Update on the GOSAT TANSO–FTS SWIR Level 2 retrieval algorithm
<p>The National Institute for Environmental Studies has provided the column-averaged dry-air mole fraction of carbon dioxide and methane (XCO<span class="inline-formula"><sub>2</sub></span> and XCH<span class="inline-formula"><sub>4</s...
| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/16/1477/2023/amt-16-1477-2023.pdf |
| Summary: | <p>The National Institute for Environmental Studies has
provided the column-averaged dry-air mole fraction of carbon dioxide and
methane (XCO<span class="inline-formula"><sub>2</sub></span> and XCH<span class="inline-formula"><sub>4</sub>)</span> products (L2 products) obtained from the
Greenhouse gases Observing SATellite (GOSAT) for more than a decade. Recently, we
updated the retrieval algorithm used to produce the new L2 product, V03.00.
The main changes from the previous version (V02) of the retrieval algorithm
are the treatment of cirrus clouds, the degradation model of the Thermal And
Near-infrared Spectrometer for carbon Observation–Fourier Transform
Spectrometer (TANSO–FTS), solar irradiance spectra, and gas absorption
coefficient tables. The retrieval results from the updated algorithm showed
improvements in fitting accuracies in the O<span class="inline-formula"><sub>2</sub></span> A, weak CO<span class="inline-formula"><sub>2</sub></span>, and
CH<span class="inline-formula"><sub>4</sub></span> bands of TANSO–FTS, although the residuals increase in the strong
CO<span class="inline-formula"><sub>2</sub></span> band over the ocean. The direct comparison of the new product
obtained from the updated (V03) algorithm with the previous version
V02.90/91 and the validations using the Total Carbon Column Observing
Network revealed that the V03 algorithm increases the amount of data without
diminishing the data qualities of XCO<span class="inline-formula"><sub>2</sub></span> and XCH<span class="inline-formula"><sub>4</sub></span> over land.
However, the negative bias of XCO<span class="inline-formula"><sub>2</sub></span> is larger than that of the previous
version over the ocean, and bias correction is still necessary.
Additionally, the V03 algorithm resolves the underestimation of the
XCO<span class="inline-formula"><sub>2</sub></span> growth rate compared with the in situ measurements over the ocean
recently found using V02.90/91 and V02.95/96.</p> |
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| ISSN: | 1867-1381 1867-8548 |