[ncl-talk] computing the model SOI index

[Dave Allured - NOAA Affiliate]

Sri, there is something wrong with the time coordinates in fslp->time.  You
show values of [18500131.99444444..20051231.99444444], but units of "hours
since 1850-01-31 23:15:00".  Time coordinates should either be offsets
relative to the base time in the units string, or else they should be
decimal coded numbers.  It looks like this file mixes the two approaches,
resulting in your error.  Relative offsets is the conventional approach,
but decimal coded may also be used with care.  Just don't mix the two.

Do you prefer to fix the input file, or try to use the decimal time values
the way they are written now?  Please keep the conversation on the mailing
list.


On Tue, Apr 13, 2021 at 9:43 AM Sri nandini via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hello dear ncl-users,
>
> I am trying to compute the model SOI index to draw a timeseries plot. I
> have studies the examples on the ncl page for indices_soi_1.ncl and
> indices_soi_2.ncl , and made my script as per the methods here. But each
> time an error occurs when reading the time: fatal:An error occurred
> reading YYYY
>
> Variable: TIME
> Type: double
> Total Size: 14976 bytes
>              1872 values
> Number of Dimensions: 1
> Dimensions and sizes:    [time | 1872]
> Coordinates:
>              time: [18500131.99444444..20051231.99444444]
> Number Of Attributes: 4
>    standard_name :    time
>    units :    hours since 1850-01-31 23:15:00
>    calendar :    standard
>    axis :    T
>
> Variable: YYYY
> Type: integer
> Total Size: 7488 bytes
>              1872 values
> Number of Dimensions: 1
> Dimensions and sizes:    [1872]
>
> Could someone reply to me offline, or help point me to a query or
> ncl-talk which already solved this or i can also transfer my datafile
> via ftp? Below is my script.
>
> ; =============================================================
>    latT    = -17.6         ; Tahiti
>    lonT    = 210.75
>    latD    = -12.5         ; Darwin
>    lonD    = 130.83
>
>    PLOT    = True
>    pltType = "png"         ; send graphics to PNG file
>    pltDir  = "./"          ; dir to which plots are sent
>
>    pltName = "indices_soi"
>    yrStrt  = 1950          ; manually specify for convenience
>    yrLast  = 2010          ; 20th century ends 2010
>
>    clStrt  = 1950          ; reference climatology for SOI
>    clLast  = 1979
> ; ======================End User
> Input=======================================
>    nmos   = 12
>    nyrs   = yrLast-yrStrt+1
>
>    fslp   = addfile("hist_1850-2005_ens_1-100.slp.nc", "r")
>    slp    = fslp->slp
>    printVarSummary(slp)
>    TIME   = fslp->time
>    printVarSummary(TIME)
>    ;YYYYMM = cd_calendar(TIME, -1) ;error here
>
>    YYYY   = cd_calendar(TIME,-2)/100
>
>    tStrt  = ind(YYYY .eq. (yrStrt*100 +  1))       ; indices 20th century
>    tLast  = ind(YYYY .eq. (yrLast*100 + 12))       ; relative to entire
> dataset
>
>    yyyymm = YYYY(tStrt:tLast)
>    tStrtP = ind(yyyymm .eq. (yrStrtP*100+  1))       ; relative to
> yrStrt, yrLast
>    tLastP = ind(yyyymm .eq. (yrLastP*100+ 12))
>
>    T      = short2flt(fslp->slp(1632:1871,:,{latT},{lonT}))
>    D      = short2flt(fslp->slp(1632:1871,:,{latD},{lonD}))
>    printVarSummary(T)
>    printVarSummary(D)
>    T&time = yyyymm                                   ; convenience
>    D&time = yyyymm
>
>    tClmStrt = ind(yyyymm.eq.(clStrt*100 +  1))       ; index for clStrt
>    tClmLast = ind(yyyymm.eq.(clLast*100 + 12))       ; index for clStrt
>    printVarSummary(tClmStrt)
>    printVarSummary(tClmLast)
>    TClm   = new ( nmos, typeof(T), T at _FillValue)     ; monthly
> climatologies
>    DClm   = new ( nmos, typeof(D), D at _FillValue)
>
>    do nmo=0,nmos-1
>     ;do n=0,99                                 ; reference clm for each
> month and each ensemble member?
>       TClm(nmo) = avg(T(tClmStrt+nmo:tClmLast:nmos))
>       DClm(nmo) = avg(D(tClmStrt+nmo:tClmLast:nmos))
>    end do
>   end do
>    printVarSummary(TClm)
>    printVarSummary(DClm)
>    TAnom    = T
>    DAnom    = D
>    do nmo=0,nmos-1                                   ; anomalies
> reference clim
>       TAnom(nmo::nmos) = T(nmo::nmos) - TClm(nmo)
>       DAnom(nmo::nmos) = D(nmo::nmos) - DClm(nmo)
>    end do
>    printVarSummary(TAnom)
>    printVarSummary(DAnom)
>
>    TAnomStd   = stddev(TAnom(tClmStrt:tClmLast))     ; stddev of
> anomalies over clStrt & clLast
>    DAnomStd   = stddev(DAnom(tClmStrt:tClmLast))
>    printVarSummary(TAnomStd)
> printVarSummary(DAnomStd) ; signal and noise
>    soi_signal = (TAnom/TAnomStd) - (DAnom/DAnomStd)  ; (ntim)
>    copy_VarCoords(TAnom, soi_signal)
>    soi_signal at long_name = "SOI: 20th Century Reanalysis:
> "+yrStrt+"-"+yrLast
>    printVarSummary(soi_signal)
>
> ;=======================================
> ; lag-0 correlation
> ;=======================================
>
>    rslp  = escorc(soi_signal,slp(lat|:,lon|:,ens:|,time|:))
>    copy_VarCoords(slp(0,:,:,:), rslp)
>    rslp at long_name = "Correlation: SOI-SLP: "+yrStrt+"-"+yrLast
>    printVarSummary(rslp)
>
> Best
>
> Sri
>
> --
> Dr. Sri, Nandini-Weiss
> Research Associate
>
> Universität Hamburg
> Center for Earth System Research and Sustainability (CEN)
> Cluster of Excellence 'Climate, Climatic Change, and Society' (CLICCS)
>
> Bundesstrasse 53, 20146 Hamburg
>
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