scholarly journals GPS Dropwindsonde and WSR-88D Observations of Tropical Cyclone Vertical Wind Profiles and Their Characteristics

2013 ◽  
Vol 28 (1) ◽  
pp. 77-99 ◽  
Author(s):  
Ian M. Giammanco ◽  
John L. Schroeder ◽  
Mark D. Powell
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Radial Distance ◽  
Flow Regimes ◽  
Vertical Wind ◽  
Wind Speed Maximum ◽  
Mean Structure ◽  
The Mean ◽  
Offshore Flow ◽  
Wind Profiles

Abstract The characteristics of tropical cyclone vertical wind profiles and their associated wind speed peaks below 1.5 km were examined through the use of a large number of GPS dropwindsondes (GPS sondes) and radar-derived velocity–azimuth display (VAD) profiles. Composite wind profiles were generated to document the mean structure of tropical cyclone vertical wind profiles and their changes with storm-relative position. Composite profiles were observed to change as the radius decreased inward toward the radius of maximum winds. Profiles also varied between three azimuthal sectors. At landfall, wind profiles exhibited changes with radial distance and differences were observed between those within offshore and onshore flow regimes. The observations support a general reduction in boundary layer depth with decreasing radial distance. Wind profiles with peaks at low altitudes were typically confined to radii less than 60 km, near and radially inward from the radius of maximum winds. Wind speed maxima, when scaled by a layer mean wind, decreased in magnitude as the radius decreased. At landfall, composite profiles showed a distinct low-level wind speed maximum in the eyewall region with significant differences between the onshore and offshore flow regimes.

scholarly journals Observations of Boundary Layer Wind and Turbulence of a Landfalling Tropical Cyclone

2021 ◽  
Author(s):  
Zhongkuo Zhao ◽  
Ruiquan Gao ◽  
Jun A. Zhang ◽  
Yong Zhu ◽  
Chunxia Liu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Radial Distance ◽  
Flux Measurement ◽  
Eddy Diffusivity ◽  
Multiple Level ◽  
A Value ◽  
Momentum Fluxes ◽  
Speed Range ◽  
Wind Profiles

Abstract This study analyzed the atmospheric boundary layer characteristics based on the multiple level observations by a 350-m height tower during the landfall of Super Typhoon Mangkhut (1822). Mean wind profiles showed logarithmic wind profiles at different wind speed ranges suggesting nearly constant flux layers. The height of the constant layer increased with the wind speed and deceased with the radial distance from the storm centre. This behaviour was supported by flux observations. Momentum fluxes and turbulent kinetic energy increased with the wind speed at all flux measurement levels. The drag coefficient (surface roughness) estimated was nearly a constant with a value of 8´10-3 (0.09 m). Both the estimated eddy diffusivity and mixing length varied with height. The eddy diffusivity also varied with the wind speed. Our results supported that the eddy diffusivity is larger over land than over ocean in a same wind speed range.

scholarly journals On the Decay of Tropical Cyclone Winds Crossing Narrow Landmasses

2006 ◽  
Vol 45 (3) ◽  
pp. 491-499 ◽  
Author(s):  
Mark DeMaria ◽  
John A. Knaff ◽  
John Kaplan
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Absolute Error ◽  
Total Sample ◽  
Forecast Errors ◽  
Modified Model ◽  
Decay Model ◽  
Prediction Scheme ◽  
Fixed Radius ◽  
The Mean

Abstract A method is developed to adjust the Kaplan and DeMaria tropical cyclone inland wind decay model for storms that move over narrow landmasses. The basic assumption that the wind speed decay rate after landfall is proportional to the wind speed is modified to include a factor equal to the fraction of the storm circulation that is over land. The storm circulation is defined as a circular area with a fixed radius. Application of the modified model to Atlantic Ocean cases from 1967 to 2003 showed that a circulation radius of 110 km minimizes the bias in the total sample of landfalling cases and reduces the mean absolute error of the predicted maximum winds by about 12%. This radius is about 2 times the radius of maximum wind of a typical Atlantic tropical cyclone. The modified decay model was applied to the Statistical Hurricane Intensity Prediction Scheme (SHIPS), which uses the Kaplan and DeMaria decay model to adjust the intensity for the portion of the predicted track that is over land. The modified decay model reduced the intensity forecast errors by up to 8% relative to the original decay model for cases from 2001 to 2004 in which the storm was within 500 km from land.

