Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China

Raindrop size distributions (DSDs) are the microphysical characteristics of raindrop spectra. Rainfall characterization is important to: (1) provide information on extreme rate, thus, it has an impact on rainfall related hazard; (2) provide data for indirect observation, model and forecast; (3) cali...

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Main Authors: Zongxu Xie, Hanbo Yang, Huafang Lv, Qingfang Hu
Format: Article
Language:English
Published: MDPI AG 2020-01-01
Series:Remote Sensing
Subjects:
Online Access:https://www.mdpi.com/2072-4292/12/2/262
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author Zongxu Xie
Hanbo Yang
Huafang Lv
Qingfang Hu
author_facet Zongxu Xie
Hanbo Yang
Huafang Lv
Qingfang Hu
author_sort Zongxu Xie
collection DOAJ
description Raindrop size distributions (DSDs) are the microphysical characteristics of raindrop spectra. Rainfall characterization is important to: (1) provide information on extreme rate, thus, it has an impact on rainfall related hazard; (2) provide data for indirect observation, model and forecast; (3) calibrate and validate the parameters in radar reflectivity-rainfall intensity (<i>Z-R</i>) relationships (quantitative estimate precipitation, QPE) and the mechanism of precipitation erosivity. In this study, the one-year datasets of raindrop spectra were measured by an OTT Parsivel-2 Disdrometer placed in Yulin, Shaanxi Province, China. At the same time, four TE525MM Gauges were also used in the same location to check the disdrometer-measured rainfall data. The theoretical formula of raindrop kinetic energy-rainfall intensity (KE-<i>R</i>) relationships was derived based on the DSDs to characterize the impact of precipitation characteristics and environmental conditions on KE-<i>R</i> relationships in semi-arid areas. In addition, seasonal rainfall intensity curves observed by the disdrometer of the area with application to erosion were characterized and estimated. The results showed that after quality control (QC), the frequencies of raindrop spectra data in different seasons varied, and rainfalls with <i>R</i> within 0.5&#8722;5 mm/h accounted for the largest proportion of rainfalls in each season. The parameters in <i>Z-R</i> relationships (<i>Z</i> = a<i>R</i><sup>b</sup>) were different for rainfall events of different seasons (a varies from 78.3&#8722;119.0, and b from 1.8&#8722;2.1), and the calculated KE-<i>R</i> relationships satisfied the form of power function KE = <i>AR</i><sup>m</sup>, in which <i>A</i> and m are parameters derived from rainfall shape factor <i>&#956;</i>. The sensitivity analysis of parameter <i>A</i> with <i>&#956;</i> demonstrated the applicability of the KE-<i>R</i> formula to different precipitation processes in the Yulin area.
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spelling doaj.art-dba7c936f6d445e6803a8226345235ed2022-12-22T04:14:17ZengMDPI AGRemote Sensing2072-42922020-01-0112226210.3390/rs12020262rs12020262Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of ChinaZongxu Xie0Hanbo Yang1Huafang Lv2Qingfang Hu3Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, ChinaDepartment of Hydraulic Engineering, Tsinghua University, Beijing 100084, ChinaDepartment of Hydraulic Engineering, Tsinghua University, Beijing 100084, ChinaState Key Laboratory of Hydro-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing 210029, ChinaRaindrop size distributions (DSDs) are the microphysical characteristics of raindrop spectra. Rainfall characterization is important to: (1) provide information on extreme rate, thus, it has an impact on rainfall related hazard; (2) provide data for indirect observation, model and forecast; (3) calibrate and validate the parameters in radar reflectivity-rainfall intensity (<i>Z-R</i>) relationships (quantitative estimate precipitation, QPE) and the mechanism of precipitation erosivity. In this study, the one-year datasets of raindrop spectra were measured by an OTT Parsivel-2 Disdrometer placed in Yulin, Shaanxi Province, China. At the same time, four TE525MM Gauges were also used in the same location to check the disdrometer-measured rainfall data. The theoretical formula of raindrop kinetic energy-rainfall intensity (KE-<i>R</i>) relationships was derived based on the DSDs to characterize the impact of precipitation characteristics and environmental conditions on KE-<i>R</i> relationships in semi-arid areas. In addition, seasonal rainfall intensity curves observed by the disdrometer of the area with application to erosion were characterized and estimated. The results showed that after quality control (QC), the frequencies of raindrop spectra data in different seasons varied, and rainfalls with <i>R</i> within 0.5&#8722;5 mm/h accounted for the largest proportion of rainfalls in each season. The parameters in <i>Z-R</i> relationships (<i>Z</i> = a<i>R</i><sup>b</sup>) were different for rainfall events of different seasons (a varies from 78.3&#8722;119.0, and b from 1.8&#8722;2.1), and the calculated KE-<i>R</i> relationships satisfied the form of power function KE = <i>AR</i><sup>m</sup>, in which <i>A</i> and m are parameters derived from rainfall shape factor <i>&#956;</i>. The sensitivity analysis of parameter <i>A</i> with <i>&#956;</i> demonstrated the applicability of the KE-<i>R</i> formula to different precipitation processes in the Yulin area.https://www.mdpi.com/2072-4292/12/2/262raindrop size distributionradar reflectivityraindrop spectrometersemi-arid area
spellingShingle Zongxu Xie
Hanbo Yang
Huafang Lv
Qingfang Hu
Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China
Remote Sensing
raindrop size distribution
radar reflectivity
raindrop spectrometer
semi-arid area
title Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China
title_full Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China
title_fullStr Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China
title_full_unstemmed Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China
title_short Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China
title_sort seasonal characteristics of disdrometer observed raindrop size distributions and their applications on radar calibration and erosion mechanism in a semi arid area of china
topic raindrop size distribution
radar reflectivity
raindrop spectrometer
semi-arid area
url https://www.mdpi.com/2072-4292/12/2/262
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AT huafanglv seasonalcharacteristicsofdisdrometerobservedraindropsizedistributionsandtheirapplicationsonradarcalibrationanderosionmechanisminasemiaridareaofchina
AT qingfanghu seasonalcharacteristicsofdisdrometerobservedraindropsizedistributionsandtheirapplicationsonradarcalibrationanderosionmechanisminasemiaridareaofchina