Re: correlating two arrays

Hi Erik,

You can create a new array before you enter the do loop, and then pass
the escorc values into the array within the do loop:

finarr = new((/ntimes,nlevels/),"float")
do it = 348,348
.....
    do level = 0,nlevels-1
........
       finarr(it,level) = escorc(ndtooned(WRFv700),ndtooned(FNLv700))
    end do
end do
Good luck,
Adam

Erik Noble wrote:
> Hi all.
> Thank you for the advice last week about correlating two arrays in NCL.
> My question now has to do with using values calculated inside a loop.
>
> If I have to use a loop to calculate a statistic over many timesteps,
> how can i "store" each value to plot later? are they automatically
> stored in an array?
> For instance, my code below uses the escorc command (last function in
> code) to calculate correlation coefficients inside of a loop (I have
> to use the do loop, sorry). I want to create an array of the r values
> so that I can make an XY plot of the r values.
> Sincerely,
> Erik
>
>
> ; Script for creating correlating V wind from Reanalysis and WRF output
> ; The purpose of this program is to create files for interpolating
> onto a regular grid
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
>
>
> begin
> ;
> ; The WRF ARW input file.
> ; This needs to have a ".nc" appended, so just do it.
> diri1 ="/Volumes/Data_and_Models/Model-Output/Athena/"
> ifile1 ="WRF-SOP3_Athena_3_1_2.nc"
> a=addfile(diri1+ifile1,"r")
> b = addfile("/Volumes/Data_and_Models/NAMA-SOP3/met_em.d01.2006-09-13_12:00:00.nc","r")
> ; What times and how many time steps are in the data set?
> times = wrf_user_list_times(a) ; get times in the file
> ntimes = dimsizes(times) ; number of times in the file
> rank = dimsizes(filevardimsizes(a,"XLAT")) ; # of dimensions
> ; The specific pressure levels that we want the data interpolated to.
> pressure_levels = (/ 850., 700., 500., 300./) ; pressure levels to plot
> nlevels = dimsizes(pressure_levels) ; number of pressure levels
> lat=a->XLAT(0,:,:)
> lon=a->XLONG(0,:,:)
> do it =348,348 ; TIME LOOP
> ; First get the variables we will need
>
> p = wrf_user_getvar(a, "pressure",it) ; pressure is our
> vertical coordinate
> v = wrf_user_getvar(a, "va",it) ; grid point variable
> u = wrf_user_getvar(a, "ua",it) ; grid point variable
>
> do level = 0,nlevels-1 ; LOOP OVER LEVELS
> pressure = pressure_levels(level)
> ;u_plane = wrf_user_intrp3d( u,p,"h",pressure,0.,False)
> v_plane = wrf_user_intrp3d( v,p,"h",pressure,0.,False)
> ;uv = table_attach_rows (u_plane, v_plane, 0) ;
> Combine both U and V
>
> v_plane!0 = "lat"
> v_plane!1 = "lon"
> ;U = u_plane(37:55,11:89) ; only if you are specifying
> lats and lons
> ;V = v_plane(37:55,11:89)
> ; printVarSummary(V)
>
> if ( pressure .eq. 700 ) then
> ;WRFv700 = V ; only if you are
> specifying lats and lons
> ;FNLv700 = b->VV(0,10,37:55,11:89) ; 700mb =level 10 ;
> only if you are specifying lats and lons
> WRFv700 = v_plane
> FNLv700 = b->VV(0,10,1::,:) ; 700mb =level 10
>
> ;Calculate the unwieghted pattern correlation between
> WRF grid and Observation Grid
> r = escorc(ndtooned(WRFv700),ndtooned(FNLv700))
> print(r)
> end if
> end do
> end do
> end
>
>
> On Jan 25, 2008 5:46 PM, Dennis Shea <shea_at_ucar.edu> wrote:
>> Erik Noble wrote:
>>> Dear Dennis.
>>> Thank you for this.
>>> If I am not concerned about weight, (i.e. Small region), then I should
>>> proceed with example 5?
>>>
>> Yes
>>> I notice that example 8 does not use the escorc function at all.
>>>
>> True, but I knew I'd be asked questions on areal weighted
>> pattern correlation, so I put it under escorc so I could
>> point people to something.
>>
>>> -Erik
>>>
>>> On 1/21/08 7:59 PM, "Dennis Shea" <shea_at_ucar.edu> wrote:
>>>
>>>
>>>> Assuming you want a areal weighted pattern correlation, see Example 8
>>>> http://www.ncl.ucar.edu/Document/Functions/Built-in/escorc.shtml
>>>>
>>>>
>>>> The "wgt" variable in this example is assumed to be the cos latitude
>>>>
>>>> lat(lat)
>>>> rad = 4.*atan(1.)/180.
>>>> wgt = cos(rad*lat)
>>>>
>>>> Then proceed as in example 8
>>>> ===============================
>>>> If the lat/lon arrays are 2D, say, XLAT, XLONG
>>>>
>>>>
>>>> wgt = cos(rad*XLAT) ; wgt[*][*]
>>>>
>>>>
>>>> xAvgArea = x*wgt/sum(wgt) ; weighted area average
>>>> yAvgArea = y*wgt/sum(wgt) **
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/wgt_areaave.shtml>
>>>>
>>>> xAnom = x - xAvgArea ; anomalies
>>>> yAnom = y - yAvgArea
>>>>
>>>> covxy = *sum*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/sum.shtml>(xAnom*yAnom*wg
>>>> t) ; weighted anomaly covariance
>>>>
>>>> r = covxy/( *sqrt*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/sqrt.shtml>(*sum*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/sum.shtml>(wgt*xAnom^2))
>>>> **sqrt* <http://www.ncl.ucar.edu/Document/Functions/Built-in/sqrt.shtml>(*sum*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/sum.shtml>(wgt*yAnom^2))
>>>> )
>>>>
>>>>
>>>> Erik Noble wrote:
>>>>
>>>>> Hi.
>>>>>
>>>>> I have two 2D arrays:
>>>>>
>>>>>
>>>>>>> whos Model1
>>>>>>>
>>>>>>>
>>>>> Name Size Bytes Class Attributes
>>>>>
>>>>> Model1 30x79 18960 double
>>>>>
>>>>>
>>>>>
>>>>>>> whos Obs
>>>>>>>
>>>>>>>
>>>>> Name Size Bytes Class Attributes
>>>>>
>>>>> Obs 30x79 18960 double
>>>>>
>>>>> I want to correlate these two arrays. Which set of NCL functions does this?
>>>>>
>>>>>
>>>>
>>>
>>
>> --
>> ======================================================
>> Dennis J. Shea tel: 303-497-1361 |
>> P.O. Box 3000 fax: 303-497-1333 |
>> Climate Analysis Section |
>> Climate & Global Dynamics Div. |
>> National Center for Atmospheric Research |
>> Boulder, CO 80307 |
>> USA email: shea 'at' ucar.edu |
>> ======================================================
>>
>>
>>
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-- 
--------------------------------------------------------------
Adam Phillips			             asphilli_at_ucar.edu
National Center for Atmospheric Research   tel: (303) 497-1726
ESSL/CGD/CAS                               fax: (303) 497-1333
P.O. Box 3000				
Boulder, CO 80307-3000	  http://www.cgd.ucar.edu/cas/asphilli
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