[ncl-talk] Averaging over time dimension

[Adam Phillips]

Hi Soma,
Please remember to always respond to the ncl-talk email list when
responding. That way others can assist and can also see the answers to
queries.

Your emailed reply stated:
> How much space is then required to process all the variables in single
run? I am using NCL in my laptop (i5 with 8GB ram)and free space in that
drive is 86 GB.

I cannot answer that question precisely. Your machine will be using part of
its' memory for core functionality and other tasks. What you can do is to
try to conserve memory in your script as best as you can. The sample coding
snippets I sent you will assist in that task. Try what I suggested and let
ncl-talk know if you have further issues. Note that beyond what I stated in
my original reply, another avenue you might have to take to save memory is
to read in the variables in  different scripts.
Adam


On Thu, Mar 8, 2018 at 8:35 AM, Soma Roy <somaroy892 at gmail.com> wrote:

> Hi,
>
> I am trying to access multiple variables from a file and need to average
> over time for each variables.
>
> I am running the following codes:
>
>    fn  = "ERA_Plev.nc"                      ; define filename
>    in  = addfile(fn,"r")                         ; open netcdf file
>    printVarSummary(in)
>
> T=in->t       ; temperature
> U=in->u      ; U wind
> V=in->v      ; V wind
>
> printVarSummary(T)
> printVarSummary(U)
> printVarSummary(V)
>
> ;T1 = dim_avg_n(T,0)
> ;T at units = "K"
> end
>
> Summary of the file is like below;
>
> Variable: in
> Type: file
> File path: ERA_Plev.nc
> Number of global attributes:     2
> Number of dimensions:    4
> Number of variables:     18
> fatal:NclMalloc Failed:[errno=12]
> Segmentation fault (core dumped)
>
> When I am calling only Temperature using the codes below;
>
> fn  = "ERA_Plev.nc"               ; define filename
> in  = addfile(fn,"r")                         ; open netcdf file
>    printVarSummary(in)
>
> T=in->t     ; temperature
> ;U=in->u     ; U wind
> ;V=in->v     ; V wind
>
> printVarSummary(T)
> ;printVarSummary(U)
> ;printVarSummary(V)
>
> ;T1 = dim_avg_n(T,0)
> ;T at units = "K"
> end
>
> It shows
>
> Variable: T
> Type: short
> Total Size: 1042566000 bytes
>             521283000 values
> Number of Dimensions: 4
> Dimensions and sizes:   [time | 120] x [level | 25] x [latitude | 721] x
> [longitude | 241]
> Coordinates:
>             time: [994176..994890]
>             level: [50..125]
>             latitude: [90..-90]
>             longitude: [60..120]
> Number Of Attributes: 7
>   scale_factor :        0.00218919045579553
>   add_offset :  252.4797479951041
>   _FillValue :  -32767
>   missing_value :       -32767
>   units :       K
>   long_name :   Temperature
>   standard_name :       air_temperature
>
>
> I have to call several other variables from this file (14 GB) and I need
> to average over time such that 'Dimensions' of each variables will be like
> below;
>
> [time | 1]* [level | 25] x [latitude | 721] x [longitude | 241]
>
> Which function I have to use in this case?
>
>
> When I am trying to call  other variables from the file I am getting the
> error message as;
>
> Variable: in
> Type: file
> File path: ERA_Plev.nc
> Number of global attributes:     2
> Number of dimensions:    4
> Number of variables:     18
> fatal:NclMalloc Failed:[errno=12]
> Segmentation fault (core dumped)
>
> Please kindly inform me how to resolve this issue.
>
>
> Thank you,
> Soma
>
>
>
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>


-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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