Tropical cyclone surface wind fields

AbstractA very large database containing 24 years of scatterometer passes is analyzed to investigate the surface wind fields within tropical cyclones. The analysis confirms the left–right asymmetry of the wind field with the strongest winds directly to the right of the tropical cyclone center (Northern Hemisphere). At values greater than 2 times the radius to maximum winds, the asymmetry is approximately equal to the storm velocity of forward movement. Observed wind inflow angle (i.e., storm motion not subtracted) is shown to vary both radially and azimuthally within the tropical cyclone. The smallest observed wind inflow angles are found in the left-front quadrant with the largest values in the right-rear quadrant. As the velocity of forward movement increases and the central pressure decreases, observed inflow angles ahead of the storm decrease and those behind the storm increase. In the right-rear quadrant, the observed inflow angle increases with radius from the storm center. In all other quadrants, the observed inflow angle is approximately constant as a function of radial distance.

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Tropical Cyclone Inner-Core Kinetic Energy Evolution

Monthly Weather Review ◽

10.1175/2008mwr2268.1 ◽

2008 ◽

Vol 136 (12) ◽

pp. 4882-4898 ◽

Cited By ~ 71

Author(s):

Katherine S. Maclay ◽

Mark DeMaria ◽

Thomas H. Vonder Haar

Keyword(s):

Tropical Cyclone ◽

Kinetic Energy ◽

Inner Core ◽

Surface Wind ◽

Statistical Testing ◽

Vertical Shear ◽

Structure Evolution ◽

Wind Fields ◽

Secondary Eyewall Formation ◽

Wind Structure

Abstract Tropical cyclone (TC) destructive potential is highly dependent on the distribution of the surface wind field. To gain a better understanding of wind structure evolution, TC 0–200-km wind fields from aircraft reconnaissance flight-level data are used to calculate the low-level area-integrated kinetic energy (KE). The integrated KE depends on both the maximum winds and wind structure. To isolate the structure evolution, the average relationship between KE and intensity is first determined. Then the deviations of the KE from the mean intensity relationship are calculated. These KE deviations reveal cases of significant structural change and, for convenience, are referred to as measurements of storm size [storms with greater (less) KE for their given intensity are considered large (small)]. It is established that TCs generally either intensify and do not grow or they weaken/maintain intensity and grow. Statistical testing is used to identify conditions that are significantly different for growing versus nongrowing storms in each intensification regime. Results suggest two primary types of growth processes: (i) secondary eyewall formation and eyewall replacement cycles, an internally dominated process, and (ii) external forcing from the synoptic environment. One of the most significant environmental forcings is the vertical shear. Under light shear, TCs intensify but do not grow; under moderate shear, they intensify less but grow more; under very high shear, they do not intensify or grow. As a supplement to this study, a new TC classification system based on KE and intensity is presented as a complement to the Saffir–Simpson hurricane scale.

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Development and Testing of Tropical Cyclone Parametric Wind Models Tailored for Midlatitude Application—Preliminary Results

Journal of Applied Meteorology and Climatology ◽

10.1175/jam2407.1 ◽

2006 ◽

Vol 45 (9) ◽

pp. 1244-1260 ◽

Cited By ~ 23

Author(s):

Allan W. MacAfee ◽

Garry M. Pearson

Keyword(s):

Tropical Cyclone ◽

Surface Wind ◽

Angular Size ◽

Absolute Error ◽

Parametric Models ◽

Wind Fields ◽

Low Latitude ◽

New Techniques ◽

Qualitative And Quantitative ◽

Using Data

Abstract Over the years, researchers have developed parametric wind models to depict the surface winds within a tropical cyclone (TC). Most models were developed using data from aircraft flights into low-latitude (south of 30°N) TCs in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. Such models may not adequately reproduce the midlatitude TC wind field where synoptic interaction and acceleration are more pronounced. To tailor these models for midlatitude application, latitude-dependent angular size and shape details were added by using new techniques to set values for model input parameters and by incorporating additional field-shaping procedures. A method to assess the different techniques and field-shaping procedures was developed in which qualitative and quantitative assessment was performed using five parametric models and samples of buoy and 2D surface wind data. Contingency tables and statistical scores such as mean absolute error and bias were used to select the techniques and procedures that create the most realistic depiction of low- and midlatitude TC surface wind fields.

