function [data,ib,jb,kb,nxl,nyl,nzl,ighost] = read_field_chunk_ucf(file,field,varargin)
    % [data,ib,jb,kb,nxl,nyl,nzl,ighost] = read_field_chunk_ucf(file,field,varargin)
    % Reads single field from one processor chunk.
    % Input
    %   file                file name (if tar-mode: ustar handle)
    %   field               field to be read 
    %                         {'u','v','w','p','s1','s2',...}
    %                         or integer with dataset index (not in tar-mode)
    % ? step                index of timestep to be read (default: 1)
    % ? ghost               keep ghost cells? (default: yes)
    % ? verbosity           verbose output? (default: no)
    % ? debug               debug output? (default: no)
    % ? tarmode             read from tar-file? (default: 0)
    % ? rank                rank of processor, ignored if not in tarmode (default: 0)
    % Output
    %   data                partial field with dim(nxl+2*ighost,nyl+2*ighost,nzl+2*ighost)
    %   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);
    addParamValue(par,'rank',0,@isnumeric);
    parse(par,varargin{:});
    istep     = par.Results.step;
    keepghost = par.Results.ghost;
    
    % Parse field
    if ischar(field)
      switch field(1)
      case 'u'; ifield=1; fbase='uvwp';
      case 'v'; ifield=2; fbase='uvwp';
      case 'w'; ifield=3; fbase='uvwp';
      case 'p'; ifield=4; fbase='uvwp';
      case 's'; ifield=str2double(field(2:end)); fbase='scal';
      end
    elseif isnumeric(field)
      if par.Results.tarmode
        error('field cannot be numeric, if tar-mode is used.');
      end
      ifield=field; fbase='';
    else
      error('field must either be numeric or string.');
    end
    
    % Open file
    obj = ucf('verbosity',par.Results.verbosity,'debug',par.Results.debug);
    if par.Results.tarmode
      subfile = sprintf('%s.%05d',fbase,par.Results.rank);
      obj.opentar(file.pointer(subfile));
    else
      obj.open(file);
    end
    
    % Read raw data
    if ~obj.validateType('field')
      error('read error: no field data.'); 
    end
    [data,params] = obj.readSet(istep,ifield);
    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);
    nx     = params(8);
    ny     = params(9);
    nz     = params(10);
    data   = reshape(data,nxl+2*ighost,nyl+2*ighost,nzl+2*ighost);
    if ighost && ~keepghost
      data = data(2:end-1,2:end-1,2:end-1);
      ighost = 0;
    end

    % Close UCF file
    obj.close();
end