Improving Wind-Based Upwelling Estimates Off the West Coasts of North and South America

摘要

Weekly upwelling was estimated at 25 sites off the North and South American west coasts from August 1999 to December 2001 using geostrophically derived winds, model-derived winds from the U.S. Navy's global atmospheric (NOGAPS) model, and QuikSCAT satellite-measure winds. Satellite-measured winds, verified with 15 U.S. west coast buoys, were within 1.3 m s-1 and 26 RMS. Upwelling estimates derived from geostrophic winds using the Pacific Fisheries Environmental Laboratory (PFEL) technique were compared to those derived from both satellite-measured winds and model- derived winds. Upwelling estimates from model-derived winds agreed with satellite-based estimates at all 14 North American sites and 9 of 11 South American sites. Estimates from geostrophic winds agreed with satellite-based estimates at 12 of 14 North American sites and 7 of 11 South American sites. These comparisons showed that upwelling estimates based on the Navy's global model winds were accurate in more regions than those based on geostrophic winds. A fine-scale upwelling investigation using the Navy's high-resolution atmospheric model (COAMPS) revealed narrow near-shore bands of strong wind-stress and wind-stress-curl missed in the above upwelling estimates. Improvements in the depiction of coastal upwelling will require wind data and upwelling estimates with at least a 10 km resolution.