[ncl-talk] climo_3.ncl + loop + conventional subscripts
Dennis Shea
shea at ucar.edu
Sun Oct 27 14:48:47 MDT 2019
[0]
As noted on ncl-talk many time the first rule of data processing is *Look
at your data!"
The temperature data were *monthly means* [K].
The precipitation data are* daily* totals [mm/day]. How do I know? I looked
at the README file at the URL. You should do that.
[1]
a =* addfiles*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/addfiles.shtml> (fils,
"r")
You have the following which is appropriate for an *addfile*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/addfile.shtml>
reference
time = a->time
However, you are using *addfiles*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/addfiles.shtml> It
should be:
time = a*[:]*->time ; *[:]* syntax is appropriate for an
*addfiles* reference
[2]
Did you read the documentation for *cd_calendar *
<http://www.ncl.ucar.edu/Document/Functions/Built-in/cd_calendar.shtml>as I
suggested? The whole point of using *cd_calendar* is to return
'human-readable' start and end times from which the actual start/stop time
index values could be determined.. Your script uses the actual time values
[ 692496 , 1016808 ] mixed with human-readable yyyymm. Further, you used
yyyymm = cd_calendar(time, *-1*) ; -1 returns YYYYMM
The precipitation files contain [as noted] daily values. You must use a
human readable time like YYYYMMDD [eg: 19790101]. The us
yyyymmdd = cd_calendar(time, *-2*) ; -2 returns YYYYMMDD
This converts the actual time values [eg: 692496] to 'human-readable'
yyyymmdd [year=>yyyy, month=>mm, day=dd>* 692496=>197901*01] values.
===
Also, your script will need to be changed to accommodate the precipitation
variable plot values
There are many examples of how to do this.
eg: *http://www.ncl.ucar.edu/Applications/HiResPrc.shtml*
<http://www.ncl.ucar.edu/Applications/HiResPrc.shtml>
===
In a previous email, you mentioned that you converted degrees Kelvin to C.
It is best to self-document the variable with its new units.
tmp = tmp-273.15
tmp at units = "degC" ; this will be automatically plotted
===
Good Luck
On Sat, Oct 26, 2019 at 8:19 AM zoe jacobs <zoejacobs1990 at gmail.com> wrote:
> Dear all,
> I would like to have climatology precipitation like temperature
> climatology discussed through previous emails. However, there are
> precipitation files for each year from 1979- 2015 (
> ftp://ftp.cdc.noaa.gov/Datasets/cpc_global_precip/). In the first step, I
> tried to merge all those files as one, and then use Dennis script to plot a
> map. I faced some errors and need your advice please. the script I am
> running has been attached.Many thanks in advance,
> Best regardsn Sat, Oct 26, 2019 at 3:20 PM zoe jacobs <
> zoejacobs1990 at gmail.com> wrote:
>
>> I just noticed that I could use res at gsnRightString = " deg C" .
>> Once again, many thanks for your guide.
>> Best wishes,
>>
>>
>> On Fri, Oct 25, 2019 at 11:07 PM Dennis Shea <shea at ucar.edu> wrote:
>>
>>> I forgot to mention that plots can be done in 'portrait' [default] or
>>> 'landscape' mode.
>>>
>>> You should experiment to see which is appropriate for your needs.
>>>
>>> resP at gsnPaperOrientation = "landscape" ; "portrait" is default
>>>
>>> do nmo=0,11 ; loop over the months
>>> res at gsnLeftString = months(nmo)
>>> plot(nmo) = gsn_csm_contour_map(wks,tmpClm(nmo,:,:), res) ; create
>>> plot
>>> end do
>>>
>>> if (resP at gsnPaperOrientation .eq."landscape") then
>>> gsn_panel(wks,plot,(/3,4/),resP)
>>> ; 3 rows x 4 columns
>>> else
>>> gsn_panel(wks,plot,(/4,3/),resP) ; portrait ; 4
>>> rows x 3 columns
>>> end if
>>>
>>> On Fri, Oct 25, 2019 at 12:15 PM Dennis Shea <shea at ucar.edu> wrote:
>>>
>>>> Hello,
>>>>
>>>> We do not usually do this but this is offline from ncl-talk.
>>>>
>>>> [1]
>>>> Conventional subscripts start at 1 for Fortran and Matlab. Hence, for
>>>> 12 months [nmos=12]
>>>> Fortran: do nmo=1,nmos
>>>> Matlab: for 1:nmos or 1:1:nmos [I am not a Matlab user so this
>>>> is a guess.]
>>>> NCL 'conventional' subscripts start at 0 [like C/C++/IDL/Python]
>>>> NCL: do nmo=0,ntim-1
>>>>
>>>> [2] Dave illustrated 'coordinate subscripting' which uses the *{*...*}*
>>>> syntax.
>>>>
>>>> The script I am attaching uses conventional subscripting. Just like
>>>> Matlab/Fortran except it uses a range fro 0 to 11 [12 elements].
