Estimation of X-band polarimetric radar attenuation and measurement uncertainty using a variational method

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Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/100109

Title:	Estimation of X-band polarimetric radar attenuation and measurement uncertainty using a variational method
Authors:	張偉裕;Chang, Wei-Yu;Vivekanandan, Jothiram;Wang, Tai-Chi Chen
Contributors:	地球科學學院大氣科學學系
Keywords:	Accuracy;Algorithms;Antennas;Attenuation;Bands;Covariance;Covariance matrices;Covariance matrix;Error analysis;Error rates;Errors;Estimation;Estimation methods;Measurement;Meteorology;Methods;Monsoon rainfall;Monsoons;Noise measurement;Noise sensitivity;Performance evaluation;Polarimetric radar;Polarimetry;Precipitation;Propagation;Radar;Radar attenuation;Radar echoes;Radar measurement;Rain;Rainfall;Reflectance;Southwest monsoon;Superhigh frequencies;Variational methods;X-band
Date:	2014-01-01
Issue Date:	2026-04-21 13:49:40 (UTC+8)
Publisher:	American Meteorological Society;Boston: American Meteorological Society
Abstract:	摘要： AbstractA variational algorithm for estimating measurement error covariance and the attenuation of X-band polarimetric radar measurements is described. It concurrently uses both the differential reflectivity ZDR and propagation phase ΦDP. The majority of the current attenuation estimation techniques use only ΦDP. A few of the ΦDP-based methods use ZDR as a constraint for verifying estimated attenuation. In this paper, a detailed observing system simulation experiment was used for evaluating the performance of the variational algorithm. The results were compared with a single-coefficient ΦDP-based method. Retrieved attenuation from the variational method is more accurate than the results from a single coefficient ΦDP-based method. Moreover, the variational method is less sensitive to measurement noise in radar observations. The variational method requires an accurate description of error covariance matrices. Relative weights between measurements and background values (i.e., mean value based on long-term DSD measurements in the variational method) are determined by their respective error covariances. Instead of using ad hoc values, error covariance matrices of background and radar measurement are statistically estimated and their spatial characteristics are studied. The estimated error covariance shows higher values in convective regions than in stratiform regions, as expected. The practical utility of the variational attenuation correction method is demonstrated using radar field measurements from the Taiwan Experimental Atmospheric Mobile-Radar (TEAM-R) during 2008’s Southwest Monsoon Experiment/Terrain-Influenced Monsoon Rainfall Experiment (SoWMEX/TiMREX). The accuracy of attenuation-corrected X-band radar measurements is evaluated by comparing them with collocated S-band radar measurements. 出版者： Boston: American Meteorological Society 出版日期： 2014-04-01 出處： Journal of Applied Meteorology and Climatology, 2014-04, Vol.53 (4), p.1099-1119 資源來源： EBSCOhost OmniFile Full Text Select 版權： 2014 American Meteorological Society 版權： Copyright American Meteorological Society Apr 2014 版權： Copyright American Meteorological Society 2014 識別號： ISSN: 1558-8424 識別號： EISSN: 1558-8432 識別號： DOI: 10.1175/jamc-d-13-0191.1 識別號： CODEN: JOAMEZ
Appears in Collections:	[Department of Atmospheric Sciences] journal & Dissertation

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