[ncl-talk] climo_3.ncl + loop + conventional subscripts
zoe jacobs
zoejacobs1990 at gmail.com
Sat Nov 2 23:26:17 MDT 2019
Dear Dennis,
Many thanks for your help. I used the attached script. I just want to check
with you to make sure that the script is correct. Would you please check it?
Best wishes,
On Mon, Oct 28, 2019 at 12:31 AM Dennis Shea <shea at ucar.edu> wrote:
> The following is untested. However, it gives you the idea.
> It is your responsibility to look up documentation and look at the printed
> output.
>
>
>
> fils = systemfunc ("ls precip.*.nc") ; file paths
> a = addfiles (fils, "r")
> printVarSummary (a)
>
> ;************************************************
> ; Read the file
> ;************************************************
>
> ymdStrt = 19790101 ; climatology start
> year/month/day
> ymdLast = 20151231 ; " last
> year/month/day
> time = a[:]->time
> yyyymmdd= cd_calendar(time, -2) ; note -2
> print(yyyymmdd)
> ntStrt = ind(yyyymmdd.eq.ymdStrt) ; start time index
> ntLast = ind(yyyymmdd.eq.ymdLast) ; last time index
> print("ntStrt="+ntStrt+" ntLast="+ntLast)
> prc = a[:]->precip(ntStrt:ntLast,:,:) ; read precip
> from all files
>
> printVarSummary (prc)
> printMinMax (prc,0)
> print("=====")
> ; you decide what you need
> prcMonth = *calculate_monthly_values(*
> <http://www.ncl.ucar.edu/Document/Functions/Contributed/calculate_monthly_values.shtml>prc,
> "avg", 0, False) ; monthly mean
> ;;prcMonth = *calculate_monthly_values(*
> <http://www.ncl.ucar.edu/Document/Functions/Contributed/calculate_monthly_values.shtml>prc,
> "sum", 0, False) ; monthly total
>
> printVarSummary (prcMonth)
> printMinMax (prcMonth,0)
> print("=====")
> opt = True ; examine data distribute
> [information only]
> opt at PrintStat = True
> stat_prc = stat_dispersion(prcMonth, opt )
>
> prcClm = *clmMonTLL*
> <http://www.ncl.ucar.edu/Document/Functions/Contributed/clmMonTLL.shtml>(prcMonth)
> ; Compute monthly climatology
> printVarSummary (prcClm)
> printMinMax (prcClm,0)
>
> ====
> Add the plot code.
> Look carefully at: http://www.ncl.ucar.edu/Applications/HiResPrc.shtml
>
> EG: The following may be inappropriate for your dataset but this is the
> idea.
>
> res at cnLevelSelectionMode = "ExplicitLevels"
> res at cnLevels = (/ 0.01, 0.02, 0.04, 0.08, 0.16, \
> 0.32, 0.64, 0.96/)
> res at cnFillColors = (/"white","cyan", "green","yellow",\
> "darkorange","red","magenta","purple",\
> "black"/)
>
>
> On Sun, Oct 27, 2019 at 2:48 PM Dennis Shea <shea at ucar.edu> wrote:
>
>>
>> [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
>>>>>>
>>>>>>
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