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Tropical Cyclone Destructive Potential by Integrated Kinetic Energy

Bulletin of the American Meteorological Society ◽

10.1175/bams-88-4-513 ◽

2007 ◽

Vol 88 (4) ◽

pp. 513-526 ◽

Cited By ~ 156

Author(s):

Mark D. Powell ◽

Timothy A. Reinhold

Keyword(s):

Wind Speed ◽

Tropical Cyclone ◽

Kinetic Energy ◽

Surface Wind ◽

Surface Wind Speed ◽

Wind Loading ◽

Wind Fields ◽

Damage Potential ◽

Spatial Coverage ◽

Destructive Potential

Tropical cyclone damage potential, as currently defined by the Saffir-Simpson scale and the maximum sustained surface wind speed in the storm, fails to consider the area impact of winds likely to force surge and waves or cause particular levels of damage. Integrated kinetic energy represents a framework that captures the physical process of ocean surface stress forcing waves and surge while also taking into account structural wind loading and the spatial coverage of the wind. Integrated kinetic energy was computed from gridded, objectively analyzed surface wind fields of 23 hurricanes representing large and small storms. A wind destructive potential rating was constructed by weighting wind speed threshold contributions to the integrated kinetic energy, based on observed damage in Hurricanes Andrew, Hugo, and Opal. A combined storm surge and wave destructive potential rating was assigned according to the integrated kinetic energy contributed by winds greater than tropical storm force. The ratings are based on the familiar 1–5 range, with continuous fits to allow for storms as weak as 0.1 or as strong as 5.99.

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An Automated, Objective, Multiple-Satellite-Platform Tropical Cyclone Surface Wind Analysis

Journal of Applied Meteorology and Climatology ◽

10.1175/2011jamc2673.1 ◽

2011 ◽

Vol 50 (10) ◽

pp. 2149-2166 ◽

Cited By ~ 60

Author(s):

John A. Knaff ◽

Mark DeMaria ◽

Debra A. Molenar ◽

Charles R. Sampson ◽

Matthew G. Seybold

Keyword(s):

Tropical Cyclone ◽

Input Data ◽

Surface Wind ◽

Information Service ◽

Wind Fields ◽

Central Pacific ◽

Wind Retrieval ◽

Research Division ◽

Satellite Platform ◽

Wind Analysis

AbstractA method to estimate objectively the surface wind fields associated with tropical cyclones using only data from multiple satellite platforms and satellite-based wind retrieval techniques is described. The analyses are computed on a polar grid using a variational data-fitting method that allows for the application of variable data weights to input data. The combination of gross quality control and the weighted variational analysis also produces wind estimates that have generally smaller errors than do the raw input data. The resulting surface winds compare well to the NOAA Hurricane Research Division H*Wind aircraft reconnaissance–based surface wind analyses, and operationally important wind radii estimated from these wind fields are shown to be generally more accurate than those based on climatological data. Most important, the analysis system produces global tropical cyclone surface wind analyses and related products every 6 h—without aircraft reconnaissance data. Also, the analysis and products are available in time for consideration by forecasters at the Joint Typhoon Warning Center, the Central Pacific Hurricane Center, and the National Hurricane Center in preparing their forecasts and advisories. This Multiplatform Tropical Cyclone Surface Wind Analysis (MTCSWA) product is slated to become an operationally supported product at the National Environmental Satellite Data and Information Service (NESDIS). The input data, analysis method, products, and verification statistics associated with the MTCSWA are discussed within.

