Mesoscale Variability in an Eddy-Resolving Global POP Simulation Julie McClean 1 , Mathew Maltrud 2 , and Detelina Ivanova 1 1 Scripps Institution of Oceanography, La Jolla, California USA 2 Los Alamos National Laboratory, Los Alamos, New Mexico USA In the past decade, supercomputing capabilities have increased to the point whereby numerical global ocean models can be run at sufficiently high vertical and horizontal resolution to be eddy-resolving (horizontal resolutions of 5-10 km and 40-50 levels) rather than eddy-permitting (35-40 km and 20-30 levels). This advance has provided the means of simulating both the large and mesoscale components of the circulation. A twenty-five year (1979-2003) 0.1-degree, 40-level global POP simulation forced with realistic surface fluxes is complete. It affords us the opportunity to study the ocean circulation, particularly mesoscale variability and processes as well as their interactions with the larger scales, in parts of the ocean where insufficient observations exist for such purposes. The POP model is configured on a displaced pole grid whereby the North Pole is rotated into Hudson Bay to avoid a polar singularity. The grid spacing is about 11 km at the equator decreasing to about 3 km in the Arctic Ocean. At mid-latitudes this spacing is 5-7 km. A blended bathymetry was created from Smith and Sandwell (1997), International Bathymetric Chart of the Arctic Ocean (IBCAO, Jakobsson et al., 2000), and British Antarctic Survey (BEDMAP) products. All important channels and sills were checked and modified to facilitate correct flow. The model was initialized from the Navy’s Modular Ocean Data Assimilation System (MODAS) 1/8° January climatology outside of the Arctic and the University of Washington’s Polar Hydrography winter climatology in the Arctic. The forcing was largely constructed from National Center for Environmental Prediction (NCEP) fluxes (Doney et al., 2002) for 1979-2003. Surface momentum, heat, and salt fluxes were calculated using bulk formulae (Large et al., 1997) and a combination of daily NCEP analyses, monthly Internal Satellite Cloud Climatology Project (ISCCP) radiation data, and monthly Microwave Sounding Unit (MSU) and Xie-Arkin precipitation data. The Large et al. (1994) mixed layer formulation, K-Profile Parameterization (KPP), was active. The simulated ocean state for the post spin-up period (1994-2003) will be examined in terms of both its mean and variability, however particular focus will be placed on the representation of the eddy variability and significant mesoscale processes. Figure 1 shows the trajectories of water parcels, released at 75 m throughout the global ocean, that have been advected through the water column in three dimensions using a fourth-order Runge-Kutta scheme. Significant mesoscale eddy activity is seen globally. Particularly we note the effect of tropical instability waves in the off- equatorial eastern Pacific. Measures of energy levels and intrinsic scales will be presented and compared with those from satellite altimetry. The mean and variability of meridional heat transports and their components from 1997-2000 will be examined. Also the role of the