You can always look at the contents of contributed.ncl
where area_hi2lores_Wrap is located. In fact, *all* _Wrap functions are
in contributed.ncl
%> less $NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl
Search for: area_hi2lores_Wrap
===
The comment "but the patterns of precipitation changed
dramatically; while the wind fields remained the same"
"Winds" tend to be correlated in space. Averaging over
small regions is not likely to change the patterns much.
"Precipitation" may be spatially correlated if you are
talking about monthly means, in particular, climatologies.
Generally, the patterns not change much.
However, if you are using 3/6/12-hr snapshots or daily means,
the patterns could change 'a lot' because
precipitations is generally highly 'fractal'.
===
FYI: area_hi2lores (_Wrap) is a very old function.
It is recommended that the new ESMF regrid functions be
used for regridding. These are high quality and offer
a true conservative remap capability. Conservative
remapping is recommended for precipitation.
http://www.ncl.ucar.edu/Applications/ESMF.shtml
On 12/9/13, 4:49 PM, Adam Phillips wrote:
> Hi Yi-Chih,
> I don't think it has anything to do with you regridding precipitation as
> opposed to wind vectors. I think it has to do with your LAT/LON arrays.
> I would think that the units attribute requirement would be necessary no
> matter what the input LAT/LON arrays are, so I'm honestly not sure..
> Adam
>
> On 12/09/2013 04:45 PM, Yi-Chih Huang wrote:
>> Adam,
>>
>> Thanks much for the suggestion. It was working. But a basic
>> question is why to give units to LON and LAT is necessary for
>> precipitation; while there is no need to do so in wind vectors? What
>> made the difference?
>>
>> Thanks a lot,
>>
>> Yi-Chih
>>
>>
>> On Tue, Dec 10, 2013 at 2:19 AM, Adam Phillips <asphilli@ucar.edu
>> <mailto:asphilli@ucar.edu>> wrote:
>>
>> Hi Yi-Chih,
>> Those error messages are hinting that the issue is either in your
>> input latitude/longitude arrays into area_hi2lores_Wrap or when
>> you go to plot the regridded arrays. (I am honestly unclear
>> whether area_hi2lores_Wrap requires the units attribute to be set
>> for input/output latitude/longitude arrays.)
>>
>> I would first try adding units attributes to the LAT/LON arrays,
>> and add some print statements to make sure the input
>> pcp&lat/pcp&lon arrays contain the necessary units attributes:
>>
>> LON = fspan( 31.25,158.75, 52)
>> LAT = fspan(-28.75, 28.75, 24)
>> LON@units = "degrees_east"
>> LAT@units = "degrees_north"
>> printVarSummary(pcp&lon) ; is a units attribute present?
>> printVarSummary(pcp&lat)
>>
>> opt = True
>> opt@critpc = 50 ; require only 50% of the values to
>> be precent
>> pLo = area_hi2lores_Wrap (pcp&lon,pcp&lat, pcp , True, 1, LON,
>> LAT, False)
>> printVarSummary(pLo&LON) ; is a units attribute present?
>> printVarSummary(pLo&LAT)
>>
>> If you need to assign a units attribute to pcp&lat for instance:
>> pcp&lat@units = "degrees_north"
>>
>> Hope that helps. If not, please respond to ncl-talk.
>> Adam
>>
>>
>> On 12/09/2013 12:37 AM, Yi-Chih Huang wrote:
>>> Hello,
>>>
>>> I am trying to use area_hi2lores_Wrap to obtain the
>>> precipitation and wind fields in different low resolutions. I
>>> used the same commands; but the patterns of precipitation changed
>>> dramatically; while the wind fields remained the same. When "pLo
>>> = area_hi2lores_Wrap (pcp&lon,pcp&lat, pcp , True, 1, LON, LAT,
>>> False)" was commented, there was no such a warning message as
>>> "Data either does not contain a valid latitude coordinate array
>>> or doesn't contain one at all." I attached the commands, output
>>> of printVarSummary, warning message, and the script as follows.
>>> Could anyone tell me what was wrong with precipitation field in
>>> area_hi2lores_Wrap?
