Bias correction of an X-band radar reflectivity data to improve spatial rainfall estimation

Jha, AK and Bhat, GS and Kalapureddy, MCR and Pandithurai, G (2024) Bias correction of an X-band radar reflectivity data to improve spatial rainfall estimation. In: Journal of Earth System Science, 133 (2).

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Abstract

Information on the spatial distribution of rainfall is required for many applications, including water and flood management. Weather radars can provide quantitative rainfall estimation over an area. Taking the example of an X-band radar installed at Mandhardev in the Western Ghats, we show that radar reflectivity data can have significant bias despite following standard calibration procedures. We report a technique to identify bias in the X-band radar reflectivity factor using collocated disdrometer observations and propose a methodology to correct it. Simultaneous data collected on 83 days during June�September of 2018 are used. Our results show that bias in the radar reflectivity factor reduced from �8.3 to �0.8 dB after correction. The estimated 83-day accumulated rainfall using uncorrected radar reflectivity data is 80 less compared to that of the disdrometer and the difference between the two reduces to 2 with correction. Bias in the estimated rainfall reduces from �30 to �0.7 mm day�1 and the RMSE reduces by 42. There are days where daily rainfall from the two instruments agrees well with each other, while large differences exist on some days. We show that the sampling issue is one of the major sources of error, and its contribution depends on the nature/type of precipitating clouds, whereas uncertainties in the Z�R relationships account for about 15 difference. © Indian Academy of Sciences 2024.

Item Type:	Journal Article
Publication:	Journal of Earth System Science
Publisher:	Springer
Additional Information:	The copyright for this article belongs to Springer.
Keywords:	correction; monsoon; radar; rainfall; spatial analysis; summer, India; Western Ghats
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	22 May 2024 12:16
Last Modified:	22 May 2024 12:16
URI:	https://eprints.iisc.ac.in/id/eprint/84757

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