Iterative correction objective analysis (Cressman, Barnes) (deprecated)
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl" function obj_anal_ic_deprecated ( zlon [*] : numeric, zlat [*] : numeric, z [*] : numeric, glon : numeric, glat : numeric, rscan [*] : numeric, option  : logical ) return_val
One-dimensional arrays of the same length containing the coordinates associated with the z values.z
A one-dimensional array containing the values associated with the zlon and zlat coordinates. Missing values, indicated via z@_FillValue, may be present but will be ignored.glon
A one-dimensional or two-dimensional array of length M containing the longitude coordinates associated with the returned two-dimensional grid.glat
A one-dimensional array or two-dimensional of length N containing the latitude coordinates associated with the returned two-dimensional grid.rscan
A one-dimensional array of length K specifying the successive radii of influence. Must be expressed in degrees of latitude and should be monotonically decreasing. eg: rscan = (/10, 5, 3/)option
If option=False, this function will operate under default mode. That is, the first guess will be 0.0 and values located outside rscan(0) will be set to _FillValue. If option=True, then this variable may have associated with it the attributes guess, zonal and/or setmsg.
- A user supplied N x M array of the same type as z containing a first guess for the output grid.
- Use a simple zonal average of the input z as a first guess.
- If set to True, then a 3-dimensional array of size K x N x M will be returned as an attribute of the returned grid. This will contain the number of observations used in each scan. Default is False.
- The default is True. This means that grid points located outside rscan(0) will be set to _FillValue.
The return array will be N x M.
This performs an iterative correction type objective analysis using an input triplet set ( zlon, zlat, z). In meteorology, this is called a Cressman or Barnes style analysis. Successively smaller radii are used to modify previous field estimates. As with other interpolation methods the results will be a function of the spatial distribution of the data values (z).
The execution time is a function of the number of z, the output grid resolution and the number and extent of search radii used.
Assume zlon, zlat and zVal are one-dimensional (1D) arrays; let lon and lat be 1D arrays specifying grid locations. Then:
rscan = (/10, 5, 2/) grid = obj_anal_ic_deprecated(zlon,zlat,zVal, lon,lat, rscan, False)
will use default behavior and return a 2D array of size N x M M.
opt = True opt@zonal = True ; use zonal averages as a 1st guess grid = obj_anal_ic_deprecated(xlon,ylat,zVal, lon,lat, rscan, opt)