I am starting research in the field of trace gases and I wanted to make a comparative study of satellite data with ground based observation as well as their percent contribution. For this purpose, I have chosen ozone measurements. What I understand from literature is that first we need to get total columnar ozone data vide OMI and subtract the value of stratospheric columnar ozone vide MLS from total columnar ozone to derive tropospheric columnar ozone. Thereafter I could calculate percent contribution of surface ozone to tropospheric columnar ozone and tropospheric columnar ozone to total columnar ozone. However, for this purpose I need stratospheric columnar ozone and total columnar ozone, of which I have total columnar ozone but I am unable to derive stratospheric columnar ozone. Can you please suggest how to derive stratospheric columnar ozone without writing program and downloading the data to MS-Excel?