Simple adjoint method for three-dimensional wind retrievals from single-Doppler radar

Abstract. 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.

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Comparison between Dual-Doppler and EnKF Storm-Scale Wind Analyses: The 29–30 May 2004 Geary, Oklahoma, Supercell Thunderstorm

Monthly Weather Review ◽

10.1175/mwr-d-12-00308.1 ◽

2013 ◽

Vol 141 (5) ◽

pp. 1612-1628 ◽

Cited By ~ 7

Author(s):

Corey K. Potvin ◽

Louis J. Wicker ◽

Michael I. Biggerstaff ◽

Daniel Betten ◽

Alan Shapiro

Keyword(s):

Doppler Radar ◽

Three Dimensional ◽

Radar Observations ◽

Field Gradients ◽

Single Moment ◽

Supercell Thunderstorm ◽

Model Initialization ◽

Wind Retrievals ◽

Microphysical Parameterization ◽

Microphysical Parameterization Scheme

Abstract Kinematical analyses of storm-scale mobile radar observations are critical to advancing our understanding of supercell thunderstorms. Maximizing the accuracy of these analyses, and characterizing the uncertainty in ensuing conclusions about storm structure and processes, requires knowledge of the error characteristics of different retrieval techniques under different observational scenarios. Using storm-scale mobile radar observations of a tornadic supercell, this study examines the impacts on ensemble Kalman filter (EnKF) wind analyses of the number of available radars (one versus two), uncertainty in the model-initialization sounding, the sophistication of the microphysical parameterization scheme (double versus single moment), and assimilating reflectivity observations. The relative accuracy of three-dimensional variational data assimilation (3DVAR) dual-Doppler wind retrievals and single- and dual-radar EnKF wind analyses of the supercell is also explored. The results generally reinforce the findings of a previous study that used observing system simulation experiments to explore the same issues. Both studies suggest that single-radar EnKF wind analyses can be very useful once enough data have been assimilated, but that subsequent analyses that operate on the retrieved wind field gradients should be interpreted with caution. In the present study, severe errors appear to occur in computed Lagrangian circulation time series, imperiling interpretation of the underlying dynamics. This result strongly suggests that dual- and multiple-Doppler radar deployment strategies continue to be used in mobile field campaigns.

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Comparison of single-Doppler and multiple-Doppler wind retrievals in Hurricane Matthew (2016)

Atmospheric Measurement Techniques ◽

10.5194/amt-14-3523-2021 ◽

2021 ◽

Vol 14 (5) ◽

pp. 3523-3539

Author(s):

Ting-Yu Cha ◽

Michael M. Bell

Keyword(s):

Tropical Cyclone ◽

Wind Field ◽

Doppler Radar ◽

Three Dimensional ◽

Limited Information ◽

Fourier Decomposition ◽

Wind Retrieval ◽

Retrieval Technique ◽

Wind Retrievals ◽

Doppler Analysis

Abstract. Hurricane Matthew (2016) was observed by the ground-based polarimetric Next Generation Weather Radar (NEXRAD) in Miami (KAMX) and the National Oceanic and Atmospheric Administration WP-3D (NOAA P-3) airborne tail Doppler radar near the coast of the southeastern United States for several hours, providing a novel opportunity to evaluate and compare single- and multiple-Doppler wind retrieval techniques for tropical cyclone flows. The generalized velocity track display (GVTD) technique can retrieve a subset of the wind field from a single ground-based Doppler radar under the assumption of nearly axisymmetric rotational wind, but it has been shown to have errors from the aliasing of unresolved wind components. An improved technique that mitigates errors due to storm motion is derived in this study, although some spatial aliasing remains due to limited information content from the single-Doppler measurements. A spline-based variational wind retrieval technique called SAMURAI can retrieve the full three-dimensional wind field from airborne radar fore–aft pseudo-dual-Doppler scanning, but it has been shown to have errors due to temporal aliasing from the nonsimultaneous Doppler measurements. A comparison between the two techniques shows that the axisymmetric tangential winds are generally comparable between the two techniques, and the improved GVTD technique improves the accuracy of the retrieval. Fourier decomposition of asymmetric kinematic and convective structure shows more discrepancies due to spatial and temporal aliasing in the retrievals. The strengths and weaknesses of each technique for studying tropical cyclone structure are discussed and suggest that complementary information can be retrieved from both single- and dual-Doppler retrievals. Future improvements to the asymmetric flow assumptions in single-Doppler analysis and steady-state assumptions in pseudo-dual-Doppler analysis are required to reconcile differences in retrieved tropical cyclone structure.

