[ncl-talk] change in vector spacing when taking difference of two wind fields
Alexander Schaefer
alexander.schaefer at mines.sdsmt.edu
Mon Jun 8 21:39:48 MDT 2015
Mira,
You have lost your lats/lons in the subtraction. It may have something to
do with that. You might want to pull them in at the beginning and then
associate them with diff_u and diff_v using:
diff_u at lon2d = lon
diff_u at lat2d = lat
diff_v at lon2d = lon
diff_v at lat2d = lat
Just pull the lats and lons on the same subsection that you are pulling u/v.
-Alex
On Mon, Jun 8, 2015 at 9:30 PM, <mberdahl at envsci.rutgers.edu> wrote:
> Hi Alex,
> I changed it so the vectors were appropriately sized. I just tried the
> script with removing the second Magnitude definition and the spacing is
> still the same. Any other thoughts?
> Mira
> > 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
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> >>
> >>
> >
>
>
>
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