Investigation of observational error sources in multi-Doppler-radar three-dimensional variational vertical air motion retrievals

Multi-Doppler-radar network observations have been used in different configurations over the last several decades to conduct three-dimensional wind retrievals in mesoscale convective systems. Here, the impacts of the selected radar volume coverage pattern (VCP), the sampling time for the VCP, the nu...

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Bibliographic Details
Published in:	Atmospheric measurement techniques 2019-03, Vol.12 (3), p.1999-2018
Main Authors:	Oue, Mariko, Kollias, Pavlos, Shapiro, Alan, Tatarevic, Aleksandra, Matsui, Toshihisa
Format:	Article
Language:	eng
Subjects:	Advection Advection (Earth sciences) Analysis Atmospheric circulation Atmospheric motion Clouds Clouds (Meteorology) Computer simulation Doppler radar Doppler sonar Dynamic meteorology Elevation ENVIRONMENTAL SCIENCES Error analysis Investigations Limiting factors Mass flux Mesoscale convective systems Meteorological research Numerical weather prediction Properties Radar Radar data Radar networks Retrieval Sampling Simulators Three dimensional models Three dimensional motion Updraft Vertical velocities Weather Weather forecasting Wind
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Summary:	Multi-Doppler-radar network observations have been used in different configurations over the last several decades to conduct three-dimensional wind retrievals in mesoscale convective systems. Here, the impacts of the selected radar volume coverage pattern (VCP), the sampling time for the VCP, the number of radars used, and the added value of advection correction on the retrieval of the vertical air motion in the upper part of convective clouds are examined using the Weather Research and Forecasting (WRF) model simulation, the Cloud Resolving Model Radar SIMulator (CR-SIM), and a three-dimensional variational multi-Doppler-radar retrieval technique. Comparisons between the model truth (i.e., WRF kinematic fields) and updraft properties (updraft fraction, updraft magnitude, and mass flux) retrieved from the CR-SIM-generated multi-Doppler-radar field are used to investigate these impacts. The findings are that (1) the VCP elevation strategy and sampling time have a significant effect on the retrieved updraft properties above 6 km in altitude; (2) 2 min or shorter VCPs have small impacts on the retrievals, and the errors are comparable to retrievals using a snapshot cloud field; (3) increasing the density of elevation angles in the VCP appears to be more effective to reduce the uncertainty than an addition of data from one more radar, if the VCP is performed in 2 min; and (4) the use of dense elevation angles combined with an advection correction applied to the 2 min VCPs can effectively improve the updraft retrievals, but for longer VCP sampling periods (5 min) the value of advection correction is challenging. This study highlights several limiting factors in the retrieval of upper-level vertical velocity from multi-Doppler-radar networks and suggests that the use of rapid-scan radars can substantially improve the quality of wind retrievals if conducted in a limited spatial domain.
ISSN:	1867-8548 1867-1381 1867-8548