Detection of optical path in spectroscopic space‐based observations of greenhouse gases: Application to GOSAT data processing

[1] We present a method to detect optical path modification due to atmospheric light scattering in space-based greenhouse gas spectroscopic sounding. This method, which was applied to the analysis of radiance spectra measured by the Greenhouse Gases Observing Satellite (GOSAT), is based on the path length probability density function (PPDF) and on retrieval of PPDF parameters from radiance spectra in the oxygen A-band of absorption at 0.76 μm. We show that these parameters can be effectively used to characterize the impact of atmospheric light scattering on carbon dioxide retrieval in the atmospheric carbon dioxide (CO2) absorption bands at 1.6 μm and 2.0 μm. The threshold for PPDF parameters is set so that the optical-path modification is negligible, and these settings are recommended as a basic guideline for selecting the clearest atmospheric scenarios. An example of data processing for six global GOSAT repeat cycles in April and July 2009 shows that PPDF-based selection efficiently removes CO2 retrieval biases associated with subvisible cirrus and sandstorm activities.

[1]  Hajime Okamoto,et al.  Global three‐dimensional simulation of aerosol optical thickness distribution of various origins , 2000 .

[2]  François-Marie Bréon,et al.  Contribution of the Orbiting Carbon Observatory to the estimation of CO2 sources and sinks: Theoretical study in a variational data assimilation framework , 2007 .

[3]  Ilse Aben,et al.  Uncertainties in the space-based measurements of CO2 columns due to scattering in the Earth's atmosphere , 2007 .

[4]  Hartmut Boesch,et al.  Orbiting Carbon Observatory: Inverse method and prospective error analysis , 2008 .

[5]  Haruma Ishida,et al.  Development of an unbiased cloud detection algorithm for a spaceborne multispectral imager , 2009 .

[6]  Masakatsu Nakajima,et al.  Thermal and near infrared sensor for carbon observation Fourier-transform spectrometer on the Greenhouse Gases Observing Satellite for greenhouse gases monitoring. , 2009, Applied optics.

[7]  Tatsuya Yokota,et al.  On the accuracy of the CO2 surface fluxes to be estimated from the GOSAT observations , 2009 .

[8]  James D. Spinhirne,et al.  Scattering layer statistics from space borne GLAS observations , 2005 .

[9]  Michael Buchwitz,et al.  A method for improved SCIAMACHY CO 2 retrieval in the presence of optically thin clouds , 2009 .

[10]  Ilse Aben,et al.  Evidence of systematic errors in SCIAMACHY-observed CO 2 due to aerosols , 2005 .

[11]  Ilse Aben,et al.  Retrievals of atmospheric CO2 from simulated space-borne measurements of backscattered near-infrared sunlight: accounting for aerosol effects. , 2009, Applied optics.

[12]  Gang Li,et al.  The HITRAN 2008 molecular spectroscopic database , 2005 .

[13]  François-Marie Bréon,et al.  Spaceborne estimate of atmospheric CO2 column by use of the differential absorption method: error analysis. , 2003, Applied optics.

[14]  Tatsuya Yokota,et al.  Role of simulated GOSAT total column CO2 observations in surface CO2 flux uncertainty reduction , 2009 .

[15]  S. Aoki,et al.  Carbon dioxide variations in the stratosphere over Japan, Scandinavia and Antarctica , 2003 .

[16]  Philippe Ciais,et al.  Transcom 3 inversion intercomparison: Model mean results for the estimation of seasonal carbon sources and sinks , 2004, Global Biogeochemical Cycles.

[17]  Nicholas C. Parazoo,et al.  TransCom model simulations of hourly atmospheric CO2: Analysis of synoptic‐scale variations for the period 2002–2003 , 2008 .

[18]  Scott C. Doney,et al.  Carbon source/sink information provided by column CO 2 measurements from the Orbiting Carbon Observatory , 2008 .

[19]  S. Wofsy,et al.  Mean Ages of Stratospheric Air Derived from in Situ Observations of Co2, Ch4, and N2o , 2013 .

[20]  P. Rayner,et al.  The utility of remotely sensed CO2 concentration data in surface source inversions , 2001 .

[21]  Shamil Maksyutov,et al.  NIES/FRCGC Global Atmospheric Tracer Transport Model: Description, Validation, and Surface Sources and Sinks Inversion , 2008 .

[22]  Tatsuya Yokota,et al.  Retrieval algorithm for CO 2 and CH 4 column abundances from short-wavelength infrared spectral observations by the Greenhouse gases observing satellite , 2010 .

[23]  Tatsuya Yokota,et al.  PPDF‐based method to account for atmospheric light scattering in observations of carbon dioxide from space , 2008 .

[24]  Sarah L. Dance,et al.  Estimating surface CO 2 fluxes from space-borne CO 2 dry air mole fraction observations using an ensemble Kalman Filter , 2008 .

[25]  Michael Buchwitz,et al.  A near-infrared optimized DOAS method for the fast global retrieval of atmospheric CH4 , 2000 .

[26]  Tatsuya Yokota,et al.  Parameterization of aerosol and cirrus cloud effects on reflected sunlight spectra measured from space: application of the equivalence theorem. , 2006, Applied optics.

[27]  Tatsuya Yokota,et al.  An improved photon path length probability density function–based radiative transfer model for space‐based observation of greenhouse gases , 2009 .

[28]  Itaru Sano,et al.  A Study of Aerosol and Cloud Information Retrievals from CAI Imager on Board GOSAT Satellite , 2008 .

[29]  Philippe Ciais,et al.  Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO2 , 2007, Science.

[30]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[31]  Shamil Maksyutov,et al.  Mass-conserving tracer transport modelling on a reduced latitude-longitude grid , 2010 .

[32]  Peter J. Rayner,et al.  Global observations of the carbon budget, 2, CO2 column from differential absorption of reflected sunlight in the 1.61 μm band of CO2 , 2002 .

[33]  Jianping Mao,et al.  Sensitivity studies for space-based measurement of atmospheric total column carbon dioxide by reflected sunlight. , 2004, Applied optics.

[34]  R. Vautard,et al.  TransCom model simulations of hourly atmospheric CO2: Experimental overview and diurnal cycle results for 2002 , 2008, Global Biogeochemical Cycles.