[ncl-talk] change in vector spacing when taking difference of two wind fields
Alexander Schaefer
alexander.schaefer at mines.sdsmt.edu
Mon Jun 8 21:20:30 MDT 2015
Mira,
Why did you change vcres at vcRefMagnitudeF = 10.0 to vcres at vcRefMagnitudeF =
1.0 after the first 2 plots were made? This is likely what is causing the
difference.
-Alex
On Mon, Jun 8, 2015 at 8:12 PM, <mberdahl at envsci.rutgers.edu> wrote:
> Hi all,
> I have a 3 panel plot which shows the winds over a region. The first two
> panels show averages for selected years, and the third panel shows the
> difference between the top 2 panels. My problem is that the spacing of
> wind vectors is much denser in the first two plots than the third
> "difference" plot. Is there a reason why the grid spacing would suddenly
> be different (more sparse) when displaying the difference of two wind
> fields? The sizes (dimensions) of the u and v fields remain the same for
> each panel.
> My script and the VarSummaries for some of the variables are below.
> I will try to attach the pdf of the figure here if possible.
> Thanks very much for any help.
> Mira
>
> ************************************************************
>
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
> ;************************************************
> begin
> ;************************************************
> ; read in netCDF file
> ;************************************************
> a = addfile("uwnd.mon.mean.nc","r")
> print(a)
> b = addfile("vwnd.mon.mean.nc","r")
>
> ;************************************************
> ; read in zonal [u] and meridional [v] winds (July)
> ;************************************************
>
> u = a->uwnd(0:803,{45:90},{270:357.5})
> v = b->vwnd(0:803,{45:90},{270:357.5}) ; Get u, v, time (1),level
> (1000hpa),latitude(-90:90) and longitude(0:360) data.
>
> printVarSummary(u)
> printVarSummary(v)
>
> ; to take the average over the first dimensions (time)
> ;uAvgTime = dim_avg_n_Wrap(u,0)
> ;vAvgTime = dim_avg_n_Wrap(v,0)
>
> ;printVarSummary(vAvgTime)
> ;printVarSummary(uAvgTime)
>
> ; calculate speed from u and v components
> ;speed = sqrt(uAvgTime^2+vAvgTime^2)
>
> ; Calculate the seasonal averages.
> uDJF = month_to_season(u, "DJF")
> vDJF = month_to_season(v, "DJF")
>
> printVarSummary(uDJF)
> printVarSummary(vDJF)
>
> ; from the matlab script i wrote: findExtremeYrs, i pulled out the extreme
> years (> or < 1std) that i want to average and plot here.
>
> ; for ans = 4 (NAO)
> ; yearList_hi = 1973 1975 1983 1989 1995
> 2000 2007 2012
> ; yearList_lo = 1963 1964 1965 1969 1977
> 1979 1996 1997 2010 2011
>
> ; ans = 5 (pressure)
> ;yearList_hi = 1963 1965 1968 1969 1970
> 1971 1977 1997 2006 2011
> ;yearList_lo = 1973 1989 1990 1991 1995
> 1999 2000 2007 2012
>
> ;ans = 7 (longitude of IL)
> ;yearList_hi =1966 1967 1968 1969 1974
> 1975 1983 1994 1995 2005
> ;yearList_lo =1963 1964 1985 1987 1991
> 1992 1996 2002 2003 2006 2009
>
>
> ; this data starts at 1948 (this is index 0), so 1953=5, 1963=10 etc.
>
> uDJF_NAO_lo = uDJF((/10,11,12,16,24,26,43,44,57,58/),:,:)
> uDJF_NAO_hi = uDJF((/20,22,30,36,42,47,54,59/),:,:)
>
> vDJF_NAO_lo = vDJF((/10,11,12,16,24,26,43,44,57,58/),:,:)
> vDJF_NAO_hi = vDJF((/20,22,30,36,42,47,54,59/),:,:)
>
> uAvgTime_hi = dim_avg_n_Wrap(uDJF_NAO_hi,0)
> uAvgTime_lo = dim_avg_n_Wrap(uDJF_NAO_lo,0)
>
> printVarSummary(uAvgTime_hi)
> printVarSummary(uAvgTime_lo)
>
> vAvgTime_hi = dim_avg_n_Wrap(vDJF_NAO_hi,0)
> vAvgTime_lo = dim_avg_n_Wrap(vDJF_NAO_lo,0)
>
> printVarSummary(vAvgTime_hi)
> printVarSummary(vAvgTime_lo)
>
>
>
> ;************************************************
> ; create plot
> ;************************************************
> wks = gsn_open_wks("eps","Panel_NAO") ; open a ps file
> plot = new(3,graphic) ; create a plot array
>
> vcres = True
> vcres at gsnDraw = False ; dont draw
> vcres at gsnFrame = False ; dont advance frame
> vcres at cnInfoLabelOn = False ; trn off cn info label
