ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Accuracy Validation and Application in Guizhou Hail Process of FY-4A/4B Temperature and Humidity Profiles
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Abstract:
To evaluate the accuracy and operational applicability of FY-4A/B GIIRS-retrieved temperature and humidity profiles in Guizhou, the FY-4A temperature profile and FY-4B temperature/humidity profiles were validated against radiosonde observations at Guiyang and Weining stations and ERA5 reanalysis data. The results indicate that only data with quality code 3 should be discarded, while retaining codes 0–2 to maximize the integrity of the profiles. Clouds significantly degrade GIIRS retrieval performance: under cloudy conditions, the RMSE of FY-4A temperature increases by 1.19°C (clear skies) and 0.96°C (cloud edges), while FY-4B temperature increases by 1.52°C and 1.21°C, and humidity by 1.28 g/kg and 0.95 g/kg, respectively. Cloud cover also amplifies vertical data dispersion. A systematic bias exists in FY-4A/B profiles; linear bias correction reduces the mean error (ME) to near zero under clear skies and improves cloudy conditions more markedly. Seasonal comparisons between sounding and satellite profiles demonstrate that FY-4A/B captures terrain-induced differences in atmospheric stratification between Guiyang and Weining. For three regional hail events in 2023, GIIRS products agreed well with radiosondes. The high-resolution profiles revealed pre-hail instability ("upper cold/lower warm" and "upper dry/lower wet"), offering valuable forecast indicators. However, near-surface layer retrieval errors caused CAPE underestimation and distorted low-level sounding structures. Surface-based 2-m temperature/dew point corrections restored realistic CAPE and thunderstorm-favorable profiles, aiding short-term convective forecasting.
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