As per the AMIPII guidelines, other standardized conditions are divided into two categories, those that are required and those that are recommended.

Requirements

·          Simulation period: 00Z 1 January 1979 through 00Z 1 March 1996.

·         Ocean surface boundary conditions: based on the extended version of the AMIP II monthly mean sea surface temperatures and sea-ice data sets (Fiorino, 1996). Explicit instructions are provided for the use of these data in AMIP II/SMIP-2 simulations (Taylor et al., PCMDI Report No. 60, 2000).

·         Solar constant: 1365 W m-2 (Hartmann, 1994)

  • Orbital parameters: (Smith et al., 1995)

- obliquity=23.441o

- eccentricity = 0.016715

- longitude of perihelion=102.7o

·         [CO2]:348 ppmv (AMIP II period average, derived from the 1995 IPCC).

Recommendations

·         Realistic calendar (with 1980, 84, 88, 92, 96 leap years): define time of vernal equinox as March x, with x=20.41-0.0078(Y - 1987) + 0.25Y(modulo 4), where Y is the year and Y (modulo 4) the remainder after dividing Y by 4 (Smith et al., 1995). A time model of twelve 30-day months is strongly discouraged.

·         Ozone concentration: use the Wang et al. (1995) latitude (zonal average)-pressure monthly climatology.

·         Land surface energy and hydrological balance: do not prescribe the temperature of the deepest land surface level, nor a deep infinite reservoir of moisture.

·         Land-sea mask and topography: use a land-sea mask (adopted to each model grid and available from PCMDI) based on the U.S. Navy 10' data set. High resolution state-of-the-art topography is also available from PCMDI, but no recommendation is made for topography smoothing.

·         Atmospheric mass & topography: prescribe observed global average values for surface pressure (982.4 hPa) and topographic height (237.33 m). If proper specification of model topography requires a deviation from the observed mean, adjust the global mean surface pressure by 1 hPa per 8 m deviation (Trenberth and Guillemot, 1994).

·         Other greenhouse gases: [CH4] = 1650 ppbv and [N2O]= 306 ppbv. Halocarbon concentrations should yield ~0.24 W m-2 radiative forcing. Use of an "equivalent" [CO2] is not recommended.

·         Aerosol concentration (for those models that account for them): prescribe a background monthly climatology only.