function [s,ib,jb,kb,nxl,nyl,nzl,ighost] = read_scal_chunk_ucf(file,varargin)
    % [s,ib,jb,kb,nxl,nyl,nzl,ighost] = read_scal_chunk_ucf(file,varargin)
    % Reads scalar fields from one processor chunk.
    % Input
    %   file                file name (if tar-mode: ustar handle)
    % ? step                index of timestep to be read (default: 1)
    % ? ghost               keep ghost cells? (default: 1)
    % ? verbosity           verbose output? (default: 0)
    % ? debug               debug output? (default: 0)
    % ? tarmode             read from tar-file? (default: 0)
    % ? rank                rank of processor, ignored if not in tarmode (default: 0)
    % Output
    %   s                   partial fields with dim(nxl+2*ighost,nyl+2*ighost,nzl+2*ighost,nscal)
    %   ib,jb,kb,...        global index of first grid point of the partial field w/o ghost cells
    %   nxl,nyl,nzl,...     local field size w/o ghost cells
    %   ighost              ghost cell flag

    % Parse optional input arguments
    par = inputParser;
    addParamValue(par,'step',1,@isnumeric);
    addParamValue(par,'ghost',1,@isnumeric);
    addParamValue(par,'verbosity',0,@isnumeric);
    addParamValue(par,'debug',0,@isnumeric);
    addParamValue(par,'tarmode',0,@isnumeric);  % deprecated
    addParamValue(par,'rank',0,@isnumeric);
    parse(par,varargin{:});
    istep     = par.Results.step;
    keepghost = par.Results.ghost;
  
    % Open file
    obj = ucf('verbosity',par.Results.verbosity,'debug',par.Results.debug);
    switch class(file)
    case 'char'
      obj.open(file);
    case {'ustar','ucfmulti'}
      subfile = sprintf('scal.%05d',par.Results.rank);
      obj.opentar(file.pointer(subfile));
    otherwise
      error('Input file type not supported: %s',class(file));
    end
  
    if ~obj.validateType('field')
      error('read error: no field data.'); 
    end
    nscal = obj.getNumDatasets(istep);

    % Read raw data
    s = cell(1,nscal);
    for iset=1:nscal
      [data,params] = obj.readSet(istep,iset);
      params = cast(params,'double');
      ighost = params(1);
      ib     = params(2);
      jb     = params(3);
      kb     = params(4);
      nxl    = params(5);
      nyl    = params(6);
      nzl    = params(7);
      s{iset} = reshape(data,nxl+2*ighost,nyl+2*ighost,nzl+2*ighost);
      if ighost && ~keepghost
        s{iset} = s{iset}(2:end-1,2:end-1,2:end-1);
        ighost = 0;
      end
    end
    
    % Close UCF file
    obj.close();
    
    % Convert cell array to 4-D array
    s = cat(4,s{:});
end