Ž . Dynamics of Atmospheres and Oceans 32 2000 239–281 www.elsevier.comrlocaterdynatmoce Model evaluation experiments in the North Atlantic Basin: simulations in nonlinear terrain-following coordinates Dale B. Haidvogel a, ) , Hernan G. Arango a , Kate Hedstrom a , Aike Beckmann b , Paola Malanotte-Rizzoli c , Alexander F. Shchepetkin d a Institute of Marine and Coastal Sciences, Rutgers UniÕersity, New Brunswick, NJ, USA b Alfred-Wegener-Institute for Polar and Marine Research, BremerhaÕen, Germany c Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA d Institute of Geophysics and Planetary Physics, UniÕersity of California at Los Angeles, Los Angeles, CA, USA Received 26 August 1998; received in revised form 4 August 1999; accepted 3 February 2000 Abstract A primitive equation ocean circulation model in nonlinear terrain-following coordinates is applied to a decadal-length simulation of the circulation in the North Atlantic Ocean. In addition to the stretched sigma coordinate, novel features of the model include the utilization of a weakly dissipative, third-order scheme for tracer advection, and a conservative and constancy-preserving time-stepping algorithm. The objectives of the study are to assess the quality of the new terrain-following model in the limit of realistic basin-scale simulations, and to compare the results obtained with it against those of other North Atlantic models used in recent multi-model comparison studies. The new model is able to reproduce many features of both the wind-driven and thermohaline Ž circulation, and to do so within error bounds comparable with prior model simulations e.g., CME . and DYNAMO . Quantitative comparison with comparable results obtained with the Miami Ž . Isopycnic Coordinate Model MICOM show our terrain-following solutions are of similar overall quality when viewed against known measures of merit including meridional overturning and heat flux, Florida Straits and Gulf Stream transport, seasonal cycling of temperature and salinity, and ) Corresponding author. Tel.: q 1-732-932-6555, ext. 256; fax: q 1-510-643-1142. Ž . E-mail address: dale@ahab.rutgers.edu D.B. Haidvogel . 0377-0265r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0377-0265 00 00049-X