Tropical Cyclone Research Current Product Development

RAMM/CIRA Tropical Cyclone IR Archive:  During April-May-June, 2006, nine tropical cyclones have been added to the archive (3 Southern Hemisphere, 2 North Indian, 1 NW Pacific, 2 E Pacific, and 1 Atlantic).  All images have been checked for quality control. (R. Zehr)

Characteristics of Atlantic Intense Hurricanes, 1995-2005: Final changes are underway following internal review on a paper by Zehr and Knaff.  Additional computations have been completed with the seven 2005 Atlantic intense hurricanes.  For example, Hurricane Wilma’s intensification rate (Fig. I.1) of 97 hPa/day in terms of 24-h change of minimum sea-level pressure using Best Track data, stands out dramatically in comparison with other 1995-2004 Atlantic intense hurricanes. (R. Zehr)


Fig. I.1. Greatest 24-h decrease of minimum sea-level pressure with each of the 45 Atlantic intense hurricanes since 1995.

Tropical cyclogenesis study: A new project documenting a systematic approach to satellite applications for tropical cyclogenesis analysis, was presented at the AMS Hurricane Conference, in Monterey , CA. April 24-28, 2006. A case study of Hurricane Rita's pre-tropical storm stages has been completed. (R. Zehr)

Development has started on a dynamic website which will display tropical cyclone products and imagery for all active global tropical cyclones and provide an integrated database for achieving this information.  Products will eventually include AMSU intensity and structure estimates, satellite only tropical cyclone wind analyses, intensity forecasts.  Imagery will eventually include the current 4km IR imagery as well as the most recent 1km IR and Vis from operational NOAA and NASA polar orbiting satellites.  (K. Micke)

The CIRA AMSU tropical cyclone intensity and wind structure estimation algorithm (Demuth et al. 2004, 2006) has been successfully transferred to NCEP Central Operations (NCO) as a fully operational package and was run for Tropical Storm Aletta in the Eastern Pacific.  The data is available on NCEP's anonymous ftp server (J. Knaff, M. DeMaria)

Monte Carlo tropical cyclone wind probabilities approved as an operational product at NOAA/TPC.  Work continues on software to verify the output from this product. The east Pacific version of a tropical cyclone rapid intensity index, developed in collaboration with HRD, was also accepted as an operational TPC product (J. Knaff, M. DeMaria)

The track and intensity error distributions, resulting from the official NHC forecasts and final best tracks, were updated to include the 5-year period 2001-2005.  These files containing the track and intensity errors in the eastern North Pacific and North Atlantic tropical cyclone basins were supplied to B. Sampson, NRL, C. Landsea, NOAA/TPC, and R. Knabb, NOAA/TPC for use in NHC and JTWC operations during the upcoming hurricane season. (J. Knaff)

A paper describing a statistical-parametric tropical cyclone wind radii prediction scheme used at the National Hurricane Center and the DOD Joint Typhoon Warning Center was revised for publication in Weather and Forecasting.  See previous quarterly reports for more details on this manuscript. (J. Knaff)

The pressure vs. wind relationships of tropical cyclones have been re-evaluated using the last 15 years of tropical cyclone best track wind estimates and aircraft MSLP values to assess the relative importance of latitude, environmental pressure and tropical cyclone size.  Both environmental pressure and tropical cyclone size are determined from numerical analyses and appear to have no dependency on the analysis used (NOGAPS, GFS, NCEP-Reanalysis).  Findings suggest that all of these factors can be used to reduce the scatter in the current pressure wind relationships.   Larger and higher latitude storms produce lower MSLP for the same maximum wind speed.  Environmental pressure is additive, or in other words storms occurring in a higher pressure environment have higher MSLP.  Relationships were developed to estimated the wind from quality pressure observations and to estimate the pressure given a good estimate of the maximum 10-m, 1-minute sustained wind.  These relationships can be utilized in operational tropical cyclone centers throughout the world and for reanalysis of past tropical cyclone events.  The paper describing this algorithm was accepted by Weather and Forecasting and is currently in press. (J. Knaff)

Work continues on a satellite only tropical cyclone surface wind analysis.  This work combines in a specially developed analysis (cylindrical, variational) observations from feature tracked winds, SSMI winds, QuickSCAT winds, AMSU-derived 2-d wind fields, and IR-derived winds.  The key ingredient is the recent development of an IR method to predict the winds associated with the core of the tropical cyclone using two pieces of information predicted from the IR imagery (size and radius of maximum winds) and other information provided from the tropical cyclone advisories (intensity, motion, and location).  The combined analyses are run in real-time while the analysis is improved.  The current version uses a standard flight-level to surface wind correction over water, and decreases (turns) these winds an additional 20% (20 degrees) over land.   Information from these algorithms is being supplied in real time to the Joint Typhoon Warning Center for operational evaluation.  Work is now concentrating on web development. (J. Knaff)

The tropical cyclone maximum intensity climatology for the western North Pacific was reanalyzed using a recently developed wind-pressure relationship.  Results indicate that the routine use of the Atkinson and Holliday (1977) wind- pressure relationship has resulted in a substantial intensity bias that can explain much of the climatological intensity trends in this region (Figure I.2).   This work was presented at the AMS 27th Conference on Hurricane and Tropical Meteorology. (J. Knaff)

Figure I.2

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