scholarly journals Characteristics and performance of vertical winds as observed by the radar wind profiler network of China

2020 ◽  
Author(s):  
Boming Liu ◽  
Jianping Guo ◽  
Wei Gong ◽  
Lijuan Shi ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Numerical Weather Prediction ◽  
Weather Prediction ◽  
Vertical Wind ◽  
Horizontal Wind ◽  
Wind Profiler ◽  
Numerical Weather ◽  
And Performance ◽  
Wind Profiles ◽  
Vertical Winds

Abstract. Vertical wind profiles are the foundation for numerical weather prediction systems research. Large-scale vertical wind data have been previously documented from network observations in several countries, but the nationwide vertical wind observations are poorly understood in China. In this study, the salient characteristics and performance of vertical winds as observed by the radar wind profiler network of China was investigated, which consists of more than 100 stations instrumented with 1290-MHz Doppler radar designed primarily for measuring vertical-resolved winds. This network has good spatial coverage, with denser sites in coastal areas. The vertical wind profiles observed by this network can provide the horizontal wind direction, horizontal wind speed, and vertical wind speed for every 120 m interval within the height of 0 to 3 km. The availability of the radar wind profiler network has been investigated in terms of effective detection height, data acquisition rate, data confidence, and data accuracy. Further comparison analysis with reanalysis data indicated that the observation data at 89 stations are recommended, and 17 stations are unrecommended. The vertical wind profiles can serve as important input dataset assimilated into numerical weather prediction system at both regional and global scales.

Uncertainty of Tropical Cyclone Best-Track Information

2012 ◽  
Vol 27 (3) ◽  
pp. 715-729 ◽  
Author(s):  
Ryan D. Torn ◽  
Chris Snyder
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Maximum Wind Speed ◽  
Sea Level Pressure ◽  
Position Uncertainty ◽  
Maximum Wind ◽  
Intensity Information ◽  
Weather And Climate ◽  
The Mean ◽  
National Hurricane Center

Abstract With the growing use of tropical cyclone (TC) best-track information for weather and climate applications, it is important to understand the uncertainties that are contained in the TC position and intensity information. Here, an attempt is made to quantify the position uncertainty using National Hurricane Center (NHC) advisory information, as well as intensity uncertainty during times without aircraft data, by verifying Dvorak minimum sea level pressure (SLP) and maximum wind speed estimates during times with aircraft reconnaissance information during 2000–09. In a climatological sense, TC position uncertainty decreases for more intense TCs, while the uncertainty of intensity, measured by minimum SLP or maximum wind speed, increases with intensity. The standard deviation of satellite-based TC intensity estimates can be used as a predictor of the consensus intensity error when that consensus includes both Dvorak and microwave-based estimates, but not when it contains only Dvorak-based values. Whereas there has been a steady decrease in seasonal TC position uncertainty over the past 10 yr, which is likely due to additional data available to NHC forecasters, the seasonal TC minimum SLP and maximum wind speed values are fairly constant, with year-to-year variability due to the mean intensity of all TCs during that season and the frequency of aircraft reconnaissance.

scholarly journals Estimates of tropical cyclone geometry parameters based on best track data

2019 ◽  
Author(s):  
Kees Nederhoff ◽  
Alessio Giardino ◽  
Maarten van Ormondt ◽  
Deepak Vatvani
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Wind Profile ◽  
Wind Fields ◽  
Engineering Applications ◽  
Wind Speeds ◽  
Pressure Fields ◽  
Ne Pacific ◽  
Wind Profiles

