Characteristics of Raindrop Size Distributions in Chongqing Observed by a Dense Network of Disdrometers

Abstract The relation between the slope and shape parameters of the raindrop size distribution parameterized by a gamma distribution is examined. The comparison of results of a simple rain shaft model with an empirical relation based on disdrometer measurements at the surface shows very good agreement, but a more detailed discussion reveals some difficulties—for example, deviations from the gamma shape and the overestimation of collisional breakup.

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Raindrop Size Distributions: Exponential or Gamma—Does the Difference Matter?

Journal of Applied Meteorology ◽

10.1175/1520-0450(2003)042<1031:rsdeog>2.0.co;2 ◽

2003 ◽

Vol 42 (7) ◽

pp. 1031-1034 ◽

Cited By ~ 45

Author(s):

Paul L. Smith

Keyword(s):

Size Distributions ◽

The Difference ◽

Raindrop Size

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Reflectivity and Liquid Water Content Vertical Decomposition Diagrams to Diagnose Vertical Evolution of Raindrop Size Distributions

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-15-0208.1 ◽

2016 ◽

Vol 33 (3) ◽

pp. 579-595 ◽

Cited By ~ 21

Author(s):

Christopher R. Williams

Keyword(s):

Water Content ◽

Liquid Water ◽

Liquid Water Content ◽

Doppler Velocity ◽

Size Distributions ◽

Vertical Column ◽

Vertical Decomposition ◽

Air Motion ◽

Raindrop Size ◽

Microphysical Processes

AbstractThis study consists of two parts. The first part describes the way in which vertical air motions and raindrop size distributions (DSDs) were retrieved from 449-MHz and 2.835-GHz (UHF and S band) vertically pointing radars (VPRs) deployed side by side during the Midlatitude Continental Convective Clouds Experiment (MC3E) held in northern Oklahoma. The 449-MHz VPR can measure both vertical air motion and raindrop motion. The S-band VPR can measure only raindrop motion. These differences in VPR sensitivities facilitates the identification of two peaks in 449-MHz VPR reflectivity-weighted Doppler velocity spectra and the retrieval of vertical air motion and DSD parameters from near the surface to just below the melting layer.The second part of this study used the retrieved DSD parameters to decompose reflectivity and liquid water content (LWC) into two terms, one representing number concentration and the other representing DSD shape. Reflectivity and LWC vertical decomposition diagrams (Z-VDDs and LWC-VDDs, respectively) are introduced to highlight interactions between raindrop number and DSD shape in the vertical column. Analysis of Z-VDDs provides indirect measure of microphysical processes through radar reflectivity. Analysis of LWC-VDDs provides direct investigation of microphysical processes in the vertical column, including net raindrop evaporation or accretion and net raindrop breakup or coalescence. During a stratiform rain event (20 May 2011), LWC-VDDs exhibited signatures of net evaporation and net raindrop coalescence as the raindrops fell a distance of 2 km under a well-defined radar bright band. The LWC-VDD is a tool to characterize rain microphysics with quantities related to number-controlled and size-controlled processes.

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Estimation of rainfall erosivity based on WRF-derived raindrop size distributions

10.5194/hess-2020-187 ◽

2020 ◽

Author(s):

Qiang Dai ◽

Jingxuan Zhu ◽

Shuliang Zhang ◽

Shaonan Zhu ◽

Dawei Han ◽

...

Keyword(s):

Soil Erosion ◽

Water Conservation ◽

Large Scale ◽

Weather Prediction ◽

Wrf Model ◽

Analysis Data ◽

Potential Effect ◽

Rainfall Erosivity ◽

Size Distributions ◽

Raindrop Size

Abstract. Soil erosion can cause various ecological problems, such as land degradation, soil fertility loss, and river siltation. Rainfall is the primary water-driving force for soil erosion and its potential effect on soil erosion is reflected by rainfall erosivity that relates to the raindrop kinetic energy (KE). As it is difficult to observe large-scale dynamic characteristics of raindrops, all the current rainfall erosivity models use the function based on rainfall amount to represent the raindrops KE. With the development of global atmospheric re-analysis data, numerical weather prediction (NWP) techniques become a promising way to estimate rainfall KE directly at regional and global scales with high spatial and temporal resolutions. This study proposed a novel method for large-scale and long-term rainfall erosivity investigations based on the Weather Research and Forecasting (WRF) model, avoiding errors caused by inappropriate rainfall–energy relationships and large-scale interpolation. We adopted three microphysical parameterizations schemes (Morrison, WDM6, and Thompson aerosol-aware [TAA]) to obtain raindrop size distributions, rainfall KE and rainfall erosivity, with validation by two disdrometers and 304 rain gauges around the United Kingdom. Among the three WRF schemes, TAA had the best performance compared with the disdrometers at a monthly scale. The results revealed that high rainfall erosivity occurred in the west coast area at the whole country scale during 2013–2017. The proposed methodology makes a significant contribution to improving large-scale soil erosion estimation and for better understanding microphysical rainfall–soil interactions to support the rational formulation of soil and water conservation planning.

