TC-Pairs Tool: General
TC-Pairs Functionality
The TC-Pairs tool provides position and intensity information for tropical cyclone forecasts in Automated Tropical Cyclone Forecast System (ATCF) format. Much like the Point-Stat tool, TC-Pairs produces matched pairs of forecast model output and an observation dataset. In the case of TC-Pairs, both the model output and observational dataset (or reference forecast) must be in ATCF format. TC-Pairs produces matched pairs for position errors, as well as wind, sea level pressure, and distance to land values for each input dataset.
TC-Pairs input data format
As mentioned above, the input to TC-Pairs is two ATCF format files, in addition to the distance_to_land.nc file generated with the TC-Dland tool. The ATCF file format is a comma-separated ASCII file containing the following fields:
Basin | basin | |
CY | annual cyclone number (1-99) | |
YYYYMMDDHH | Date - Time - Group | |
TECHNUM/MIN | Objective sorting technique number, minutes in Best Track | |
TECH | acronym for each objective technique | |
TAU | forecast period | |
LatN/S | Latitude for the date time group | |
LonE/W | Longitude for date time group | |
VMAX | Maximum sustained wind speed | |
MSLP | Minimum sea level pressure | |
TY | Highest level of tropical cyclone development | |
RAD | wind intensity for the radii at 34, 50, 64 kts | |
WINDCODE | radius code | |
RAD1 | full circle radius of wind intensity, 1st quadrant wind intensity | |
RAD2 | radius of 2nd quadrant wind intensity | |
RAD3 | radius of 3rd quadrant wind intensity | |
RAD4 | radius of 4th quadrant wind intensity | |
... |
These are the first 17 columns in the ATCF file format. MET-TC requires the input file has all 17 comma-separated columns present (although valid data is not required). For a full list of the columns as well as greater detail on the file format, see: http://www.nrlmry.navy.mil/atcf_web/docs/database/new/abdeck.txt
Model data must be run through a vortex tracking algorithm prior to becoming input for MET-TC. Running a vortex tracker is outside to scope of this tutorial, however a freely available and supported vortex tracking software is available at: http://www.dtcenter.org/HurrWRF/users/downloads/index.php
If users choose to use operational model data for input to MET-TC, all U.S. operational model output in ATCF format can be found at: ftp://ftp.nhc.noaa.gov/atcf/archive. Finally, the most common use of MET-TC is to use the best track analysis (used as observations) to generate pairs between the model forecast and the observations. Best track analyses can be found at the same link as the operational model output.
Open files /classroom/wrfhelp/MET/OBS/tc_data/aal182012.dat (model data) and /classroom/wrfhelp/MET/OBS/tc_data/bal182012.dat (BEST track). Take a look at the columns and gain familarity with ATCF format. These files are your input for TC-Pairs.
In addition to the files above, data from five total storms over hurricane seasons 2011-2012 in the AL basin will be used to run TC-Pairs. Rather than running a single storm, these storms were choosen to provide a larger sample size to provide more robust statistics.
- aal092011: Irene
- aal182011: Rina
- aal052012: Ernesto
- aal092012: Isaac
- aal182012: Sandy