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NOAA/AOML Altimetric Products

Joaquin Trinanes(1) , Gustavo Goni(2) , and Pedro Di Nezio(1)

(1) University of Miami, 4301 Rickenbacker Causeway, Miami, FL 33149, United States
(2) NOAA/AOML, 4301 Rickenbacker Causeway, Miami, FL 33149, United States

Abstract

NOAA/AOML distributes on its web server several products derived from altimetric sea height anomaly fields, for weather and climate studies. These products are validated using data from a variety of platforms, such as XBTs, drifters, moorings, and profiling floats:

1. Near-real time global geostrophic currents 2. Near-real time Tropical Cyclone Heat Potential (TCHP) 3. Surface currents 4. Upper ocean heat storage

The global near real-time surface currents, a project of the NOAA CoastWatch Caribbean Node that is housed at NOAA/AOML, are produced daily using altimeter-blended data obtained from NRL. A Java-powered web interface allows users to dynamically specify the output settings. The geostrophic current estimates involve two components: a mean topography, which can be selected from a menu offering several choices; and an anomaly component, obtained from the altimeter sea height anomaly fields. In addition to the current velocity vectors, which are overlaid on the image, concurrent drifter paths can also be displayed superimposed to the current field. This feature serves as a way to visually compare and evaluate modeled and observed currents. Results can yield important information on the dynamics and structure of the upper ocean circulation. This implementation is a showcase of how altimetry can serve this purpose.

The fields of TCHP, a parameter proportional to the integrated vertical temperature from the sea surface to the depth of the 26C isotherm, are produced for each of the seven basins where tropical cyclones occur with a two-day delay. These fields are estimated within a two-layer reduced gravity scheme using near-real time sea surface temperature and climatological fields of vertical temperature. The TCHP fields have shown to be a critical tool to investigate the role that the ocean has in tropical cyclone intensification. Typical examples where the ocean has been closely linked to hurricane intensification are hurricanes Opal (1995), Brett (1999) and Katrina (2005). The validation of these fields are done in near-real using temperature profiles available through the GTS.

The spatial and temporal variability of several surface currents, which are key components of the Meridional Overturning Circulation (MOC) are also being monitored on this web site. One of the goals of this monitoring is to identify cycles in the variability of these currents that could be linked to climate signals. Some of the currents monitored through this project are the Agulhas and North Brazil Currents, and their associated rings, the Yucatan Straits and Florida currents.

 

 

                 Last modified: 07.10.03