[ncl-talk] accumulate data on grid

[Dave Allured - NOAA Affiliate]

Debasish,

Sorry, you originally said "I have ... 2d lat, lon grid" and I
misunderstood what that meant.  See other answers from Barry and Dennis.
If you need more help, please show printVarSummary for your input variables
x, lat, and lon, so we can be clear about what type of input data you have.


On Sun, Oct 18, 2020 at 11:32 AM Paimazumder, Debasish <
Debasish.Paimazumder at aig.com> wrote:

> Dave- getind_latlon2d needs two-dimensional lat/lon while my output grid
> 1-d lat/lon.
> Interpolation from location to 1-d grid could be an option but we won’t
> get the accumulation (sum) at the output grid.
>
> Best regards,
> Dave
>
> On Oct 18, 2020, at 12:54 PM, Barry Lynn <barry.h.lynn at gmail.com> wrote:
>
> Right, that can be done.  Or, you can interpolate the data from the fine
> to coarse grid.
>
> I am not sure if the latter will conserve the averages like doing the
> averaging in a loop.
>
> On Sun, Oct 18, 2020 at 6:58 PM Dave Allured - NOAA Affiliate via ncl-talk
> <ncl-talk at mailman.ucar.edu> wrote:
>
>> Use the function *getind_latlon2d* to get the (i,j) grid point indices
>> for the point data coordinates.  Then do a single loop over the point data
>> to accumulate sums and counts on the output grid.
>>
>>
>> On Sun, Oct 18, 2020 at 9:09 AM Paimazumder, Debasish via ncl-talk <
>> ncl-talk at mailman.ucar.edu> wrote:
>>
>>> Hi Barry,
>>> Thanks for your response. Actually I don’t have time dimension. I have
>>> location level data (at high resolution).
>>> For example, x(m) with lat(m) and lon (m) where m = 300k location
>>>
>>> My output grid is 32x32 km and I would like to do following
>>> 1. Estimate the number of locations are in each 32x32 km grid
>>> 2. Accumulate (sum) the x at each output grid.
>>> For example- if I have 100 locations at one of the 32x32km grid, I will
>>> sum all x from 100 locations and assign the sum to the output grid.
>>>
>>> Best regards,
>>> Dave
>>>
>>> On Oct 18, 2020, at 3:50 AM, Barry Lynn <barry.h.lynn at gmail.com> wrote:
>>>
>>> Hi:
>>>
>>> If you have two grids of the same dimensions, but different times, you
>>> can simply add them together.
>>>
>>> If you have grids of a different size, you can interpolate the data to
>>> this grid, one grid at a time.
>>>
>>> See for example:
>>>
>>> https://www.ncl.ucar.edu/Applications/regrid.shtml
>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ncl.ucar.edu_Applications_regrid.shtml&d=DwMFaQ&c=kn4_INW_mBCDHV_xJEVJkg&r=fpudUXThXLQwAKQPDCnmVaSzm2dwE9OxcWi7MuJ0jbo&m=IaFm8AuXStzIPZXMbIRmp6fjt5zy74eAUUQzoQb5pBc&s=tUIMDu-yehcnE2-mHTaX2NhZiAg5eBHJsqf3e1Bmbl8&e=>
>>>
>>> This may also help.
>>>
>>> https://www.ncl.ucar.edu/Document/Functions/Built-in/dim_sum_n.shtml
>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ncl.ucar.edu_Document_Functions_Built-2Din_dim-5Fsum-5Fn.shtml&d=DwMFaQ&c=kn4_INW_mBCDHV_xJEVJkg&r=fpudUXThXLQwAKQPDCnmVaSzm2dwE9OxcWi7MuJ0jbo&m=IaFm8AuXStzIPZXMbIRmp6fjt5zy74eAUUQzoQb5pBc&s=4tdKFBxFBOUpMYFj95WyO8MUdUcYRniTWsJIvCCbhAE&e=>
>>>
>>> On Sun, Oct 18, 2020 at 7:59 AM Paimazumder, Debasish via ncl-talk <
>>> ncl-talk at mailman.ucar.edu> wrote:
>>>
>>>> Hi NCL users
>>>>
>>>> I have location level data and 2d lat, lon grid and I’m trying to
>>>> accumulate the data on  2d lat, lon grid.
>>>>
>>>>
>>>>
>>>> For example
>>>>
>>>> Input - x (n) with lat(n), lon(n)
>>>>
>>>> Output grid - lat(i)xlon(j)
>>>>
>>>> I’m trying to estimate number of location within each grid and
>>>> accumulate x at each grid.
>>>>
>>>> Is there any function in NCL that will solve this problem?
>>>>
>>>>
>>>>
>>>> With regards
>>>>
>>>> -Debasish
>>>>
>>>>
>>>>
>>>> *Debasish PaiMazumder, PhD |*Tel +1 215 255 6052
>>>> <%2B1%20215%20255%206371> | Cell +1 267 449 5226
>>>> <%2B1%20718%20913%206946> |*Debasish.Paimazumder at aig.com
>>>> <Debasish.Paimazumder at aig.com>*
>>>>
>>>
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