ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Study on Height Reassignment Method of FY-4A Atmospheric Motion VectorsBased on Cloud-Top Pressure
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Abstract:
The primary source of the bias of Atmospheric Motion Vectors (AMVs) is related to inaccuracies in assigning heights.. The cloud top height algorithm employed by China‘s new generation geostationary meteorological satellite FY-4 series make use of both the infrared window channel and CO2 slicing channel. This leads to an improvement in its accuracy. In this study, cloud top height has been used to correct AMVs of FY-4A through spatiotemporal matching between and the two products. Representative pixels within the AMVs tracking box are searched, and their average cloud top pressure is used to replace the original cloud pressure of the AMVs, achieving height reassignment. Verification using ERA5 reanalysis data shows that after height reassignment, the root mean square error (RMSE) of FY-4A infrared channel AMVs is significantly reduced across high, middle, and low levels. Specifically, the RMSE for the high level decreased from 4.06 m·s?1 to 3.25 m·s?1, for the middle level from 4.25 m·s?1 to 3.71 m·s?1, and for the low level from 2.42 m·s?1 to 2.13 m·s?1. Height reassignment alleviates the problem of AMVs being assigned to overly high altitudes, reducing biases, particularly improving slow motion biases. Case studies of the Northeast Cold Vortex and Typhoon "Chaba" demonstrate that this method can improve the consistency between cloud-derived winds and the background field. Promising applications in numerical weather prediction assimilation and weather process analysis are envisioned.
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Project Supported:
National Key Research and Development Program of China (2022YFC3004102)、Wenjiang National Climate Observatory Scientific Research Team Building Program
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