## Yonsei University: Model YONU Tr7.1 (4x5 L7) 1995

### Model Designation

YONU Tr7.1 (4x5 L7) 1995

### Model Lineage

The model extends the vertical domain and resolution of the AMIP baseline model YONU Tr5.1 (4x5 L5) 1994 by the inclusion of 2 more vertical levels. The method of obtaining surface values of air temperature and moisture for purposes of calculating surface fluxes is also changed.

## Numerical/Computational Properties

### Vertical Domain

Surface to 100 hPa (model top). For a surface pressure of 1000 hPa, the lowest prognostic vertical level is at about 990 hPa (rather than 900 hPa as in the baseline model), but the highest vertical level remains at 150 hPa.

### Vertical Resolution

There are 7 *modified* sigma layers (rather than 5 as in the baseline model). The 7 layers are centered on sigma = 0.0555, 0.222, 0.444, 0.666, 0.844, 0.944, and 0.989. For a surface pressure of 1000 hPa, 3 levels are below 800 hPa and 1 level is above 200 hPa.

### Computational Performance

The AMIP integration required approximately 1.5 minutes of Cray C90 computational time per simulated day.

## Dynamical/Physical Properties

### Surface Fluxes

In a departure from the formulation of the baseline model, the surface air temperature and moisture are taken to be the same as the values at the lowest atmospheric level (modified sigma value of 0.989, or approximately 990 hPa for a surface pressure of 1000 hPa). The treatment of surface fluxes is otherwise the same as in the baseline model.

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Last update May 23, 1996. For further information, contact: Tom Phillips ( phillips@tworks.llnl.gov)

UCRL-ID-116384