Re: Maximum Covariance Analysis

Hi all again

I'm trying to use the svdcov function but it don't work well.

ncl 0> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
ncl 1> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
ncl 2> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
ncl 3>
ncl 4>
ncl 5>
ncl 6> latS = -21.
ncl 7> latN = 32.
ncl 8> lonL = -74.
ncl 9> lonR = 15.
ncl 10>
ncl 11> nsvd = 2
ncl 12> ncolf1 = 471128
ncl 13> ncolf2 = 471128
ncl 14>
ncl 15>
ncl 16> homlft = new((/nsvd,ncolf1/),float)
ncl 17> hetlft = new((/nsvd,ncolf1/),float)
ncl 18> homrgt = new((/nsvd,ncolf2/),float)
ncl 19> hetrgt = new((/nsvd,ncolf2/),float)
ncl 20>
ncl 21> f1 = addfile ("EH5_OM_20C_2_TSURF_DETRENDRUNMEAN.nc", "r")
ncl 22> tsm = f1->tsurf
ncl 23>
ncl 24> f2 = addfile ("EH5_OM_20C_2_U10M_DETRENDRUNMEAN.nc", "r")
ncl 25> u = f2->u10
ncl 26>
ncl 27> dimtsm = dimsizes(tsm)
ncl 28> ntim = dimtsm(0)
ncl 29> nlat = dimtsm(1)
ncl 30> mlon = dimtsm(2)
ncl 31>
ncl 32> dimu10 = dimsizes(u)
ncl 33> ntim1 = dimu10(0)
ncl 34> nlat1 = dimu10(1)
ncl 35> mlon1 = dimu10(2)
ncl 36>
ncl 37> T = onedtond( ndtooned(tsm), (/ntim,nlat*mlon/))
ncl 38> U = onedtond( ndtooned(u), (/ntim1,nlat1*mlon1/))
ncl 39>
ncl 40> covar = svdcov(T,U,nsvd,homlft,hetlft,homrgt,hetrgt)

and I got it like answer:
fatal:svdcov: The rightmost dimension of the homlft/hetlft arrays must
be the same as the leftmost dimension of x, and the leftmost dimension
must be nsvx
fatal:Execute: Error occurred at or near line 40

I think the problem is in the space allocate to the matrices

The two fields used in the calculus are shown below:

dimensions:
         lon = 47 ;
         lat = 28 ;
         time = UNLIMITED ; // (358 currently)
variables:
         double lon(lon) ;
                 lon:long_name = "longitude" ;
                 lon:units = "degrees_east" ;
                 lon:standard_name = "longitude" ;
         double lat(lat) ;
                 lat:long_name = "latitude" ;
                 lat:units = "degrees_north" ;
                 lat:standard_name = "latitude" ;
         double time(time) ;
                 time:units = "day as %Y%m%d.%f" ;
                 time:calendar = "proleptic_gregorian" ;
         float u10(time, lat, lon) ;
                 u10:long_name = "10m u-velocity" ;
                 u10:units = "m/s" ;
                 u10:code = 165 ;
                 u10:table = 128 ;
                 u10:grid_type = "gaussian" ;

dimensions:
         lon = 47 ;
         lat = 28 ;
         time = UNLIMITED ; // (358 currently)
variables:
         double lon(lon) ;
                 lon:long_name = "longitude" ;
                 lon:units = "degrees_east" ;
                 lon:standard_name = "longitude" ;
         double lat(lat) ;
                 lat:long_name = "latitude" ;
                 lat:units = "degrees_north" ;
                 lat:standard_name = "latitude" ;
         double time(time) ;
                 time:units = "day as %Y%m%d.%f" ;
                 time:calendar = "proleptic_gregorian" ;
         float tsurf(time, lat, lon) ;
                 tsurf:long_name = "surface temperature" ;
                 tsurf:units = "K" ;
                 tsurf:code = 169 ;
                 tsurf:table = 128 ;
                 tsurf:grid_type = "gaussian" ;

May I ask if anyone can help me?

I appreciate any help.

