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OAS accession Detail for 0222754
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| accessions_id: | 0222754 | archive |
|---|---|
| Title: | Ocean currents from lowered acoustic Doppler current profilers (LADCP) of the cDrake Experiment aboard RVIB Nathaniel B. Palmer cruise nbp0908, cDrake 3, in the Drake Passage from 2009-11-19 to 2009-12-19 (NCEI Accession 0222754) |
| Abstract: | This submission is for lowered Acoustic Doppler Current Profiler (LADCP) data collected as part of the cDrake experiment for RVIB Nathaniel B. Palmer cruise NBP0908, cDrake 3, 2009-11-19 to 2009-12-19. The goal of cDrake was to quantify the transport and understand the dynamical balances of the Antarctic Circumpolar Current (ACC) in Drake Passage. For this purpose, a transport line and a local dynamics array of Current and Pressure recording Inverted Echo Sounders (CPIES) and current meter moorings were deployed, spanning all of Drake Passage. Annual cruises were made to deploy (NBP0710), obtain data from (NBP0812, NBP0908, NBP1004) and recover (NBP1107) the CPIES. On each cruise, full depth CTD/LADCP profile casts were made for the purpose of calibrating the CPIES. The LADCP provides a full-depth profile of ocean current from a self-contained ADCP mounted on the CTD rosette. Using the conventional "shear method" for processing (Fischer and Visbeck, 1993), overlapping profiles of vertical shear of horizontal velocity are averaged and gridded, to form a full-depth shear profile. The shear profile is integrated vertically to obtain the baroclinic velocity (velocity profile with zero depth-averaged mean value); the unknown integration constant is the depth-averaged or barotropic velocity. This barotropic component is computed as the sum of the time-averaged, measured velocity and the ship drift (minus a small correction, less than 1 cm/s, to account for a nonconstant fall rate). A newer method ("inverse method") improves the calculation by adding additional constraints, such as shipboard ADCP (SADCP) and bottom tracking, to solve for the velocity profile using a linear least squares inverse technique (Visbeck, 2002). Lowered ADCP data makes use of ancillary information to produce the processed data product. The ancillary datasets include CTD data (used to estimate speed of sound, depth, vertical velocity), GPS (used to estimate ship drift), magnetic declination (for ADCP magnetic compass correction), and shipboard ADCP (added as a constraint for the inverse method). Data files for the processed set are in ASCII text, and NetCDF. Raw data are given in a variety of formats, some proprietary binary files, and made available in case a user prefers to reprocess the set from “level-0” status. |
| Date received: | 20201204 |
| Start date: | 20091119 |
| End date: | 20091219 |
| Seanames: | |
| West boundary: | -70.02 |
| East boundary: | -60.37 |
| North boundary: | -52.72 |
| South boundary: | -67.85 |
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| Submitter: | Chereskin, Dr. Teresa K. |
| Submitting institution: | University of California San Diego; Scripps Institution of Oceanography |
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| Number of observations: | |
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| Metadata version: | 3 |
| Keydate: | 2020-12-05 00:46:05+00 |
| Editdate: | 2024-09-10 16:46:42+00 |