Hi Folks,

      The wind speed calculations are done in the routine uwint.c in the
directory /usr/local/packages/rvdas/src/utilities on the DAS SGI.  Here is
the pertinent code, note that we only have speed over ground to work with,
since the Furuno speed log does not function properly (which would provide
speed through water).  Any changes proposed MUST be cleared through this
office first.

Dave Leger

      /* Calculate true wind speed and direction   
       * note I set up to use gyro for heading - kag, Nov 15, 97
       * changed for actual speed through water from CI30 speed log
       * not functional as of 11-17-97, so this will not run  - DCL
       */


      status = dsGet("LMGPcodeCOG",&trmcog);
      status1 = dsGet("LMGGyroHeading",&gyro);
/*       status2 = dsGet("LMGFurCIFspeed",&fursow); */
      status2 = dsGet("LMGPcodeSOGkm",&fursow); 

  
/*  KAG note: need to fix units here if sow (km/hr) is not same as wind
(m/s)  */
      fursow *= 0.278;

      dtrmcog = trmcog;
      dgyro = (double)gyro;
      dfursow = (double)fursow;

/*  KAG note: need to fix units here if sow is not same as wind (m/s)  */

      /* only compute a true wind if we got both gyro and furuno speed */
      if(status1 >= 0 && status2 >= 0)  { 
	if( pwindavail > 1 )  {
	  windspeed = pwsavg;
	  winddir = pwdir;

	  CalcTrueWind(dfursow, dgyro, dtrmcog, &windspeed, &winddir);

	  if ( verbose_flag >= 4 ) {
	    fprintf(stderr,"LMG Port True Wind Speed
%lf\n",windspeed);
	    fprintf(stderr,"LMG Port True Wind Direction   %lf\n",winddir);
	  }
	  status = dsUpdate("LMGpTrueWindSpeed",sizeof(double),&windspeed);
	  status = dsUpdate("LMGpTrueWindDir",sizeof(double),&winddir);
	  windspeedkn = windspeed/0.51444;
	  status =
dsUpdate("LMGpTrueWindSpeedKn",sizeof(double),&windspeedkn);
	}
	if( swindavail > 1 )  {
	  windspeed = swsavg;
	  winddir = swdir;

	  CalcTrueWind(dfursow, dgyro, dtrmcog, &windspeed, &winddir);

	  if ( verbose_flag >= 4 ) {
	    fprintf(stderr,"LMG Starboard True Wind Speed
%lf\n",windspeed);
	    fprintf(stderr,"LMG Starboard True Wind Direction
%lf\n",winddir);
	  }

	  status = dsUpdate("LMGsTrueWindSpeed",sizeof(double),&windspeed);
	  status = dsUpdate("LMGsTrueWindDir",sizeof(double),&winddir);
	  windspeedkn = windspeed/0.51444;
	  status =
dsUpdate("LMGsTrueWindSpeedKn",sizeof(double),&windspeedkn);
	}


> -----Original Message-----
> From:	Alice Doyle [SMTP:AliceDoyle@excite.com]
> Sent:	Wednesday, April 11, 2001 8:49 PM
> To:	admin@nbp.polar.org
> Cc:	legerda@polar.org
> Subject:	Fwd: hi and met
> 
> Hi guys-
> 
> Any input on this?
> 
> Thanks-
> Alice
> 
> ----- Original Message -----
> >  Message-Id: <3.0.1.32.20010411205140.01211e40@mail.lmg.polar.org>
> >  Date: Wed, 11 Apr 2001 20:51:40 -0400
> >  To: doyleal@polar.org
> >  From: "Robert C. Beardsley" <beardsro@lmg.polar.org>
> >  Subject: hi and met
> >  
> >  hi alice,
> >  
> >  the cruise has been going well.  i wanted to ask you if you have a
> >  description or the actual code that is used to convert the ship's wind
> >  sensor (relative spped and direction) into true wind speed. i think it
> >  might not be doing a good job, ie.e, allowing some of the ship's motion
> to
> >  enhance the "true" winds.  so if possible, i would like to see the
> code.
> >   thanks..
> >  bob
> >  
> >  
> >  robert c. beardsley            beardsro@lmg.polar.org
> >
> 
> 
> 
> 
> 
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