This directory contains Remote Sensing Systems'
NSCAT Wind  Vectors.

Two reading routines are available to assist in reading
the data files:
		get_nscat_orbit_v02.pro		an IDL routine
		get_nscat_orbit_v02.f		Fortran subroutine


The data files, once decoded contain:
	ATIME is the 21 character time string as given in the L2A files
	PHI_TRACK is the direction of the subtract velocity vector relative to North
	XLAT is the geodetic latitude
	XLON is the east longitude

      ICLASS indicates the expected quality of the vector retrieval
         ICLASS=0 denotes no retrieval was done (either no observations or only one flavor of observation)
         ICLASS=1 denotes 2 flavors of observations in wind vector cell
         ICLASS=2 denotes 3 flavors of observations in wind vector cell
         ICLASS=3 denotes 4 flavors of observations in wind vector cell
      We suggest using just cases for which ICLASS.GE.2

      NUM_AMBIG is the number of ambiguites (0 to 4)
      ISELECT is the selected ambiguity (0 to 4)

      IRAIN_SCAT is the rain flag derived from the scatterometer measurements
      IRAIN_SCAT=1 indicates rain

      WINAL is the wind speed for the various ambiguities
      PHIAL is the wind direction for the various ambiguties (oceanographic convention)

      SOSAL is the normalized rms after-the-fit residual of the observation minus model sigma-nought
      Large SOSAL values indicate the observations did not fit the geophysical model function.
      We suggest discarding observations for which SOSAL of the selected ambiuity is GT 1.9.

      WINDS is the smoothed version of WINAL(ISELECT)
      PHIWS is the smoothed version of PHIAL(ISELECT)

      WINGCM is the general circulation model wind speed used for nudging (either NCEP or ECMWF)
      DIRGCM is the general circulation model wind direction used for nudging (either NCEP or ECMWF)

      RAD_RAIN is the TMI or SSMI columar rain rate (rain rate times rain column height, km mm/hour)
	        RAD_RAIN=-999              no TMI or SSMI rain avaliable
     		RAD_RAIN=0                 no rain
     		RAD_RAIN=0.1               possible rain
     		RAD_RAIN=0.2 through 25.4  definite rain and the give value is the columnar rain rate
     		"no rain"         means no   rain was detected within +- 50 km and +- MIN_DIFF time.
     		"possible rain"   means some rain was detected within +- 50 km and +- MIN_DIFF time.
     		"definite rain"   means rain was detected within      +- 25 km and +- MIN_DIFF time.
      We suggest discarding observations for which RAD_RAIN.GT.0.15
	
      MIN_DIFF is the time difference in minutes between the scatterometer and radiometer observations.

It is important to not use the data if the quality is suspect.  We recommend the 
following conditions be satisfied for the best quality data:

	ICLASS(icel,iscan) gt 1     
	SOSAL(iselect,icel,iscan).le.1.9
	IRAIN_SCAT(icel,iscan).ne.1
	MIN_DIFF(icel,iscan).le.30 .and. RAD_RAIN(icel,iscan).le.0.15

The NSCAT dataset contains known data gaps.  The following revs do not exist.
	revs	 443 -  469
	 	 536 -  575
		 777 -  826
		 920 -  992
		1049 - 1054
		2017
		2155 - 2183
		3347 - 3351
		4046 - 4050


If you have questions about the data, contact:
	Deborah Smith
	smith@remss.com
	(707) 545-2904 ext.11
	9am - 6pm  PST