RemoTeC version 2.0: XCO2 and XCH4 retrievals from GOSAT
Abstract
The RemoTeC algorithm is dedicated to the accurate retrieval of the column average dry air mole fractions of carbon dioxide (XCO2) and methane (XCH4) from solar backscatter measurements in the shortwave infrared spectral range such as conducted by GOSAT and in the future, by OCO-2 and the Sentinel-5 Precursor. RemoTeC simultaneously retrieves XCO2 and XCH4 together with scattering properties of the atmosphere in order to take into account lightpath modification due to particle scattering. Version 1.0 of the algorithm has been shown to yield greenhouse gas concentrations from GOSAT with an accuracy of generally better than 0.5% and a precision better than 1%. Albeit being small, some systematic biases such as a Southern hemisphere high-bias for XCO2 hindered inverse modeling of sources and sink.
Here, we report on progress made toward RemoTeC version 2.0. Systematic errors have been greatly reduced by (1) refining the Philipps-Tikhonov inverse method, (2) implementing a meteorological database based on high spatial resolution (0.75x0.75 degree) ECMWF ERA interim, (3) replacing the topography database, and (4) developing a bias correction scheme based on error correlations with retrieval and ambient parameters. When evaluated against ground-based observations of the Total Carbon Column Observing Network (TCCON), RemoTeC version 2.0 retrievals show improvement among all statistical diagnostics such regional bias variability and data scatter for both, XCO2 and XCH4. Further, the Southern hemisphere bias for XCO2 is largely reduced. We show that inverse modeling of sources and sinks benefits greatly from these improvements.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.A41N..05B
- Keywords:
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- 0315 ATMOSPHERIC COMPOSITION AND STRUCTURE / Biosphere/atmosphere interactions;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0414 BIOGEOSCIENCES / Biogeochemical cycles;
- processes;
- and modeling;
- 3360 ATMOSPHERIC PROCESSES / Remote sensing