An Observing System for Meridional Heat Transport Variability in the Subtropical North Atlantic

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0241438 JohnsThe objective of this project is to develop a series of measurements that can provide a long-term, sustainable monitoring system for the meridional ocean heat flux in the subtropical North Atlantic. The goal is to provide continuous estimates of the heat flux and the meridional overturning circulation that are of suitable accuracy for detecting important trends and variability related to climate change. This goal is different from, but complementary to, the more established method of occupying high-resolution zonal trans-basin hydrographic sections to estimate the heat flux at irregular intervals. Regular estimates are needed to determine the magnitude and dominant time scales of variability, the climatological seasonal cycle, and to help filter out the higher frequency "noise" that may alias the determination of longer term heat ?ux variations from trans-basin sections that are widely spaced in time. The proposed program is a collaborative effort between the PI.'s and investigators from the Southampton Oceanography Centre in the United Kingdom who are funded as part of the Rapid Climate Change (RAPID) program of the National Environmental Research Council.The U.S. contribution to the proposed in-situ observation system consists of the following elements:1. Florida Current monitoring using the operational submarine cable, weekly shipboard Acoustic Doppler Current Pro?ler (ADCP) cross sections from a volunteer observing ship, and quarterly hydrographic/lowered-ADCP sections.2. Continuous moored time series measurements across the Deep Western Boundary Current (DWBC) and Antilles Current region east of the Bahamas, including semiannual hydrographic/lowered-ADCP sections.3. Repeated (quarterly) high-resolution volunteer observing ship XBT sections across the Atlantic from Gibraltar to Miami, on the "AX7" line.This component of the project will implement the moored component of element (2) for a four year period beginning in winter 2004, and to supplement element (3) with deeper reaching XBT's as a contribution to the CLImate VARiability and predictability (CLIVAR) program. The U.K. will support the trans-basin hydrographic cruises and an array of profiling moorings along 26.5?N that will complete the continuous time series observing system.