[ncl-talk] Averaging over time dimension

[Soma Roy]

Thank you Adam Phillips.
I will check this. Another way I think, using CDO first 'split' time steps
or 'timmean' entire file then perform the operations over different
variables in NCL.

Soma

On Mar 9, 2018 01:15, "Adam Phillips" <asphilli at ucar.edu> wrote:

> 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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