IUGG 2003 Abstract

P02 Marginal and Semi-Enclosed Seas and their Exchange with the Open Ocean  Tuesday, July 1 AM Location: Site C, Room 25 Presiding Chair:C. Mooers

TIME [ 1040 ] [ P02/01A/C25-005 ] [ Invited ]

CONNECTIVITY OF VARIABILITY IN THE INTRA-AMERICAS SEA: MODELING AND REAL-TIME OPERATIONAL PREDICTION

Harley E. HURLBURT(Naval Research Laboratory)

Sylvia J. MURPHY(National Center for Atmospheric Research, Boulder, CO, 80305, USA) Ole Martin SMEDSTAD ( Planning Systems, Inc., Stennis Space Center, MS, 39529, USA ) Tamara L. TOWNSEND ( Naval Research Laboratory ) Steven P. ANDERSON ( Horizon Marine, Inc., Marion, MA, 02738, USA ) Eric P. CHASSIGNET ( University of Miami, Division of Meteorology and Physical Oceanography, Miami, FL, 33149, USA ) Patrick J. HOGAN ( Naval Research Laboratory ) Jay F. SHRIVER ( Naval Research Laboratory ) Alan J. WALLCRAFT ( Naval Research Laboratory )

Global and basin-scale simulations by the Naval Research Laboratory (NRL) Layered Ocean Model (NLOM) and the Hybrid Coordinate Ocean Model (HYCOM) have been used to study the circulation and dynamics of the Intra-Americas Sea (IAS), including the connectivity of variability from east of the Lesser Antilles to the Gulf of Mexico. These models have also been used in real-time eddy-resolving global and basin-scale ocean prediction. Our research using global model simulations without data assimilation and with a careful representation of the Lesser Antilles has shown that some North Brazil Retroflection rings can squeeze through the Lesser Antilles with reduced amplitude and diameter. The anti-cyclonic eddies propagate westward through the Caribbean at about 15 cm/sec and can greatly amplify due to flow instabilities of the Caribbean Current, especially during periods when the current is relatively strong. After about a 10 month transit across the Caribbean, some squeeze through the Yucatan Channel and some influence the timing of eddy shedding in the Gulf of Mexico. A significant correlation of .45 was found between Loop Current eddy shedding and eddies near the Lesser Antilles with a lag time of 11 months. However, the Caribbean eddies showed no statistically significant net influence on the mean eddy-shedding period or on the size and strength of shed eddies in the Gulf of Mexico. Two real-time ocean prediction systems have been developed, both with ~8 km resolution in the IAS. A 1/16° eddy-resolving, nearly global ocean prediction system using NLOM was developed by NRL. It has been run by the Naval Oceanographic Office, Stennis Space Center, MS, USA since 18 Oct 2000 and it became an operational system on 27 Sep 2001. The nowcasts are updated daily and 30-day forecasts are performed every Wednesday. Recently, the HYCOM Consortium began running a 1/12° HYCOM Atlantic prediction system in near real time under a grant from the National Ocean Partnership Program (NOPP). Both systems assimilate real-time altimeter sea surface height (SSH) data from ERS-2, GFO and JASON-1. Multi-channel sea surface temperature (MCSST) from satellite IR is also used. Real-time and archived results can be seen at the NLOM web site, http://www.ocean.nrlssc.navy.mil/global_nlom and the HYCOM web site, http://hycom.rsmas.miami.edu. The web pages include a zoom on the IAS, which shows snapshots and animations of nowcasts and forecasts of SSH, surface layer currents, and SST plus a variety of forecast verification statistics for the region. The 30-day NLOM forecasts typically show skill for at least 30 days. Both systems show the ability to map, track and forecast the evolution of individual eddies and current meanders.