scholarly journals Three-Dimensional Wind Retrieval: Application of MUSCAT to Dual-Doppler Lidar

2009 ◽  
Vol 26 (3) ◽  
pp. 635-646 ◽  
Author(s):  
Susanne Drechsel ◽  
Georg J. Mayr ◽  
Michel Chong ◽  
Martin Weissmann ◽  
Andreas Dörnbrack ◽  
...  
Keyword(s):  
Complex Terrain ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Doppler Lidar ◽  
Wind Fields ◽  
Owens Valley ◽  
Horizontal Structure ◽  
Wind Retrieval ◽  
Weather Radars ◽  
Spatial Coverage

Abstract During the field campaign of the Terrain-induced Rotor Experiment (T-REX) in the spring of 2006, Doppler lidar measurements were taken in the complex terrain of the Californian Owens Valley for six weeks. While fast three-dimensional (3D) wind analysis from measured radial wind components is well established for dual weather radars, only the feasibility was shown for dual-Doppler lidars. A computationally inexpensive, variational analysis method developed for multiple-Doppler radar measurements over complex terrain was applied. The general flow pattern of the 19 derived 3D wind fields is slightly smoothed in time and space because of lidar scan duration and analysis algorithm. The comparison of extracted wind profiles to profiles from radiosondes and wind profiler reveals differences of wind speed and direction of less than 1.1 m s−1 and 3°, on average, with standard deviations not exceeding 2.7 m s−1 and 27°, respectively. Standard velocity–azimuth display (VAD) retrieval method provided higher vertical resolution than the dual-Doppler retrieval, but no horizontal structure of the flow field. The authors suggest a simple way to obtain a good first guess for a dual-lidar scan strategy geared toward 3D wind retrieval that minimizes scan duration and maximizes spatial coverage.

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

2010 ◽  
Vol 3 (5) ◽  
pp. 4459-4495 ◽  
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.

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

2011 ◽  
Vol 4 (12) ◽  
pp. 2717-2733 ◽  
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.

scholarly journals Volume Scanning Strategies for 3D Wind Retrieval from Dual-Doppler Lidar Measurements

2010 ◽  
Vol 27 (11) ◽  
pp. 1881-1892 ◽  
Author(s):  
Susanne Drechsel ◽  
Georg J. Mayr ◽  
Michel Chong ◽  
Fotini K. Chow
Keyword(s):  
Retrieval Algorithm ◽  
Doppler Lidar ◽  
Wind Fields ◽  
Actual Measurement ◽  
Trade Off ◽  
Wind Retrieval ◽  
Scan Time ◽  
Temporal Smoothing ◽  
Spatial Coverage ◽  
Scanning Strategies

Abstract Dual-Doppler lidar volume scans for 3D wind retrieval must accommodate the conflicting goals of dense spatial coverage and short scan duration. In this work, various scanning strategies are evaluated with semisynthetic wind fields from analytical solutions and numerical simulations over flat and complex terrain using the Multiple-Doppler Synthesis and Continuity Adjustment Technique (MUSCAT) retrieval algorithm. The focus of this study is to determine how volume scan strategies affect performance of the wind retrieval algorithm. Interlaced scanning methods that take into account actual maximum measurement ranges are found to be optimal because they provide the best trade-off between retrieval accuracy, volume coverage, and scan time. A recommendation for scanning strategies is given, depending on actual measurement ranges, the variability of the wind situation, and the trade-off between spatial coverage and temporal smoothing.

scholarly journals Comparison between the 2D wind fields retrieved by a scanning Doppler lidar and anemometric measurements

2021 ◽  
Author(s):  
José Antonio Benavent-Oltra ◽  
Djordje Romanic ◽  
Milos Lompar ◽  
Massimiliano Burlando
Keyword(s):  
Wind Velocity ◽  
Wind Direction ◽  
Doppler Radar ◽  
Sampling Rate ◽  
Three Dimensional ◽  
Theoretical Work ◽  
Radar Data ◽  
Doppler Lidar ◽  
Wind Fields ◽  
Software Module