Abstract. Parametric wind profiles are commonly applied in a number of engineering applications for the generation of tropical cyclone (TC) wind and pressure fields. Nevertheless, existing formulations for computing wind fields often lack the required accuracy when the TC geometry is not known. This may affect the accuracy of the computed impacts generated by these winds. In this paper, empirical stochastic relationships are derived to describe two important parameters affecting the TC geometry: radius of maximum winds (RMW) and the radius of gale force winds (∆AR35). These relationships are formulated using best track data (BTD) for all seven ocean basins (Atlantic, S/NW/NE Pacific, N/SW/SE Indian Oceans). This makes it possible to a) estimate RMW and ∆AR35 when these properties are not known and b) generate improved parametric wind fields for all oceanic basins. Validation results show how the proposed relationships allow the TC geometry to be represented with higher accuracy than when using relationships available from the literature. Outer wind speeds can be well reproduced by the commonly used Holland wind profile when calibrated using information either from best-track-data or from the proposed relationships. The scripts to compute the TC geometry and the outer wind speed are freely available via Delft Dashboard.

A Statistical Perspective on Wind Profiles and Vertical Wind Shear in Tropical Cyclone Environments of the Northern Hemisphere

2017 ◽  
Vol 145 (1) ◽  
pp. 361-378 ◽  
Author(s):  
Peter M. Finocchio ◽  
Sharanya J. Majumdar
Keyword(s):  
Tropical Cyclone ◽  
Northern Hemisphere ◽  
Wind Shear ◽  
Deep Layer ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Vertical Shear ◽  
Intensity Change ◽  
Upper Level ◽  
Wind Profiles

Abstract A statistical analysis of tropical cyclone (TC) environmental wind profiles is conducted in order to better understand how vertical wind shear influences TC intensity change. The wind profiles are computed from global atmospheric reanalyses around the best track locations of 7554 TC cases in the Northern Hemisphere tropics. Mean wind profiles within each basin exhibit significant differences in the magnitude and direction of vertical wind shear. Comparisons between TC environments and randomly selected “non-TC” environments highlight the synoptic regimes that support TCs in each basin, which are often characterized by weaker deep-layer shear. Because weaker deep-layer shear may not be the only aspect of the environmental flow that makes a TC environment more favorable for TCs, two new parameters are developed to describe the height and depth of vertical shear. Distributions of these parameters indicate that, in both TC and non-TC environments, vertical shear most frequently occurs in shallow layers and in the upper troposphere. Linear correlations between each shear parameter and TC intensity change show that shallow, upper-level shear is slightly more favorable for TC intensification. But these relationships vary by basin and neither parameter independently explains more than 5% of the variance in TC intensity change between 12 and 120 h. As such, the shear height and depth parameters in this study do not appear to be viable predictors for statistical intensity prediction, though similar measures of midtropospheric vertical wind shear may be more important in particularly challenging intensity forecasts.

scholarly journals Estimates of tropical cyclone geometry parameters based on best-track data

2019 ◽  
Vol 19 (11) ◽  
pp. 2359-2370 ◽  
Author(s):  
Kees Nederhoff ◽  
Alessio Giardino ◽  
Maarten van Ormondt ◽  
Deepak Vatvani
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Wind Profile ◽  
Wind Fields ◽  
Engineering Applications ◽  
Wind Speeds ◽  
Pressure Fields ◽  
Ne Pacific ◽  
Wind Profiles

Abstract. Parametric wind profiles are commonly applied in a number of engineering applications for the generation of tropical cyclone (TC) wind and pressure fields. Nevertheless, existing formulations for computing wind fields often lack the required accuracy when the TC geometry is not known. This may affect the accuracy of the computed impacts generated by these winds. In this paper, empirical stochastic relationships are derived to describe two important parameters affecting the TC geometry: radius of maximum winds (RMW) and the radius of gale-force winds (ΔAR35). These relationships are formulated using best-track data (BTD) for all seven ocean basins (Atlantic; S, NW, and NE Pacific; and N, SW, and SE Indian oceans). This makes it possible to (a) estimate RMW and ΔAR35 when these properties are not known and (b) generate improved parametric wind fields for all oceanic basins. Validation results show how the proposed relationships allow the TC geometry to be represented with higher accuracy than when using relationships available from literature. Outer wind speeds can be reproduced well by the commonly used Holland wind profile when calibrated using information either from best-track data or from the proposed relationships. The scripts to compute the TC geometry and the outer wind speed are freely available via the following URL: https://bit.ly/2k9py1J (last access: October 2019).

