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OAS accession Detail for 0206572
| << previous | |revision: 2 |
| accessions_id: | 0206572 | archive |
|---|---|
| Title: | Ocean currents from lowered acoustic Doppler current profilers (LADCP) aboard R/V Knorr cruise KN9412 along World Ocean Circulation Experiment (WOCE) section I08S_I09S from 1994-12-01 to 1995-01-19 (NCEI Accession 0206572) |
| Abstract: | This data set contains the Lowered Acoustic Doppler Current Profile (LADCP) estimates of ocean currents and shear in a profile to deep waters. A raw and a processed version are given in each dataset, both of which include ancillary data streams from CTD, ship navigation, and shipboard ADCP. The data were collected on R/V Knorr for cruise KN9412 on World Ocean Circulation Experiment (WOCE) section I08S_I09S from 1994-12-01 to 1995-01-19. This cruise is one of 53 cruises within the NCEI collections WOCE-LADCP and CLIVAR-LADCP. The finalized datasets have been assembled and submitted to NCEI by the University of Hawaii and the Scripps Institution of Oceanography. The originators of each LADCP set are defined within the accession documentation. |
| Date received: | 20190628 |
| Start date: | 19941206 |
| End date: | 19950118 |
| Seanames: | Indian Ocean, Southern Ocean |
| West boundary: | 81.8629 |
| East boundary: | 115.06199 |
| North boundary: | -30.29669 |
| South boundary: | -64.86489 |
| Observation types: | physical, profile |
| Instrument types: | ADCP |
| Datatypes: | CURRENT SPEED - EAST/WEST COMPONENT (U), CURRENT SPEED - NORTH/SOUTH COMPONENT (V), CURRENT SPEED - UP/DOWN COMPONENT (W) |
| Submitter: | Hummon, Julia M. |
| Submitting institution: | University of Hawai'i at Mānoa |
| Collecting institutions: | University of Hawai'i at Mānoa, Woods Hole Oceanographic Institution |
| Contributing projects: | WOCE |
| Platforms: | Knorr (316N) |
| Number of observations: | |
| Supplementary information: | ADCPs use the Doppler shift of an outgoing frequency along a beam to return measured velocity along that beam. ADCPs typically have 4 beams, allowing measurement of velocity in 3 dimensions, in bins of varying distance from the transducer head. In this application, the ADCP is mounted on a CTD rosette frame and lowered along with the rest of the package, hence called Lowered ADCP ("LADCP"). LADCP requires less ship time in estimating deep currents as compared to historic measuring systems such as Pegasus systems. The goal is to determine water velocities to the full depth of the ocean for each LADCP deployment. Ocean velocities are very small (few cm/s), especially in the deep water. The package is typically lowered or raised at 1m/s for much of the water column, creating a challenging data processing situation. To reduce the LADCP measurements, one must utilize other data streams such as CTD at both standard levels and at the highest frequency of recording, GPS positions, ship navigation, ocean depth, and shipboard ADCP. Lowered ADCP data requires ancillary information to improve the processed data product. Over generations, the processing has improved and these ancillary components are systematically collected along with the LADCP data. In older datasets, they may be missing entirely. The directory structure and naming convention for the submitted LADCP datasets (WOCE plus CLIVAR) attempt to rationalize 20 years of data acquisition and processing by a collection of scientists who were inventing the field of LADCP acquisition and processing, so there is some variety in the organization and naming of the original datasets. Evolution of the instrumentation and processing techniques have continued. For the NCEI archive, three levels are defined: 1) Level-0, raw LADCP and ancillary data streams of the down- and up-cast, 2) Level-1, processed LADCP and ancillary data streams for the down-, up-, and averaged cast, and 3) Level-2 science-ready subset of select parameters. Presently only Levels 0 and 1 will be archived since work continues for defining error associated with Level 2. Note, Level 1 data are "as processed" based on the processing code pertinent at that time. There is one processed file per station cast. The ancillary streams of Level-1 are the basic oceanographic variables of interest, and may also include a variety of additional fields associated with the processing. |
| Availability date: | |
| Metadata version: | 2 |
| Keydate: | 2019-11-06 07:30:08+00 |
| Editdate: | 2020-05-07 16:11:21+00 |