ATLANTIC BASIN BEST TRACK DOCUMENTATION............BY CHRIS LANDSEA (2/16/95) This documentation is based upon "A tropical cyclone data tape for the North Atlantic basin, 1886-1983: Contents, limitations, and uses", _NOAA Technical Memorandum NWS NHC 22_, 1984 written by B.R. Jarvinen, C.J. Neumann, and M.A.S. Davis. The North Atlantic 'best track' (so named as it is the 'best' track and intensity estimates of tropical cyclones as determined in a post-analysis of all available data) is maintained by the forecasters and researchers at the National Hurricane Center in Miami, Florida. Permission to make free access of this data and documentation were provided by Dr. Robert Sheets - director of NHC and by Mr. Neal Lott of the National Climatic Data Center in Asheville, NC. Questions regarding the format and/or errors in the documentation/data should be directed to Chris Landsea (landsea@downdry.atmos.colostate.edu). Currently, the database extends from 1886 to 1993. The database filename is 'tra86to93.atl. Updates for the coming year will be provided as soon as the analysis is final at NHC. So, I hope this data provides some insight into the workings of the Atlantic hurricane for you as it, to some degree, has for me........CWL Note that the 'tra86to93.atl' file is UNIX compressed to save space on our computer so that the filename is 'tra86to93.atl.Z'. To read the file after you've ftp'ed it, you need to UNCOMPRESS the file. Otherwise, you can't access the data. $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ P.S. Though the data extends back to 1886, one is cautioned in deriving seasonal statistics back that many years. The advent of aircraft reconn- aissance in 1944 is suggested (both by myself and C.J. Neumann) to be the start of reliable seasonal statistics on the frequency and duration of storms. However, as reported in Landsea (1993) ["A climatology of intense (or major) Atlantic hurricanes", _Mon. Wea. Rev._, 121, 1703-1713], there is a bias in the best track data in that strong hurricanes were over- reported in windstrength for the years 1944 to 1969 (and possibly before 1944 as well). This bias amounted to a five knot overestimation at the 100kt threshold for major hurricane status. The amount of overestimation is even worse for yet stronger storms. $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ There are three basic types of datalines in the Best Track. TYPE A: 92620 08/16/1992 M=13 2 SNBR= 899 ANDREW XING=1 SSS=4 Card# MM/DD/Year Days S# Total#... Name........US Hit.Hi US category TYPE B: 92580 04/22S2450610 30 1003S2490615 45 1002S2520620 45 1002S2550624 45 1003* Card# MM/DD&LatLongWindPress&LatLongWindPress&LatLongWindPress&LatLongWindPress TYPE C: 92760 HRCFL4BFL3 LA3 Card# TpHit.Hit.Hit. .......................................................................... TYPE A: Card# = Sequential card number starting at 00010 in 1886 MM/DD/Year = Month, Day, and Year of storm Days = Number of days in which positions are available (note that this also means number of lines to follow of type B and then one line of type C) S# = Storm number for that particular year (including subtropical storms) Total# = Storm number since the beginning of the record (since 1886) Name = Storms only given official names since 1950 US Hit = '1' = Made landfall over the United States as tropical storm or hurricane, '0' = did not make U.S. landfall Hi US category = '9' = Used before 1899 to indicate U.S. landfall as a hurricane of unspecified Saffir-Simpson category '0' = Used to indicate U.S. landfall as tropical storm, but this has not been utilized in recent years '1' to '5' = Highest category on the Saffir-Simpson scale that the storm made landfall along the U.S. '1' is a minimal hurricane, '5' is a catastrophic hurricane ........................................................................... TYPE B: Card# = As above. MM/DD = Month and Day of Storm & = 'S' (Subtropical stage), '*' (tropical cyclone stage), 'E' (extratropical stage), 'W' (wave stage - rarely used) LatLong = Position of storm: 24.5N, 61.0W Wind = Maximum sustained (1 minute) surface (10m) windspeed in knots (in general, these are to the nearest 5 knots). Press = Central surface pressure of storm in mb (if available). Since 1979, central pressures are given everytime even if a satellite estimation is needed. Positions and intensities are at 00Z, 06Z, 12Z, 18Z .......................................................................... TYPE C: Card# = As above. Tp = Maximum intensity of storm ('HR' = hurricane, 'TS' = tropical storm, 'SS' = subtropical storm) Hit = U.S. landfallings as hurricane ('LA' = Louisiana, etc.) and Saffir-Simpson category at landfall ('1' = minimal hurricane... '5' = super hurricane). (Note that Florida and Texas are split into smaller regions: 'AFL' = Northwest Florida, 'BFL' = Southwest Florida, 'CFL' = Southeast Florida, 'DFL' = Northeast Florida, 'ATX' = South Texas, 'BTX' = Central Texas, 'CTX' = North Texas.) .......................................................................... CWL Code example by Bill Thorson integer year(200),month(200),day(200),hour(200), + vmax(200),mslp(200) real lat(200),lon(200) character state(200),stname*10,what*2 character arg*60 if (iargc() .ne. 1) then print *, 'usage: atlread track-file' goto 1000 endif call getarg(1,arg) open(unit=3,file=arg,status='old',err=1) goto 2 1 print *, 'cannot open track file ',arg goto 1000 2 continue 10 read (3,11,end=100) imonth,iday,iyear, nbrdays, istmnr, + stname 11 format(6x,i2,x,i2,x,i4,3x,i2,x,i2,11x,,a10) do 20 i = 1, nbrdays j = (i-1)*4+1 read (3,101) imonth, iday, + (state(k),lat(k),lon(k),vmax(k),mslp(k),k=j,j+3) 101 format(6x,i2,x,i2,4(a1,f3.1,f4.1,x,i3,x,i4)) do 15 k=j,j+3 if (imonth .eq. 1) then year(k) = iyear+1 else year(k) = iyear endif month(k) = imonth day(k) = iday hour(k) = mod(k+3,4)*6 if (vmax(k) .eq. 0) vmax(k)=-99 if (mslp(k) .eq. 0) mslp(k)=-999 15 continue 20 continue read (3,102) what 102 format(6x,a2) do 30 i=1,j+3 if (lat(i).ne.0.0 .and. lon(i).ne.0.0) then print 103, iyear,istmnr,stname, + year(i),month(i),day(i),hour(i), + lat(i),lon(i),vmax(i),mslp(i) 103 format(i4,i2.2,1x,a10,1x,i4,3(1x,i2),1x,f5.1,1x,f6.1,1x, + i3,1x,i4) endif 30 continue goto 10 100 close(3) 1000 end