Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 4 2004 10.5194/acpd-4-4227-2004 http://www.atmos-chem-phys-discuss.net/4/4227/2004/ http://www.atmos-chem-phys-discuss.net/4/4227/2004/acpd-4-4227-2004.html http://www.atmos-chem-phys-discuss.net/4/4227/2004/acpd-4-4227-2004.pdf 4227 4284 2004-08-04 NOGAPS-ALPHA model simulations of stratospheric ozone during the SOLVE2 campaign J. P. McCormack mccormack@nrl.navy.mil S. D. Eckermann L. Coy D. R. Allen Y.-J. Kim T. Hogan B. Lawrence A. Stephens E. V. Browell J. Burris T. McGee C. R. Trepte E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington DC, USA Remote Sensing Division, Naval Research Laboratory, Washington DC, USA Marine Meteorology Division, Naval Research Laboratory, Monterey, California, USA British Atmospheric Data Center, Rutherford Appleton Laboratory, Oxfordshire, UK NASA Langley Research Center, Hampton, Virginia, USA NASA Goddard Space Flight Center, Greenbelt, Maryland, USA This paper presents three-dimensional prognostic ozone simulations with parameterized photochemistry from the new NOGAPS-ALPHA middle atmosphere forecast model. We compare 5-day NOGAPS-ALPHA hindcasts of stratospheric ozone with a combination of satellite and DC-8 aircraft measurements for two specific cases during the SOLVE II campaign: (1) the cold, isolated vortex during 11–16 January 2003; and (2) the rapidly developing stratospheric warming of 17–22 January 2003. In the first case we test three different photochemistry parameterizations. NOGAPS-ALPHA ozone simulations using the NRL-CHEM2D parameterization give the best overall agreement with SAGE III and POAM III profile measurements. 5-day NOGAPS-ALPHA hindcasts of polar ozone initialized with the NASA GEOS4 ozone analyses produce better agreement with observations than do the operational ECMWF ozone forecasts. In the second case, comparisons between NOGAPS-ALPHA and ECMWF 114-h forecasts of the split vortex structure in stratospheric ozone on 21 January 2003 show comparable skill. Updated ECMWF ozone forecasts of this case at hour 42 display marked improvement from the 114-h forecast; corresponding updated 42-h NOGAPS-ALPHA prognostic ozone simulations do not improve significantly. In general, these results demonstrate that the spectral advection component in NOGAPS-ALPHA is well-suited for middle atmosphere tracer transport. In particular, we find that stratospheric ozone forecasts at high latitudes in winter can depend on both model initial conditions and the treatment of photochemistry even over a period of 5 days.