Three-dimensional wind profiles using a stabilized shipborne cloud radar in wind profiler mode

Abstract. In this study, a shipborne 95 GHz Doppler cloud radar mounted on a stabilized platform is used to retrieve vertical profiles of three-dimensional (3D) winds by sequentially pointing the stabilized platform in different directions. A specific challenge is that the maximum angle off zenith is 8°, which implies that the projection of the horizontal wind components onto the radar beam directions is a small component of Doppler velocity in most cases. A variational 3D wind retrieval technique is then described, allowing for 1-minute resolution 3D wind profiles to be retrieved. Statistical comparisons with 3-hourly radiosonde launches and qualitative comparisons with ship-level horizontal winds demonstrate that accurate 3D wind profiles can be obtained from such cloud radar observations at small off-zenith angles.

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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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Monitoring observations of meteor echo at the EKB ISTP SB RAS radar: algorithms, validation, statistics

Solar-Terrestrial Physics ◽

10.12737/stp-71202107 ◽

2021 ◽

Vol 7 (1) ◽

pp. 47-58

Author(s):

Roman Fedorov ◽

Oleg Berngardt

Keyword(s):

Least Squares Method ◽

Weighted Least Squares ◽

Three Dimensional ◽

Radar Data ◽

Meteor Shower ◽

Horizontal Wind ◽

Doppler Velocity ◽

Wind Model ◽

Weighted Least Squares Method ◽

Meteor Trails

The paper considers the implementation of algorithms for automatic search for signals scattered by meteor trails according to EKB ISTP SB RAS radar data. In general, the algorithm is similar to the algorithms adopted in specialized meteor systems. The algorithm is divided into two stages: detecting a meteor echo and determining its parameters. We show that on the day of the maximum Geminid shower, December 13, 2016, the scattered signals detected by the algorithm are foreshortening and correspond to scattering by irregularities extended in the direction of the meteor shower radiant. This confirms that the source of the signals detected by the algorithm is meteor trails. We implement an additional program for indirect trail height determination. It uses a decay time of echo and the NRLMSIS-00 atmosphere model to estimate the trail height. The dataset from 2017 to 2019 is used for further testing of the algorithm. We demonstrate a correlation in calculated Doppler velocity between the new algorithm and FitACF. We present a solution of the inverse problem of reconstructing the neutral wind velocity vector from the data obtained by the weighted least squares method. We compare calculated speeds and directions of horizontal neutral winds, obtained in the three-dimensional wind model, and the HWM-14 horizontal wind model. The algorithm allows real-time scattered signal processing and has been put into continuous operation at the EKB ISTP SB RAS radar.

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Evaluation of gridded scanning ARM cloud radar reflectivity observations and vertical doppler velocity retrievals

Atmospheric Measurement Techniques ◽

10.5194/amt-7-1089-2014 ◽

2014 ◽

Vol 7 (4) ◽

pp. 1089-1103 ◽

Cited By ~ 5

Author(s):

K. Lamer ◽

A. Tatarevic ◽

I. Jo ◽

P. Kollias

Keyword(s):

Great Plains ◽

Spatial Scales ◽

Domain Size ◽

Horizontal Wind ◽

Cape Cod ◽

Doppler Velocity ◽

Cloud Radar ◽

Stratiform Clouds ◽

Atmospheric Observations ◽

Atmospheric Radiation Measurement

Abstract. The scanning Atmospheric Radiation Measurement (ARM) cloud radars (SACRs) provide continuous atmospheric observations aspiring to capture the 3-D cloud-scale structure. Sampling clouds in 3-D is challenging due to their temporal–spatial scales, the need to sample the sky at high elevations and cloud radar limitations. Thus, a suggested scan strategy is to repetitively slice the atmosphere from horizon to horizon as clouds advect over the radar (Cross-Wind Range-Height Indicator – CW-RHI). Here, the processing and gridding of the SACR CW-RHI scans are presented. First, the SACR sample observations from the ARM Southern Great Plains and Cape Cod sites are post-processed (detection mask, gaseous attenuation correction, insect filtering and velocity de-aliasing). The resulting radial Doppler moment fields are then mapped to Cartesian coordinates with time as one of the dimensions. Next the Cartesian-gridded Doppler velocity fields are decomposed into the horizontal wind velocity contribution and the vertical Doppler velocity component. For validation purposes, all gridded and retrieved fields are compared to collocated zenith-pointing ARM cloud radar measurements. We consider that the SACR sensitivity loss with range, the cloud type observed and the research purpose should be considered in determining the gridded domain size. Our results also demonstrate that the gridded SACR observations resolve the main features of low and high stratiform clouds. It is established that the CW-RHI observations complemented with processing techniques could lead to robust 3-D cloud dynamical representations up to 25–30 degrees off zenith. The proposed gridded products are expected to advance our understanding of 3-D cloud morphology, dynamics and anisotropy and lead to more realistic 3-D radiative transfer calculations.

