JAXA EORC GOSAT retrieval

1. Introduction

TANSO-FTS-2 simultaneously observes both reflected shortwave-infrared (SWIR) solar light and thermal infrared (TIR) emissions with a single FTS-mechanism. We use an entire TIR band to add only one piece of information in the troposphere. Assuming the CO2 and CH4 partial column-averaged dry air mole fractions of the two individual layers of LT and UT are constant, we retrieve the difference between the partial column-averaged dry mole fractions of the lower troposphere (LT) and upper troposphere (UT) by combining TIR and SWIR spectra data simultaneously, constraining accurate total column density. The pressure-height ranges of LT and UT are taken as 1 -0.6 and 0.6 -0.2 of the retrieved surface pressure, respectively.

2. Data description

About parameter

• yyyy/mm/dd and hh:mm:ss :
  
  Observation time defined as the start time of the exposure.
  
• XCO2_apr:
  
  A priori of the column averaged dry air mole fraction of CO2 calculated from CarbonTracker.
  units = ppmv
• XCO2_tot:
  
  Retrieved column averaged dry air mole fraction of CO2.
  units = ppmv
• XCO2_low:
  
  Retrieved dry air mole fraction of CO2 in the lower troposphere defined as the partial layer from Psrf_ret up to 0.6 Psrf_ret.
  units = ppmv
• XCO2_upp:
  
  Retrieved dry air mole fraction of CO2 in the upper troposphere defined as the partial layer from 0.6 Psrf_ret up to 0.2 Psrf_ret.
  units = ppmv
• XCH4_apr
  A priori of the column averaged dry air mole fraction of CH4 calculated from CarbonTracker-CH4.
  units = ppmv
• XCH4_tot
  Retrieved column averaged dry air mole fraction of CH4.
  units = ppmv
• XCH4_low
  Retrieved dry air mole fraction of CH4 in the lower troposphere defined as the partial layer from Psrf_ret up to 0.6 Psrf_ret.
  units = ppmv
• XCH4_upp
  Retrieved dry air mole fraction of CH4 in the upper troposphere defined as the partial layer from 0.6 Psrf_ret up to 0.2 Psrf_ret.
  units = ppmv
• XCO_apr:
  
  A priori of the column averaged dry air mole fraction of CO calculated from CarbonTracker.
  units = ppmv
• XCO_tot:
  
  Retrieved column averaged dry air mole fraction of CO.
  units = ppmv
• Psrf_apr
  A priori of the surface pressure calculated from NCEP Reanalysis 2. units = hPa
• Psrf_ret
  Retrieved surface pressure. units = ppmv
• AOT_076
  Retrieved aerosol optical thickness at 0.76 µm.
• AOT_160
  Retrieved aerosol optical thickness at 1.6 µm.
• AOT_206
  Retrieved aerosol optical thickness at 2.06 µm.
• SIF
  Retrieved solar-induces fluorescence which is assumed to be constant in the O2 A band.
  units = 10^-9 W/cm²/sr/cm^-1
• Cloud
  Cloud index from onboard camera images.
  0 = clear
  1 = cloudy
  -1 = not available
• latitude and longitude
  Observation location.
  units = degree

3. Citation

Algorithm:

• Kikuchi, N., Kuze, A., Kataoka, F., Shiomi, K., Hashimoto, M., Suto, H., et al. (2017), Three-dimensional distribution of greenhouse gas concentrations over megacities observed by GOSAT, AGU fall meeting.
• The SWIR part of the algorithm is described by Kikuchi et al. (2016): Kikuchi, N., Y. Yoshida, O. Uchino, J. Morino, and T. Yokota: An advanced retrieval algorithm for greenhouse gases using polarization information measured by GOSAT TANSO-FTS SWIR I: Simulation study, J. Geophys. Res., 121, 21, 13129-13157, doi:10.1002/2015JD024720, 2016

Ancillary data

• NCEP_Reanalysis 2 data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd/
• CarbonTracker results provided by NOAA ESRL, Boulder, Colorado, USA from the website at http://carbontracker.noaa.gov.
• CarbonTracker-CH4 results provided by NOAA ESRL, Boulder, Colorado, USA from the website at http://www.esrl.noaa.gov/gmd/ccgg/carbontracker-ch4/.

4. Links

• CONTRAIL
  http://www.cger.nies.go.jp/contrail/
• TCCON
  https://tccon-wiki.caltech.edu/

5. Acknowledgments

GHG Long term trend viewer was developed by JAXA/EORC. We would like to thank NIES GOSAT project members, and JAXA GOSAT project members.