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Stepped-Frequency Microwave Radiometer
SFMR

Versions 1 and 2 are g-zipped ASCII files, Version 3 is in NetCDF format.

Version 1 (ASCII)

The data files containing surface windspeeds measured by the SFMR are ascii columnar time series of data, recorded at a nominal rate of 1 Hz. The 11 columns contain the following data:

Date is YYYYMMDD (like the file name)
Time is HHMMSS (hour,minute,second) UTC
Lon is decimal longitude (negative west)
Lat is decimal latitude
Alt is radar altitude (meters) of aircraft
Pres is flight-level pressure (milibars)
Rad is radial distance to storm center (kilometers)
Az is clockwise azimuth angle (degrees) of measurement relative to storm motion direction
(e.g. 45 deg. is in the right-front quadrant of the storm).
Sfc WS is the surface windspeed measurement from the SFMR (meters/second)
Fltlvl WS is the windspeed at flight-level (meters/second)
Fltlvl WDIR is the wind direction at flight level (degrees)

Version 2 (ASCII)

The data files containing surface windspeeds measured by the SFMR are ascii columnar time series of data, recorded at a nominal rate of 1 Hz. The 12 columns contain the following data:

Date is YYYYMMDD (like the file name)
Time is HHMMSS (hour,minute,second) UTC
Lon is decimal longitude (negative west)
Lat is decimal latitude
Alt is radar altitude (meters) of aircraft
Pres is flight-level pressure (milibars)
Rad is radial distance to storm center (kilometers)
Az is clockwise azimuth angle (degrees) of measurement relative to storm motion direction
(e.g. 45 deg. is in the right-front quadrant of the storm).
Sfc WS is the surface windspeed measurement from the SFMR (meters/second)
RR is the path-mean rain rate (mm/hr)
Fltlvl WS is the windspeed at flight-level (meters/second)
Fltlvl WDIR is the wind direction at flight level (degrees)

Wind data (both surface and flight-level) are filtered to 10-second averages along the flight track. Processing details, as well as correction factors applied to the measurements can be found in:

Uhlhorn, E. and P. Black, 2003: Verification of remotely sensed sea surface winds in hurricanes. J. Atmos. Ocean. Tech., 20, 99-116.
Haiyan, J., P.G. Black, E.J. Zipser, F.D. Marks Jr., E. W. Uhlhorn, 2006: Validation of rain-rate estimation in hurricanes from the Stepped Frequency Microwave Radiometer: Algorithm correction and error analysis. J. Atmos. Sci., 63, 252-267

Version 3 (NetCDF)

These data files are now encoded in NCAR's NetCDF format. Each file contains data from one flight. The files are named according to the convention:

AAAA_SFMRYYYYMMDD[AC].nc

AAAA is the aircraft agency NOAA for AOC aircraft or AFRC for Air Force.

"_SFMR" denotes a Stepped Frequncy Microwave Radiometer file.

YYYYMMDD is the starting year, month, and day of the mission

[AC] is the aircraft ID (H=N42RF, I=N43RF, U=Air Force)
followed by the sequential number of that flight for the day.

".nc" designates a NetCDF file
(examples: AFRC_SFMR20110823U1.nc NOAA_SFMR20140916H1.nc)

