - Ocean (CIAO). This program could be utilized in further versions of full physics algorithm for direct processing of both polarized states. Another application of this method for space-based observations of greenhouse gases resides in testing of photon path length probability density function (PPDF) method that effectively accounts of atmospheric light scattering. The CIAO code is based on the solution of the vectorial radiative transfer equation (VRTE) with elimination of the anisotropic part of the radiance angular distribution that allows finding the solution of the discretized VRTE in the closed matrix form. There are no any limitations of the media parameters in this code. The comparison of this algorithm with known ones such as DISORT, P-star, RT3, and SCIATRAN showed that similar accuracy could be accessed under significantly lower time consuming. The difference in computation time reaches one order of magnitude and even higher with increasing the degree of scattering anisotropy the total atmospheric optical depth
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.A51C0112B
- Keywords:
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- 0360 ATMOSPHERIC COMPOSITION AND STRUCTURE / Radiation: transmission and scattering