# [ncl-talk] question about "dtrend" function

Dennis Shea shea at ucar.edu
Mon Sep 8 10:15:57 MDT 2014

```mstd = dim_stddev_n_Wrap(Methanes,1)    ; mstd(lat)

---
https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_stddev_n_Wrap.shtml

On Fri, Sep 5, 2014 at 3:12 PM, Verena Lili <verena.prick at gmail.com> wrote:

> Hi Denis,
>
> I meant something like this (attached).
> My data is zonal mean Methanes (lat,time).
> How could i determine the standard deviation of the trend each latitudes.
> Thanks
>
>
>
> On Friday, September 5, 2014, Dennis Shea <shea at ucar.edu> wrote:
>
>> This question is a bit ambiguous.
>>
>> Assuming y(time,lat,lon)      ; (ntim,nlat,mlon)
>>
>>    yNew = dtrend_n(y, True, 0)                     ;
>> yNew=dtrend(y(lat|:,lon|:,time|:), True)
>>
>>    slope  = *onedtond*
>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/onedtond.shtml>
>> (yNew at slope,(/nlat,nlon/))    ; slope(nlat,mlon)
>>    copy_VarCoords(y(0,:,:), slope)
>>    slope at long_name = "..."
>>    slope at units           = "..."
>>    printVarSummary(slope)
>>
>> ; arithmetic stddev
>>
>>    slope_std = stddev(slope)
>>
>> The weighted stddev could also be determined by weight the grid by (say)
>>
>>
>>
>>
>>
>>
>>
>> On Sat, Aug 30, 2014 at 2:51 PM, Verena Lili <verena.prick at gmail.com>
>> wrote:
>>
>>> Hallo,
>>>
>>> Anybody try to have a standard deviation of the trend using "dtrend"
>>> function? I'd like to plot the trend values together with the
>>> their stdev. Thank you..,
>>>
>>> Cheers
>>>
>>>
>>> --
>>> Regards,
>>> Dr. Verena.
>>> School of Marine and Atmospheric Sciences
>>> Stony Brook University
>>> homepage: http://www.somas.stonybrook.edu/
>>>
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> List instructions, subscriber options, unsubscribe:
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>>>
>>>
>>
>
> --
> Regards,
> Dr. Verena.
> School of Marine and Atmospheric Sciences
> Stony Brook University
> homepage: http://www.somas.stonybrook.edu/
>
>
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