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Investigation of observational error sources in multi Doppler radar vertical air motion retrievals: Impacts and possible solutions

10.5194/amt-2018-442 ◽

2018 ◽

Author(s):

Mariko Oue ◽

Pavlos Kollias ◽

Alan Shapiro ◽

Aleksandra Tatarevic ◽

Toshihisa Matsui

Keyword(s):

Doppler Radar ◽

Three Dimensional ◽

Sampling Time ◽

Added Value ◽

Limiting Factors ◽

Convective System ◽

Mesoscale Convective ◽

Air Motion ◽

Wind Retrievals ◽

The Impact

Abstract. 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 impact 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 is 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. In overall, the VCP elevation strategy and sampling time is found to have a significant effect on the retrieved updraft properties above 6 km altitude. Retrievals conducted using a 2-min or shorter VCPs show small impacts on the updraft retrievals, and the errors are comparable to retrievals using a snapshot cloud field. Increasing the density of elevations angles and/or an addition of data from one more radar can reduce this uncertainty. It is found that the VCP with dense elevation angles appears to be more effective than the addition of data from the fourth radar, if the VCP is performed in 2 minutes. The use of dense elevation angles combined with an advection correction applied to the 2-min VCPs can effectively improve the updraft retrievals. For longer VCP sampling periods (5 min) the errors are considerably larger, and the value of advection correction is challenging due to the rapid deformation of the dynamical structures in the simulated mesoscale convective system. 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.

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The Coplane Analysis Technique for Three-Dimensional Wind Retrieval Using the HIWRAP Airborne Doppler Radar

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-14-0203.1 ◽

2015 ◽

Vol 54 (3) ◽

pp. 605-623 ◽

Cited By ~ 9

Author(s):

Anthony C. Didlake ◽

Gerald M. Heymsfield ◽

Lin Tian ◽

Stephen R. Guimond

Keyword(s):

Global Optimization ◽

Doppler Radar ◽

Three Dimensional ◽

Optimization Method ◽

Vertical Wind ◽

Wind Component ◽

Global Optimization Method ◽

Analysis Technique ◽

Radar Measurements ◽

Cross Track

AbstractThe coplane analysis technique for mapping the three-dimensional wind field of precipitating systems is applied to the NASA High-Altitude Wind and Rain Airborne Profiler (HIWRAP). HIWRAP is a dual-frequency Doppler radar system with two downward-pointing and conically scanning beams. The coplane technique interpolates radar measurements onto a natural coordinate frame, directly solves for two wind components, and integrates the mass continuity equation to retrieve the unobserved third wind component. This technique is tested using a model simulation of a hurricane and compared with a global optimization retrieval. The coplane method produced lower errors for the cross-track and vertical wind components, while the global optimization method produced lower errors for the along-track wind component. Cross-track and vertical wind errors were dependent upon the accuracy of the estimated boundary condition winds near the surface and at nadir, which were derived by making certain assumptions about the vertical velocity field. The coplane technique was then applied successfully to HIWRAP observations of Hurricane Ingrid (2013). Unlike the global optimization method, the coplane analysis allows for a transparent connection between the radar observations and specific analysis results. With this ability, small-scale features can be analyzed more adequately and erroneous radar measurements can be identified more easily.

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Retrieval of three-dimensional wind fields from Doppler radar data using an efficient two-step approach

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-3-4459-2010 ◽

2010 ◽

Vol 3 (5) ◽

pp. 4459-4495 ◽

Cited By ~ 1

Author(s):

C. López Carrillo ◽

D. J. Raymond

Keyword(s):

Variational Approach ◽

Continuity Equation ◽

Doppler Radar ◽

Three Dimensional ◽

Relevant Information ◽

Radar Data ◽

Wind Fields ◽

Wind Retrieval ◽

Complex Sampling ◽

Doppler Radar Data

Abstract. In this work, we describe an efficient approach for wind retrieval from dual Doppler radar data. The approach produces a gridded field that not only satisfies the observations, but also satisfies the anelastic mass continuity equation. The method is based on the so-called three-dimensional variational approach to the retrieval of wind fields from radar data. The novelty consists in separating the task into steps that reduce the amount of data processed by the global minimization algorithm, while keeping the most relevant information from the radar observations. The method is flexible enough to incorporate observations from several radars, accommodate complex sampling geometries, and readily include dropsonde or sounding observations in the analysis. We demonstrate the usefulness of our method by analyzing a real case with data collected during the TPARC/TCS-08 field campaign.

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Vertical Vortex Development in Hurricane Michael (2018) during Rapid Intensification

Monthly Weather Review ◽

10.1175/mwr-d-21-0098.1 ◽

2021 ◽

Author(s):

Alexander J. DesRosiers ◽

Michael M. Bell ◽

Ting-Yu Cha

Keyword(s):

Inner Core ◽

Doppler Radar ◽

Three Dimensional ◽

Vertical Gradient ◽

Machine Learning Techniques ◽

Rapid Intensification ◽

Wind Retrieval ◽

Retrieval Technique ◽

Budget Analysis ◽

Tangential Wind

AbstractThe landfall of Hurricane Michael (2018) at category 5 intensity occurred after rapid intensification (RI) spanning much of the storm’s lifetime. Four Hurricane Hunter aircraft missions observed the RI period with tail Doppler radar (TDR). Data from each of the 14 aircraft passes through the storm were quality controlled via a combination of interactive and machine learning techniques. TDR data from each pass were synthesized using the SAMURAI variational wind retrieval technique to yield three-dimensional kinematic fields of the storm to examine inner core processes during RI. Vorticity and angular momentum increased and concentrated in the eyewall region. A vorticity budget analysis indicates the tendencies became more axisymmetric over time. In this study we focus in particular on how the eyewall vorticity tower builds vertically into the upper levels. Horizontal vorticity associated with the vertical gradient of tangential wind was tilted into the vertical by the eyewall updraft to yield a positive vertical vorticity tendency inward atop the existing vorticity tower, that is further developed locally upward and outward along the sloped eyewall through advection and stretching. Observed maintenance of thermal wind balance from a thermodynamic retrieval shows evidence of a strengthening warm core, which aided in lowering surface pressure and further contributed to the efficient intensification in the latter stages of this RI event.