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Estimation of rainfall erosivity based on WRF-derived raindrop size distributions

Hydrology and Earth System Sciences ◽

10.5194/hess-24-5407-2020 ◽

2020 ◽

Vol 24 (11) ◽

pp. 5407-5422

Author(s):

Qiang Dai ◽

Jingxuan Zhu ◽

Shuliang Zhang ◽

Shaonan Zhu ◽

Dawei Han ◽

...

Keyword(s):

Soil Erosion ◽

Kinetic Energy ◽

Water Conservation ◽

Large Scale ◽

Weather Prediction ◽

Wrf Model ◽

Analysis Data ◽

Rainfall Erosivity ◽

Size Distributions ◽

Raindrop Size

Abstract. Soil erosion can cause various ecological problems, such as land degradation, soil fertility loss, and river siltation. Rainfall is the primary water-driven force for soil erosion, and its potential effect on soil erosion is reflected by rainfall erosivity that relates to the raindrop kinetic energy. As it is difficult to observe large-scale dynamic characteristics of raindrops, all the current rainfall erosivity models use the function based on rainfall amount to represent the raindrops' kinetic energy. With the development of global atmospheric re-analysis data, numerical weather prediction techniques become a promising way to estimate rainfall kinetic energy directly at regional and global scales with high spatial and temporal resolutions. This study proposed a novel method for large-scale and long-term rainfall erosivity investigations based on the Weather Research and Forecasting (WRF) model, avoiding errors caused by inappropriate rainfall–energy relationships and large-scale interpolation. We adopted three microphysical parameterizations schemes (Morrison, WDM6, and Thompson aerosol-aware) to obtain raindrop size distributions, rainfall kinetic energy, and rainfall erosivity, with validation by two disdrometers and 304 rain gauges around the United Kingdom. Among the three WRF schemes, Thompson aerosol-aware had the best performance compared with the disdrometers at a monthly scale. The results revealed that high rainfall erosivity occurred in the west coast area at the whole country scale during 2013–2017. The proposed methodology makes a significant contribution to improving large-scale soil erosion estimation and for better understanding microphysical rainfall–soil interactions to support the rational formulation of soil and water conservation planning.

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Microphysical Origin of Raindrop Size Distributions During Indian Monsoon

Geophysical Research Letters ◽

10.1029/2021gl093581 ◽

2021 ◽

Author(s):

Bhupendra A. Raut ◽

Mahen Konwar ◽

P. Murugavel ◽

Dhananjay Kadge ◽

Dinesh Gurnule ◽

...

Keyword(s):

Indian Monsoon ◽

Size Distributions ◽

Raindrop Size

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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 ◽

10.3390/rs12020262 ◽

2020 ◽

Vol 12 (2) ◽

pp. 262 ◽

Cited By ~ 1

Author(s):

Zongxu Xie ◽

Hanbo Yang ◽

Huafang Lv ◽

Qingfang Hu

Keyword(s):

Rainfall Intensity ◽

Shaanxi Province ◽

Theoretical Formula ◽

Size Distributions ◽

Seasonal Characteristics ◽

Different Seasons ◽

Raindrop Size ◽

Radar Calibration ◽

The Impact ◽

Semi Arid

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 (Z-R) 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-R) relationships was derived based on the DSDs to characterize the impact of precipitation characteristics and environmental conditions on KE-R 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 R within 0.5–5 mm/h accounted for the largest proportion of rainfalls in each season. The parameters in Z-R relationships (Z = aRb) were different for rainfall events of different seasons (a varies from 78.3–119.0, and b from 1.8–2.1), and the calculated KE-R relationships satisfied the form of power function KE = ARm, in which A and m are parameters derived from rainfall shape factor μ. The sensitivity analysis of parameter A with μ demonstrated the applicability of the KE-R formula to different precipitation processes in the Yulin area.

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