[RegCNET] Can the domain of RegCM3 not be set to cover a large area?

[XUNQIANG BI]

Hi, Xuguang:

When you design one domain by using regional climate model, you
have to consider all the calculation is on an projected plane.
Too big domain is not reasonable (if you figure out the domain
coverage).

By using 60km resolution, how can you set jx=720 ?
720*60/110 > 360, but it is not possible to let your projected plane
(using the Lambert projection) cover the whole circle of the Earth?

The other way to judge whether a domain is reasonable or not, is to
check the map factor, xmap cannot exceed 1.5 (it's better if less
than 1.35).

Regards,
Bi Xunqiang

On Sat, 7 Feb 2009, Xuguang SUN wrote:

> Hi,
>
> I met some problems when I set the RegCM3 domain.
>
> In domain.param, if I set
>      parameter(iproj='LAMCON') ! Map projection (LAMCON,NORMER,POLSTR,ROTMER)
>      parameter(iy=74)          ! number of grid points in y direction (i)
>      parameter(jx=128)         ! number of grid points in x direction
> ...
>      parameter(clat= 35.50)    ! Central latitude (North positive)
>      parameter(clon= 105.00)   ! Central longitude (East positive)
>
> the DOMAIN.DAT and DOMAIN.CTL can be generated correctly. However, if I only change
>      parameter(jx=128)         ! number of grid points in x direction
> to be
>      parameter(jx=720)         ! number of grid points in x direction
>
> and leave the other parameters unchanged, then there comes the error,
>
> ntypec=          10
> iy=          74
> jx=         720
> ds=   60.00000
> clat=   35.50000
> clon=   105.0000
> rin=   1.500000
> iproj=LAMCON
>
>
> **************************************************
> FILE ALREADY EXISTS:  ../../Input/DOMAIN.INFO
> Do you want to overwrite the existing file? [y/n/q]
> y
> **************************************************
> FILE ALREADY EXISTS:  ../../Input/DOMAIN.CTL
> Do you want to overwrite the existing file? [y/n/q]
> y
> ***** Terrain resolution (min):    10.00000
> after calling SETUP
> PSX,PSI1 =   0.9512044      0.5235988
> PSX,PSI1 =   0.9512044      0.5235988
> XN,TRUELATL,TRUELATH =   0.7155668       30.00000       60.00000
> after calling MAP PROJECTION
> xminlat,xmaxlat,xminlon,xmaxlon,ntypec=     -49.91     56.06     -2.91    212.96        10
> after calling MXMNLL
>     814086 terrain heights read from land use volume
> after calling RDLDTR
> after calling XYOBSLL
>  rin,ds(m) =   0.150E+01   0.600E+05
>  rin,ds(m) =   0.150E+01   0.600E+05
> after calling ANAL2
> after calling SURF
> LANDUSE MASK           0 exceed the limit
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> And on the other hand, if I only change
>      parameter(clon= 105.00)   ! Central longitude (East positive)
> to be
>      parameter(clon= 180.00)   ! Central longitude (East positive)
>
> there comes the same error as above.
>
> So how to solve this problem?
>
> Thanks in advance.
>
>
> Best regards,
>
> Xuguang
> 2009-02-07
>
> =============================================
>
> Dr. SUN Xuguang
>
> Global Ocean-Atmosphere interaction Lab (GOAL)
> Institute of Severe Weather and Climate (ISWC)
> School of Atmospheric Sciences
> Nanjing University
> 22 Hankou Road, Nanjing 210093
> Jiangsu Province, P.R.China
> Tel     : +86-025-83597203 (office)
> Email   : xgsun at nju.edu.cn
> =============================================
>

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   Dr. Xunqiang Bi         email:bixq at ictp.it
   Earth System Physics Group
   The Abdus Salam ICTP
   Strada Costiera, 11
   P.O. BOX 586, 34100 Trieste, ITALY
   Tel: +39-040-2240302  Fax: +39-040-2240449
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~