[ncl-talk] About regridding from
Tao Lu
hakufu.asano at gmail.com
Tue Jan 17 10:14:00 MST 2017
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>
>> *****************************************************
>>
>> _______________________________________________
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>>
>
>
> --
> 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
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>
--
******************************************************
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>
*****************************************************
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