{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T03:44:12Z","timestamp":1783395852082,"version":"3.54.6"},"reference-count":39,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2023,2,22]],"date-time":"2023-02-22T00:00:00Z","timestamp":1677024000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["92037000"],"award-info":[{"award-number":["92037000"]}]},{"name":"National Natural Science Foundation of China","award":["NMICJY202104"],"award-info":[{"award-number":["NMICJY202104"]}]},{"name":"National Natural Science Foundation of China","award":["NMICJY202106"],"award-info":[{"award-number":["NMICJY202106"]}]},{"name":"National Natural Science Foundation of China","award":["FY-APP-2021.0207"],"award-info":[{"award-number":["FY-APP-2021.0207"]}]},{"name":"National Natural Science Foundation of China","award":["FY-APP-2022.0608"],"award-info":[{"award-number":["FY-APP-2022.0608"]}]},{"name":"Balance Funding Project of National Meteorological Information Centre","award":["92037000"],"award-info":[{"award-number":["92037000"]}]},{"name":"Balance Funding Project of National Meteorological Information Centre","award":["NMICJY202104"],"award-info":[{"award-number":["NMICJY202104"]}]},{"name":"Balance Funding Project of National Meteorological Information Centre","award":["NMICJY202106"],"award-info":[{"award-number":["NMICJY202106"]}]},{"name":"Balance Funding Project of National Meteorological Information Centre","award":["FY-APP-2021.0207"],"award-info":[{"award-number":["FY-APP-2021.0207"]}]},{"name":"Balance Funding Project of National Meteorological Information Centre","award":["FY-APP-2022.0608"],"award-info":[{"award-number":["FY-APP-2022.0608"]}]},{"name":"Fengyun Application Pioneering Project","award":["92037000"],"award-info":[{"award-number":["92037000"]}]},{"name":"Fengyun Application Pioneering Project","award":["NMICJY202104"],"award-info":[{"award-number":["NMICJY202104"]}]},{"name":"Fengyun Application Pioneering Project","award":["NMICJY202106"],"award-info":[{"award-number":["NMICJY202106"]}]},{"name":"Fengyun Application Pioneering Project","award":["FY-APP-2021.0207"],"award-info":[{"award-number":["FY-APP-2021.0207"]}]},{"name":"Fengyun Application Pioneering Project","award":["FY-APP-2022.0608"],"award-info":[{"award-number":["FY-APP-2022.0608"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>As China\u2019s 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\u2019s influence on the satellite instrument, the brightness temperature observations of the Fengyun-4B\/AGRI 3.75 \u03bcm 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\u201315 were more obvious than channels 9\u201311, 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\u201315 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\u00b0; and (5) the biases and standard deviations of Fengyun-4B\/AGRI IR channels showed scene brightness temperature dependence over the ocean.<\/jats:p>","DOI":"10.3390\/rs15051224","type":"journal-article","created":{"date-parts":[[2023,2,23]],"date-time":"2023-02-23T01:31:06Z","timestamp":1677115866000},"page":"1224","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Characterization of Bias in Fengyun-4B\/AGRI Infrared Observations Using RTTOV"],"prefix":"10.3390","volume":"15","author":[{"given":"Zhi","family":"Zhu","sequence":"first","affiliation":[{"name":"National Meteorological Information Centre, Beijing 100081, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunxiang","family":"Shi","sequence":"additional","affiliation":[{"name":"National Meteorological Information Centre, Beijing 100081, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junxia","family":"Gu","sequence":"additional","affiliation":[{"name":"National Meteorological Information Centre, Beijing 100081, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1637","DOI":"10.1175\/BAMS-D-16-0065.1","article-title":"Introducing the new generation of Chinese geostationary weather satellites, FengYun 4","volume":"98","author":"Yang","year":"2017","journal-title":"Bull. 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