Objectives: To parameterize the vertical fluxes and rate of TKE dissipation in the upper mixed layer and buoyancy and momentum fluxes in the atmospheric marine boundary layer during the passage of an adverse weather front over the warm continental self, off the east coast of Florida. Both fixed and autonomous underwater vehicle (AUV) platforms will be utilized in making the measurements. The aim is to investigate the impact of the front on mixing, air-sea interaction, and sediment transport in the shallow water column. Pertinent flow and thermohaline data collected during the experiment will help parameterize the active processes in the air sea interaction during the passage of the front. The measurements will, in particular, be utilized to test the validity of current, laboratory based, sub-grid closure models for predicting turbulence levels in the water column over the continental shelf. Estimates of the storm induced distribution of rates of turbulent kinetic energy production and dissipation, the Reynolds stresses and the heat and salt fluxes in the water column will be obtained.
Dates of Experiment: April 3 - April 27, 2000. Atmospheric and surface current measurements will be made continuously over this period. A 5-day window over this period is targeted for AUV-based measurements.
Location: On the NSWC range off Ft. Lauderdale, approximately at 260 2.9'N, 800 5.4'W.
: AUV surveys were carried out on April 8-9 and April 18-19 to capture two cold front events.
AUV Mission 1. During the first cold front mission, the AUV operated continuously for around 17 hours. Downward-looking ADCP and in-situ CTD measurements were made from the AUV and from the research ship, the Stephan. Unfortunately, the turbulence package cpu malfunctioned after 2 hours of operation. Also the upward-looking ADCP malfunctioned. Nevertheless, the measurements from the mission will provide important information about a fairly good cold front.
AUV Mission 2. The cpu in the turbulence package was replaced, a heat sink was added to the package and the upward looking ADCP was made operational for this second cold front mission. The mission involved AUV survey of the water column over 22 hours, in three extended periods (3 hours, 12 hours, and 5 hours). All instruments functioned properly. Besides the CTD and ADCP data from the AUV and research ship platforms, around 1.5Gbytes of turbulence data have been gathered, setting new records for the available continuous time series for microstructure measurements.
During both missions the OSCR surface current radar and the ASIS buoy were in place continously recording corresponding measurements. The OSCR measurements can be seen online at http://storm.rsmas.miami.edu/awe00/anim/0408.html
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Click here for a Map of the region and AUV survey site
Click here for: Plan for OEX-AUV deployment
Click here to track the cold fronts approaching South Florida.
Click here for daily wind cast information.
Click here for daily temperature cast information
Click here for local atmospheric data at Miami
Click here for local atmospheric data at Lake Worth C-MAN buoy
Click here for water temperature information
Click here for wave height information
Click here for water current and wind data at SFTF(updated every 15 minutes)
Click here for sea
surface temperature satellite map
Participants:
Investigators:
- Manhar Dhanak (PI), FAU. Phone: 954 924 7242/561 297 2827;
Home: 561 737 4317- Ken Holappa (Co-PI), FAU. Phone: 954 924 7219
- Rolf Lueck University of Victoria.
- Nick Shay, University of Miami.
- William Drennan, University of Miami
AUV team: Jim Jalbert, Reed Christenson, Joe Kuntz, Samuel Smith, FAUGraduate Students: Micheal Chernys (954 693 8757), Eric Liendecker (561 620 2875), FAU.
Technical Staff: Robert Raye (954 924 4571)
Funding Agency: Office of Naval Research. Program Manager: Tom Curtin.
AUV platforms: An Ocean EXplorer-series AUV with extended payload and MADDOG. In-situ turbulence measurement surveys in the upper mixed layer and the close-bottom boundary layer will be made using these AUV platforms, before, during and following an adverse weather front. Significant regions will be surveyed, using the full potential of the AUV platforms. The measurements in the upper mixed layer will be made using the OEX. The vehicle will carry the turbulence package ( consisting of two shear probes, a pressure and pressure derivative sensor, a microstructure thermister, a microstructure conductivity sensor and a 3-axis accelerometer), an upward looking and a downward looking 1200kHz ADCPs, a CTD package, a GPS system, a Watson - block self motion package . The MADDOG, a smaller AUV, will survey the close-bottom boundary layer at an altitude of less than 1m. It will be fitted with a turbulence package (as above), a Falmouth CTD package, a Tritech altimeter and a self motion package.
Surface Current Measurements: Surface currents will be measured using OSCR in VHF mode.
Meteorological measurements: Buoyancy flux, wind stress, air temperature, humidity and wave spectrum measurements will be made from ASIS spar buoy which will be located at 260 2.4'N, 800 5.43'W. Local wind velocity, air temperature, humidity, solar irradiance will also be recorded by a MET station mounted on a Navy tower at Dania.
Wave Measurement: Wave measurements will be made by the ASIS buoy.
Bottom mounted instruments: 2 ADCPs located on the site at : (i) 260 3.7405'N, 800 3.5359'W (Deep). (ii) 260 5.7355'N, 800 5.2263'W (Shallow).
Other Measurements:
Ship : R/V Stephan
Seatech: 954 924 7297, 954 924 7296; Cell phone 954 240 1516
Contacts: B Franks: 954 924 7061, 954 231 0629(Pager), Chuck
Perkins: 954 970 6158(Pager )
Last Updated on 4/7/2000 by M Dhanak