Wind Speed Profile and Gradient Height in Typhoons Observed by Vehicular Doppler Radar in South China

2010 ◽  
Vol 163-167 ◽  
pp. 3887-3892
Author(s):  
Li Xiao Li ◽  
Yi Qing Xiao ◽  
Li Li Song ◽  
Peng Qin
Keyword(s):  
Wind Speed ◽  
Doppler Radar ◽  
Probability Method ◽  
Wall Region ◽  
Wind Speed Profile ◽  
Wind Speeds ◽  
Mean Wind Speed ◽  
The Mean ◽  
The Times ◽  
Wind Profiles

The recent development of Doppler radar sensor has allowed to study the typhoon wind structure more accuracy and systematic. In order to obtain more wind data near typhoon eye-wall, vehicular Doppler radar emerge as the times require. Based on two typhoon observed results carried out by vehicular Doppler radar in category A terrain, firstly the 10min mean wind profiles under 1000m height in different regions of typhoon were analyzed. The typhoon mean wind speeds increase a logarithmic law with height at nearly lower two hundred meters in all regions of typhoons. Using the power law to fit wind profiles, the exponential index α in pre-eye-wall region is greater than it in post-eye-wall region, and it decreases with increasing the mean wind speed. Secondly, based on analyzing the relationship between mean wind speed and wind ratio, the calculation formula for nominal gradient height were established in category A terrain. Finally introducing the probability method to study the mean wind profile, the exponential index α was established in category A terrain.

scholarly journals Observed characteristics of tropical cyclone vertical wind profiles

2012 ◽  
Vol 15 (1) ◽  
pp. 65-86 ◽  
Author(s):  
Ian M. Giammanco ◽  
John L. Schroeder ◽  
Mark D. Powell
Keyword(s):  
Tropical Cyclone ◽  
Vertical Wind ◽  
Wind Profiles

scholarly journals An Experimental Investigation of Streamwise and Vertical Wind Fields on a Typical Three-Dimensional Hill

2020 ◽  
Vol 10 (4) ◽  
pp. 1463
Author(s):  
Guohui Shen ◽  
Jianfeng Yao ◽  
Wenjuan Lou ◽  
Yong Chen ◽  
Yong Guo ◽  
...  
Keyword(s):  
Wind Speed ◽  
Three Dimensional ◽  
Vertical Wind ◽  
Streamwise Direction ◽  
Wind Fields ◽  
Wind Speeds ◽  
Upstream Side ◽  
Speed Up ◽  
The Mean ◽  
The Hill

To study the streamwise and vertical wind fields on a typical three-dimensional hill, wind tunnel tests were performed. The mean values and turbulence intensities of the streamwise and vertical wind speeds of the typical positions above the hill were measured, and they are presented in the form of contour maps for design. Furthermore, the speed-up of the mean wind speeds in the streamwise direction was compared with codes. Finally, the windage yaw of a jumper cable was examined as an example of how to take into account the streamwise and vertical wind field influence on the wind load in the analysis of wind-induced responses. The results show that the most significant speed-up effect in the streamwise direction occurs on the hill crest, and the wind speed-up decreases with the increase of the height. Overall, the wind speed-up along the crosswind center line is larger than that along the along-wind center line of the hill. In the codes, the speed-up effect specified for the structure at half the height of the upstream side of the hill is relatively conservative. With regard to the mean wind speed in the vertical direction, the wind climbing effect located at half the height of the upstream side of the hill is the most significant. The area with the stronger turbulence intensity appears at the foot of the upstream and downstream sides of the hill. The influence of the vertical wind on the jumper cable is remarkable where the wind climbing effect is the most significant, which is worthy of attention in the design of the structure immersed in a hilly terrain-disturbed wind field.

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