Here is a listing of the parameters as recorded in the SFMR files 

netcdf NOAA_SFMR20050828I1 {
dimensions:
        time = 34172 ;
variables:
        int DATE(time) ;
                DATE:units = "YYYYMMDD" ;
                DATE:valid_range = 0, 100000000 ;
                DATE:C_format = "%.8d" ;
                DATE:long_name = "Date" ;
        int TIME(time) ;
                TIME:units = "HHMMSS UTC" ;
                TIME:valid_range = 0, 235959 ;
                TIME:C_format = "%.6d" ;
                TIME:long_name = "Time" ;
        float LON(time) ;
                LON:units = "deg. E." ;
                LON:valid_range = -180.f, 180.f ;
                LON:C_format = "%8.3f" ;
                LON:long_name = "Longitude" ;
        float LAT(time) ;
                LAT:units = "deg. N." ;
                LAT:valid_range = -90.f, 90.f ;
                LAT:C_format = "%8.3f" ;
                LAT:long_name = "Latitude" ;
        float RALT(time) ;
                RALT:units = "m" ;
                RALT:valid_range = 0.f, 9999.f ;
                RALT:C_format = "%9.1f" ;
                RALT:long_name = "Radar altitude" ;
        float RANG(time) ;
                RANG:units = "deg." ;
                RANG:valid_range = -30.f, 30.f ;
                RANG:C_format = "%8.2f" ;
                RANG:long_name = "Roll angle" ;
        float PANG(time) ;
                PANG:units = "deg." ;
                PANG:valid_range = -30.f, 30.f ;
                PANG:C_format = "%8.2f" ;
                PANG:long_name = "Pitch angle" ;
        float ATEMP(time) ;
                ATEMP:units = "deg. Celsius" ;
                ATEMP:valid_range = -60.f, 60.f ;
                ATEMP:C_format = "%7.1f" ;
                ATEMP:long_name = "Air temperature" ;
        float SST(time) ;
                SST:units = "deg. Celsius" ;
                SST:valid_range = 22.f, 36.f ;
                SST:C_format = "%7.2f" ;
                SST:long_name = "Sea-surface temperature" ;
        float SALN(time) ;
                SALN:units = "g/kg" ;
                SALN:valid_range = 35.f, 37.f ;
                SALN:C_format = "%7.1f" ;
                SALN:long_name = "Salinity" ;
        float SWS(time) ;
                SWS:units = "m/s" ;
                SWS:valid_range = 0.f, 999.f ;
                SWS:C_format = "%9.1f" ;
                SWS:missing_value = -999.9f ;
                SWS:long_name = "SFMR wind speed" ;
        float SRR(time) ;
                SRR:units = "mm/hr" ;
                SRR:valid_range = 0.f, 999.f ;
                SRR:C_format = "%9.1f" ;
                SRR:missing_value = -999.9f ;
                SRR:long_name = "SFMR rain rate" ;
        float FWS(time) ;
                FWS:units = "m/s" ;
                FWS:valid_range = 0.f, 999.f ;
                FWS:C_format = "%9.1f" ;
                FWS:long_name = "Flt. lvl. wind speed" ;
        float FDIR(time) ;
                FDIR:units = "deg. meteor." ;
                FDIR:valid_range = 0.f, 360.f ;
                FDIR:C_format = "%9.1f" ;
                FDIR:long_name = "Flt. lvl. wind direction" ;
        int FLAG(time) ;
                FLAG:units = "unitless" ;
                FLAG:valid_range = 0, 3 ;
                FLAG:C_format = "%.1d" ;
                FLAG:valid_data = 0 ;
                FLAG:questionable_data = 1 ;
                FLAG:invalid_data = 2 ;
                FLAG:no_solution = 3 ;
                FLAG:long_name = "Validity flag" ;
        int NGC(time) ;
                NGC:units = "channels" ;
                NGC:valid_range = 0, 6 ;
                NGC:C_format = "%.1d" ;
                NGC:long_name = "Number of channels" ;
        float TB1(time) ;
                TB1:units = "Kelvin" ;
                TB1:valid_range = 0.f, 325.f ;
                TB1:C_format = "%7.1f" ;
                TB1:missing_value = -999.9f ;
                TB1:long_name = "Bright. Temp. (4.74 GHz)" ;
        float TB2(time) ;
                TB2:units = "Kelvin" ;
                TB2:valid_range = 0.f, 325.f ;
                TB2:C_format = "%7.1f" ;
                TB2:missing_value = -999.9f ;
                TB2:long_name = "Bright. Temp. (5.31 GHz)" ;
        float TB3(time) ;
                TB3:units = "Kelvin" ;
                TB3:valid_range = 0.f, 325.f ;
                TB3:C_format = "%7.1f" ;
                TB3:missing_value = -999.9f ;
                TB3:long_name = "Bright. Temp. (5.57 GHz)" ;
        float TB4(time) ;
                TB4:units = "Kelvin" ;
                TB4:valid_range = 0.f, 325.f ;
                TB4:C_format = "%7.1f" ;
                TB4:missing_value = -999.9f ;
                TB4:long_name = "Bright. Temp. (6.02 GHz)" ;
        float TB5(time) ;
                TB5:units = "Kelvin" ;
                TB5:valid_range = 0.f, 325.f ;
                TB5:C_format = "%7.1f" ;
                TB5:missing_value = -999.9f ;
                TB5:long_name = "Bright. Temp. (6.69 GHz)" ;
        float TB6(time) ;
                TB6:units = "Kelvin" ;
                TB6:valid_range = 0.f, 325.f ;
                TB6:C_format = "%7.1f" ;
                TB6:missing_value = -999.9f ;
                TB6:long_name = "Bright. Temp. (7.09 GHz)" ;

// global attributes:
                :Source = "NOAA/AOML/HRD/" ;
                :Project = "SFMR hurricane surface winds" ;
                :Update = "Reprocessed using 2015 operational algorithm" ;
                :FlightDate = "2005/08/28" ;
                :Aircraft = "NOAA43" ;
                :TimeInterval = "16:08:51-01:54:10" ;
                :StormName = "Katrina" ;
SFMR processing is documented in:
Klotz, B. W. and E. W. Uhlhorn, 2014: "Improved Stepped Frequency Microwave Radiometer Tropical Cyclone Surface Winds in Heavy Precipitation." J. Atmos. Oceanic Technol., 31, 2392-2408.

Uhlhorn, E.W., P.G. Black, J.F. Franklin, M. Goodberlet, J. Carswell, A.S. Goldstein, 2007: "Hurricane surface wind measurements from an operational Stepped-Frequency Microwave Radiometer." Mon. Wea. Rev., 135, 3070-3085.

Questions or comments, contact Heather Holbach
Last update 2017/03/14

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