Report 60:  The Sea Surface Temperature and Sea-Ice Concentration Boundary Conditions for AMIP II Simulations

Taylor, Karl E., David Williamson, and Francis Zwiers

September 2000, 28 pp. 

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In many atmospheric general circulation model (AGCM) simulations, the sea surface temperature (SST) and sea-ice concentration (i.e., percentage of area covered by sea ice) are both prescribed, based on observations. In particular this experimental design is fundamental to the Atmospheric Model Intercomparison Project simulations. For AMIP, observed monthly mean SSTs and sea-ice concentration have been compiled for the period January 1979 through February 1996 and also for the month preceding and for several months following the designated AMIP II period. These observed monthly means do not constitute the official AMIP II "boundary conditions," but the boundary conditions are based on them, as explained in this brief report.

In AMIP II the SST and sea-ice concentration boundary conditions should be specified such that the monthly means computed from the model output precisely agree with the observed monthly means. There are several ways to assure compliance with this AMIP II requirement, but for most models which rely on linear interpolation between monthly values, appropriate AMIP II boundary condition data sets can be obtained from the Program for Climate Model Diagnosis and Intercomparison (PCMDI).

This report contains a description of and justification for the procedure recommended here for preparing and applying the AMIP II boundary condition data sets.(pdf file)

UCRL-MI-123395