DeMaria, Zehr,
Knaff, Dostalek
The real-time processing of AMSU data over tropical cyclones occurring in the east Pacific and Atlantic tropical cyclone basins has been upgraded to collect real-time data using input from the new version of the Automated Tropical Cyclone Forecasting system (ATCF). Using the Navy’s version of the ATCF, efforts are underway to incorporate Northwest Pacific and Indian Ocean tropical cyclones in this processing. In a similar effort, NOAA 16 data and algorithms to determine the intensity and wind structure of tropical cyclones using these AMSU data are being integrated into the real-time processing. Look for these changes in the near future. Current analyses can be seen at
http://www.cira.colostate.edu/ramm/tropic/amsustrm.asp
The tropical rainfall potential (TRaP) products,
which integrate the rain rate along the official forecast track of a tropical
cyclone track continues. This product provides the forecaster estimates
of rainfall potential given two assumptions: that the rainfall rates persist,
and the track forecast is good. Processing these products is done
in real-time and shared with NOAA’s Satellite Analysis Branch. Efforts
are underway to create real-time web pages displaying these informative
products. Updates and improvements this quarter include, 1) the use
of the Navy’s tracks for the Northwest Pacific and Indian Ocean and 2)
the active collaboration with both the Satellite Analysis Branch, and the
NESDIS/ARAD Hydrology Team in the assessment and verification efforts.
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Figure 1. Example of the output from
this product (rain rate, four 6-hourly rainfall estimates, and a 24-hour
total) for Tropical Storm Allison, which made landfall in east Texas on
6 June.
Click on image to enlarge. |
The vertical shear and its relation to intensity change, and satellite observed cloud asymmetry was analyzed for Tropical Storm Chantal. The preliminary study showed details of the vertical shear velocity changes and vertical distribution of the average wind over a 444 km radius circle centered on the tropical storm using initial analyses of two operational global models. Tropical Storm Chantal was observed as it transitioned from an environment with easterly shear to one with southwesterly shear.
Jack Dostalek provided programming support for the development of a new program that computes and plots a vertical profile average wind from McIDAS grid point files according to user specified center location, and dimensions of a circle or ring. This is an improvement over previous software because of its versatility of handling input formats, graphic display, and output to a text file. The program was run for most time periods (initial model analysis at 12-hour interval) using a 444 km radius circle, during the life cycle of recent Atlantic Hurricanes Erin, Felix, and a few analyses of Hurricane Gabrielle. The output data sets have been saved are currently being analyzed.
The updated version of the Statistical Hurricane
Intensity Forecast (SHIFOR) created at CIRA, which generates intensity
forecasts of Atlantic and Eastern Pacific tropical cyclones based upon
past climatology (1967-1999) and persistence has been installed at the
National Hurricane Center and has been creating these forecasts for the
entire hurricane season. A publication is being prepared discussing
the details of these forecasts. Plots of error and biases calculated
using this model are shown in Figures 2 and 3, respectively for the 1995-2000
period. Note these statistics were compiled using operational input
and that only the year 2000 was a truly independent sample. Click
on images to enlarge.
 Figure 2. Intensity forecast errors created by SHIFOR and persistence forecasts during the 1995-2000 test period. |
 Figure 3. Intensity forecast biases created by SHIFOR and persistence forecasts during the 1995-2000 test period. |
The development and delivery to the Naval Research
Lab, Monterey of the Statistical Typhoon Intensity Forecast 5-Day (STIFOR5D)
is complete. Errors and Biases for this model are shown in Figures
4 and 5, respectively. Also, notable is this model’s (ST5D) ability
in a homogeneous test verses its predecessor (CLIP) and the official Joint
Typhoon Warning Center (JTWC) forecast shown in Figure 6. This simple
model developed for verification and forecast purposes has been installed
in the Navy’s version of the Automated Tropical Cyclone Forecasting system
(ATCF) and has been making forecasts since July. A publication is
being prepared discussing the details of this model.
 Figure 4. Intensity forecast errors created by STIFOR and persistence forecasts during the 1998-2000 test period. |
 Figure 5. Intensity forecast biases created by STIFOR and persistence forecasts during the 1998-2000 test period. |
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Figure 6. Homogeneous forecast errors for storms with intensities greater than 14 knots calculated the period 1998-2000 for STIFOR 5-d (ST5D), initialized with operational input (semi-independent), STIFOR (CLIP), and the official JTWC forecasts. Note that ST5D is driven with operation input and verified verses the post analyzed best track. |
An effort has begun to understand the relationships between overshooting convective towers in the eyewall region and changes in the near tropopause winds using several cases of super rapid scan imager data over hurricanes that have been compiled.
The project by J. Knaff, J. Kossin, M. DeMaria, and V. Larson to document what appears to be a subclass of tropical cyclones termed "annular hurricanes" or "doughnut hurricanes” continues. The documentation of these hurricanes, which are symmetric with little or little outer rainband activity, and have large eyes, is being prepared for publication. See past quarterly reports for greater detail.
Datasets for studying global tropical cyclones are being collected and archived in a real-time basis. Routine datasets include high-density cloud drift winds, ERS-2 and QuikScat winds, hurricane reconnaissance, surface and upper air reports, and AMSU quick look data sets.
The tropical cyclone genesis parameter web site has been activated for the 2001 hurricane season:
http://www.cira.colostate.edu/ramm/gparm/genesis.asp
A routine that converts grib data to a packed ASCII format was written for use with the Navy’s NOGAPS (Naval Operational Global Atmospheric Prediction System) model. The data will be used to develop a statistical intensity forecast model for West Pacific tropical storms.
Aviation model (AVN) data for the West Pacific (in addition to the Atlantic) is now converted from grib format to packed ASCII format.
A draft of a paper for journal submission, “Three Approaches to Quantitative Observations of Environmental Vertical Wind Shear with Hurricane Bertha” was completed. It is currently in internal review with final revisions underway.
New images from the 2001 Hurricane Season are being added to the CIRA IR archive, as well as some Southern Hemisphere and early season western Pacific cases. As of September 1, 2001, there are approximately 180 tropical cyclones in the archive, with over 44,000 images on 25 CDs. Images are extracted from the 4 km resolution Mercator remaps archived by Tropical RAMSDIS. All images are reviewed for quality and if necessary re-sectorized. Matt McClurg (CIRA hourly) continues to provide support in saving Tropical RAMSDIS images to CD, and assisting with data processing.
A simple tropical cyclone rain estimation model based upon climatology and persistence (R-CLIPER) has been installed at the National Hurricane Center. The R-CLIPER model will be used as a bench mark for evaluating more general rainfall forecast models.