Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV
As China’s first operational second-generation geostationary satellite, Fengyun-4B carries the newly developed Advanced Geostationary Radiation Imager (AGRI), which adds a low-level water vapor detection channel and an adjusted spectrum range of four channels to improve the quality of observation. T...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-02-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/5/1224 |
| _version_ | 1827752341728657408 |
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| author | Zhi Zhu Chunxiang Shi Junxia Gu |
| author_facet | Zhi Zhu Chunxiang Shi Junxia Gu |
| author_sort | Zhi Zhu |
| collection | DOAJ |
| description | As China’s first operational second-generation geostationary satellite, Fengyun-4B carries the newly developed Advanced Geostationary Radiation Imager (AGRI), which adds a low-level water vapor detection channel and an adjusted spectrum range of four channels to improve the quality of observation. To characterize biases of the infrared (IR) channels of Fengyun-4B/AGRI, RTTOV was applied to simulate the brightness temperature of the IR channels during the period of Fengyun-4B trial operation (from June to November 2022) under clear-sky conditions based on ERA5 reanalysis, which may provide beneficial information for the operational applications of Fengyun-4B/AGRI, such as data assimilation and severe weather monitoring. The results are as follows: (1) due to the sun’s influence on the satellite instrument, the brightness temperature observations of the Fengyun-4B/AGRI 3.75 μm channel were abnormally high around 1500 UTC in October, although the data producer made efforts to eliminate abnormal data; (2) the RTTOV simulations were in good agreement with the observations, and the absolute mean biases of the RTTOV simulations were less than 1.39 K over the ocean, and less than 1.77 K over land, for all IR channels under clear-sky conditions, respectively; (3) for the variation of spatial distribution bias over land, channels 12–15 were more obvious than channels 9–11, which indicates that the skin temperature of ERA-5 reanalysis and surface emissivity may have greater spatial uncertainty than the water vapor profile; (4) the biases and standard deviations of Fengyun-4B/AGRI channels 9–15 had negligible dependence on the satellite zenith angles over the ocean, while the standard deviation of channels 8 and 12 had a positive correlation with satellite zenith angles when the satellite zenith angles were larger than 30°; and (5) the biases and standard deviations of Fengyun-4B/AGRI IR channels showed scene brightness temperature dependence over the ocean. |
| first_indexed | 2024-03-11T07:12:36Z |
| format | Article |
| id | doaj.art-f176fdb4430c43e183030616b7dfea0e |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-11T07:12:36Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-f176fdb4430c43e183030616b7dfea0e2023-11-17T08:30:07ZengMDPI AGRemote Sensing2072-42922023-02-01155122410.3390/rs15051224Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOVZhi Zhu0Chunxiang Shi1Junxia Gu2National Meteorological Information Centre, Beijing 100081, ChinaNational Meteorological Information Centre, Beijing 100081, ChinaNational Meteorological Information Centre, Beijing 100081, ChinaAs China’s first operational second-generation geostationary satellite, Fengyun-4B carries the newly developed Advanced Geostationary Radiation Imager (AGRI), which adds a low-level water vapor detection channel and an adjusted spectrum range of four channels to improve the quality of observation. To characterize biases of the infrared (IR) channels of Fengyun-4B/AGRI, RTTOV was applied to simulate the brightness temperature of the IR channels during the period of Fengyun-4B trial operation (from June to November 2022) under clear-sky conditions based on ERA5 reanalysis, which may provide beneficial information for the operational applications of Fengyun-4B/AGRI, such as data assimilation and severe weather monitoring. The results are as follows: (1) due to the sun’s influence on the satellite instrument, the brightness temperature observations of the Fengyun-4B/AGRI 3.75 μm channel were abnormally high around 1500 UTC in October, although the data producer made efforts to eliminate abnormal data; (2) the RTTOV simulations were in good agreement with the observations, and the absolute mean biases of the RTTOV simulations were less than 1.39 K over the ocean, and less than 1.77 K over land, for all IR channels under clear-sky conditions, respectively; (3) for the variation of spatial distribution bias over land, channels 12–15 were more obvious than channels 9–11, which indicates that the skin temperature of ERA-5 reanalysis and surface emissivity may have greater spatial uncertainty than the water vapor profile; (4) the biases and standard deviations of Fengyun-4B/AGRI channels 9–15 had negligible dependence on the satellite zenith angles over the ocean, while the standard deviation of channels 8 and 12 had a positive correlation with satellite zenith angles when the satellite zenith angles were larger than 30°; and (5) the biases and standard deviations of Fengyun-4B/AGRI IR channels showed scene brightness temperature dependence over the ocean.https://www.mdpi.com/2072-4292/15/5/1224bias characterizationFengyun-4B/AGRIRTTOV |
| spellingShingle | Zhi Zhu Chunxiang Shi Junxia Gu Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV Remote Sensing bias characterization Fengyun-4B/AGRI RTTOV |
| title | Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV |
| title_full | Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV |
| title_fullStr | Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV |
| title_full_unstemmed | Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV |
| title_short | Characterization of Bias in Fengyun-4B/AGRI Infrared Observations Using RTTOV |
| title_sort | characterization of bias in fengyun 4b agri infrared observations using rttov |
| topic | bias characterization Fengyun-4B/AGRI RTTOV |
| url | https://www.mdpi.com/2072-4292/15/5/1224 |
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