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Tropical Cyclone Wind Retrievals from the Advanced Microwave Sounding Unit: Application to Surface Wind Analysis

Journal of Applied Meteorology and Climatology ◽

10.1175/jam2352.1 ◽

2006 ◽

Vol 45 (3) ◽

pp. 399-415 ◽

Cited By ~ 32

Author(s):

Kotaro Bessho ◽

Mark DeMaria ◽

John A. Knaff

Keyword(s):

Tropical Cyclone ◽

Wind Direction ◽

Surface Wind ◽

Wind Fields ◽

Directional Bias ◽

Wind Speeds ◽

Research Division ◽

Microwave Sounding Unit ◽

Microwave Sounding ◽

Advanced Microwave Sounding Unit

Abstract Horizontal winds at 850 hPa from tropical cyclones retrieved using the nonlinear balance equation, where the mass field was determined from Advanced Microwave Sounding Unit (AMSU) temperature soundings, are compared with the surface wind fields derived from NASA's Quick Scatterometer (QuikSCAT) and Hurricane Research Division H*Wind analyses. It was found that the AMSU-derived wind speeds at 850 hPa have linear relations with the surface wind speeds from QuikSCAT or H*Wind. There are also characteristic biases of wind direction between AMSU and QuikSCAT or H*Wind. Using this information to adjust the speed and correct for the directional bias, a new algorithm was developed for estimation of the tropical cyclone surface wind field from the AMSU-derived 850-hPa winds. The algorithm was evaluated in two independent cases from Hurricanes Floyd (1999) and Michelle (2001), which were observed simultaneously by AMSU, QuikSCAT, and H*Wind. In this evaluation the AMSU adjustment algorithm for wind speed worked well. Results also showed that the bias correction algorithm for wind direction has room for improvement.

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Large Roll Vortices Exhibited by Post-Tropical Cyclone Sandy during Landfall

Atmosphere ◽

10.3390/atmos12020259 ◽

2021 ◽

Vol 12 (2) ◽

pp. 259

Author(s):

James A. Schiavone ◽

Kun Gao ◽

David A. Robinson ◽

Peter J. Johnsen ◽

Mathieu R. Gerbush

Keyword(s):

Tropical Cyclone ◽

Doppler Radar ◽

Surface Wind ◽

Weather Research And Forecasting ◽

Wind Fields ◽

Horizontal Scale ◽

Vortex Model ◽

Roll Vortices ◽

O 10 ◽

Horizontal Wavelength

Roll vortices are frequent features of a hurricane’s boundary layer, with kilometer or sub-kilometer horizontal scale. In this study, we found that large roll vortices with O (10 km) horizontal wavelength occurred over land in Post-Tropical Cyclone Sandy (2012) during landfall on New Jersey. Various characteristics of roll vortices were corroborated by analyses of Doppler radar observations, a 500 m resolution Weather Research and Forecasting (WRF) simulation, and an idealized roll vortex model. The roll vortices were always linear-shaped, and their wavelengths of 5–14 km were generally larger than any previously published for a tropical cyclone over land. Based on surface wind observations and simulated WRF surface wind fields, we found that roll vortices significantly increased the probability of hazardous winds and likely caused the observed patchiness of treefall during Sandy’s landfall.

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Paradigm of surface wind fields generated using Scatsat-1 and low-level adjusted INSAT-3D winds during tropical cyclone Amphan

Remote Sensing Letters ◽

10.1080/2150704x.2021.1985738 ◽

2021 ◽

Vol 13 (1) ◽

pp. 44-54

Author(s):

Abhisek Chakraborty ◽

Bipasha Paul Shukla ◽

Sanjib Kumar Deb ◽

R.M. Gairola

Keyword(s):

Tropical Cyclone ◽

Surface Wind ◽

Wind Fields ◽

Low Level

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On the Hyperbolicity of the Bulk Air–Sea Heat Flux Functions: Insights into the Efficiency of Air–Sea Moisture Disequilibrium for Tropical Cyclone Intensification

