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41
Simulation of interannual variability of tropical storm frequency in an ensemble of GCM integrations
- J. Climate
, 1997
"... The present study examines the simulation of the number of tropical storms produced in GCM integrations with a prescribed SST. A 9-member ensemble of 10-yr integrations (1979–88) of a T42 atmospheric model forced by observed SSTs has been produced; each ensemble member differs only in the initial at ..."
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The present study examines the simulation of the number of tropical storms produced in GCM integrations with a prescribed SST. A 9-member ensemble of 10-yr integrations (1979–88) of a T42 atmospheric model forced by observed SSTs has been produced; each ensemble member differs only in the initial atmospheric conditions. An objective procedure for tracking-model-generated tropical storms is applied to this ensemble during the last 9 yr of the integrations (1980–88). The seasonal and monthly variations of tropical storm numbers are compared with observations for each ocean basin. Statistical tools such as the Chi-square test, the F test, and the t test are applied to the ensemble number of tropical storms, leading to the conclusion that the potential predictability is particularly strong over the western North Pacific and the eastern North Pacific, and to a lesser extent over the western North Atlantic. A set of tools including the joint probability distribution and the ranked probability score are used to evaluate the simulation skill of this ensemble simulation. The simulation skill over the western North Atlantic basin appears to be exceptionally high, particularly during years of strong potential predictability. 1.
An operational statistical typhoon intensity prediction scheme for
- the Western North Pacific, Weather and Forecasting
, 2005
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Estimating hurricane wind structure in the absence of aircraft reconnaissance
- Wea. Forecasting
, 2007
"... New objective methods are introduced that use readily available data to estimate various aspects of the two-dimensional surface wind field structure in hurricanes. The methods correlate a variety of wind field metrics to combinations of storm intensity, storm position, storm age, and information der ..."
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Cited by 16 (8 self)
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New objective methods are introduced that use readily available data to estimate various aspects of the two-dimensional surface wind field structure in hurricanes. The methods correlate a variety of wind field metrics to combinations of storm intensity, storm position, storm age, and information derived from geo-stationary satellite infrared (IR) imagery. The first method estimates the radius of maximum wind (RMW) in special cases when a clear symmetric eye is identified in the IR imagery. The second method estimates RMW, and the additional critical wind radii of 34-, 50-, and 64-kt winds for the general case with no IR scene–type constraint. The third method estimates the entire two-dimensional surface wind field inside a storm-centered disk with a radius of 182 km. For each method, it is shown that the inclusion of infrared satellite data measurably reduces error. All of the methods can be transitioned to an operational setting or can be used as a postanalysis tool. 1.
2004: Evaluation of Advanced Microwave Sounding Unit tropical-cyclone intensity and size estimation algorithms
- J. Appl. Meteor
"... Advanced Microwave Sounding Unit (AMSU) data are used to provide objective estimates of 1-min maximum sustained surface winds, minimum sea level pressure, and the radii of 34-, 50-, and 64-kt (1 kt [ 0.5144 m s21) winds in the northeast, southeast, southwest, and northwest quadrants of tropical cycl ..."
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Cited by 15 (3 self)
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Advanced Microwave Sounding Unit (AMSU) data are used to provide objective estimates of 1-min maximum sustained surface winds, minimum sea level pressure, and the radii of 34-, 50-, and 64-kt (1 kt [ 0.5144 m s21) winds in the northeast, southeast, southwest, and northwest quadrants of tropical cyclones. The algorithms are derived from AMSU temperature, pressure, and wind retrievals from all tropical cyclones in the Atlantic and east Pacific basins during 1999–2001. National Hurricane Center best-track intensity and operational radii estimates are used as dependent variables in a multiple-regression approach. The intensity algorithms are eval-uated for the developmental sample using a jackknife procedure and independent cases from the 2002 hurricane season. Jackknife results for the maximum winds and minimum sea level pressure estimates are mean absolute errors (MAE) of 11.0 kt and 6.7 hPa, respectively, and rmse of 14.1 kt and 9.3 hPa, respectively. For cases with corresponding reconnaissance data, the MAE are 10.7 kt and 6.1 hPa, and the rmse are 14.9 kt and 9.2 hPa. The independent cases for 2002 have errors that are only slightly larger than those from the developmental sample. Results from the jackknife evaluation of the 34-, 50-, and 64-kt radii show mean errors of 30, 24, and 14 n mi, respectively. The results for the independent sample from 2002 are generally comparable to the developmental sample, except for the 64-kt wind radii, which have larger errors. The radii errors for the 2002 sample with aircraft reconnaissance data available are all comparable to the errors from the jackknife sample, including the 64-kt radii.
