# [ncl-talk] Area averaging

Setareh Rahimi setareh.rahimi at gmail.com
Wed Oct 18 11:44:17 MDT 2023

```Dear Dave,
Thanks a lot for your help.
Best wishes,

On Wed, Oct 18, 2023 at 4:37 PM Dave Allured - NOAA Affiliate <
dave.allured at noaa.gov> wrote:

> Setareh, please see the examples page for Weighted Averages.  The first
> two examples are both area averages.  Example ave_2.ncl demonstrates
> coordinate subsetting on a grid with 1-D coordinates.  Use that syntax on
> both the X and Y dimensions to define the bounding box.  I suggest compute
> your own weights as the cosines of the latitudes.  There are cosine weight
> functions available in the lat/lon function category, or just compute your
> own with cos().
>
>
> On Wed, Oct 18, 2023 at 6:21 AM Setareh Rahimi <setareh.rahimi at gmail.com>
> wrote:
>
>> Hi Dave,
>> Thanks for your email. Well, the area that I consider to have an area
>> average is a bounding box. So how can I do this, please? any examples?
>> Best wishes,
>>
>> On Sat, Oct 14, 2023 at 10:16 PM Dave Allured - NOAA Affiliate <
>> dave.allured at noaa.gov> wrote:
>>
>>> Yes it is possible.  If the grid has 1-D coordinates, then see the
>>> family of *wgt_areaave* functions.  If 2-D, then more work is needed.
>>> Also, what kind of region definition do you need?  Bounding box, polygon,
>>> shape file, list of grid points, or something else?
>>>
>>>
>>> On Sat, Oct 14, 2023 at 9:39 AM Setareh Rahimi via ncl-talk <
>>> ncl-talk at mailman.ucar.edu> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I have a question about area averaging in NCL. I have my WRF-Chem
>>>> output file and would like to calculate average of aerosol optical depth
>>>> (AOD)
>>>> For an area at let's say 06:00 UTC. So I wonder if this would be
>>>> possible through NCL?
>>>>
>>>> Best wishes,
>>>>
>>>
>>
>> --
>> S.Rahimi
>>
>>

--
S.Rahimi
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