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Assessing the benefits of specific attenuation for quantitative precipitation estimation with a C-band radar network
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2021
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Source: Journal of Hydrometeorology
Details:
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Journal Title:Journal of Hydrometeorology
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Description:Recent advances demonstrate the benefits of radar-derived specific attenuation at horizontal polarization(AH) for quantitative precipitation estimation (QPE) at S and X band. To date the methodology has, however, not beenadapted for the widespread European C-band radars such as those installed in the network of the German MeteorologicalService (DWD, Deutscher Wetterdienst). Simulations based on a large dataset of drop size distributions (DSDs) measuredover Germany are performed to investigate the DSD dependencies of the attenuation parameteraHfor theAHestimates. Thenormalized raindrop concentration (Nw) and the change of differential reflectivity (ZDR) with reflectivity at horizontal po-larization (ZH) are used to categorize radar observations into regimes for which scan-wise optimizedaHvalues are derived. Forheavier continental rain withZH.40 dBZ,theAH-based rainfall retrievalR(AH) is combined with a rainfall estimator using asubstitute of specific differential phase (KDP*). We also assess the performance of retrievals based on specific attenuation atvertical polarization (AV). Finally, the regime-adapted hybrid QPE algorithms are applied to four convective cases andone stratiform case from 2017 to 2019, and compared to DWD’s operational Radar-Online-Aneichung (RADOLAN)RW rainfall product, which is based onZhonly but adjusted to rain gauge measurements. For the convective cases, ourhybrid retrievals outperform the traditionalR(Zh) and pureR(AH/V) retrievals with fixedaH/Vvalues when evaluatedwith gauge measurements and outperform RW when evaluatedby disdrometer measurements. Potential improvementsusing ray-wiseaH/Vand segment-wise applications of the ZPHI method along the radials are discussed.
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Source:Journal of Hydrometeorology
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Rights Information:CC BY
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Compliance:Submitted
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