function calcozo(form,val,index)
  // converts ozone columns
  // last change Dec.04, 2004
  // update constants Nov. 11,2007
  // copyright Bernd Krueger, Cactus2000, 2007-2009
{
  var P0  = 101325.;             // standard pressure in Pa
  var T0  = 273.15;              // 0 C in Kelvin
  var nAvo    = 6.02214179e23;   // Avogadro constant, mol-1 (NIST, CODATA 2006)
  var kBoltz  = 1.3806504e-23;   // Boltzmann constant, J K-1 (NIST, CODATA 2006)
  var kuniv   = nAvo*kBoltz;     // universal gas constant J mol-1 K-1
  var MO3 = 3.*15.9994*1.0e-3;   // molar mass of ozone in kg/mol

  var factor1 = 1.0e-9*P0/kuniv/T0;

  if(index==0) v=parseFloat(val);            // mol/cm2 (base)
  if(index==1) v=parseFloat(val)*factor1;    // DU
  if(index==2) v=parseFloat(val)/1.0e4/MO3;  // kg/m2
  if(index==3) v=parseFloat(val)/nAvo;       // molecules / cm2

  form.mcm.value = ausgab(v);           // mol/cm2 (base)
  form.dob.value = ausgab(v/factor1);	// DU
  form.kgm.value = ausgab(v*1.0e4*MO3); // kg/m2
  form.mol.value = ausgab(v*nAvo);	// molecules / cm2
}