Science

The primary purpose of this cruise is to recover and then deploy again a well-instrumented surface mooring from Woods Hole Oceanographic Institute (WHOI) under the stratocumulus clouds found off Chile and Peru in the vicinity of 20S, 85W. The mooring is being maintained at that site as a long-term Surface Reference site, part of the Global Ocean Observing System. The first deployment was in October 2000. The buoy was recovered and redeployed in October 2001 and in October 2002. Cruises will follow each October-November. In addition to this work, the cruise will, if possible, recover an Ecuadorian buoy at roughly 2°S, 84°W and transfer key hardware to an Ecuadorian vessel, will collect underway oceanographic and meteorological data including aerosol data (Jason Tomlinson, Texas A&M) and atmospheric profiles, turbulent fluxes, and cloud radar data (Chris Fairall, NOAA ETL). At 20°S, 85°W a tsunami observing station will be installed (Juan Andueza, SHOA, Chile; Scott Stalin, NOAA PMEL), the existing WHOI surface mooring will be recovered, and a new WHOI surface mooring will be deployed. Extensive comparison of the shipboard sensors will be made with the existing buoy prior to recovery and the new buoy after deployment. During the six days at 20°S, 85°W, atmospheric and oceanographic observations will be carried out to add to our understanding of the stratus clouds. In addition, the cruise will host two teachers in the NOAA teacher at sea program, Deb Brice from San Marcos, CA and Viviana Zamorano from Arica, Chile.

The science objectives of the long-term mooring program off northern Chile are to observe the surface meteorology and air-sea exchanges of heat, freshwater, and momentum, to observe the temporal evolution of the vertical structure of the upper 500 m of the ocean, and to document and quantify the local coupling of the atmosphere and ocean in this region. Air-sea coupling under the stratus clouds is not well understood, and numerical models show broad scale sensitivity over the Pacific to how the clouds and air-sea interaction and this region are parameterized.

The approach taken to meet these objectives is to establish and maintain a well-instrumented surface mooring under the stratus deck and to use the in-situ data sets to investigate how well oceanic, atmospheric, and coupled models perform in this region. The buoy will carry two redundant sets of meteorological sensors (wind speed and direction, air and sea surface temperature, barometric pressure, relative humidity, incoming shortwave radiation, incoming longwave radiation, and precipitation). In the mooring line, temperature recorders, temperature/conductivity recorders, Vector Measuring Current Meters, and an Acoustic Doppler Current Profiler (ADCP) will be deployed to observe temperature, salinity, and velocity in the upper 500 m.

Using ship's equipment we will continuously sample surface meteorology, sea surface temperature and salinity, upper ocean currents using the ship's ADCP, and bottom topography (using the ship's SeaBeam). The transit from Ecuador to the WHOI mooring site will take about 5 days. We will stop at 2°S, 84°W to recover the Ecuadorian buoy. Along the way after that we will stop to test acoustic releases and the CTD. In international waters we will conduct the underway measurements mentioned above and deploy surface drifters and profiling ARGO floats. We will spend 6 days at the WHOI mooring site. The first day the tsunami station will be deployed followed by comparison of ship and WHOI buoy meteorological sensors, obtaining an end-point calibration of the moored sensors. Day 2 at the mooring site will be used to recover the mooring there now. Day 3 will be devoted to work on recovered instrumentation and preparation to deploy the new mooring. Day 4 will be used to deploy the new mooring, and days 5 and 6 will be used to compare shipboard sensors to the new mooring. We will make 4 deep CTDs at the mooring site, two while the old mooring is in the water and 2 while the new mooring is in the water. After leaving the site, we will continue east along 20°S, deploying surface drifters and ARGO floats and maintaining underway sampling into Chilean waters in accord with the clearance granted by Chile.

*Information provided by Dr. Bob Weller

Note for educators:
Consider this web site, as well as the other NOAA Teacher at Sea Web sites, a resource for teaching your students. If you would like more information about the NOAA Teacher at Sea program or other NOAA Education Materials, please contact Jennifer Hammond (Jennifer.hammond@noaa.gov).

Consider this web site, as well as the EPIC website, a resource for teaching your students.

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