[ncl-talk] Question about regrid 1) different commands get different results; 2)input emission amount or emission intensity

[Dennis Shea]

[1]
re:  "Or any command can return the area of certain grid directly?"

There is no explicit function.

[2]
Your formula:
      area(i,j)=rr*(lat(i+1)-lat(i))*rr*(lon(j+1)-lon(j))*cos(rad*lat(i))
is more appropriate  for area *between* lat(i+1) and lat(i) .. so i=1.5 so
to speak

Maybe ...
      area(i,j)=rr*(0.5*(lat(i+1)-lat(i-1)))
*rr*(0.5*((j+1)-lon(j-1)))*cos(rad*lat(i))
      area(i,j)=0.25*rr^2 *(lat(i+1)-lat(i-1)*(lon(j+1)-lon(j-1))*cos(rad*
lat(i))

[3]
The following a the 'correct' formulation
       http://mathforum.org/library/drmath/view/63767.html

Good luck





On Sun, Mar 5, 2017 at 9:33 AM, 王梓元 <ziyuanwang at pku.edu.cn> wrote:

> Dear Shea
> Thank you for sharing scripts, it's really helpful. One more question, if
> I want to calculate the meission amount x(i,j) into emission intensity,
> should I calculate area manually, as this scipts：
> rad    = tofloat(4.0*atan(1.0)/180.0)
>   re     = 6.3712200E+03
>   rr     = tofloat(re*rad)
>   area(i,j)=rr*(lat(i+1)-lat(i))*rr*(lon(j+1)-lon(j))*cos(rad*lat(i))
> Or any command can return the area of certain grid directly?
> Thank you
>
> Ziyuan
>
>
>
> -----原始邮件-----
> *发件人:*"Dennis Shea" <shea at ucar.edu>
> *发送时间:*2017-03-05 00:09:00 (星期日)
> *收件人:* "Ziyuan Wang" <1301111586 at pku.edu.cn>
> *抄送:* "ncl-talk at ucar.edu" <ncl-talk at ucar.edu>
> *主题:* Re: [ncl-talk] Question about regrid 1) different commands get
> different results; 2)input emission amount or emission intensity
>
>
> I have nor run your script.
>
> I am not sure what you mean "results are different." The three methods are
> different.
>
> (a) linint2 takes the 4 nearest source grid locations and does a bilinear
> interpolation.
> (b) does some form of 'global' area conservation
> (c) does a local area average
>
> Hence, I am not surprised that they return different results.
>
> ===
> Attached is a script that uses ESMF regridding via bilinear, patch and
> conserve methods.
>
>  If you run the script you will also get a nc fil with the interpolated
> grids
>
> Good Luck
>
> On Fri, Mar 3, 2017 at 2:18 PM, Ziyuan Wang <1301111586 at pku.edu.cn> wrote:
>
>> Hi ncl-talk members
>>
>> Now I have an emission amount inventory (lat 33:73, lon -12:45), with
>> resolution 0.1*0.1, the emission variable E_HFC_1234 is the emission amount
>> of each grid with unit Mg, as 'HFC.nc' show. I want to interpolate to lower
>> resolution 1*1.
>>
>> 1. I tried 3 different commands: "linint2", "*area_conserve_remap_Wrap
>> <http://www.ncl.ucar.edu/Document/Functions/Contributed/area_conserve_remap_Wrap.shtml>",
>> and "*area_hi2lores_Wrap" But three return results are different (try in
>> regrid.ncl)
>>
>> 2) The input "fi" of each command should be the emission amout? or the
>> emission intensity of each grid? Do I need to calculate E_HFC_1234 into
>> emission intensity, by dividing the area of each grid? If so, which command
>> can I use to calculate area?
>>
>> Thanks
>>
>> Best
>>
>> Ziyuan
>>
>>
>>
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>>
>
>
> 王梓元(WANG Ziyuan)
>
> 中国北京大学环境科学与工程学院
>   College of Environmental Science and Engineering
>   Peking University, China
> ● 中国北京海淀区颐和园路5号 邮编：100871
>   No.5, Yiheyuan Road, Haidian Dist.
>   Beijing 100871, P.R. China
> ● 手机 Cell： (+86)132-6999-2003 <+86%20132%206999%202003>
>
> ● 电子邮件 Email：wangziyuan91 at 163.com, ziyuanwang at pku.edu.cn
> <ziyuanwang at oku.edu.cn>
>
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