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)

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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

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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.

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Current list of available flights (1998-2006):

1998	Bonnie		19980823
			19980824
			19980826
	Danielle	19980829
			19980830
	Earl		19980902
	Georges		19980919
			19980925
			19980928

1999	Bret		19990822
	Dennis		19990826
			19990827
			19990829
	Floyd		19990913
			19990914
			19990915
	Irene		19991014
			19991015
	Lenny		19991116
			19991119

2000	*** No data due to instrument failures ***

2001	Humberto	20010923
			20010924

2002	Edouard		20020903
	Isidore		20020921
			20020922
			20020925			
	Lili		20020929
			20020930
			20021002
			20021003

2003	Fabian		20030902
			20030903
			20030904
	Isabel		20030912
			20030913
			20030914

2004	Frances		20040830
			20040831
			20040901
			20040902
			20040903
			20040904
	Ivan		20040907
			20040909
			20040912
			20040913
			20040914
			20040915
	Jeanne		20050922
			20050924
			20050925

2005*	Cindy		20050705H
	Dennis		20050708H
			20050709H
			20050710H
	Katrina		20050825I
			20050827I
			20050828I
			20050829I
	Ophelia		20050907H
			20050907I
			20050908I
			20050909I
			20050911H
			20050911I
			20050912H
			20050916H
			20050917H
	Rita		20050919I
			20050920I
			20050921I
			20050922H
			20050922I
			20050923H
			20050923I
	Wilma		20051022H
			20051023H

2006	Ernesto		20060831H
	Helene		20060917H
			20060918H
			20060919H
			20060920H

* NOTE: Both P-3 aircraft carried NOAA SFMRs after the 2004 season, so there may be multiple flights for the same day.

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Questions or comments, contact Eric Uhlhorn
Last update 2007/04/09