>>>
>>> Thanks much,
>>>
>>> Yi-Chih
>>>
>>> #####
>>> LON = fspan( 31.25,158.75, 52)
>>> LAT = fspan(-28.75, 28.75, 24)
>>> opt = True
>>> opt@critpc = 50 ; require only 50% of the values
>>> to be precent
>>> pLo = area_hi2lores_Wrap (pcp&lon,pcp&lat, pcp , True, 1, LON,
>>> LAT, False)
>>>
>>> LON := fspan( 30.,160., 261)
>>> LAT := fspan(-30., 30., 121)
>>> opt = True
>>> opt@critpc = 50 ; require only 50% of the values
>>> to be precent
>>> uLo = area_hi2lores_Wrap (uwnd&lon, uwnd&lat, uwnd, True, 1,
>>> LON, LAT, False)
>>> vLo = area_hi2lores_Wrap (vwnd&lon, vwnd&lat, vwnd, True, 1,
>>> LON, LAT, False)
>>> #####
>>> Variable: uLo
>>> Type: float
>>> Total Size: 126324 bytes
>>> 31581 values
>>> Number of Dimensions: 2
>>> Dimensions and sizes: [LAT | 121] x [LON | 261]
>>> Coordinates:
>>> LAT: [-30..30]
>>> LON: [30..160]
>>> Number Of Attributes: 13
>>> DataFreq : Monthly
>>> average_op_ncl : dim_avg_n over dimension(s): year
>>> lv_ISBL1 : 850
>>> center : US National Weather Service - NCEP (WMC)
>>> long_name : u-component of wind
>>> units : m/s
>>> level_indicator : 100
>>> gds_grid_type : 0
>>> parameter_table_version : 2
>>> parameter_number : 33
>>> model : Climate Data Assimilation System (CDAS)
>>> initial_time : 02/05/2006 (00:00)
>>> _FillValue : 1e+20
>>>
>>> Variable: pLo
>>> Type: float
>>> Total Size: 4992 bytes
>>> 1248 values
>>> Number of Dimensions: 2
>>> Dimensions and sizes: [lat | 24] x [lon | 52]
>>> Coordinates:
>>> lat: [-28.75..28.75]
>>> lon: [31.25..158.75]
>>> Number Of Attributes: 12
>>> _FillValue : 1e+20
>>> initial_time : 02/05/1981 (00:00)
>>> model : Climate Data Assimilation System (CDAS)
>>> parameter_number : 59
>>> parameter_table_version : 2
>>> gds_grid_type : 0
>>> level_indicator : 1
>>> units : kg/m^2/s
>>> long_name : Precipitation rate
>>> center : US National Weather Service - NCEP (WMC)
>>> average_op_ncl : dim_avg_n over dimension(s): time
>>> DataFreq : Monthly
>>> (0) 0
>>> (0) check_for_y_lat_coord: Warning: Data either does not
>>> contain a valid latitude coordinate array or doesn't contain one
>>> at all.
>>> (0) A valid latitude coordinate array should have a 'units'
>>> attribute equal to one of the following values:
>>> (0) 'degrees_north' 'degrees-north' 'degree_north'
>>> 'degrees north' 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN'
>>> 'degreesN' 'deg north'
>>> (0) check_for_lon_coord: Warning: Data either does not
>>> contain a valid longitude coordinate array or doesn't contain one
>>> at all.
