MIPAS HDO netCDF files 24th January 2008, Vivienne Payne (vpayne@aer.com) These MIPAS retrievals were produced using the MORSE retrieval code (http://www.atm.ox.ac.uk/MORSE) Files contain profiles of pressure, temperature, H2O, HDO, O3 and CH4 Further description of this dataset can be found in: ----------------------------------------------------------------------------------- V. H. Payne, D. Noone, A. Dudhia, C. Piccolo and R. G. Grainger, "Global satellite measurements of HDO and implications for understanding the transport of water vapour into the stratosphere", QJRMS, 133, 1459-1471, 2007 ----------------------------------------------------------------------------------- If these data are obtained for potential use in a publication or presentation, we would appreciate if you could inform us of the nature of this work. If an important result or conclusion depends on this data, co-authorship may be appropriate. HDO mixing ratios are normalised for abundance. The values in ppmv are already divided by the HITRAN abundance for HDO relative to H2O. So to clarify, to get the delta values from the H2O and HDO values in these files, you should do the following: deltaD = 1000. * ( ( (HITVMR * HDO) / (2 * H2O ) - R0 ) / R0 ) where HITVMR is the number that HITRAN use for isotope abundance in SMOW, (=3.1e-4), and R0 is the reference ratio (=1.55e-4). (HITVMR=2*R0) MIPAS terminology: "Scan" means the whole limb scan of 17 tangent altitudes, and 'sweep', means one sweep of the interferometer, corresponding to one tangent altitude. There are always 17 sweeps in a scan, generally around 74 scans in an orbit, and generally around 14 orbits per day. The MIPAS nominal tangent altitudes over the period of this dataset are 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 47, 52, 60 and 68 km. The retrievals had an extra level of 80 km at the top for stability reasons, but note that there is no measurement at this atltitude. Joint retrievals of pressure, temperature and water vapor were performed for the first step. The retrieved pressure profile is supplied for each scan. It is possible to come up with some kind of "retrieved altitude" based on the hydrostatic equation, but we recommend working with pressures rather than altitudes. Suggested quality flags: The cloud flag is set to 1 for cloudy altitudes. Use only sweeps where the cloud flag is zero. Profiles of chi squared values are supplied for each species (these are averaged over the set of microwindows used.) I would recommend using only the sweeps where chisq < 5. You could be stricter if you want. Profiles of 'qmwflg' flag aare supplied for each species for each sepcies. This is related to the number of microwindows for which the retrieval converged at each sweep. Use only sweeps where qmwflg is equal to 1. Profiles of the sum of the row of the averaging kernel are supplied for each species. In Payne et al (2007), we used only sweeps where this quantity is greater than 0.85. The full averaging kernel is also supplied.