[ncl-talk] vertically integrated moisture flux convergence

[tms_l]

hi,

The usage of the functions for moisture flux convergence is not much clear
to me.I have to calculate the moisture flux convergence between pressure
levels 850hpa AND 200hpa pressure levels..and I THINK i need to consider
the specific humidity at 850 & 200 hpa pressure levels too ...finally
integrating between the two pressure levels to get the moisture flux
convergence...

I already calculated the wind divergence at two pressure levels using the
function, uv2dvG_Wrap..I am not clear about the next step..

can anyone describe it little more..how to use the functions to get the
moisture flux convergence..



thanks in advance

On Sat, Dec 20, 2014 at 3:38 AM, Dennis Shea <shea at ucar.edu> wrote:

>    MFC = Moisture Flux Convergence
>
>    MFC_advect = -( u*(dq/dx)+v*(dq/dy) )    ; advection term
>    MFC_conv    = -q*( (du/dx)+  (dv/dy) )      ; con(div)-vergence
>
>    MFC = MFC_advect + MFC_conv
>
>
>
>
> -----------------------------
>
> In shea_util.ncl there are several functions. These are *NOT* supported.
> I put them there for people to look at and modify.  They require global
> grids
> ordered South->North because I use spherical harmonic functions.
> Documentation is in the functions only.
>
> %> less $NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl
>
> --------------------
> undef("vertint")
> function vertint (X:numeric, dp:numeric, con[1]:numeric \
>                  ,long_name:string, units:string, iopt:integer)
> ;
> ; Perform vertical integration:  dim_sum_n(X*dp,lind)
>
> ------------------------------
> undef("advect_gradient")
> function advect_gradient (u:numeric, v:numeric, x:numeric \
>                          ,gridType[1]:integer, con[1]:numeric \
>                          ,long_name:string, units:string, iopt[1]:integer)
> ;
> ; linear advection of a scalar quantity: UV.GRADIENT(X)
> ;                                      : U*(dX/dlon) + V*(dX/dlat)
> ;
> ; Requires:
> ;    (1) grid be global cuz spherical harmonics are used
> ;    (2) required dimension order ([time,[lev,]]lat,lon)
> ;    (3) the input grids *must* be ordered South==>North
>
> Divergence can be calculated via spherical harmonics
>
> Good luck
>
>
>
> On Thu, Dec 18, 2014 at 6:48 PM, tms_l <littithomas at gmail.com> wrote:
>
>> hi,
>>
>> does any one having any idea of calculating vertically integrated
>> moisture flux convergence at different pressure levels , using ncl?
>>
>> thanks in advance
>>
>> thomas
>>
>
>
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