>>> (0) A valid longitude coordinate array should have a 'units'
>>> attribute equal to one of the following values:
>>> (0) 'degrees_east' 'degrees-east' 'degree_east' 'degrees
>>> east' 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE'
>>> 'deg east'
>>> (0) 1
>>> yhuang@arc-env:/fs3/yhuang/nmm$
>>>
>>> #####
>>> load "$SysE/lib/ncl/helper_libs.ncl"
>>>
>>> begin
>>> latS = -30.0
>>> latN = 30.0
>>> lonE = 30.0
>>> lonW = 160.0
>>>
>>> dir1 = "/fs3/SysE_DB/nmm/NMM/Monthly/Mean/"
>>> yrStrt = 1981
>>> yrLast = 2006
>>> year = ispan(yrStrt, yrLast,1) ; integer
>>> yrDir = year + "/" ; string
>>> varName= (/"precip"/)
>>> nyr = dimsizes(year)
>>>
>>> dir = str_concat(dir1+yrDir(0))
>>> fil = systemfunc("cd "+dir+" ; ls precip.nc
>>> <http://precip.nc>") ;;;;;;;; read precipitation
>>> f = addfile (dir+fil, "r")
>>> x = f->$varName(0)$
>>> dims= getfilevardims(f,varName(0))
>>> xs = x(:,{latS:latN},{lonE:lonW}) ; JJAS tropical Pacific
>>> xu = dim_avg_n_Wrap( xs,0)
>>> ds = dimsizes(xs)
>>> xx = new((/nyr,ds(0),ds(1),ds(2)/),float)
>>> YYYYMM= new ( (/nyr,ds(0)/), double)
>>> printVarSummary(xs)
>>> printVarSummary(YYYYMM)
>>>
>>> delete (fil)
>>> do ny= 0,nyr-1
>>> dir = str_concat(dir1+yrDir(ny))
>>> fil = systemfunc("cd "+dir+" ; ls precip.nc <http://precip.nc>")
>>> f = addfile (dir+fil, "r")
>>>
>>> x := f->$varName(0)$
>>> dims= getfilevardims(f,varName(0))
>>> xs := x(:,{latS:latN},{lonE:lonW}) ; Indian Ocean
>>> xx(ny,:,:,:)= xs
>>> YYYYMM(ny,:) = cd_calendar(xs&$xs!0$, 1)
>>> end do
>>> printMinMax(xx,True)
>>> print(YYYYMM(0:2,0:3))
>>>
>>> xx!0 = "year"
>>> xx!1 = "month"
>>> pcp = dim_avg_n_Wrap( xx,(/0,1/) ) *86400 ; kg/m^2/s -> mm/day
>>> copy_VarMeta(xu,pcp)
>>> printMinMax(pcp,True)
>>> printVarSummary(pcp)
>>>
>>> LON = fspan( 31.25,158.75, 52)
>>> LAT = fspan(-28.75, 28.75, 24)
>>> opt = True
>>> opt@critpc = 50 ; require only 50% of the values
>>> to be precent
>>> pLo = area_hi2lores_Wrap (pcp&lon,pcp&lat, pcp , True, 1, LON,
>>> LAT, False)
>>> pLo!0 = "lat"
>>> pLo!1 = "lon"
>>> printVarSummary(pcp&lon)
>>> printVarSummary(pcp&lat)
>>> printVarSummary(LON)
>>> printVarSummary(LAT)
>>>
>>> delete ([/fil,varName/])
>>> dir1= "/fs3/SysE_DB/nmm/NMM/Monthly/Mean/"
>>> dir = str_concat(dir1+yrDir(0))
>>> fil = systemfunc("cd "+dir+" ; ls *wnd_850.nc
>>> <http://wnd_850.nc>") ; input file name(s)
>>> f = addfile (dir+fil(0), "r")
>>>
>>> varName= (/"uwnd","vwnd"/)
>>> x := f->$varName(0)$
>>> dims = getfilevardims(f,varName(0))
>>> xs := x(:,{latS:latN},{lonE:lonW}) ; Indian Ocean
>>> ds = dimsizes(xs)
>>> xx := new((/nyr,ds(1),ds(2)/),float,"No_FillValue")
>>>
>>> delete (fil)
>>> do nf= 0,1
>>> do ny= 0,nyr-1
>>> dir = str_concat(dir1+yrDir(ny))
>>> fil = systemfunc("cd "+dir+" ; ls *wnd_850.nc
>>> <http://wnd_850.nc>") ; input file name(s)
>>>
>>> f = addfile (dir+fil(nf), "r")
>>> x = f->$varName(nf)$
>>> dims = getfilevardims(f,varName(nf))
>>> xs := x(:,{latS:latN},{lonE:lonW}) ; Indian Ocean
