Development and Applications of the TOMCAT/SLIMCAT 3-D CTM Wuhu Feng and Martyn Chipperfield

1. Development and Applications of the TOMCAT/SLIMCAT 3-D CTM Wuhu Feng and Martyn Chipperfield NCAS, School of Earth and Environment, University of Leeds, UK w.feng@leeds.ac.uk; m.chipperfield@leeds.ac.uk 1. Introduction 2. TOMCAT/SLIMCAT 3D CTM 3. Applications • TOMCAT/SLIMCAT is a 3-D offline chemical transport model (www.see.leeds.ac.uk/tomcat). It contains a detailed description of stratospheric and tropospheric chemistry. • TOMCAT is also the host CTM for the GLOMAP global aerosol model. • TOMCAT is a test-bed for development of aerosol and chemistry schemes for the UM and UKCA. It shares common chemistry / aerosol code. • Since mid 2011 NCAS has been supporting the development of TOMCAT/SLIMCAT in Leeds through the co-funding of Wuhu Feng. • A major aim of the current NCAS-funded work is the development of a new version of the model which combines best aspects of older versions (inc. pTOMCAT used in Cambridge). • The new version is now ready and available for ‘beta’ testing. • The model is currently being used in a wide variety of scientific studies. • Stratospheric ozone loss • Tracer transport • Atmospheric trace gas trends • Solar variability impacts on the middle/lower atmosphere • Interpretation of satellite, aircraft, ground-based measurements, etc. • Chemistry-Climate interactions • Atmospheric chemistry and physical processes • Air pollution • Data assimilation • Inverse modelling / flux estimation • See examples 4-7 below. 4. Computationally Efficient High Resolution Model 4. Arctic ozone depletion 5. Stratospheric vortex edge and atmospheric mixing Figure 2 (right top panel). Atmospheric mixing is diagnosed as the equivalent length of effective diffusivity. Small (large) values mean weak (strong) mixing Figure 2 (left panels) . Contours of log -normalized equivalent length of effective diffusivity against the vortex-following PV-equivalent latitude at 493 K (20 km), 456 K (17km) .and 423 K (13 km), respectively. Polar vortex edge is clearly seen around 67oS equivalent latitude. There is strong mixing inside the polar vortex. For details see Roscoe et al. (2012). Figure 1. Percentage loss of ozone averaged inside the polar vortex (inside 36 PVU contour) at around 18 km for 18 Arctic winters calculated with the TOMCAT/SLIMCAT 3D CTM, updated from Feng et al. (2007). The model shows year-to-year variations of O3 depletion and a record large loss (-85%) in the cold Arctic winter of 2010/11. 6. Inferred total bromine in the atmosphere 7. Impact of solar variation on stratospheric O3 change Figure 4: Modelled tropical ozone solar signal from satellite data (HALOE, SBUV/SAGE, MLS and SABER) and various SLIMCAT model experiments, for details see Dhomse et al. (2013). The model can reproduce the broad positive ozone anomaly in the middle stratosphere using NRL (A) and SATIRE (B) solar fluxes and ERA-Interim meteorology. Figure 3: Modelled tropical bromine, for details see Hossaini et al. (2012). Explicit modelling of the sources and chemical sinks of a range of minor bromine compounds shows that VSLS species contribute about 6pptv to stratospheric bromine. • References: • Roscoe, H., W. Feng , M.P. Chipperfield , M. Trainic , E. Shuckburgh, J. Geophys. Res., 117, D04301, doi:10.1029/2011JD015940, 2012. • Feng W., M.P. Chipperfield, S. Davies, P. von der Gathen, E. Kyro, C.M. Volk, A. Ulanovsky, G. Belyaev, Geophys. Res. Lett., 34, L09803, doi:10.1029/2006GL029098, 2007. • Hossaini, R., M.P. Chipperfield, W. Feng, T. J. Breider, E. Atlas, E., S.A. Montzka, B.R. Miller, F. Moore, F., and J. Elkins, Atmos. Chem. Phys., 12, 371-380, 2012. • Dhomse, S.S., M.P. Chipperfield, W. Feng, W.T. Ball, Y.C. Unruh, J.D. Haigh, N.A. Krivova, S.K. Solanki, and A.K. Smith, Atmos. Chem. Phys. Discuss., 2013.