<p>In this work, two-dimensional (2D) wind fields retrieved by SingleDop software using scanning Doppler lidar data are compared with anemometric measurements in Genoa (Italy). SingleDop is a software module based on the theoretical work described in Xu et al. (2006), which is intended to retrieve 2D low-level winds from either real or simulated Doppler radar data. The lidar used in this work is a three-dimensional (3D) scanning WindCube 400S lidar, developed by Leosphere (France), which scans the azimuthal range of 100º –250º, up to a maximum distance of 14 km in the radial direction, for 4 elevations corresponding to 2.5º, 5°, 7.5° and 10º from the horizontal. The anemometer used for comparison is located about 1.3 km (horizontally) from the Doppler lidar and provides the wind velocity with a sampling rate of 1 Hz.</p><p>The dataset analyzed is from November 2019 to June 2020. The total number of available lidar scans per day is ~420 for each elevation (2.5º, 5º, 7.5º and 10º). The 2D wind fields are retrieved by SingleDop for different de-correlated lengths (L= 10, 5 and 1 km). The overall number of measurements available for the comparison is therefore approximately 420 scans per day <em>×</em> 180 days <em>× </em>4 heights <em>× </em>3 L, which results in nearly 10<sup>6</sup> wind velocity values. The wind direction retrieved by SingleDop properly corresponds to the anemometric data with a  BIAS ~13º, RMSE ~40º and a circular correlation of 0.8. Concerning the wind intensity, the results obtained for L = 5 km show the best agreement with the anemometric measurements with a BIAS of 0.8 m/s, RMSE around 1.8 m/s and a correlation coefficient higher than 0.9. Both for wind direction and velocity, the BIAS and RMSE slightly increase with the elevation whereas the circular and linear correlations decrease, as expected due to the increasing distance between lidar and anemometric measurements.</p>

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

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.

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

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

<p>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 Muğla cities which are located on the Mediterranean coast of Türkiye. 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 İstanbul 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.</p><p><strong>Key Words</strong>: Antalya, Extreme rainfall, MeteoRadar, Muğla, RN1, SRI, Weather radar.</p>

scholarly journals Simultaneous Assimilation of Radar and All-Sky Satellite Infrared Radiance Observations for Convection-Allowing Ensemble Analysis and Prediction of Severe Thunderstorms

2019 ◽  
Vol 147 (12) ◽  
pp. 4389-4409 ◽  
Author(s):  
Yunji Zhang ◽  
David J. Stensrud ◽  
Fuqing Zhang
Keyword(s):  
Doppler Radar ◽  
Three Dimensional ◽  
Lead Times ◽  
Probabilistic Prediction ◽  
Ensemble Forecasts ◽  
Radar Observations ◽  
Weather Radars ◽  
Infrared Radiance ◽  
Severe Thunderstorms ◽  
Ensemble Analysis

Abstract This study explores the benefits of assimilating infrared (IR) brightness temperature (BT) observations from geostationary satellites jointly with radial velocity (Vr) and reflectivity (Z) observations from Doppler weather radars within an ensemble Kalman filter (EnKF) data assimilation system to the convection-allowing ensemble analysis and prediction of a tornadic supercell thunderstorm event on 12 June 2017 across Wyoming and Nebraska. While radar observations sample the three-dimensional storm structures with high fidelity, BT observations provide information about clouds prior to the formation of precipitation particles when in-storm radar observations are not yet available and also provide information on the environment outside the thunderstorms. To better understand the strengths and limitations of each observation type, the satellite and Doppler radar observations are assimilated separately and jointly, and the ensemble analyses and forecasts are compared with available observations. Results show that assimilating BT observations has the potential to increase the forecast and warning lead times of severe weather events compared with radar observations and may also potentially complement the sparse surface observations in some regions as revealed by the probabilistic prediction of mesocyclone tracks initialized from EnKF analyses as various times. Additionally, the assimilation of both BT and Vr observations yields the best ensemble forecasts, providing higher confidence, improved accuracy, and longer lead times on the probabilistic prediction of midlevel mesocyclones.

