[ncl-talk] About regridding from
Barry Lynn
barry.h.lynn at gmail.com
Tue Jan 17 10:41:26 MST 2017
Hi Tao:
I apologize, but I can't answer right now as I am traveling.
However, in order to provide ncl-talkers with enough information/data, you
can write out the data grid (lat/lon) you are trying to plot on from WRF,
and upload one time step of it (or two). You should also upload the radar
data.
;---Write wrf variables lat/lon to file for ncltalk.nc
system("rm -f file_for_ncltalk.nc")
fout = addfile("file_for_ncltalk.nc","c")
fout->xlat = xlat
fout->xlong = xlong
Barry
On Tue, Jan 17, 2017 at 7:14 PM, Tao Lu <hakufu.asano at gmail.com> wrote:
> Hello Barry:
>
> Thank you very much for your reply.
> I am very appreciated that you shared your codes with us.
>
> Some editions have been done in my situation.
> However, I could not get contour after grid =
> obj_anal_ic(lon_o,lat_o,obs_o,xlon_m,xlat_m,rscan,False).
> I attached the edited code and run information, please help me check that.
>
> I also have some questions about the method for regridding:
> 1. There is a item named "rightmost dimension or leftmost dimension" in
> http://www.ncl.ucar.edu/Document/Functions/Built-in/obj_anal_ic.shtml
> I googled it but have no ideal.
>
> 2. Also according to the webpage in 1. obs_o at _FillValue will be ignored.
> Does it mean that missing value won't be accounted for when
> interpolation?
>
> 3. "cband radar observations: min=0 max=220" before regridding
> "var_zoom min=0 max=23.5354" after regridding
> After regridding the radar density is much smaller than original
> maximum.
> Is it normal? Maybe as you said rscan is important.
>
> 4. When you use
> grid = obj_anal_ic(lon_o,lat_o,obs_o,xlon_m,xlat_m,rscan,False)
>
> You calculate this
> ;---Get slice of lat/lon data at halfway points.
> nlat = dims2d(0)
> nlon = dims2d(1)
> xlat_m = xlat2d_m(:,nlon/2)
> xlon_m = xlon2d_m(nlat/2,:)
>
> Is it reasonable to calculate lat/lon at a quarter points?
>
> 5. If use halfway points to regrid radar data,
> [image: Inline image 1]
> We will get a n(xlat_m) x n(xlon_m) regridded array.
> So, what will the array's lat/lon will be?
>
> 6. This method is to interpolate radar data to wrf grid.
> Is the mean average method more suitable for radar data? Because radar
> have
> so many data points unlike rain gauge data?
>
>
> My ascii data converted from radar is too large, if you need it I will
> send it to you.
> The data is something like below:
> # crain_composite_data:rain_density:lat:lon:ndata=2406400:
> # 2015-09-09_00:00:00
> -9999 47.32916666666667 137.01874999999998
> -9999 47.32916666666667 137.03125
> -9999 47.32916666666667 137.04375
> -9999 47.32916666666667 137.05625
> -9999 47.32916666666667 137.06875
> -9999 47.32916666666667 137.08124999999998
>
>
> Waiting for your reply.
> Thank you very much.
>
> Tao
>
>
> On Tue, Jan 17, 2017 at 4:05 AM, Barry Lynn <barry.h.lynn at gmail.com>
> wrote:
>
>> Hi Tao:
>>
>> Here, I gridded the radar data to the WRF grid.
>>
>> You will need to adapt what I did to your situation, but the most
>> important step is to decide on the degree of smoothing (which is set by
>> rscan).
>>
>> grid = obj_anal_ic(lon_o,lat_o,obs_o,xlon_m,xlat_m,rscan,False)
>>
>> Please write if you have questions.
>>
>> Barry
>>
>> On Mon, Jan 16, 2017 at 9:11 AM, Tao Lu <hakufu.asano at gmail.com> wrote:
>>
>>> Dear ncl-talk
>>>
>>> Hello.
>>>
>>> I am new to regridding, if possible please give me some help and advice.
