{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T00:56:21Z","timestamp":1760144181184,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2024,3,14]],"date-time":"2024-03-14T00:00:00Z","timestamp":1710374400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["U2142213"],"award-info":[{"award-number":["U2142213"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The higher the atmosphere is, the larger the deviations in atmospheric temperature and humidity are between the vertical column atmosphere above the cross-section of a satellite instrument and a ray\u2019s trajectory from the cross-section to the satellite. In general, satellite instruments that observe using cross-orbit scanning result in the difference between the observed radiance and the simulations using this method becoming incrementally larger and larger as the cross-section moves to the edge of the satellite\u2019s orbit. The deviations depend on the distance from the column to the ray trajectory and on the horizontal gradient of variables in the distance. In fact, the horizontal gradient of water vapour is larger than the gradient of temperature in clear scenarios, which could introduce an impact of temperature and water vapour on the simulated radiance of a satellite. In this study, a new method to simulate upgoing and downgoing radiation synchronously was developed, using the observing path tracking method. The conventional vertical initial atmospheric profile (Exp.1) and the profiles along the upgoing and downgoing rays of the satellite\u2019s observation (Exp.2) were established, in order to simulate the observed radiance of MWHS-II of FY-3D using global numerical forecasts with resolutions of 15 km and 25 km. The results showed that, for channels in the oxygen and water vapour absorption line on the microwave spectrum, deviations of the two atmospheric profiles were larger at the scan edge (0.01 K) than those at the nadir (0.001 K), and were larger in the upper atmosphere than in the lower atmosphere. The deviation was usually negative in low-latitude regions and was positive in southern high-latitude regions. Such results were obtained in experiments using both the numerical forecast method with 15 km grids and the forecast method with 25 km grids. Deviations were analysed for representative channels at 118 GHz and 183 GHz. Then, the results indicated that bigger deviations between the two experiments were observed in the water vapour absorption line than in the oxygen absorption line in the microwave spectrum. In conclusion, this indicates that, because of the greater horizontal gradient of water vapour, the stronger localisation of water vapour makes the atmospheric profile along the satellite\u2019s observing ray have more increments in the simulated radiance at the scan edge, compared to the atmospheric column profile.<\/jats:p>","DOI":"10.3390\/rs16061030","type":"journal-article","created":{"date-parts":[[2024,3,15]],"date-time":"2024-03-15T04:47:05Z","timestamp":1710478025000},"page":"1030","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Fast Forward Modelling Method for Simulating Satellite Observations Using Observing Path Tracking"],"prefix":"10.3390","volume":"16","author":[{"given":"Xiaofang","family":"Guo","sequence":"first","affiliation":[{"name":"Center for Earth System Modeling and Prediction of CMA, Beijing 100081, China"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-6902-9429","authenticated-orcid":false,"given":"Zongru","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Oceanography, Hohai University, Nanjing 210024, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8729-9356","authenticated-orcid":false,"given":"Gang","family":"Ma","sequence":"additional","affiliation":[{"name":"Center for Earth System Modeling and Prediction of CMA, Beijing 100081, China"},{"name":"Key Laboratory of Earth System Modeling and Prediction, China Meteorological Administration, Beijing 100081, China"},{"name":"State Key Laboratory of Severe Weather (LaSW), Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100081, China"}]},{"given":"Yi","family":"Yu","sequence":"additional","affiliation":[{"name":"College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410022, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7115-1389","authenticated-orcid":false,"given":"Peng","family":"Zhang","sequence":"additional","affiliation":[{"name":"National Satellite Meteorological Centre, Beijing 100081, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7836-8102","authenticated-orcid":false,"given":"Banglin","family":"Zhang","sequence":"additional","affiliation":[{"name":"Guangzhou Institute of Tropical and Marine Meteorology, CMA, Guangzhou 510000, China"},{"name":"Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, CMA, Guangzhou 510000, China"},{"name":"College of Atmospheric Science, Lanzhou University, Lanzhou 730000, China"}]}],"member":"1968","published-online":{"date-parts":[[2024,3,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1002\/qj.4228","article-title":"Assimilation of Satellite Data in Numerical Weather Prediction. 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