“…The model is central in time with a semi-implicit treatment of gravity wave propagation, implicit zonal advection of moisture and vorticity, and Robert (Asselin) time filtering (Simmons et al, 1978;Simmons and Jarraud, 1983). The operational model includes physical parameterizations of vertical diffusive transport in the planetary boundary layer (Louis, 1979;Louis et al, 1982) coupled to a land surface model , orographic gravitywave and flow-blocking drag (Webster et al, 2003), shallow cumulus mixing (Tiedtke, 1984), deep cumulus convection (Emanuel and Zivkovic-Rothman, 1999;Peng et al, 2004), convective, stratiform and boundary layer clouds and precipitation (Slingo, 1987;Teixeira and Hogan, 2002), and shortwave and longwave radiation (Harshvardhan et al, 1987). NOGAPS runs operationally at T239L30 with only a few thick highly-diffused stratospheric levels above ∼25 hPa.…”