>>> xy = dim_avg_n_Wrap( xs, 0 )
>>> xx(ny,:,:)= xy
>>> xx!0 = "year"
>>>
>>> if ( ny .eq. nyr-1 .and. nf .eq. 0 ) then
>>> uwnd= dim_avg_n_Wrap( xx, 0 )
>>> else if ( ny .eq. nyr-1 .and. nf .eq. 1 ) then
>>> vwnd= dim_avg_n_Wrap( xx, 0 )
>>> end if
>>> end if
>>> end do
>>> end do
>>> printVarSummary(uwnd)
>>>
>>> LON := fspan( 30.,160., 261)
>>> LAT := fspan(-30., 30., 121)
>>> opt = True
>>> opt@critpc = 50 ; require only 50% of the values
>>> to be precent
>>> uLo = area_hi2lores_Wrap (uwnd&lon, uwnd&lat, uwnd, True, 1,
>>> LON, LAT, False)
>>> vLo = area_hi2lores_Wrap (vwnd&lon, vwnd&lat, vwnd, True, 1,
>>> LON, LAT, False)
>>> printVarSummary(uwnd&lon)
>>> printVarSummary(uLo)
>>> printVarSummary(pLo)
>>>
>>> wks= gsn_open_wks("X11","pcpWind_nmm")
>>> gsn_define_colormap(wks,"BlueRed")
>>>
>>> pres= True
>>> opt= True
>>> myfill(pres,opt)
>>> pres@gsnAddCyclic = False
>>> pres@mpMinLatF = -30
>>> pres@mpMaxLatF = 30
>>> pres@mpMinLonF = 30
>>> pres@mpMaxLonF = 160
>>>
>>> pres@cnFillOn = True
>>> pres@gsnSpreadColors = True ; use full colormap
>>> pres@gsnSpreadColorStart = 10 ; for BlueRed
>>> pres@gsnSpreadColorEnd = 250 ; for BlueRed
>>> pres@cnLevelSelectionMode = "ManualLevels"
>>> pres@cnMinLevelValF = 1.
>>> pres@cnMaxLevelValF = 20.
>>> pres@cnLevelSpacingF = 1.
>>>
>>> pres@lbLabelBarOn = True
>>> pres@pmLabelBarWidthF= 0.8
>>> pres@lbLabelStride = 4
>>> pres@mpFillOn = False
>>> pres@mpOutlineBoundarySets = "National" ; turns on
>>> country boundaries.
>>> pres@gsnRightString = "mm/day"
>>> pres@gsnLeftString = "NMM: Average Monthly Precipitation Rate
>>> during JJAS"
>>> pres@cnFillDrawOrder = "Predraw"
>>> pres@gsnDraw = False
>>> pres@gsnFrame = False
>>> print("0")
>>> plot1= gsn_csm_contour_map(wks,pLo,pres)
>>> print("1")
>>>
>>> wres= True
>>> wres@vcRefMagnitudeF = 10.0 ; define vector
>>> ref mag
>>> wres@vcRefLengthF = 0.045 ; define length
>>> of vec ref
>>> wres@vcMinDistanceF = 0.025 ; thin out
>>> windbarbs
>>> wres@vcVectorDrawOrder = "Predraw"
>>> wres@gsnLeftString = "NMM: Average Monthly Wind
>>> Vectors on 850 hPa during JJAS"
>>> wres@gsnLeftStringFontHeightF = 0.025
>>> wres@gsnRightStringFontHeightF = 0.025
>>> wres@gsnDraw = False
>>> wres@gsnFrame = False
>>> plot2= gsn_csm_vector(wks,uLo,vLo,wres)
>>>
>>> overlay(plot1,plot2)
>>> maximize_output(wks,True)
>>> end
>>>
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>> -- ______________________________________________________________
>> Adam Phillipsasphilli@ucar.edu <mailto:asphilli@ucar.edu>
>> NCAR/Climate and Global Dynamics Division(303) 497-1726
>> <tel:%28303%29%20497-1726> P.O. Box 3000
>> Boulder, CO 80307-3000http://www.cgd.ucar.edu/cas/asphilli
>>
>>
>>
>>
>> _______________________________________________
>> ncl-talk mailing list
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
>
>
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Received on Mon Dec 9 17:16:38 2013
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