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Development and Application of a Simplified Coplane Wind Retrieval Algorithm Using Dual-Beam Airborne Doppler Radar Observations for Tropical Cyclone Prediction

Monthly Weather Review ◽

10.1175/mwr-d-15-0323.1 ◽

2016 ◽

Vol 144 (7) ◽

pp. 2645-2666

Author(s):

Christopher Melhauser ◽

Fuqing Zhang

Keyword(s):

Radial Velocity ◽

Doppler Radar ◽

Statistical Significance ◽

Three Dimensional ◽

Horizontal Wind ◽

Retrieval Algorithm ◽

Average Error ◽

Scanning Angle ◽

Wind Retrieval ◽

Research Division

Abstract Based on established coplane methodology, a simplified three-dimensional wind retrieval algorithm is proposed to derive two-dimensional wind vectors from radial velocity observations by the tail Doppler radars on board the NOAA P3 hurricane reconnaissance aircraft. Validated against independent in situ flight-level and dropsonde observations before and after genesis of Hurricane Karl (2010), each component of the retrieved wind vectors near the aircraft track has an average error of approximately 1.5 m s−1, which increases with the scanning angle and distance away from the aircraft track. Simulated radial velocities derived from a convection-permitting simulation of Karl are further used to systematically quantify errors of the simplified coplane algorithm. The accuracy of the algorithm is strongly dependent on the time between forward and backward radar scans and to a lesser extent, the zero vertical velocity assumption at large angles relative to a plane parallel with the aircraft wings. A proof-of-concept experiment assimilating the retrieved wind vectors with an ensemble Kalman filter shows improvements in track and intensity forecasts similar to assimilating radial velocity super observations or the horizontal wind vectors from the analysis retrievals provided by the Hurricane Research Division of NOAA. Future work is needed to systematically evaluate this simplified coplane algorithm with proper error characteristics for TC initialization and prediction through a large number of events to establish statistical significance.

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Assessing Errors in Variational Dual-Doppler Wind Syntheses of Supercell Thunderstorms Observed by Storm-Scale Mobile Radars

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-11-00177.1 ◽

2012 ◽

Vol 29 (8) ◽

pp. 1009-1025 ◽

Cited By ~ 22

Author(s):

Corey K. Potvin ◽

Louis J. Wicker ◽

Alan Shapiro

Keyword(s):

Three Dimensional ◽

Middle Level ◽

Radar Observations ◽

Wind Retrieval ◽

Convective Storms ◽

Retrieval Technique ◽

Invaluable Tool ◽

Close Range ◽

Upper Level ◽

Scanning Strategies

Abstract Dual-Doppler wind retrieval is an invaluable tool in the study of convective storms. However, the nature of the errors in the retrieved three-dimensional wind estimates and subsequent dynamical analyses is not precisely known, making it difficult to assign confidence to inferred storm behavior. Using an Observing System Simulation Experiment (OSSE) framework, this study characterizes these errors for a supercell thunderstorm observed at close range by two Doppler radars. Synthetic radar observations generated from a high-resolution numerical supercell simulation are input to a three-dimensional variational data assimilation (3DVAR) dual-Doppler wind retrieval technique. The sensitivity of the analyzed kinematics and dynamics to the dual-Doppler retrieval settings, hydrometeor fall speed parameterization errors, and radar cross-beam angle and scanning strategy is examined. Imposing the commonly adopted assumptions of spatially constant storm motion and intrinsically steady flow produces large errors at higher altitudes. On the other hand, reasonably accurate analyses are obtained at lower and middle levels, even when the majority of the storm lies outside the 30° dual-Doppler lobe. Low-level parcel trajectories initiated around the main updraft and rear-flank downdraft are generally qualitatively accurate, as are time series of circulation computed around material circuits. Omitting upper-level radar observations to reduce volume scan times does not substantially degrade the lower- and middle-level analyses, which implies that shallower scanning strategies should enable an improved retrieval of supercell dynamics. The results suggest that inferences about supercell behavior based on qualitative features in 3DVAR dual-Doppler and subsequent dynamical retrievals may generally be reliable.

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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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Monitoring observations of meteor echo at the EKB ISTP SB RAS radar: algorithms, validation, statistics

Solnechno-Zemnaya Fizika ◽

10.12737/szf-71202107 ◽

2021 ◽

Vol 7 (1) ◽

pp. 59-73

Author(s):

Roman Fedorov ◽

Oleg Berngardt

Keyword(s):

Least Squares Method ◽

Weighted Least Squares ◽

Three Dimensional ◽

Radar Data ◽

Meteor Shower ◽

Horizontal Wind ◽

Doppler Velocity ◽

Wind Model ◽

Weighted Least Squares Method ◽

Meteor Trails

The paper considers the implementation of algorithms for automatic search for signals scattered by meteor trails according to EKB ISTP SB RAS radar data. In general, the algorithm is similar to the algorithms adopted in specialized meteor systems. The algorithm is divided into two stages: detecting a meteor echo and determining its parameters. We show that on the day of the maximum Geminid shower, December 13, 2016, the scattered signals detected by the algorithm are foreshortening and correspond to scattering by irregularities extended in the direction of the meteor shower radiant. This confirms that the source of the signals detected by the algorithm is meteor trails. We implement an additional program for indirect trail height determination. It uses a decay time of echo and the NRLMSIS-00 atmosphere model to estimate the trail height. The dataset from 2017 to 2019 is used for further testing of the algorithm. We demonstrate a correlation in calculated Doppler velocity between the new algorithm and FitACF. We present a solution of the inverse problem of reconstructing the neutral wind velocity vector from the data obtained by the weighted least squares method. We compare calculated speeds and directions of horizontal neutral winds, obtained in the three-dimensional wind model, and the HWM-14 horizontal wind model. The algorithm allows real-time scattered signal processing and has been put into continuous operation at the EKB ISTP SB RAS radar.

