[ncl-talk] change in vector spacing when taking difference of two wind fields
mberdahl at envsci.rutgers.edu
mberdahl at envsci.rutgers.edu
Mon Jun 8 21:30:28 MDT 2015
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
>>
>>
>>
>>
>>
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>
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