Adapting the Knaff and Zehr wind-pressure relationship for operational use in Tropical Cyclone Warning Centres

Courtney, Joseph B.; Knaff, John A.

doi:10.22499/2.5803.002

Cited by 73 publications

(74 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the spatial distribution of individual tropical cyclones varies, numerous studies [1][2][3][4][5][6][7][8][9] have represented the mature tropical cyclone wind field as a translating vortex. Although there are differences between these forms, a commonly used model is that of Holland [1].…”

Section: Tropical Cyclone Wind Fieldmentioning

confidence: 99%

A Review of Parametric Descriptions of Tropical Cyclone Wind-Wave Generation

Young

2017

Atmosphere

View full text Add to dashboard Cite

More than three decades of observations of tropical cyclone wind and wave fields have resulted in a detailed understanding of wave-growth dynamics, although details of the physics are still lacking. These observations are presented in a consistent manner, which provides the basis to be able to characterize the full wave spectrum in a parametric form throughout tropical cyclones. The data clearly shows that an extended fetch model can be used to represent the maximum significant wave height in such storms. The shape stabilizing influence of nonlinear interactions means that the spectral shape is remarkably similar to fetch-limited cases. As such, the tropical cyclone spectrum can also be described by using well-known parametric models. A detailed process is described to parameterize the wave spectrum at any point in a tropical cyclone.

show abstract

Section: Tropical Cyclone Wind Fieldmentioning

confidence: 99%

A Review of Parametric Descriptions of Tropical Cyclone Wind-Wave Generation

Young

2017

Atmosphere

View full text Add to dashboard Cite

show abstract

“…More recently, AUGUST 2013 K N A P P E T A L . Knaff and Zehr (2007, hereafter KZ07) developed a more universal WPR, which Courtney and Knaff (2009) adjusted for lower latitudes and adapted for operational use. When both MSW and MCP are provided in best-track data, one can diagnose how they were related at an agency by deriving an empirical wind-pressure relationship.…”

Section: Empirical Estimates Of Agency Procedures Using Wind-pressmentioning

confidence: 99%

A Pressure-Based Analysis of the Historical Western North Pacific Tropical Cyclone Intensity Record

Knapp

Knaff

Sampson

et al. 2013

Monthly Weather Review

View full text Add to dashboard Cite

The western North Pacific Ocean is the most 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 maximum 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 observations; 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 calculated 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 lifetime maximum 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, reconnaissance ended in the western Pacific in 1987. Since then, interagency differences in maximum wind estimates noted here and by others also exist in the minimum central pressure reports. Reconciling these recent interagency differences is further exasperated by the lack of adequate ground truth. This study suggests efforts to intercalibrate 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.

show abstract

“…This finding resulted in the technique being modified by reducing the time that the CI is held steady upon initial weakening. Brown et al (2008) and Courtney and Knaff (2009) demonstrate that when reconnaissance data is used for validation, Dvorak-derived maximum winds show strong agreement with reconnaissance-based best track data in the North Atlantic. Olander and Velden (2007) even suggest that there is a slight under-estimation of intensity using operational Dvorak values.…”

Section: Satellite Imagery Interpretationmentioning

confidence: 97%

“…in Courtney and Knaff (2009), they are insufficient in number to match those in the North Atlantic. Figure 4 shows that for a given DP there is considerable scatter in the maximum winds plotted here as the 1-minute wind in knots.…”

Section: Re-interpreting Tracymentioning

confidence: 99%

“…K&Z (2007) tried to account for the scatter in this dataset and found that the WPR appeared to vary as a function of size, latitude and speed of movement. Courtney and Knaff (2009) adapted the K&Z (2007) WPR for operational use in Tropical Cyclone Warning Centres (TCWCs) known as KZC, and it is now being used in Australian and some international TCWCs including the U.S. National Hurricane Centre. Based on the inputs of pressure (950 hPa), latitude (12.5°S), size (30 nm radius of gales), environmental pressure (1004 hPa) and motion (3 knots), the derived maximum 10-minute wind is 174 kmh -1 (94 knots) equating to a maximum gust of 245 kmh -1 (133 knots) using a gust factor of 1.41.…”

Section: Re-interpreting Tracymentioning

confidence: 99%

See 1 more Smart Citation