>>>>
>>>> [3] Please carefully read the documentation for *clmMonTLL*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Contributed/clmMonTLL.shtml>,
>>>> *cd_calendar*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/cd_calendar.shtml>
>>>> ,* ind* <http://www.ncl.ucar.edu/Document/Functions/Built-in/ind.shtml>
>>>>
>>>> [4] Look at the output from '*printVarSummary*
>>>> <http://www.ncl.ucar.edu/Document/Functions/Built-in/printVarSummary.shtml>'.
>>>> USE *printVarSummary *frequently.
>>>> Note the dimensions and added attributes:
>>>> time_op_ncl : Climatology: 29 years
>>>> info : function clmMonTLL: contributed.ncl
>>>>
>>>> [5] NCL offer a large number of color tables [palettes]:
>>>>
>>>> *http://www.ncl.ucar.edu/Document/Graphics/color_table_gallery.shtml*
>>>> <http://www.ncl.ucar.edu/Document/Graphics/color_table_gallery.shtml>
>>>> Using a color map that emphasizes features can be very useful.
>>>>
>>>> [6] You must invest the time to learn any new language.
>>>> Karin Meier-Fliesher and Michael Bottinger [DKRZ] wrote a wonderful
>>>> tutorial.
>>>>
>>>> *http://www.ncl.ucar.edu/Document/Manuals/NCL_User_Guide/*
>>>> <http://www.ncl.ucar.edu/Document/Manuals/NCL_User_Guide/>
>>>>
>>>> I suggest you read it.
>>>>
>>>> Good luck
>>>> ==============
>>>> *%>* ncl zoe_jacobs.hgcn_cams.ncl
>>>>
>>>> will produce a png file.
>>>>
>>>>
>>>>
>>>> On Fri, Oct 25, 2019 at 11:16 AM Dave Allured - NOAA Affiliate via
>>>> ncl-talk <ncl-talk at ucar.edu> wrote:
>>>>
>>>>> 1. In your example, please notice that the month loop has a stride of
>>>>> 3. Therefore it is making plots for only four months: January, April,
>>>>> July, and October.
>>>>>
>>>>> If you want all 12 months, remove the stride. Then make sure the
>>>>> array "plot" is dimensioned 12. I think you can interchangeably use either
>>>>> a 1-D or 2-D plot array (i.e. 3*4), your choice.
>>>>>
>>>>> The secondary index "i" is used to write the four plots into positions
>>>>> 0, 1, 2, 3 in the "plot" graphics array. If you are making 12 plots, you
>>>>> do not really need to use a secondary index.
>>>>>
>>>>> Panel plotting uses a graphics array containing multiple plots.
>>>>> Please study basic examples and documentation for making panel plots.
>>>>>
>>>>> 2. That data file has full coordinates. Therefore you can use either
>>>>> conventional or coordinate subscripting, or mixed, your choice.
>>>>>
>>>>> I suggest using one of the date functions with coordinate
>>>>> subscripting, to index the time subset that you want. Something like this:
>>>>>
>>>>> time_units = f->air&time at units
>>>>> time1 = cd_inv_calendar (year1, 1, 1, 0, 0, 0, time_units, 0)
>>>>> time2 = cd_inv_calendar (year2, 12, 31, 23, 0, 0, time_units, 0)
>>>>> air_subset = f->air({time1:time2},:,:)
>>>>>
>>>>> Use printVarSummary to ensure that the subset has the dimension sizes
>>>>> that you expect. Then you can proceed to compute the climatology.
>>>>>
>>>>>
>>>>> On Fri, Oct 25, 2019 at 10:14 AM zoe jacobs via ncl-talk <
>>>>> ncl-talk at ucar.edu> wrote:
>>>>>
>>>>>> Hi all,
>>>>>> regarding climo_3.ncl (
>>>>>> https://www.ncl.ucar.edu/Applications/Scripts/climo_3.ncl) ,
>>>>>> I have 2 questions:
>>>>>> 1. I need to plot all months on one panel (say 3*4), and cannot
>>>>>> understand the logic behind the below loop, which used in the climo_3.ncl
>>>>>> script :
>>>>>>
>>>>>> i = -1 ; Climatologies
>>>>>> do nmo=0,11,3 ; loop over the months
>>>>>> i = i+1
>>>>>> res at gsnCenterString = months(nmo)+":"+time(0)/100 +"-"+ time(ntim-1)/100
>>>>>> plot(i) = gsn_csm_contour_map(wks,prcClm(nmo,:,:), res) ; create plot
>>>>>> end do
>>>>>>
>>>>>> How does it work??/
>>>>>>
>>>>>> 2. I would like to show climotology temperature from 1987- 2015. Data which I am using is air.mon.mean.nc ( https://www.esrl.noaa.gov/psd/data/gridded/data.ghcncams.html) and it is using conventional subscripts. I am not familiar with conventional subscripts. So how can I convert coordinate subscripting to conventional subscripts?!!
>>>>>>
>>>>>> Please kindly advice me .
>>>>>>
>>>>>> Many thanks in advance,
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>> _______________________________________________
>>>>> ncl-talk mailing list
>>>>> ncl-talk at ucar.edu
>>>>> List instructions, subscriber options, unsubscribe:
>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>
>>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20191027/83d74a14/attachment.html>
More information about the ncl-talk
mailing list