An Application of the Immersed Boundary Method for Recovering the Three-Dimensional Wind Fields over Complex Terrain Using Multiple-Doppler Radar Data

2012 ◽  
Vol 140 (5) ◽  
pp. 1603-1619 ◽  
Author(s):  
Yu-Chieng Liou ◽  
Shao-Fan Chang ◽  
Juanzhen Sun
Keyword(s):  
Radial Velocity ◽  
Immersed Boundary Method ◽  
Doppler Radar ◽  
Synthesis Method ◽  
Three Dimensional ◽  
Simulated Data ◽  
Radar Data ◽  
Immersed Boundary ◽  
Wind Fields ◽  
Boundary Method

This study develops an extension of a variational-based multiple-Doppler radar synthesis method to construct the three-dimensional wind field over complex topography. The immersed boundary method (IBM) is implemented to take into account the influence imposed by a nonflat surface. The IBM has the merit of providing realistic topographic forcing without the need to change the Cartesian grid configuration into a terrain-following coordinate system. Both Dirichlet and Neumann boundary conditions for the wind fields can be incorporated. The wind fields above the terrain are obtained by variationally adjusting the solutions to satisfy a series of weak constraints, which include the multiple-radar radial velocity observations, anelastic continuity equation, vertical vorticity equation, background wind, and spatial smoothness terms. Experiments using model-simulated data reveal that the flow structures over complex orography can be successfully retrieved using radial velocity measurements from multiple Doppler radars. The primary advantages of the original synthesis method are still maintained, that is, the winds along and near the radar baseline are well retrieved, and the resulting three-dimensional flow fields can be used directly for vorticity budget diagnosis. If compared with the traditional wind synthesis algorithm, this method is able to merge data from different sources, and utilize data from any number of radars. This provides more flexibility in designing various scanning strategies, so that the atmosphere may be probed more efficiently using a multiple-radar network. This method is also tested using the radar data collected during the Southwest Monsoon Experiment (SoWMEX), which was conducted in Taiwan from May to June 2008 with reasonable results being obtained.

scholarly journals Evaluation of the Hurricane Research Division Doppler Radar Analysis Software Using Synthetic Data

2013 ◽  
Vol 30 (6) ◽  
pp. 1055-1071 ◽  
Author(s):  
Sylvie Lorsolo ◽  
John Gamache ◽  
Altug Aksoy
Keyword(s):  
Doppler Radar ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Vertical Component ◽  
Radar Data ◽  
Weather Research And Forecasting ◽  
Analysis Software ◽  
Wind Fields ◽  
Research Division ◽  
Tangential Wind

Abstract The Hurricane Research Division Doppler radar analysis software provides three-dimensional analyses of the three wind components in tropical cyclones. Although this software has been used for over a decade, there has never been a complete and in-depth evaluation of the resulting analyses. The goal here is to provide an evaluation that will permit the best use of the analyses, but also to improve the software. To evaluate the software, analyses are produced from simulated radar data acquired from an output of a Hurricane Weather Research and Forecasting (HWRF) model nature run and are compared against the model “truth” wind fields. Comparisons of the three components of the wind show that the software provides analyses of good quality. The tangential wind is best retrieved, exhibiting an overall small mean error of 0.5 m s−1 at most levels and a root-mean-square error less than 2 m s−1. The retrieval of the radial wind is also quite accurate, exhibiting comparable errors, although the accuracy of the tangential wind is generally better. Some degradation of the retrieval quality is observed at higher altitude, mainly due to sparser distribution of data in the model. The vertical component of the wind appears to be the most challenging to retrieve, but the software still provides acceptable results. The tropical cyclone mean azimuthal structure and wavenumber structure are found to be very well captured. Sources of errors inherent to airborne Doppler measurements and the effects of some of the simplifications used in the simulation methodology are also discussed.

scholarly journals Comparison of Single Doppler and Multiple Doppler Wind Retrievals in Hurricane Matthew (2016)

2020 ◽  
Author(s):  
Ting-Yu Cha ◽  
Michael M. Bell
Keyword(s):  
Tropical Cyclone ◽  
Wind Field ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Airborne Radar ◽  
Limited Information ◽  
Fourier Decomposition ◽  
Wind Retrieval ◽  
Advantages And Disadvantages ◽  
Doppler Analysis

Abstract. Hurricane Matthew (2016) was observed by the NEXRAD KAMX polarimetric radar and NOAA P-3 airborne 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 is shown to have errors from 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 is shown to have errors due to temporal aliasing from the non-simultaneous Doppler measurements. A comparison between the two techniques shows that the axisymmetric tangential winds are generally comparable between the two techniques after the improvements to GVTD retrievals. Fourier decomposition of asymmetric kinematic and convective structure shows more discrepancies due to spatial and temporal aliasing in the retrievals. The advantages and disadvantages of each technique for studying tropical cyclone structure are discussed, and suggest that complementary information can be retrieved from both single and multiple 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.

Sign in / Sign up

Export Citation Format

Share Document