# Re: "month_to_annual" function

From: Maria Gehne <mgehne_at_nyahnyahspammersnyahnyah>
Date: Wed Jul 17 2013 - 13:12:04 MDT

Hi Mahesh,

that's not really an error message you're getting. That's just NCL
telling you that some grid points have missing values, which is not
surprising since there shouldn't be SST values over land.

The description of the month_to_annual routine
(http://www.ncl.ucar.edu/Document/Functions/Contributed/month_to_annual.shtml)
says that all values for a year need to be there for an average to be
computed. Over the land grid points you have only missing values and so
no annual values can be computed.

My guess is that you are computing the mean values for all ocean grid
points. Have you tried plotting the result for one year?

Also, I noticed your data has the format [lat,lon,time]. The routine
needs the time dimension first to compute annual values (so reordered to
[time,lat,lon]). Is that what you are doing?

Hope this helps,
Maria

On 07/17/2013 12:23 PM, Mahesh Varma wrote:
> Hello,
> I am trying to average monthly SST values to yearly values. I use
> "month_to_annual" function to do this. When I use "month_to_annual"
> function, NCL prints something like
>
> (0)month_to_annual: some grid points have missing data: nt=0 nyr=0
> num(nGood)=43425
> (0)month_to_annual: some grid points have missing data: nt=12 nyr=1
> num(nGood)=43425
> ........... and so on
>
> I am not sure what this error means?.I then tried printing VarSummary
> and missing values and here's the result
> ----------------------------------------
> Variable: SSTt_anom
> Type: float
> Total Size: 286156800 bytes
> 71539200 values
> Number of Dimensions: 3
> Dimensions and sizes:[lat | 180] x [lon | 360] x [time | 1104]
> Coordinates:
> lat: [89.5..-89.5]
> lon: [-179.5..179.5]
> time: [16822368..17628096]
> Number Of Attributes: 11
> long_name :Monthly 1 degree resolution SST
> standard_name :sea_surface_temperature
> units :degC
> cell_methods :time: lat: lon: mean
> scale_factor : 1
> _FillValue :-1e+30
> missing_value :-1e+30
> actual_range :( -1.8, 34.76296 )
> description :HadISST 1.1 monthly average sea surface temperature
> anomaly_op_ncl :function calcMonAnomLLT: contributed.ncl
> (0)Number missing=25350203
> -------------------------------------------
>
> Thanks,
> Mahesh
>
>
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```--
Maria Gehne
Postdoctoral Fellow
NCAR/CGD/CAS
P.O. Box 3000
Boulder, CO 80307

```

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Received on Wed Jul 17 13:12:17 2013

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