regridding TRMM data to 0.5 degree grid

From: Erik Noble <nobleeu_at_nyahnyahspammersnyahnyah>
Date: Mon Jan 17 2011 - 16:46:23 MST

Hi. This is a follow-on to the question posed by B N here
http://www.ncl.ucar.edu/Support/talk_archives/2009/1554.html

If TRMM data is already on a grid 0.25 by 0.25 grid, where its
coordinate variables are
( from example 7 at http://www.ncl.ucar.edu/Applications/HiResPrc.shtml)

   nlat = 400
   mlon = 1440
   lat = ispan(0,nlat-1,1)*0.25 - 49.875
   lon = ispan(0,mlon-1,1)*0.25 - 179.875

   lat@long_name = "latitude"
   lat@units = "degrees_north"
   lat!0 = "lat"
   lat&lat = lat

   lon@long_name = "longitude"
   lon@units = "degrees_east"
   lon!0 = "lon"
   lon&lon = lon

which method ( A or B ) below would be better for re-gridding
specifically the TRMM data to 0.5 by 0.5?
Both?
Any advice is greatly appreciated.
Sincerely,
Erik

  A)
  ;****************
  ; Regrid to 0.50 degree
  ;****************
  nlat = 200
  mlon = 720

  latGRID = ispan(0,nlat-1,1)*0.50 - 49.875
  latGRID!0 = "lat"
  latGRID@units = "degrees_north"
  latGRID&lat = latGRID
  NLAT = dimsizes(latGRID)

  lonGRID = ispan(0,mlon-1,1)*0.50 - 179.875
  lonGRID!0 = "lon"
  lonGRID@units = "degrees_east"
  lonGRID&lon = lonGRID
  MLON = dimsizes(lonGRID)

  var = rain
  ; var = lonFlip(var)
  rad = 4.*atan(1.0)/180.
  lat = var(0,:,0)
  clat_025 = cos(lat*rad)
  opt = True
  var_o = area_hi2lores_Wrap (var&lon,var&lat, var , True, 1, lonGRID,
latGRID, False)

or B)

  ;****************
  ; Regrid to 0.50 degree
  ;****************
  nlat = 233
  mlon = 720
  dlon = 0.5

  latGRID = fspan(-58,58,nlat)
  latGRID!0 = "lat"
  latGRID@units = "degrees_north"
  latGRID&lat = latGRID
  NLAT = dimsizes(latGRID)

  lonGRID = fspan(0,mlon-1,dlon)*dlon, mlon)
  lonGRID!0 = "lon"
  lonGRID@units = "degrees_east"
  lonGRID&lon = lonGRID
  MLON = dimsizes(lonGRID)

  var = rain
  ; var = lonFlip(var)
  rad = 4.*atan(1.0)/180.
  lat = var(0,:,0)
  clat_025 = cos(lat*rad)
  opt = True
  var_o = area_hi2lores_Wrap (var&lon,var&lat, var , True, 1, lonGRID,
latGRID, False)
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Received on Mon Jan 17 16:46:30 2011

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