2007: Tropical cyclone destructive potential by integrated kinetic energy
- Bull. Amer. Meteo. Soc
"... T he Hurricane Katrina disaster and recent studies examining hurrcanes and global climate change have generated discussion on tropical cyclone intensity and its relevance to destructive potential. Climate scientists are trying to determine whether hurricanes are becoming more frequent or destructive ..."
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T he Hurricane Katrina disaster and recent studies examining hurrcanes and global climate change have generated discussion on tropical cyclone intensity and its relevance to destructive potential. Climate scientists are trying to determine whether hurricanes are becoming more frequent or destructive (e.g. Webster et al. 2005; Emanuel 2005), with resulting impacts on increasingly vulnerable coastal populations. People who lived in areas affected by Hurricane Katrina are wondering how a storm weaker than Hurricane Camille at landfall, could have contributed to so much more destruction. While intensity provides a measure to compare the maximum sustained surface winds (VMS) of different storms, it is a poor measure X The maximum sustained surface wind speed and the Saffir–Simpson scale are poor indicators of a hurricane’s destructive potential; integrated kinetic energy is more relevant to damage by wind, storm surge, and waves. H*Wind analysis of Hurricane Camille at landfall. See figure 1 on page 4 for more information. 513APRIL 2007AMERICAN METEOROLOGICAL SOCIETY | of the destructive potential of a storm since it does not account for storm size. The Saffir–Simpson scale (SS) is currently used to communiate the disaster potential of hurricanes in the Western Hemisphere. It serves a useful purpose for communicating risk to individuals and communities, but is a poor measure of the destructive potential of a hurricane because it depends only on intensity. Destruction can be quantified in terms of mortality and economic loss, but these measures cannot easily be associated with hurricanes of a given size and intensity, because they also depend on population density and coastal vulnerability in the affected area. Mortality is complicated by direct and indirect causes (Combs et al. 1996; Shultz et al. 2005), while total insured or estimated economic loss additionally depends on the wealth of the impacted area. Therefore mortality and insured losses do not necessarily scale with hurricane intensity. For example, the south Florida landfall of Hurricane Andrew (1992) contributed to insured losses of $22 billion (in 2006 dollars) with 40 deaths in Miami–
Statistical Tropical Cyclone Wind Radii Prediction Using Climatology and Persistence
, 2005
"... An operational model used to predict tropical cyclone wind structure in terms of significant wind radii (i.e., 34-, 50-, and 64-kt wind radii, where 1 kt � 0.52 m s �1) at the National Oceanic and Atmospheric Administration/National Hurricane Center (NHC) and the Department of Defense/Joint Typhoon ..."
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Cited by 11 (4 self)
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An operational model used to predict tropical cyclone wind structure in terms of significant wind radii (i.e., 34-, 50-, and 64-kt wind radii, where 1 kt � 0.52 m s �1) at the National Oceanic and Atmospheric Administration/National Hurricane Center (NHC) and the Department of Defense/Joint Typhoon Warning Center (JTWC) is described. The statistical-parametric model employs aspects of climatology and persistence to forecast tropical cyclone wind radii through 5 days. Separate versions of the model are created for the Atlantic, east Pacific, and western North Pacific by statistically fitting a modified Rankine vortex, which is generalized to allow wavenumber-1 asymmetries, to observed values of tropical cyclone wind radii as reported by NHC and JTWC. Descriptions of the developmental data and methods used to formulate the model are given. A 2-yr verification and comparison with operational forecasts and an independently developed wind radii forecast method that also employs climatology and persistence suggests that the statistical-parametric model does a good job of forecasting wind radii. The statistical-parametric model also provides reliable operational forecasts that serve as a baseline for evaluating the skill of operational forecasts and other wind radii forecast methods in these tropical cyclone basins. 1.
