Surface Pressure

Surface pressure is particularly a good variable to begin the model comparison because, representing the mass of the atmosphere, it gives the overall movement of mass over the planet. Notice that the pressure has maxima about 30^o north and south of the Equator. Can you recall the dominant climatic characteristic of these regions 30^o north and south of the Equator as discussed in an earlier unit? The minimum near -70^o marks the pressure minimum of the Southern Hemisphere ocean. Most models represent the pressure distribution reasonably well except near the polar regions, especially the South Pole. Recall that the Antarctic continent is very high with a very deep layer of ice. These factors create severe difficulties for the simulation of pressure over this region. In some cases (such as UKLO in JJA), a low-resolution model gives results closer to the observations than high-resolution models. Note that the UKLO model does not give results as accurate in the DJF simulation.

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