[ncl-talk] Trying to draw circles with different radius in Km around a station
Soumik Basu
sbasu at alaska.edu
Thu Feb 8 13:41:40 MST 2018
Hi,
I got the first part working but the circles are not showing up in the
plot. I used "gsn_add_polyline" to draw the circle.
Is it wrong to use gsn_add_polyline for drawing the circle?
Here is the plotting part of the code.
; *********************************
; Draw circle
;**********************************
;---One station
slat = 70.192 ; station lat
slon = -148.477 ; station lon
srad_km = (/ 50, 100, 150, 200, 250/)*1.0 ; station radii (km)
km2deg = 1/110.57 ; conversion factor: deg ==> km
; one degree is approximately 110.57 km.
srad_dg = srad_km*km2deg ; km ==> deg; nggcog requires degrees
Nrad = dimsizes(srad_dg) ; # of radii
Npts = 360 ; # of points at each radii (arbitrary)
Rlat = new((/Nrad, Npts/), "float") ; lat at each radius
Rlon = new((/Nrad, Npts/), "float")
do nr=0,Nrad-1
print("nr="+nr+" srad_km="+srad_km(nr)+"; srad_dg="+srad_dg(nr))
print("")
nggcog(slat, slon, srad_dg(nr), Rlat(nr,:), Rlon(nr,:))
print(Rlat(nr,:)+" "+ Rlon(nr,:))
print("========")
end do
;*************************************************
; Plot
;*************************************************
res = True
res at gsnSpreadColors = True
res at gsnDraw = False ; don't
draw
res at gsnFrame = False
; res at gsnPolar = "NH"
res at cnFillOn = True
res at cnLinesOn = False
res at cnLevelSelectionMode = "ManualLevels"
res at cnMinLevelValF = 0
res at cnMaxLevelValF = 30
res at cnLevelSpacingF = 0.25
res at cnLineLabelsOn = False
res at lbLabelStride = 0.1
res at lbOrientation = "horizontal" ;vertical label bar
res at lbLabelBarOn = False
res at tmLabelAutoStride = True
res at tmXTOn = False
res at tmYROn = False
res at mpProjection = "CylindricalEquidistant" ; choose map
projection
res at mpLimitMode = "LatLon"
res at mpMinLatF = 60.
res at mpMaxLatF = 80.
res at mpMinLonF = 190.
res at mpMaxLonF = 230.
res at mpCenterLonF = 210
res at mpGeophysicalLineThicknessF = 1.5
colors = (/"gray0","gray2","gray10","gray40","gray50"/)
;*****************************************************
; Plot
;*****************************************************
wks = gsn_open_wks("x11","extreme_wind_days_spatial")
plot = new(12,graphic)
; plot_c = new(12,graphic)
gsn_define_colormap(wks,"precip3_16lev")
do ii = 0,nmon-1
plot(ii) = gsn_csm_contour_map(wks,wind_ext_count_1(ii,:,:),res)
do cc = 0,Nrad-1
plres = True
mks = unique_string("mks")
plres at gsLineColor = colors(cc)
plot@$mks$ = gsn_add_polyline(wks, plot(ii), Rlat(cc,:), Rlon(cc,:),
plres)
end do
end do
resPanel = True
resPanel at gsnFrame = False
resPanel at gsnSpreadColors = True
resPanel at gsnPanelLabelBar = True ; add
color bar
resPanel at gsnMaximize = True
resPanel at gsnPanelFigureStrings =
(/"Jan","Feb","Mar","Apr","May","June","July","Aug","Sep","Oct","Nov","Dec"/)
resPanel at gsnPanelFigureStringsFontHeightF = 0.012
resPanel at gsnPanelFigureStringsPerimOn = True
resPanel at gsnPanelFigureStringsBackgroundFillColor = -1
resPanel at amJust = "BottomRight"
resPanel at lbLabelBarOn = True
resPanel at lbOrientation = "Vertical"
resPanel at lbLabelAutoStride = False
resPanel at lbLabelStride = 20
resPanel at lbBoxLineThicknessF = 0.1
resPanel at lbLabelFontThicknessF = 1.75
resPanel at lbLabelFontHeightF = 0.015
resPanel at lbBoxLinesOn = False
resPanel at gsnPanelMainString = "Test"
gsn_panel(wks,plot,(/4,3/),resPanel)
frame(wks)
end
Thanks,
Soumik
On Thu, Feb 8, 2018 at 5:45 AM, Dennis Shea <shea at ucar.edu> wrote:
> An alternative:
>
> nggog can be used. Sample code segments follow. For small radii Npts=100
> is fine but for large radii and nice circles, Npts=360 might be better.
>
> ;=========================================================================
> ; On a sphere with radius 6371 km, one degree is approximately 110.57 km.
