Physical Oceanography Technical Reports Copyright (c) 2013 University of Rhode Island All rights reserved. http://digitalcommons.uri.edu/physical_oceanography_techrpts Recent documents in Physical Oceanography Technical Reports en-us Mon, 20 May 2013 09:35:33 PDT 3600 cDrake CPIES Data Report November 2007 to December 2011 http://digitalcommons.uri.edu/physical_oceanography_techrpts/4 http://digitalcommons.uri.edu/physical_oceanography_techrpts/4 Mon, 28 Jan 2013 12:22:38 PST The goal of cDrake is to quantify the transport and understand the dynamic balances of the Antarctic Circumpolar Current (ACC) in Drake Passage. For this purpose, a transport line spanning all of Drake Passage and a local dynamics array of CPIES were deployed for a period of four years. A CPIES comprises an inverted echo sounder equipped with a bottom pressure gauge and a current meter tethered 50 m above the bottom.

In addition to the CPIESs, three current meter moorings were deployed along the continental margins for the initial two years of the field program. Subsequently, a current meter comparison mooring was deployed in a region of strong bottom currents for a period of one year. Conductivity-temperature-depth and lowered acoustic Doppler current profiler measurements were taken at each CPIES site. Shipboard acoustic Doppler current profiler measured the velocity structure along the cruise track.

In this report, the CPIES data collected during the field experiment are presented. The collection, processing and calibration of the CPIES are described.

]]> Karen L. Tracey et al. An Intercomparison of Four Models of Current Meter in High Current Conditions in Drake Passage http://digitalcommons.uri.edu/physical_oceanography_techrpts/3 http://digitalcommons.uri.edu/physical_oceanography_techrpts/3 Thu, 03 Jan 2013 10:13:55 PST Seven current meters representing four models were placed for an 11 month deployment on a stiffly buoyed mooring to intercompare their velocity measurements: two VMCMs, two Aanderaa RCM11s, two Aanderaa SEAGUARDSs, and a Nortek Aquadopp. The current meters were placed 6 m apart from each other at about 4000 m depth in an area of Drake Passage expected to have strong near-bottom currents, that were nearly independent of depth. Two high-current events occurred in bursts of semi-diurnal pulses lasting several days, one with peak speeds up to 67 cm/s and the other above 35 cm/s. The current speed measurements all agreed within about 5% when vector-averaged over simultaneous time intervals: the full time interval (198 days) when all instruments were working, and the two high-speed events lasting 21 days and 7 days. The VMCMs, chosen as the reference measurements, were found to measure the median of the mean-current magnitudes. The RCM11 and SEAGUARD current speeds had a nearly 1:1 relationship with the median. They agreed within 2% at higher speeds (35-70 cm/s), whereas in lower speed ranges (0-35 cm/s) the vector-averaged speeds for the RCM11s and SEAGUARDS were, respectively, 4-5% lower and 3-5% higher than the median. The Aquadopp current speeds were about 7% higher than the VMCMs over the range (0-40 cm/s) encountered through their shorter common time period.

]]> Maureen A. Kennelly et al. Inverted Echo Sounder Data Processing Manual http://digitalcommons.uri.edu/physical_oceanography_techrpts/2 http://digitalcommons.uri.edu/physical_oceanography_techrpts/2 Fri, 17 Jun 2011 06:44:03 PDT The Inverted Echo Sounder (IES) is an ocean bottom-moored instrument that measures the vertical acoustic travel time (VATT) round-trip from the sea floor to the sea surface and back. The VATT varies principally due to changes in the temperature profile of the water column, making the IES well-suited for monitoring changes in temperature structure and dynamic height (baroclinic signal). Currently, the Model 6.2, a combined IES, data-logger, and acoustic release, with optional measurements of bottom pressure, temperature and current speed and direction (with attached AanderaaTM Doppler current sensor) is produced at URI/GSO. Data are processed in situ and are available (optional) remotely by an acoustic telemetry link or expendable, satellite-link data shuttle. In addition to the IES-measured baroclinic signals, barotropic near-bottom pressure variations may be measured with the optional pressure sensor. A report was written in 1991 describing IES data processing (Fields et al., 1991). Since that report, significant improvements have been made to both IES hardware and software, warranting an update of the IES data processing. This report will document standard processing steps currently carried out for IES Models 6.1 and 6.2 at URI/GSO. A separate document, Inverted Echo Sounder User’s Manual, IES Model 6.2, describes the IES hardware and instrument configuration.

]]> Maureen Kennelly et al. Inverted Echo Sounder Data Report, Kuroshio Extension System Study (KESS) April 2004 to July 2006 http://digitalcommons.uri.edu/physical_oceanography_techrpts/1 http://digitalcommons.uri.edu/physical_oceanography_techrpts/1 Fri, 13 May 2011 11:51:48 PDT Maureen Kennelly et al.