[ncl-talk] need help to understand how to change the scales in a spectrum plot
Adam Phillips
asphilli at ucar.edu
Mon Dec 5 12:16:51 MST 2016
Hi Ruksana,
If all you want is 3 different spectra overlaid on the same plot you could
use the overlay procedure. You will need to tell NCL to not draw the plot
nor advance the frame before creating the 3 spectra. You may also need to
set trYMaxF if portions of one spectra go off the plot.
Here's an example:
res at gsnDraw = False
res at gsnFrame = False
res at xyLineColor = "green"
plot=gsn_csm_xy(wks,spec at frq,spec at spcx,res) ; create plot
res at xyLineColor = "black"
plot2 = gsn_csm_xy(wks,spec2 at frq,spec2 at spcx,res) ; create plot
res at xyLineColor = "blue"
plot3 = gsn_csm_xy(wks,spec3 at frq,spec3 at spcx,res) ; create plot
overlay(plot,plot2)
overlay(plot,plot3)
draw(plot)
frame(wks)
Hope that helps. If not, please respond to the ncl-talk email list.
Adam
On Mon, Dec 5, 2016 at 12:09 PM, Ruksana Abedin <ruksana.abedin at gmail.com>
wrote:
> Hi,
>
> I could figure the required process out. This time followed the example 4
> at http://www.ncl.ucar.edu/Applications/Scripts/spec_4.ncl. However, I
> would still like to know how can I plot three spectrums of three colours in
> one single plot. Your help is always useful.
>
> Thank you for putting up wonderful resources.
>
> Best regards,
> Ruksana
>
> On Mon, Dec 5, 2016 at 5:30 PM, Ruksana Abedin <ruksana.abedin at gmail.com>
> wrote:
>
>> Hi,
>>
>>
>>
>> I have followed the http://www.ncl.ucar.edu/Applic
>> ations/Scripts/spec_1.ncl script to plot a spectrum for my data but the
>> specs are very difficult to visualize clearly in the plot. Data is daily
>> precipitation from model and two observations for 1988-2007.
>>
>>
>> 1. How to change the x and y axis scales to make it more visible.
>>
>> 2. Can I have the cycles per day instead of months? How to change this
>> aspect?
>>
>> 3. Can I plot three spectrums for three different files in a panel
>> together?
>>
>>
>> The variable summary, script and the resultant plot are attached. Your
>> time and efforts to help me out is highly appreciated.
>>
>>
>>
>> Variable: PPT_mod
>> Type: float
>> Total Size: 25056000 bytes
>> 6264000 values
>> Number of Dimensions: 3
>> Dimensions and sizes: [time | 7200] x [lat | 30] x [lon | 29]
>> Coordinates:
>> time: [52950.5..60149.5]
>> lat: [15.25..29.75]
>> lon: [ 83.. 97]
>> Number Of Attributes: 10
>> z1 : 0
>> standard_name : precipitation_flux
>> long_name : TOTAL PRECIPITATION RATE KG/M2/S
>> units : kg m-2 s-1
>> _FillValue : 1e+20
>> missing_value : 1e+20
>> stash_item : 216
>> stash_section : 5
>> field_code : 90
>> cell_method : time: mean
>>
>> Variable: PPT_obs1
>> Type: float
>> Total Size: 25056000 bytes
>> 6264000 values
>> Number of Dimensions: 3
>> Dimensions and sizes: [time | 7200] x [lat | 30] x [lon | 29]
>> Coordinates:
>> time: [19880101.5..20071230.5]
>> lat: [15.25..29.75]
>> lon: [ 83.. 97]
>> Number Of Attributes: 5
>> long_name : daily precipitation analysis interpolated onto 0.5deg
>> grids [mm/day]
>> units : mm/day
>> _FillValue : -99.9
>> missing_value : -99.9
>> level_description : Earth surface
>>
>> Variable: PPT_obs2
>> Type: float
>> Total Size: 25056000 bytes
>> 6264000 values
>> Number of Dimensions: 3
>> Dimensions and sizes: [time | 7200] x [lat | 30] x [lon | 29]
>> Coordinates:
>> time: [19880101.5..20071230.5]
>> lat: [15.25..29.75]
>> lon: [ 83.. 97]
>> Number Of Attributes: 5
>> long_name : full data daily product version 1 precipitation per grid
>> units : mm/day
>> code : 20
>> _FillValue : -99999.99
>> missing_value : -99999.99
>>
>>
>>
>> ;************************************************
>> begin
>> ;*****************************************************
>> ;read in data
>> ;*****************************************************
>> f0 = addfile ("/../1WAH_daily_precip_b387clim_Bangladesh_100_1988_2007_
>> land_only.nc", "r");
>> f1 = addfile("/../APHRO_1988_2007_correct_daily_precip.nc", "r")
>> f2 = addfile("/../GPCC_1988_2007_correct_daily_precip.nc","r")
>>
>> ;*****************************************************
>> ; parameters
>> ;*****************************************************
>>
>> PPT_mod = f0->precip(:,0,:,:)
>> PPT_mod = PPT_mod*60*60*24
>> PPT_obs1 = f1->precip
>> PPT_obs2 = f2->precip
>>
>> fldmean0 = wgt_areaave_Wrap(PPT_mod,1.0,1.0,1)
>> fldmean1 = wgt_areaave_Wrap(PPT_obs1,1.0,1.0,1)
>> fldmean2= wgt_areaave_Wrap(PPT_obs2,1.0,1.0,1)
>>
>> ;printVarSummary(time)
>>
>> printVarSummary(PPT_mod)
>> printVarSummary(PPT_obs1)
>> printVarSummary(PPT_obs2)
>>
>> ;************************************************
>> ; set function arguments
>> ;************************************************
>> ; detrending opt: 0=>remove mean 1=>remove mean and detrend
>> d = 0
>> ; smoothing periodogram: (0 <= sm <= ??.) should be at least 3 and odd
>> sm = 7
>> ; percent tapered: (0.0 <= pct <= 1.0) 0.10 common.
>> pct = 0.10
>> ;************************************************
>> ; calculate spectrum
>> ;************************************************
>> spec = specx_anal(fldmean2,d,sm,pct)
>> ;************************************************
>> ; plotting
>> ;************************************************
>> wks = gsn_open_wks("eps","spec") ; Opens a eps file
>>
>> res = True ; no plot mods desired
>> res at tiMainString = "Precipitation" ; title
>> res at tiXAxisString = "Frequency (cycles/month)" ; xaxis
>> res at tiYAxisString = "Variance" ; yaxis
>>
>> plot=gsn_csm_xy(wks,spec at frq,spec at spcx,res) ; create plot
>> ;***********************************************
>> end
>>
>>
>>
>
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--
Adam Phillips
Associate Scientist, Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/ 303-497-1726
<http://www.cgd.ucar.edu/staff/asphilli>
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