Re: Possible incorrect code in WRFUserARW.ncl

I don't think this has been fixed yet. I will report it to the WRF folks and find out what the status is.

Thanks to both of you for bringing it to our attention.

--Mary

On Mar 17, 2012, at 12:19 AM, Andrea N. Hahmann wrote:

> I reported on this a few months ago. The code is wrong and itwas confirmed by the wrf group who is responsible for the script. Please check the ncl archives.
> Regards, Andrea
>
> Andrea Hahmann
> Copenhagen, Denmark
>
> On 17/03/2012, at 03.36, "李嘉鹏" <lijpbasin@126.com> wrote:
>
>> Hi,
>> The code in "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl" lines from 770 to 781 might be incorrect!
>> 770 cone = 1.
>> 771 if( map_projection .eq. 1) then ; Lambert Conformal mapping
>> 772 if( (fabs(true_lat1 - true_lat2) .gt. 0.1) .and. \
>> 773 (fabs(true_lat2 - 90. ) .gt. 0.1) ) then
>> 774 cone = 10^(cos(true_lat1*radians_per_degree)) \
>> 775 -10^(cos(true_lat2*radians_per_degree))
>> 776 & nbsp; cone = cone/(10^(tan(45. -fabs(true_lat1/2.)*radians_per_degree)) - \
>> 777 10^(tan(45. -fabs(true_lat2/2.)*radians_per_degree)) )
>> 778 else
>> 779 cone = sin(fabs(true_lat1)*radians_per_degree)
>> 780 end if
>> 781 end if
>> lines from 774 to 776 should be
>> 774 cone = log(cos(true_lat1*radians_per_degree)) \
>> 775 -log(cos(true_lat2*radians_per_degree))
>> 776 cone = cone/( log(tan(( 45. -fabs(true_lat1/2.))*radians_per_degree)) - \
>> 777 log(tan((45. -fabs(true_lat2/2.))*radians_per_degree)) )
>> according to the following web pages:
>> http://mathworld.wolfram.com/LambertConformalConicProjection.html
>> http://en.wikipedia.org/wiki/Lambert_conformal_conic_projection
>>
>>
>> The code which calculates cone factor in ARWpost V3.1's source file
>> ARWpost/src/module_map_utils.f90
>> is also provided (lines 634 to 642)
>> 634 IF (ABS(truelat1-truelat2) .GT. 0.1) THEN
>> 635
>> 636 ! Compute cone fac tor following:
>> 637 cone=(ALOG(COS(truelat1*rad_per_deg))-ALOG(COS(truelat2*rad_per_deg))) / &
>> 638 (ALOG(TAN((90.-ABS(truelat1))*rad_per_deg*0.5 ))- &
>> 639 ALOG(TAN((90.-ABS(truelat2))*rad_per_deg*0.5 )) )
>> 640 ELSE
>> 641 cone = SIN(ABS(truelat1)*rad_per_deg )
>> 642 ENDIF
>>
>> NCL version: 6.0.0
>> my system:
>> Linux balance 3.2.9-1-ARCH #1 SMP PREEMPT Thu Mar 1 09:31:13 CET 2012 x86_64 AMD Phenom(tm) 9150e Quad-Core Processor AuthenticAMD GNU/Linux
>>
>> --
>> LiJiapeng (lijpbasin@126.com)
>>
>>
>> <名片.vcf>
>> <ATT00001.c>
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Received on Mon Mar 19 08:24:06 2012