Monthly Weather Review ◽

10.1175/mwr-d-20-0324.1 ◽

2021 ◽

Vol 149 (5) ◽

pp. 1517-1534

Author(s):

Benjamin Jaimes de la Cruz ◽

Lynn K. Shay ◽

Joshua B. Wadler ◽

Johna E. Rudzin

Keyword(s):

Tropical Cyclone ◽

Surface Wind ◽

Heat Content ◽

Surface Heat ◽

Heat Fluxes ◽

Ocean Heat Uptake ◽

Surface Heat Fluxes ◽

Heat Uptake ◽

Moisture Fluxes ◽

New Perspective

AbstractSea-to-air heat fluxes are the energy source for tropical cyclone (TC) development and maintenance. In the bulk aerodynamic formulas, these fluxes are a function of surface wind speed U10 and air–sea temperature and moisture disequilibrium (ΔT and Δq, respectively). Although many studies have explained TC intensification through the mutual dependence between increasing U10 and increasing sea-to-air heat fluxes, recent studies have found that TC intensification can occur through deep convective vortex structures that obtain their local buoyancy from sea-to-air moisture fluxes, even under conditions of relatively low wind. Herein, a new perspective on the bulk aerodynamic formulas is introduced to evaluate the relative contribution of wind-driven (U10) and thermodynamically driven (ΔT and Δq) ocean heat uptake. Previously unnoticed salient properties of these formulas, reported here, are as follows: 1) these functions are hyperbolic and 2) increasing Δq is an efficient mechanism for enhancing the fluxes. This new perspective was used to investigate surface heat fluxes in six TCs during phases of steady-state intensity (SS), slow intensification (SI), and rapid intensification (RI). A capping of wind-driven heat uptake was found during periods of SS, SI, and RI. Compensation by larger values of Δq > 5 g kg−1 at moderate values of U10 led to intense inner-core moisture fluxes of greater than 600 W m−2 during RI. Peak values in Δq preferentially occurred over oceanic regimes with higher sea surface temperature (SST) and upper-ocean heat content. Thus, increasing SST and Δq is a very effective way to increase surface heat fluxes—this can easily be achieved as a TC moves over deeper warm oceanic regimes.

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The Evolution of Asymmetries in the Tropical Cyclone Boundary Layer Wind Field during Landfall

Monthly Weather Review ◽

10.1175/mwr-d-21-0191.1 ◽

2021 ◽

Keyword(s):

Boundary Layer ◽

Tropical Cyclone ◽

Wind Field ◽

Surface Wind ◽

Frictional Stress ◽

Homogeneous Surface ◽

Sudden Decrease ◽

The Right ◽

Tropical Cyclone Boundary Layer

Abstract The evolution of the tropical cyclone boundary layer (TCBL) wind field before landfall is examined in this study. As noted in previous studies, a typical TCBL wind structure over the ocean features a supergradient boundary layer jet to the left of motion and Earth-relative maximum winds to the right. However, the detailed response of the wind field to frictional convergence at the coastline is less well known. Here, idealized numerical simulations reveal an increase in the offshore radial and vertical velocities beginning once the TC is roughly 200 km offshore. This increase in the radial velocity is attributed to the sudden decrease in frictional stress once the highly agradient flow crosses the offshore coastline. Enhanced advection of angular momentum by the secondary circulation forces a strengthening of the supergradient jet near the top of the TCBL. Sensitivity experiments reveal that the coastal roughness discontinuity dominates the friction asymmetry due to motion. Additionally, increasing the inland roughness through increasing the aerodynamic roughness length enhances the observed asymmetries. Lastly, a brief analysis of in-situ surface wind data collected during the landfall of three Gulf of Mexico hurricanes is provided and compared to the idealized simulations. Despite the limited in-situ data, the observations generally support the simulations. The results here imply that assumptions about the TCBL wind field based on observations from over horizontally-homogeneous surface types - which have been well-documented by previous studies - are inappropriate for use near strong frictional heterogeneity.

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