[ncl-talk] accumulate data on grid

[Paimazumder, Debasish]

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:


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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<mailto: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<mailto: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<mailto: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<mailto: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<tel:%2B1%20215%20255%206371> | Cell +1 267 449 5226<tel:%2B1%20718%20913%206946> |Debasish.Paimazumder at aig.com<mailto:Debasish.Paimazumder at aig.com>
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Barry H. Lynn, Ph.D
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