>
> vcres = True ; plot mods desired
> vcres at gsnAddCyclic = False ; has to do with wrapping
> the longitude at 0/360
> vcres at vcRefAnnoOrthogonalPosF = -1.0 ; move ref vector up
> vcres at vcRefMagnitudeF = 10.0 ; define vector ref mag
> vcres at vcRefLengthF = 0.045 ; define length of vec ref
> vcres at vcGlyphStyle = "CurlyVector" ; turn on curly vectors
> vcres at vcMinDistanceF = 0.017
>
> ;************************************************
> ; Choose a subregion
> ;************************************************
> vcres at mpFillOn = False ; turn off gray fill
> vcres at mpOutlineBoundarySets = "National" ; turn on country
> boundaries
> vcres at mpGeophysicalLineColor = "Navy" ; color of cont. outlines
> vcres at mpGeophysicalLineThicknessF = 1.5 ; thickness of outlines
>
> vcres at mpMaxLatF = 90 ;maximum latitude
> vcres at mpMinLatF = 45 ;minimum latitude
> vcres at mpMaxLonF = 357.5 ;maximum longitude
> vcres at mpMinLonF = 270 ;minimum longitude
>
> diff_u = uAvgTime_hi - uAvgTime_lo
> diff_v = vAvgTime_hi - vAvgTime_lo
>
> printVarSummary(diff_u)
> printVarSummary(diff_v)
>
> vcres at gsnLeftString = "DJF High NAO"
> plot(0) = gsn_csm_vector_map_ce(wks,uAvgTime_hi,vAvgTime_hi,vcres)
>
> vcres at gsnLeftString = "DJF Low NAO"
> plot(1) = gsn_csm_vector_map_ce(wks,uAvgTime_lo,vAvgTime_lo,vcres)
>
>
> vcres at vcRefMagnitudeF = 1.0 ; define vector ref mag
> vcres at vcRefLengthF = 0.045 ; define length of vec ref
> vcres at gsnLeftString = "Difference of High - Low"
> plot(2) = gsn_csm_vector_map_ce(wks, diff_u, diff_v,vcres)
>
> ;************************************************
> ; create panel
> ;************************************************
> resP = True ; modify the panel plot
> resP at txString = "NAO"
> gsn_panel(wks,plot,(/3,1/),resP) ; now draw as one plot
>
>
>
> end
>
>
>
> OUTPUT
> *******************************************************
> Variable: vAvgTime_hi
> Type: float
> Total Size: 2736 bytes
> 684 values
> Number of Dimensions: 2
> Dimensions and sizes: [lat | 19] x [lon | 36]
> Coordinates:
> lat: [45..90]
> lon: [270..357.5]
> Number Of Attributes: 17
> NMO : 0
> _FillValue : -9.96921e+36
> actual_range : ( -15.43516, 19.79167 )
> parent_stat : Other
> statistic : Mean
> level_desc : Surface
> dataset : CDC Derived NCEP Reanalysis Products
> var_desc : v-wind
> least_significant_digit : 1
> precision : 2
> missing_value : -9.96921e+36
> scale_factor : 1
> add_offset : 0
> units : m/s
> valid_range : ( -102.2, 102.2 )
> long_name : DJF: Monthly Mean Meridional Wind at sigma level 0.995
> average_op_ncl : dim_avg_n over dimension(s): time
>
> Variable: vAvgTime_lo
> Type: float
> Total Size: 2736 bytes
> 684 values
> Number of Dimensions: 2
> Dimensions and sizes: [lat | 19] x [lon | 36]
> Coordinates:
> lat: [45..90]
> lon: [270..357.5]
> Number Of Attributes: 17
> NMO : 0
> _FillValue : -9.96921e+36
> actual_range : ( -15.43516, 19.79167 )
> parent_stat : Other
> statistic : Mean
> level_desc : Surface
> dataset : CDC Derived NCEP Reanalysis Products
> var_desc : v-wind
> least_significant_digit : 1
> precision : 2
> missing_value : -9.96921e+36
> scale_factor : 1
> add_offset : 0
> units : m/s
> valid_range : ( -102.2, 102.2 )
> long_name : DJF: Monthly Mean Meridional Wind at sigma level 0.995
> average_op_ncl : dim_avg_n over dimension(s): time
>
>
> Variable: diff_u
> Type: float
> Total Size: 2736 bytes
> 684 values
> Number of Dimensions: 2
> Dimensions and sizes: [19] x [36]
> Coordinates:
> Number Of Attributes: 1
> _FillValue : -9.96921e+36
>
> Variable: diff_v
> Type: float
> Total Size: 2736 bytes
> 684 values
> Number of Dimensions: 2
> Dimensions and sizes: [19] x [36]
> Coordinates:
> Number Of Attributes: 1
> _FillValue : -9.96921e+36
>
>
>
>
>
> _______________________________________________
> 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/20150608/861c236f/attachment-0001.html
More information about the ncl-talk
mailing list