Inverse problem solution methods for remote sounding of the atmosphere regarding retrieval of isotopic tracers of water and carbon cycles

"Global monitoring of carbon and water cycles in the atmosphere is an important task in modern climatology. Some water and carbon gases isotopologues can be representative tracers of the relevant cycles. Quantitative data on relative content of such isotopologues as 13СО2 /12СО2, 13СН4/12СН4 in the atmosphere characterize their emission sources allowing their separation on the natural and
anthropogenic with an estimate of their flow rates. Monitoring of relative contents of HDO/H2(16O) and Н2(18О)/H2(16O) in the atmospheric water vapor provides data to identify hidden processes and trends in atmospheric water cycle. Validation of modern atmospheric general circulation models ECHAM-wiso, LMDz-iso, NASA GISS GCM ModelE and others is important task which can be solved using the isotopic data. Global coverage of isotopic data can be provided only by using satellite remote sensing. The aim of this research project is development of methods for the retrieval of relative content (with respect to the content of main isotopologue) of such greenhouse gases isotopologues as 13CO2, 13CH4, HDO, H2(18O), H2(17O) from satellite and ground-based spectral measurements. Ground-based spectral measurements are used for verification of methods for satellite remote sensing.
This proposal is the further development and implementation of studies supported by the following grants:
INTAS 03-51-6294, RFBR 09-01-00474-а, RFBR 12-01-00801 and megagrant of Government of RF №11.G34.31.0064. Novelty of the proposed research is development of pioneer methods, algorithms and software for solution of inverse problems regarding remote sensing of the atmosphere combining both thermal infrared and near infrared spectral ranges.
The project is based on ongoing development of inverse task solution methods with a priori information in Institute of Mathematics and Mechanics UB RAS and original software package FIREARMS (Fine InfraRed Explorer for Atmospheric Radiations MeasurementS) developing in Climate and Environmental Physics Laboratory of Ural Federal University for forward and inverse tasks of infrared radiative transfer in cloudless atmosphere.
To achieve of this goal it is planned to perform the following tasks:
- modeling of radiative transfer of thermal and near infrared radiation in cloudless atmosphere for various latitudes, seasons, surface types using modern databases of atmospheric molecule spectral parameters such as HITRAN and GEISA;
- search and selection of enough solitary and strong spectral features in micro-windows belonging to given isotopologues in simulated high resolution spectra for satellite and ground-based geometries of sounding for various latitudes, seasons, and surface types;
- analysis of the simulated atmospheric spectra within the selected micro-windows in order to most prospective micro-windows determination for remote sensing of the given isotopologues in the atmosphere to minimize errors in result of retrieval of the relative contents of the given isotopologues in the atmosphere due to errors in retrieved tropospheric temperature profiles;
- development and testing of original methods for the retrieval of relative content of given isotopologues from infrared spectra measured by satellite and ground-based spectrometers with high spectral resolution in thermal and near IR ranges with the use of variety of a priori information for ill-posed task solution constraining;
- error analysis for inverse task solutions including errors in modern spectral databases HITRAN, GEISA and in advanced line lists for the given isotopologues, influence of spectral resolution, signal to noise ratio, a priori statistics, etc.
As input data we plan to use spectra measured in thermal infrared by IASI onboard ESA satellite METOPA and METOP-B and spectra of TANSO-FTS onboard Japanese satellite GOSAT. Original spectral data measured by Bruker IFS-125M at UrFU atmospheric station in Kourovka will be used for validation of newly developed methods and algorithms for satellite remote sensing.
The novelty of proposed project is in satellite remote sensing of carbon gases isotopologues (13СО2, 13СН4) using infrared Fourier spectrometers of high spectral resolution in thermal infrared. In addition, it is planned to develop the methods of joint use of thermal and near infrared ranges measurements for the retrieval of given isotopologues relative content with the accuracy sufficient for climate studies. Another innovative task is retrieval of relative content of Н2(17O) in the atmosphere from infrared spectra measured by ground-based Fourier transform spectrometers of high spectral resolution in near IR range. As for applied aspect of the project, the original software for forward and inverse radiative transfer modeling accounting multiple scattering in near infrared spectral region for cloudless conditions will be developed."