Assessment of the Meridional Overturning Circulation and Meridional Heat Transport and Their Meridional Variability in the South Atlantic Ocean
- (National Oceanic and Atmospheric Administration)
This proposal represents a collaborative project between the University of Miami and the National Oceanic and Atmospheric Administration in which satellite altimetry observations will be the main data set used with other in situ data to estimate the Meridional Heat Transport (MHT) and Meridional Overturning Circulation (MOC) in the South Atlantic.
This proposal addresses the following research theme of the Ocean Surface Topography Science Team (OSTST): To supports studies in physical oceanography utilizing Jason-series mission data, as well as the combined ~20 year TP/Jason/Jason2 data in support of basic research to resolve the large-scale redistribution of heat and mass in the upper ocean. The research proposed here is also related to the U. S. CLIVAR AMOC program and makes use of observations obtained from the Global Ocean Observing System. Results obtained from analysis derived from these studies will be shared with the international South Atlantic Meridional Overturning Circulation (SAMOC) community, distributed through NOAA/AOML web pages, and published in peer-reviewed literatures. It is anticipated that assessments and analyses obtained throughout this work will serve in the design of future altimetry missions.
The Atlantic component of the Meridional Overturning Circulation (AMOC) is characterized by a northward flow of warm water in the upper layers from the South Atlantic into the North Atlantic, sinking and formation of North Atlantic Deep Water at high latitudes, and a southward return flow of cold water at depth. The AMOC carries a significant fraction of the total global ocean-atmosphere northward heat flux (e.g. Trenberth and Caron, 2001). The majority of this heat is lost to the atmosphere in the mid-latitudes where warm water meets cold, dry continental air masses. Changes in AMOC can have a direct and pronounced impact on a variety of climate phenomena (e.g., Vellinga and Wood, 2002), such as African and Indian monsoon rainfall, hurricane activity, and climate variability over North America and Western Europe. Thus, monitoring the AMOC variability is crucial for improving the understanding of important climate processes and for assessing future climate change.
Several efforts are currently underway involving in situ observations and numerical models seeking to design and establish a sustained observational system for the South Atlantic MOC. The PIs of this proposal contribute to several of these projects. The PIs propose here to incorporate satellite altimetry into these analyses in order to demonstrate how these crucial observations complement and expand the in situ observations and to expand our ability to observe the South Atlantic MOC and MHT. Of particular interest is to assess how well altimetry can be used to evaluate the spatial and temporal resolution of the MOC and MHT in the South Atlantic. It is expected that satellite altimetry observations will be able to extend assessment of MOC and MHT back to 1993 where sea height fields can be used as a proxy for upper ocean thermal structure and dynamics, and, therefore, to provide estimates in regions where there are no in situ observations and to develop 20-year indices against which model performance can be evaluated in the South Atlantic.