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New flexible retrieval for gusts and mean winds from Doppler wind lidars

10.5194/egusphere-egu21-2867 ◽

2021 ◽

Author(s):

Julian Steinheuer ◽

Carola Detring ◽

Frank Beyrich ◽

Ulrich Löhnert ◽

Stephanie Fiedler

Keyword(s):

Radial Velocity ◽

Sonic Anemometer ◽

Three Dimensional ◽

Time Interval ◽

Wind Vector ◽

Meteorological Tower ◽

Wind Retrieval ◽

Retrieval Technique ◽

Wind Gusts ◽

Spatio Temporal

<p>Phenomena in the atmospheric boundary layer are investigated in the Field Experiment on Sub-Mesoscale Spatio-Temporal Variability in Lindenberg (FESSTVaL, www.fesstval.de). Our aim is the retrieval of wind gusts from measurements of a Doppler wind lidar (DWL). DWLs allow the determination of wind vector profiles with high vertical resolution (&#8764;30 m) and represent an alternative to classical meteorological tower observations. They can receive signals from altitudes higher than towers and are flexible in positioning. However, the retrieval of wind gusts from DWL measurements is not trivial because a monostatic lidar provides only one radial velocity, i.e., only one component of a three-dimensional vector, and measurements in three linearly independent directions are necessary to derive the wind vector. These have to be performed sequentially which limits the achievable time resolution, while wind gusts are short-lived phenomena. Therefore, we have developed a new wind retrieval that is applicable to different scanning configurations and various requested time resolutions. We tested several DWL configurations in autumn 2019 using DWL systems &#8217;StreamLine&#8217; from Halo Photonics and evaluated gust peaks and the 10min mean wind at 90 m height against data from a sonic anemometer at the meteorological tower. The most useful configuration for retrieving wind gusts is a fast continuous scan mode (CSM) that completes a full circulation cone within 3.4s. During this time interval, about eleven radial velocity measurements are completed. This fast CSM configuration was again successfully operated over a three-months period in summer 2020. We found that CSM paired with our new retrieval technique provides gusts which compare well to classical anemometer measurements from a meteorological tower. Future work includes the application of the new retrieval to DWL data during the FESSTVaL campaign in 2021 when DWL measurements are planned at different sites in order to study the sub-mesoscale variability of wind gusts.</p>

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Evaluation of gridded Scanning ARM Cloud Radar reflectivity observations and vertical Doppler velocity retrievals

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-9579-2013 ◽

2013 ◽

Vol 6 (6) ◽

pp. 9579-9621 ◽

Cited By ~ 3

Author(s):

K. Lamer ◽

A. Tatarevic ◽

I. Jo ◽

P. Kollias

Keyword(s):

Spatial Scales ◽

Domain Size ◽

Horizontal Wind ◽

Cape Cod ◽

Doppler Velocity ◽

Cloud Radar ◽

Stratiform Clouds ◽

Atmospheric Observations ◽

Processing Techniques ◽

High Elevations

Abstract. The Scanning ARM Cloud Radars (SACR's) provide continuous atmospheric observations aspiring to capture the 3-D cloud-scale structure. Sampling clouds in 3-D is challenging due to their temporal-spatial scales, the need to sample the sky at high elevations and cloud radar limitations. Thus, a common scan strategy is to repetitively slice the atmosphere from horizon to horizon as clouds advect over the radar (Cross-Wind Range Height Indicator – CWRHI). Here, the processing and gridding of the SACR CW-RHI scans are presented. First, the SACR sample observations from the ARM Oklahoma (SGP) and Cape-Cod (PVC) sites are post-processed (detection mask, velocity de-aliasing and gaseous attenuation correction). The resulting radial Doppler moment fields are then mapped to Cartesian coordinates with time as one of the dimension. The Cartesian-gridded Doppler velocity fields are next decomposed into the horizontal wind velocity contribution and the vertical Doppler velocity component. For validation purposes, all gridded and retrieved fields are compared to collocated zenith pointing ARM cloud radar measurements. We consider that the SACR sensitivity loss with range, the cloud type observed and the research purpose should be considered in determining the gridded domain size. Our results also demonstrate that the gridded SACR observations resolve the main features of low and high stratiform clouds. It is established that the CW-RHI observations complemented with processing techniques could lead to robust 3-D clouds dynamical representations up to 25–30° off zenith. The proposed gridded products are expected to advance our understanding of 3-D cloud morphology, dynamics, anisotropy and lead to more realistic 3-D radiative transfer calculations.

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