Ocean currents from lowered acoustic Doppler current profilers (LADCP) aboard various cruises of the World Ocean Circulation Experiment (WOCE) project from 1991 to 1997
This collection holds the Lowered Acoustic Doppler Current Profile (LADCP) estimates of ocean currents collected for the World Ocean Circulation Experiment (WOCE) project. LADCPs estimate deep ocean absolute currents and shear. The project has been completed (WOCE ended in 1999).
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 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 3. 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.
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 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 3. 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.
Dataset Citation
- Cite as: Chereskin, Teresa K.; Firing, Eric; Hacker, Peter; Hummon, Julia M.; Kosro, P. Michael (2019). Ocean currents from lowered acoustic Doppler current profilers (LADCP) aboard various cruises of the World Ocean Circulation Experiment (WOCE) project from 1991 to 1997. [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/WOCE-LADCP. Accessed [date].
Dataset Identifiers
ISO 19115-2 Metadata
gov.noaa.nodc:WOCE-LADCP
Search Data |
|
Distribution Formats |
|
Ordering Instructions | Contact NCEI for other distribution options and instructions. |
Distributor |
NOAA National Centers for Environmental Information +1-301-713-3277 NCEI.Info@noaa.gov |
Dataset Point of Contact |
NOAA National Centers for Environmental Information ncei.info@noaa.gov |
Time Period | 1991-05-31 to 1997-11-19 |
Spatial Bounding Box Coordinates |
West: 30.338
East: -9.335
South: -67.
North: 64.902
|
Spatial Coverage Map |
General Documentation |
|
Associated Resources |
|
Publication Dates |
|
Data Presentation Form | Digital table - digital representation of facts or figures systematically displayed, especially in columns |
Dataset Progress Status | Complete - production of the data has been completed Historical archive - data has been stored in an offline storage facility |
Data Update Frequency | As needed |
Purpose | Physical oceanographers with need of understanding ocean currents. LADCP provides estimates of deep currents for large scale circulation studies and smaller scale mixing and internal wave investigations. |
Use Limitations |
|
Theme keywords |
NODC DATA TYPES THESAURUS
|
Data Center keywords |
NODC COLLECTING INSTITUTION NAMES THESAURUS
|
Platform keywords | NODC PLATFORM NAMES THESAURUS Global Change Master Directory (GCMD) Platform Keywords ICES/SeaDataNet Ship Codes |
Instrument keywords | NODC INSTRUMENT TYPES THESAURUS Global Change Master Directory (GCMD) Instrument Keywords |
Place keywords |
NODC SEA AREA NAMES THESAURUS
|
Project keywords |
NODC PROJECT NAMES THESAURUS
Cruise ID
|
Keywords | NCEI ACCESSION NUMBER |
Use Constraints |
|
Access Constraints |
|
Fees |
|
Lineage information for: series | |
---|---|
Processing Steps |
|
Acquisition Information (collection) | |
---|---|
Instrument |
|
Platform |
|
Last Modified: 2024-02-08T13:39:51Z
For questions about the information on this page, please email: ncei.info@noaa.gov
For questions about the information on this page, please email: ncei.info@noaa.gov