Summary of the Final Report of Research Results1) Title of the proposed research
Cloud remote sensing using GOSAT instruments
2) Principal Investigator (PI) and Co-Investigators (Co-Is)
PI:Dr. Alexander Kokhanovsky
3) PI’s affiliation
The University of Bremen
4) Summary of the Final Report of Research Results
The work has been composed of two separate work packages. The first one was centered aroundthe inter-comparison of the radiative transfer models used in the solution of the inverse problems.
The results are given by Kokhanovsky et al. (2010). The following algorithms have beeninter-compared: SCIATRAN (University of Bremen, Bremen, Germany), PSTAR (NationalInstitute of Environmental Studies, Tsukuba, Japan), RAY (Institute of Physics, Minsk, Belarus),MYSTIC (University of Munich, Munich, Germany), SOSVRT(Institute of AtmosphericPhysics, Beijing, China), 3DMCPOL (Lille University, Lille, France), MVDOM (PowerEngineering Institute, Moscow, Russia). We have found a high accuracy of all above –mentioned algorithms as far as the first three Stokes parameters are of concern. Theinter-comparisons have been performed for aerosol, cloud and Rayleigh phase functions for thecase of black underlying surface.The second work package was aimed at the application of thesemi-analytical cloud retrieval algorithm SACURA developed at University of Bremen to theFTS data. In particular, we have applied SACURA to the TANSO-FTS observations in theoxygen A-band absorption spectral range. The task was to derive cloud optical thickness (COT)and cloud bottom/top heights (CBH/CTH). The TANSO-FTS performs measurements at about1000 wavelengths in the oxygen A-band with the FWHM (at each wavelength in the oxygenA-band) equal to 0.022nm. Such detailed measurements are needed to derive the trace gas
concentrations. However, fine spectral resolution is not needed to derive just three parameters ofclouds (CBH, CTH, COT). Therefore, the spectral observations of the TANSO-FTS weredegraded to that of SCIAMACHY (FWHM=0.48nm) flown on board ENVISAT(March 1, 2002
- April 8, 2012) and then the retrievals have been performed. This also enables fast retrievals
needed for the processing of large satellite datasets.
The top of atmosphere reflectance was calculated as

R=Here µ0 is the cosine of the solar zenith angle,π (Is + I p ).
2 µ0 E0(1)I s , I p are the s- and p- components of the reflected

light intensity as detected by the TANSO-FTS (Kuze et al., 2009). The solar irradiance E0 was
calculated as recommended by O’Dell (2012). The retrievals have been performed for the cloudscene located at 30.8946N, 161.5325E (case 1) 29.5398N, 161.2108E (case2). The measurements
have been performed on April 23, 2009 from the GOSAT satellite. For the case 1, we have derived
the cloud optical thickness of 8, CBH=0.54km, CTH=3.83km, cloud albedo 0.5. For the case 2, wehave derived: COT=14.16, CBH=0.22km, CTH=1.53km, and cloud albedo of 0.63. The accuracy of
fit is demonstrated in Fig. 1.

1.0

convoluted GOSAT spectrum
retrieved spectrum

COT=8.0

reflection function

0.8

0.6

0.4

0.2

0.0758760762764

wavelength,nma)

766

7687701.0

convoluted GOSAT spectrum
retrieved spectrum

COT=14.16

reflection function

0.8

0.6

0.4

0.20.0758760762764766768770

wavelength,nmb)
Figure 1. The accuracy of fits for the cases 1(a) and 2(b) as derived from GOSAT
observations.
5) List of publications relating to the proposed research
A. A. Kokhanovsky, V. P. Budak, C. Cornet, M. Duan, C. Emde, I. L. Katsev, D. A. Klyukov, S. V.
Korkin, L. C-Labonnote, B. Mayer, Q. Min, T. Nakajima, Y. Ota, A. S. Prikhach, V. V. Rozanov, T.
Yokota, and E. P. Zege. Benchmark results in vector atmospheric radiative transfer. J. Quant.
Spectrosc. Radiat. Transfer, 111(12-13):1931 - 1946, 2010.