> ;---
> ; Of course, the earth is an oblate spheroid:
> ; http://www.longitudestore.com/how-big-is-one-gps-degree.html
> ;=========================================================================
> ; https://www.ncl.ucar.edu/Document/Functions/Built-in/nggcog.shtml
> ;=========================================================================
>
> ;---One station
>
> slat = 0.0 ; station lat
> slon = 0.0 ; lon
> srad_km = (/ 50, 100, 150, 5*110.57/)*1.0 ; station radii (km)
> km2deg = 1/110.57 ; conversion factor: deg ==> km
> ; one degree is approximately 110.57
> km.
> srad_dg = srad_km*km2deg ; km ==> deg; nggcog requires degrees
>
> Nrad = dimsizes(srad_dg) ; # of radii
> Npts = 100 ; # of points at each radii (arbitrary)
>
> Rlat = new((/Nrad, Npts/), "float") ; lat at each radius
> Rlon = new((/Nrad, Npts/), "float")
>
> do nr=0,Nrad-1
> print("nr="+nr+" srad_km="+srad_km(nr)+"; srad_dg="+srad_dg(nr))
> print("")
>
> nggcog(slat, slon, srad_dg(nr), Rlat(nr,:), Rlon(nr,:))
>
> print(Rlat(nr,:)+" "+ Rlon(nr,:))
> print("========")
> end do
>
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> ;---Multiple stations
>
> slat = (/ 0.0, 50.0 /) ; station lat
> slon = (/ 0.0, 30.0 /) ; lon
> srad_km = (/ 50, 100, 150, 5*110.57/)*1.0 ; station radii (km)
> km2deg = 1/110.57 ; conversion factor: deg ==> km
> ; one degree is
> approximately 110.57 km.
> srad_dg = srad_km*km2deg ; km ==> deg; nggcog requires degrees
> Nrad = dimsizes(srad_dg) ; # of radii
>
> Nsta = dimsizes(slat) ; # stations
> Nrad = dimsizes(srad) ; # of radii
> Npts = 100 ; # of points at each radii
> (arbitrary; eg 360)
>
> Rlat = new((/Nsta, Nrad, Npts/), "float") ; lat at each radius
> Rlon = new((/Nsta, Nrad, Npts/), "float")
>
> do ns=0,Nsta-1
> do nr=0,Nrad-1
> nggcog(slat(ns), slon(ns), srad(nr), Rlat(ns,nr,:), Rlon((ns,nr,:))
> end do
> end do
>
>
> On Thu, Feb 8, 2018 at 2:38 AM, Karin Meier-Fleischer <
> meier-fleischer at dkrz.de> wrote:
>
>> Hi Soumik,
>>
>> you can use polymarkers to plot the circles around lat/lon locations.
>> Have a look at example newcolor_4.ncl at http://ncl.ucar.edu/Applicatio
>> ns/Scripts/newcolor_4.ncl
>>
>> I've attached an example script using random data for marker size and
>> lat/lon locations overlayed on filled contour map.
>>
>> Hope this helps.
>>
>> -Karin
>>
>> Am 08.02.18 um 00:55 schrieb Soumik Basu:
>>
>> Hello NCL-users,
>>
>> I am trying to draw circles around a station with different radius. For
>> example 50 Km, 100 Km, 150 Km etc.
>>
>> So, I am wondering if there is any way to do it in NCL.
>>
>> I looked at the "nggcog" function but from the description what I
>> understand is that it can draw circles along a great circle only not
>> according to a given distance.
>>
>> Thank you for any help.
>>
>> Thanks,
>> Soumik
>>
>> --
>> --
>> “We’ve all got both light and dark inside us. What matters is the part we
>> choose to act on. That’s who we really are.” – J.K. Rowling
>>
>> ************************************************************
>> **************************************
>> Dr. Soumik Basu
>> Post Doctoral Research Faculty
>> International Arctic Research Center, UAF, Fairbanks, AK, USA
>> PhD in Atmospheric Sciences
>> M.Sc. in Atmospheric Sciences
>> Email: suvro05 at gmail.com
>> website: http://soumikbasu.weebly.com/
>>
>> ************************************************************
>> ***************************************
>>
>>
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--
--
“We’ve all got both light and dark inside us. What matters is the part we
choose to act on. That’s who we really are.” – J.K. Rowling
**************************************************************************************************
Dr. Soumik Basu
Post Doctoral Research Faculty
International Arctic Research Center, UAF, Fairbanks, AK, USA
PhD in Atmospheric Sciences
M.Sc. in Atmospheric Sciences
Email: suvro05 at gmail.com
website: http://soumikbasu.weebly.com/
***************************************************************************************************
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