[ncl-talk] JRA 55 wind interpolation using ncl

[Dennis Shea]

The following is not the approach to use for reversing a grid's order.
The following only changes the (local) variable 'lat'.

It has *no* effect on the variable data structure.

fi=addfile("wind.nc","r")
lat=fi->lat
lon=fi->lon
lat=lat(::-1)                ; latitude only
printVarSummary(lat)

Assuming your input grids are ordered North->South, change to:

fi=addfile("wind.nc","r"))
uwnd=month_to_season(fi->uwnd(276:635,30,:,:),"DJF")
vwnd=month_to_season(fi->vwnd(276:635,30,:,:),"DJF")
uwnd=uwnd(:,::-1,:)
vwnd=vwnd(:,::-1,:)
printVarSummary(uwnd)  ; ordered South to North
printVarSummary(vwnd)

Same for rainfall.nc, if ordered North->South

====
uwnd_ave=dim_avg_n_Wrap(uwnd,0)
vwnd_ave=dim_avg_n_Wrap(vwnd,0)
printVarSummary(uwnd_ave)            ; look at coordinates

The **only** reason for the South->North ordering is that linint2_Wrap
requires that order.

The following explicitly illustrates using the lat & lon associated with
the variable's data structure.

uwnd_jra=linint2_Wrap (uwnd_ave&lon, uwnd_ave&lat, uwnd_ave, True,
lon0,lat0, 0)
vwnd_jra=linint2_Wrap (vwnd_ave&lon, vwnd_ave&lat,  vwnd_ave, True,
lon0,lat0, 0)
printVarSummary(uwnd_jra)            ; look at coordinates


On Wed, Jan 3, 2018 at 2:48 PM, 刘振 via ncl-talk <ncl-talk at ucar.edu> wrote:

> Dear all,
>
>   I am using ncl to plot 850hPa-wind. But after I interpolate the original
> wind to another resolution. It seems to me the latitude reversed (attached
> the 1st and 2nd plot[The wind from original file is right]). I try to use
> ::-1 for latitude to reverse the plot but failed (attached 3rd plot). Could
> you please help me to solve the problem? Thanks.
>
> Best regards,
> zhen
>
> ------------------
> 刘振
> 中山大学
> 环境科学与工程学院
> 大气科学系
> Phone: +86-15013246049 <+86%20150%201324%206049>
> Liu  Zhen
> Department of Atmospheric Science
> School of Environmental Science and Engineering
> Sun Yat-sen University
> Email address: liuzhen9 at mail2.sysu.edu.cn
>
>
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