Tropical Depression 20S

Passive Microwave (PMW) Intensity Information
Advanced Dvorak Technique
Version 9.1


       --Overpass--              --ARCHER--   Ring  Ring            Eye              BT   -Forecast-  
       Date    Time      Sat     Lat    Lon   Diam   Pct  TbDiff   Score  Meaning   Vmax  Lat    Lon                 
     20240325 100608     AMSR2  -13.8   50.1   N/A   N/A     N/A     N/A      N/A   35.0 -12.7   50.7 Analysis Plot     
     20240326 065500       GMI  -12.3   50.5    34  100%   30.29  -45.29      N/A   45.0 -12.7   50.6 Analysis Plot     
     20240326 213949     AMSR2  -12.9   50.2    34  100%   27.51   42.51  >65 kts   65.0 -13.0   50.5 Analysis Plot     
     20240327 061339       GMI  -12.7   49.6   N/A   N/A     N/A     N/A      N/A   90.0 -13.2   49.9 Analysis Plot     
     20240327 095435     AMSR2  -13.3   49.4   N/A   N/A     N/A     N/A      N/A   80.0 -13.4   49.8 Analysis Plot     
     20240327 174511       GMI  -13.3   48.8   N/A   N/A     N/A     N/A      N/A   55.0 -13.7   49.0 Analysis Plot     
     20240327 222224     AMSR2  -13.7   48.8   N/A   N/A     N/A     N/A      N/A   50.0 -14.1   49.0 Analysis Plot     
     20240328 103608     AMSR2  -13.0   48.4   N/A   N/A     N/A     N/A      N/A   30.0 -14.5   48.9 Analysis Plot     
     20240328 170322       GMI  -14.4   48.9   N/A   N/A     N/A     N/A      N/A   30.0 -14.5   48.1 Analysis Plot

Legend

  - Overpass Date/Time are determined from satellite overpass of targeted TC (position determined from Best Track Lat/Lon position). Date is YYYYMMDD and time in HHMMSS (UTC).

  - Forecast (Best Track) and ARCHER positions (deg) of the TC center at overpass day/time. Positive/Negative: Latitude = North/South Hemisphere; Longitude = Eastern/Western Hemisphere.

  - BT Vmax is the concurrent ATCF Best Track (BT) wind speed intensity estimate (Vmax) value from either NOAA/National Hurricane Center (NHC) (North Atlantic and Northeast Pacific), NOAA/Central Pacific Hurricane Center (CPHC) (North-central Pacific) or Joint Typhoon Warning Center (JTWC) (Northwest Pacific, Indian Ocean, or Southwest Pacific).

  - Sat is the satellite descriptor providing the overpass. Currently the satellites used are the DMSP/SSMIS-16/17/18, GPM/GMI, and GCOM/AMSR2.

  - Ring Diam (km) indicates the estimated surface eyewall diameter if one is analyzed in the PMW imagery. The value listed is the average PMW-estimated inner eyewall edge diameter minus 10 km for eyewall slope. N/A indicates no appreciable eyewall is analyzed.

  - Ring Pct is the percentage of the analyzed "ring" (eyewall inner boundary) that is 1) colder than the eye Tb (the "hot spot" -- warmest eye pixel) by at least 20K, or 2) that is colder than 232K and colder than the eye Tb by 10K, whichever is greater. Values are red if Ring % ≤65,yellow/brown if Ring % ≤85 and green if Ring % >85. N/A indicates no appreciable eyewall is analyzed. A value over 85% is used in the intensity score by adding 15 points to it.

  - TbDiff is the difference between the warmest eye pixel and the warmest pixel on the eyewall. This value is used in the Intensity Score. N/A indicates no appreciable eyewall is analyzed.

  - Eye Score values are based on the strength and organization of the convective/eyewall signatures in the PMW imagery, and based on the ARCHER center location. They normally range from 0 to 100 with empirically-determined thresholds related to intensity (Vmax) in the "Meaning" column (≥20 suggests ≥65kts; ≥60 suggests ≥85kts). Scores are listed as negative, and not used by the ADT, when the NHC, CPHC, or JTWC Best Track Vmax is <55 kts in order to filter out occasional "false eye" cases. A value of -920 is used when the warmest eye pixel is <200K to prevent false positives; -930 means edge of overpass and <85% of eyewall is captured and therefore can't fully be analyzed.