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Aerodynamic Design Optimization of Three Dimensional Rocket Nozzles Using Adjoint Method

10.2514/6.2013-2851 ◽

2013 ◽

Author(s):

Sinan Eyi ◽

Mine Yumusak

Keyword(s):

Design Optimization ◽

Adjoint Method ◽

Three Dimensional ◽

Aerodynamic Design ◽

Aerodynamic Design Optimization

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Relationships between Deep Convection Updraft Characteristics and Satellite-Based Super Rapid Scan Mesoscale Atmospheric Motion Vector–Derived Flow

Monthly Weather Review ◽

10.1175/mwr-d-18-0119.1 ◽

2018 ◽

Vol 146 (10) ◽

pp. 3461-3480 ◽

Cited By ~ 10

Author(s):

Jason M. Apke ◽

John R. Mecikalski ◽

Kristopher Bedka ◽

Eugene W. McCaul ◽

Cameron R. Homeyer ◽

...

Keyword(s):

Doppler Radar ◽

Deep Convection ◽

Motion Vector ◽

Three Dimensional ◽

Radar Data ◽

Severe Weather ◽

Lightning Flash ◽

Rapid Scan ◽

Total Lightning ◽

The Relationship

Abstract Rapid acceleration of cloud-top outflow near vigorous storm updrafts can be readily observed in Geostationary Operational Environmental Satellite-14 (GOES-14) super rapid scan (SRS; 60 s) mode data. Conventional wisdom implies that this outflow is related to the intensity of updrafts and the formation of severe weather. However, from an SRS satellite perspective, the pairing of observed expansion and updraft intensity has not been objectively derived and documented. The goal of this study is to relate GOES-14 SRS-derived cloud-top horizontal divergence (CTD) over deep convection to internal updraft characteristics, and document evolution for severe and nonsevere thunderstorms. A new SRS flow derivation system is presented here to estimate storm-scale (<20 km) CTD. This CTD field is coupled with other proxies for storm updraft location and intensity such as overshooting tops (OTs), total lightning flash rates, and three-dimensional flow fields derived from dual-Doppler radar data. Objectively identified OTs with (without) matching CTD maxima were more (less) likely to be associated with radar-observed deep convection and severe weather reports at the ground, suggesting that some OTs were incorrectly identified. The correlation between CTD magnitude, maximum updraft speed, and total lightning was strongly positive for a nonsupercell pulse storm, and weakly positive for a supercell with multiple updraft pulses present. The relationship for the supercell was nonlinear, though larger flash rates are found during periods of larger CTD. Analysis here suggests that combining CTD with OTs and total lightning could have severe weather nowcasting value.

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Investigation of Extreme Rainfall Patterns around Antalya and Muğla Cities in Türkiye by Using C Band Doppler Radar Data

10.5194/egusphere-egu21-14529 ◽

2021 ◽

Author(s):

Emir Yapıcı ◽

Ahmet Öztopal ◽

Erdem Erdi

Keyword(s):

Doppler Radar ◽

Three Dimensional ◽

Extreme Rainfall ◽

Radar Data ◽

Mediterranean Coast ◽

Extreme Rainfall Events ◽

Weather Radars ◽

Hourly Rainfall ◽

Raingauge Data ◽

Rainfall Patterns

As is known, rainfall varies spatially and temporally with regard to intensity and frequency. Floods, related to extreme rainfall cases, cause stress on geophysical system and community if climate change is considered. For this reason determining of extreme rainfall patterns is very important. While obtaining three dimensional status of hydrometors in atmosphere is not possible only by using ground station networks, it is possible by using weather radars. Therefore, weather radars provide significant contribution to studies about getting cloud and rainfall patterns. The aim of this study is to investigate spatial patterns of extreme rainfall events in Antalya and Mu&#287;la cities which are located on the Mediterranean coast of T&#252;rkiye. Firstly, hourly rainfall (RN1) and rain rate (SRI) products of 2 C band doppler radars and raingauge data between 2015 and 2020 will be processed by a software named MeteoRadar which is developed by &#304;stanbul Technical University. It is capable of reading, decoding, parallel processing and visualization. Secondly, extreme rainfall patterns will be obtained over 2 study areas. Finally, after validation by using raingauge data, results will be discussed in detail.Key Words: Antalya, Extreme rainfall, MeteoRadar, Mu&#287;la, RN1, SRI, Weather radar.

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