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.

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

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.

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 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.

scholarly journals A Variational Multiple–Doppler Radar Three-Dimensional Wind Synthesis Method and Its Impacts on Thermodynamic Retrieval

2009 ◽  
Vol 137 (11) ◽  
pp. 3992-4010 ◽  
Author(s):  
Yu-Chieng Liou ◽  
Ya-Ju Chang
Keyword(s):  
Boundary Conditions ◽  
Wind Field ◽  
Continuity Equation ◽  
Field Experiments ◽  
Doppler Radar ◽  
Traditional Approach ◽  
Synthesis Method ◽  
Three Dimensional ◽  
Retrieval Algorithm ◽  
Thermodynamic Retrieval

Abstract A multiple–Doppler radar synthesis method is developed to recover the three-dimensional wind field. In this method the solutions are obtained by variationally adjusting the winds to satisfy a series of constraints in weak formats. Among them, the primary ones are multiple-radar radial velocity observations, the anelastic continuity equation, the vertical vorticity equation, the background wind, and spatial smoothness terms. The retrieved wind products are at two time levels, and can be readily applied to deduce the information about the pressure and temperature through the use of the thermodynamic retrieval algorithm, in which the temporal derivatives of the wind fields are required. Experiments using model-simulated data are conducted, from which two major findings are obtained. First, the wind field along and near the radar baseline can still be recovered. This is a major advantage over the traditional approach. Therefore, the proposed method is capable of providing uninterrupted observations of a weather system as it passes the baseline. This allows for more flexibility when designing the radar deployment in field experiments. Second, if the winds are applied to infer the thermodynamic fields using the traditional dynamic retrieval method, and an extra sounding (e.g., radiosonde or dropsonde) is combined in order to specify the horizontal average of the thermodynamic perturbations, the preferable place to release this sounding is within the region of weak, rather than strong, convection. In additional to the aforementioned findings, with this method there is no need to prescribe the top or bottom boundary conditions for the vertical velocities in the traditional sense. Since the computation is performed without explicit vertical integration of the continuity equation, the problem of error accumulation due to inappropriate boundary conditions for the vertical velocities is prevented. These finding are consistent with some previous publications. Furthermore, the instability that occurs during traditional iterative dual-Doppler wind synthesis based on a Cartesian coordinate can also be avoided. Finally, data from any number of radars can be easily added to the computation. This method is also tested using the radar datasets collected during the Southwest Monsoon Experiment/Terrain-Influenced Monsoon Rainfall Experiment (SoWMEX/TiMREX), which was conducted from May to June 2008 in Taiwan, and reasonable results are obtained.

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 The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment – Part 3: Dynamics of low-level spin-up during the genesis

2013 ◽  
Vol 13 (10) ◽  
pp. 26795-26840
Author(s):  
L. L. Lussier ◽  
M. T. Montgomery ◽  
M. M. Bell
Keyword(s):  
Tropical Cyclone ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Radar Data ◽  
Tropical Cyclogenesis ◽  
Low Level ◽  
Tangential Wind ◽  
Tropical Wave ◽  
Wind Profiles

Abstract. Aircraft reconnaissance data collected during the Tropical Cyclone Structure 2008 field campaign are used to examine further kinematical, dynamical and thermodynamical aspects of the genesis of Typhoon Nuri. Data from the first two missions into the pre-Nuri disturbance document the transition from a tropical wave to a tropical depression. Dropwindsonde-derived tangential wind profiles at several radii from the low-level circulation center indicate that the magnitude of low-level circulation increases and that the corresponding tangential velocity maximum moves inward from the first to second reconnaissance mission. To compliment these findings, a three-dimensional variational analysis incorporating both dropwindsonde and aircraft Doppler radar data is conducted. These data are used to perform circulation tendency calculations at multiple distances from the low-level circulation center. The results demonstrate a net spin-up of the system-scale circulation in the low-levels near the center and in the outer regions of the recirculating Kelvin cat's eye circulation. In these regions, the spin-up tendency due to the influx of cyclonic absolute vorticity exceeds the frictional spin-down tendency for both Nuri missions. The system-scale spin up is found to be accompanied by areas of low-level vorticity concentration through vortex-tube stretching associated with cumulus convection. The areal coverage and intensity of these high-vorticity regions increase between the first and second Nuri missions. The findings of this study are consistent in some respects to the Nuri observational analysis carried out by Raymond and Lopez (2011), but differ in their suggested key result and related scientific implication that the pre-Nuri disturbance was spinning down on the first day of observations. The findings herein strongly support a recent tropical cyclogenesis model positing that the Kelvin cat's eye circulation of the parent wave-like disturbance provides a favorable environment for convective-vorticity organization and low-level spin-up on the mesoscale.

scholarly journals Environmental Flow Impacts on Tropical Cyclone Structure Diagnosed from Airborne Doppler Radar Composites

2013 ◽  
Vol 141 (9) ◽  
pp. 2949-2969 ◽  
Author(s):  
Paul D. Reasor ◽  
Robert Rogers ◽  
Sylvie Lorsolo
Keyword(s):  
Tropical Cyclone ◽  
Wind Shear ◽  
Doppler Radar ◽  
Statistical Significance ◽  
Three Dimensional ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Asymmetric Structure ◽  
The Impact ◽  
Airborne Doppler Radar

Abstract Following a recent demonstration of multicase compositing of axisymmetric tropical cyclone (TC) structure derived from airborne Doppler radar measurements, the authors extend the analysis to the asymmetric structure using an unprecedented database from 75 TC flights. In particular, they examine the precipitation and kinematic asymmetry forced by the TC's motion and interaction with vertical wind shear. For the first time they quantify the average magnitude and phase of the three-dimensional shear-relative kinematic asymmetry of observed TCs through a composite approach. The composite analysis confirms principal features of the shear-relative TC asymmetry documented in prior numerical and observational studies (e.g., downshear tilt, downshear-right convective initiation, and a downshear-left precipitation maximum). The statistical significance of the composite shear-relative structure is demonstrated through a stratification of cases by shear magnitude. The impact of storm motion on eyewall convective asymmetry appears to be secondary to the much greater constraint placed by vertical wind shear on the organization of convection, in agreement with prior studies using lightning and precipitation data.

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.

Sign in / Sign up

Export Citation Format

Share Document