Variability of the Outer Wind Profiles of Western North Pacific Typhoons: Classifications and Techniques for Analysis and Forecasting
, 2001
"... The hazard posed by tropical cyclones (TCs) is often quantified in terms of the minimum central pressure (MCP) or maximum wind speed. While significant, these qualities must be balanced against considerations for the strength and spatial extent of the outer-core circulation, which also significantly ..."
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Cited by 6 (0 self)
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The hazard posed by tropical cyclones (TCs) is often quantified in terms of the minimum central pressure (MCP) or maximum wind speed. While significant, these qualities must be balanced against considerations for the strength and spatial extent of the outer-core circulation, which also significantly determines the total peril posed by these storms. To this end, the results of recent studies on the time evolution of the outer wind structure of western North Pacific typhoons are presented. The results include a technique for diagnosing the azimuthally averaged wind profile from a combination of regional synoptic data and estimates of MCP. Aircraft reconnaissance data, augmented with available synoptic and scatterometer data, are used to determine the radial extent of 15 (R15), 25 (R25), and 33 (R33) m s �1 winds for 50 typhoons. Thirty-five of these typhoons were designated as the developmental dataset and 15 were reserved for use as independent data. Using the developmental data, concurrent time series were constructed for outer wind radii and MCP values for TCs whose life cycles were unperturbed by proximity to land. Analysis of these time series revealed a distinct type of TC with very large R15 and weak intensity values. These ‘‘gyre’ ’ systems were examined as a special TC class. The remaining TCs were divided according to the size of their outer circulations into groups termed small, medium, and large. Observations stratified for these size categories revealed that for about 40 % of the
A Pressure-Based Analysis of the Historical Western North Pacific Tropical Cyclone Intensity Record
, 2012
"... ThewesternNorthPacificOcean is themost active tropical cyclone (TC) basin.However, recent studies are not conclusive on whether the TC activity is increasing or decreasing, at least when calculations are based on max-imum sustained winds. For this study, TC minimum central pressure data are analyzed ..."
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ThewesternNorthPacificOcean is themost active tropical cyclone (TC) basin.However, recent studies are not conclusive on whether the TC activity is increasing or decreasing, at least when calculations are based on max-imum sustained winds. For this study, TC minimum central pressure data are analyzed in an effort to better understand historical typhoons. Best-track pressure reports are compared with aircraft reconnaissance obser-vations; little bias is observed. An analysis of wind and pressure relationships suggests changes in data and practices at numerous agencies over the historical record. New estimates of maximum sustained winds are cal-culated using recent wind–pressure relationships and parameters from International Best Track Archive for Climate Stewardship (IBTrACS) data. The result suggests potential reclassification of numerous typhoons based on these pressure-based lifetimemaximum intensities. Historical documentation supports these new intensities in many cases. In short, wind reports in older best-track data are likely of low quality. The annual activity based on pressure estimates is found to be consistent with aircraft reconnaissance and between agencies; however, re-connaissance ended in thewestern Pacific in 1987. Since then, interagencydifferences inmaximumwind estimates noted here and by others also exist in theminimumcentral pressure reports. Reconciling these recent interagency differences is further exasperated by the lack of adequate ground truth. This study suggests efforts to intercali-brate the interagency intensity estimate methods. Conducting an independent and homogeneous reanalysis of past typhoon activity is likely necessary to resolve the remaining discrepancies in typhoon intensity records. 1.
Observation and tracking of tropical cyclones using resolution enhanced scatterometry
, 2006
"... of a thesis submitted by ..."
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An Evaluation of QuikSCAT UHR Wind Product’s Effectiveness in Determining Selected Tropical Cyclone Characteristics
, 2009
"... While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics su ..."
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Cited by 1 (1 self)
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While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics such as TC eye center and wind radii. Two studies are conducted in this thesis, in which QuikSCAT UHR wind product’s effectiveness in estimating these TC characteristics is evaluated. First, a comparison is made between the analyst’s choice of eye location based on UHR images and interpolated best-track position. In this analysis, the UHR images are divided into two categories, based on the analyst’s confidence
