Supplement to: Ocean Climate Observations and Analyses NTAS Ship Charter

Robert Weller, Woods Hole Oceanographic Institution

Abstract

The Woods Hole Oceanographic Institution (WHOI) Ocean Reference Station (ORS) project is carried out to provide critical, sustained observations of a key region of the ocean – theeasterly trade wind region that covers roughly 50% of the ocean surface in a wide belt spanning the equator. This region is where the equatorial concentration of solar heating leads to net oceanheating and where evaporation and latent heat flux provide energy and moisture to drive the atmosphere over a range of scales, from the general Hadley circulation that is the source of the trade winds down to intense hurricanes intensified by that heat and moisture. Integrated across the expanse of the trade wind regions, errors and uncertainties in the exchange of heat, freshwater, momentum, and compounds such as CO2, can challenge our ability to understand the way in which the atmosphere and ocean interact and how that interaction should be represented in models used to predict weather and climate variability. To provide sustained, climate-quality observing of the trade wind region, we have developed surface moorings with the capability of making sustained, accurate observations at the sea surface and in the water column, and have chosen and occupied three key trade wind sites. The Northwest Tropical Atlantic Station (NTAS) at 15°N, 51°W is one of three sites maintained by WHOI. The NTAS mooring samples the trade winds close to the convergence zone, which is the ascending branch of the Hadley circulation and lies in the North Atlantic