>>>
>>> What I am doing?: Compare two kind of grid data
>>> *I have two kind of data.*
>>> 1. radar data:
>>> resolution: 0.5 minute x 0.75 minute, as seen not regular
>>> grids
>>> file format: ascii
>>> [image: Inline image 1]
>>> 2. output data from WRF:
>>> dx = 30000,
>>> dy = 30000,
>>> map_proj = 'lambert',
>>> ref_lat = 36.00,
>>> ref_lon = 140.00,
>>> truelat1 = 30.0,
>>> truelat2 = 60.0,
>>> stand_lon = 140.0,
>>> file fomat: netcdf
>>> [image: Inline image 3]
>>>
>>> *I have to regrid the two data to each other or to new grid.*
>>> 1. Regrid wrf data grid to radar data grid?
>>> 2. Regrid radar data to wrf data?
>>> 3. Regrid both to another data?
>>> Which is easiest?
>>>
>>> I am really new to this, please give me some guide line, I will further
>>> operation on my work.
>>>
>>> Thank you very much for your kind help.
>>>
>>> Tao
>>>
>>>
>>> --
>>> ******************************************************
>>> Tao Lu (M. Eng)
>>> Laboratory of River Engineering and Hydrology,
>>> Dept. of Civil and Environmental Engineering,
>>> Graduate School of Science and Engineering,
>>> Chuo University
>>>
>>> 1-13-27,Kasuga,Bunkyo-ku,Tokyo
>>> 112-8551, Japan
>>> TEL: 03-3817-1805; Phone: 070-2188-7509
>>> Email1: hakufu.asano at gmail.com <mail%3Amet.yamos at gmail.com>
>>> Email2: lutao at civil.chuo-u.ac.jp <mail%3Ayamoto at civil.chuo-u.ac.jp>
>>> *****************************************************
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at ucar.edu
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>
>>>
>>
>>
>> --
>> Barry H. Lynn, Ph.D
>> Senior Lecturer,
>> The Institute of the Earth Science,
>> The Hebrew University of Jerusalem,
>> Givat Ram, Jerusalem 91904, Israel
>> Tel: 972 547 231 170
>> Fax: (972)-25662581
>>
>> C.E.O, Weather It Is, LTD
>> Weather and Climate Focus
>> http://weather-it-is.com
>> Jerusalem, Israel
>> Local: 02 930 9525
>> Cell: 054 7 231 170
>> Int-IS: x972 2 930 9525
>> US 914 432 3108 <(914)%20432-3108>
>>
>
>
>
> --
> ******************************************************
> 盧 涛 (ル タオ) 修士課程2年
>
> 〒112-8551 東京都文京区春日1-13-27
>
> 中央大学理工学研究科都市環境学専攻
>
> 河川・水文研究室（山田正教授）
>
>
> TEL: 03-3817-3406; Phone: 070-2188-7509
> Email1: hakufu.asano at gmail.com <mail%3Amet.yamos at gmail.com>
> Email2: lutao at civil.chuo-u.ac.jp <mail%3Ayamoto at civil.chuo-u.ac.jp>
> *******************************************************
> ******************************************************
> Tao Lu (M. Eng)
> Laboratory of River Engineering and Hydrology,
> Dept. of Civil and Environmental Engineering,
> Graduate School of Science and Engineering,
> Chuo University
>
> 1-13-27,Kasuga,Bunkyo-ku,Tokyo
> 112-8551, Japan
> TEL: 03-3817-1805; Phone: 070-2188-7509
> Email1: hakufu.asano at gmail.com <mail%3Amet.yamos at gmail.com>
> Email2: lutao at civil.chuo-u.ac.jp <mail%3Ayamoto at civil.chuo-u.ac.jp>
> *****************************************************
>
--
Barry H. Lynn, Ph.D
Senior Lecturer,
The Institute of the Earth Science,
The Hebrew University of Jerusalem,
Givat Ram, Jerusalem 91904, Israel
Tel: 972 547 231 170
Fax: (972)-25662581
C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525
US 914 432 3108
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