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Quantile-based Bayesian Model Averaging approach towards merging of rainfall products
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  • Karisma Yumnam,
  • Ravi Kumar Guntu,
  • Ankit Agarwal,
  • Rathinasamy Maheswaran
Karisma Yumnam
Indian Institute of Technology Roorkee

Corresponding Author:[email protected]

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Ravi Kumar Guntu
Indian Institute of Technology Roorkee
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Ankit Agarwal
Indian Institute of Technology Roorkee
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Rathinasamy Maheswaran
MVGR College of Engineering
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Abstract

Due to the advancement in satellite and remote sensing technologies, a number of satellite precipitation products (SPPs) are easily accessible online at free of cost. These precipitation products have a huge potential for hydro-meteorological applications in data-scare catchments. However, the use of such products is still limited owing to their lack of accuracy in capturing the ground truth. To improve the accuracy of these products, we have developed a quantile based Bayesian model averaging (QBMA) approach to merge the satellite precipitation products. QBMA is a probabilistic approach to assign optimal weights to the SPPs depending on their relative performances. The QBMA approach is compared with simple model averaging and one outlier removed. TRMM, PERSIANN-CDR, CMORPH products were experimented for QBMA merging during the monsoon season over India’s coastal Vamsadhara river basin. QBMA optimal weights were trained using 2001 to 2013 daily monsoon rainfall data and validated for 2014 to 2018. Results indicated that QBMA approach with bias corrected precipitation inputs outperformed the other merging methods. On monthly evaluation, it is observed that all the products perform better during July and September than that in June and August. The QBMA approaches do not have any significant improvement over the SMA approach in terms of POD. However, the bias-corrected QBMA products have lower FAR. The developed QBMA approach with bias-corrected inputs outperforms the IMERG product in terms of RMSE.