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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:

YYYYMMDD[AC].[UNIT]_[VERSION].nc

YYYYMMDD is the year, month, and day

[AC] is the aircraft ID (H=N42RF, I=N43RF)

[UNIT] is the SFMR instrument unit (HSFMR=HRD, ASFMR2/3 are AOC SFMRs 002/003)

[VERSION] is the product version # (V2.0 is current)

Here is an example file header dump (> ncdump -h)

> ncdump -h 20050829I.asfmr3_v2.0.nc
netcdf 20050829I.asfmr3_v2.0 {
dimensions:
        time = 31659 ;
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 = "%7.3f" ;
                LAT:long_name = "Latitude" ;
        float RALT(time) ;
                RALT:units = "m" ;
                RALT:valid_range = 0.f, 9999.f ;
                RALT:C_format = "%6.1f" ;
                RALT:long_name = "Radar altitude" ;
        float PRES(time) ;
                PRES:units = "mb" ;
                PRES:valid_range = 0.f, 9999.f ;
                PRES:C_format = "%6.1f" ;
                PRES:long_name = "Pressure" ;
        float RDIST(time) ;
                RDIST:units = "km" ;
                RDIST:valid_range = 0.f, 9999.f ;
                RDIST:C_format = "%8.3f" ;
                RDIST:long_name = "Radial distance" ;
        float AZ(time) ;
                AZ:units = "deg. clockwise" ;
                AZ:valid_range = 0.f, 360.f ;
                AZ:C_format = "%5.1f" ;
                AZ:long_name = "Storm-relative azimuth" ;
        float SWS(time) ;
                SWS:units = "m/s" ;
                SWS:valid_range = 0.f, 999.f ;
                SWS:C_format = "%6.1f" ;
                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 = "%6.1f" ;
                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 = "%6.1f" ;
                FWS:long_name = "Flt. lvl. wind speed" ;
        float FDIR(time) ;
                FDIR:units = "deg. meteor." ;
                FDIR:valid_range = 0.f, 360.f ;
                FDIR:C_format = "%6.1f" ;
                FDIR:long_name = "Flt. lvl. wind direction" ;

// global attributes:
                :Source = "NOAA/AOML/HRD" ;
                :Project = "SFMR hurricane surface winds" ;
                :FlightDate = "2005/08/29" ;
                :Aircraft = "N43RF" ;
                :TimeInterval = "06:53:06-15:40:55" ;
                :FlightNumber = "20050829I" ;
                :StormName = "Katrina" ;
                :SfmrUnit = "ASFMR-003" ;
}
Current version 3 products are documented in:
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., In press.


Questions or comments, contact Brad Klotz
Last update 2016/03/31

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