Thanks a lot

Leonardo
= = = = = = = =
Quoting Dennis Shea <shea@ucar.edu>:

> http://www.ncl.ucar.edu/Document/Functions/Built-in/svdcov.shtml
>
> function svdcov (
> x [*][*] : numeric,
> y [*][*] : numeric,
> nsvd : integer,
> homlft [*][*] : numeric,
> hetlft [*][*] : numeric,
> homrgt [*][*] : numeric,
> hetrgt [*][*] : numeric
> )
>
>
> You took
>> tempsup = tsm( time|:, lat|:, lon|: ) ; 3d
>> uwnd = u( time|:, lat|:, lon|: ) ; 3d
>
> which are 3-dimensional, and then invoked svdcov
>
>> covar = svdcov(tempsup(time|:, tsurf|:),uwnd(time|:, \
>> tsurf|:),nsvd,homlft,hetlft,homrgt,hetrgt)
>
> with
> tempsup(time|:, tsurf|:) ; 2d
> and
> uwnd(time|:, tsurf|:) ; 2d
>
>
> Where did "tsurf" come from?
>
> A transformation from 3d-to-2d does not happen automatically.
> The user must do this.
>
> dimu = dimsizes( u )
> ntim = dimu(0)
> nlat = dimu(1)
> mlon = dimu(2)
>
> T = onedtond( ndtooned(tempsup), (/ntim,nlat*mlon/)) ; 2D
> U = onedtond( ndtooned( uwnd ), (/ntim,nlat*mlon/)) ; 2D
>
> covar = svdcov(T,U,nsvd,homlft,hetlft,homrgt,hetrgt)
>
>
> ===
> If you are new to NCL I suggest you read the mini-language manual.
> Later, if interested in the graphics, the min-graphics manual.
>
> http://www.ncl.ucar.edu/Document/Manuals/
>
> They are pdf. They do have color so if you have a color
> printer, I suggest using it.
>
> Good luck
>
> leonardo.silva@cptec.inpe.br wrote:
>> Hi all,
>>
>> I'm a new ncl user and I would like to construct an Atlantic
>> Meridional Mode (AMM) Index like done by ERSL
>> (http://www.esrl.noaa.gov/psd/data/timeseries/monthly/AMM/). I have
>> to apply a Maximum Covariance Analysis to a SST field (left field)
>> and the zonal and meridional 10m wind (right field) through a
>> Singular Value Decomposition (SVD). I have to extract the first
>> left (SST) and right (winds) maps resulting from singular value
>> decomposition of the covariance matrix. The AMM time series is
>> calculated via projecting SST or the 10m wind field. onto the
>> spatial structure resulting from the MCA.
>>
>> I tried to construct that thing using the scrpt below:
>>
>> 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"
>>
>>
>>
>> latS = -21.
>> latN = 32.
>> lonL = -74.
>> lonR = 15.
>>
>> nsvd = 2
>> ncolf1 = 1316
>> ncolf2 = 1316
>>
>> homlft = new((/nsvd,ncolf1/),float)
>> hetlft = new((/nsvd,ncolf1/),float)
>> homrgt = new((/nsvd,ncolf2/),float)
>> hetrgt = new((/nsvd,ncolf2/),float)
>>
>> f1 = addfile ("EH5_OM_20C_2_TSURF_DETRENDRUNMEAN.nc", "w")
>> tsm = f1->tsurf
>> f1!0 = "time"
>> f2 = addfile ("EH5_OM_20C_2_U10M_DETRENDRUNMEAN.nc", "w")
>> u = f2->u10
>> tempsup = tsm( time|:, lat|:, lon|: )
>> uwnd = u( time|:, lat|:, lon|: )
>>
>> covar = svdcov(tempsup(time|:, tsurf|:),uwnd(time|:,
>> tsurf|:),nsvd,homlft,hetlft,homrgt,hetrgt)
>>
>> asciiwrite("mca.dat", covar(0,:))
>>
>> and I got it like answer:
>>
>> ncl 28> covar = svdcov(tempsup(time|:, tsurf|:),uwnd(time|:,
>> tsurf|:),nsvd,homlft,hetlft,homrgt,hetrgt)
>> fatal:Number of subscripts do not match number of dimensions of
>> variable,(2) Subscripts used, (3) Subscripts expected
>> fatal:Execute: Error occurred at or near line 28
>>
>> I have more one question:
>>
>> How can I put the wind (u+v) components onto a one variable? Have I
>> to sum the u and v.nc files?
>>
>> Regards
>>
>> Leonardo
>>
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Received on Sat Nov 28 13:10:40 2009