The purpose of this talk is to summarize the conservation properties of the ECMWF spectral semi-Lagrangian, semi-implicit IFS model and present results from some recently implemented algorithms for correcting global mass imbalances due to advection.
Several established algorithms of different complexity, such as the ones described in [1,2,3,4], will be summarized and assessed in the context of NWP forecasts. Results from water species advection and passive tracer advection will be presented. Strengths and limitations of these schemes will be analyzed as well as their ability to preserve monotonicity and the impact they have on forecast skill.
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A. Priestley, 1993: A Quasi-Conservative Version of the Semi-Lagrangian Advection Scheme, MWR, 121, 621-629.
Zerroukat M., 2010, A simple mass conserving semi-Lagrangian scheme for transport problems, JCP, 229, 9011-9019.
Williamson D.L., Rasch P.J., 1994, Water vapor transport in the NCAR CCM2, Tellus, 46A, 34-51.