This collection holds the Lowered Acoustic Doppler Current Profile (LADCP) estimates of ocean currents collected for the Climate Variability (CLIVAR) project. LADCPs estimate deep ocean absolute currents and shear. The project has been completed (CLIVAR ended in 2014). 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.

This collection holds the Lowered Acoustic Doppler Current Profile (LADCP) estimates of ocean currents collected for the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). GO-SHIP brings together scientists with interests in physical oceanography, the carbon cycle, marine biogeochemistry and ecosystems, and other users and collectors of ocean interior data, and coordinates a network of globally sustained hydrographic sections as part of the global ocean/climate observing system including physical oceanography, the carbon cycle, marine biogeochemistry and ecosystems. To understand the ocean currents through the water column, LADCPs are employed. LADCPs estimate deep ocean absolute currents and shear. LADCP specialists of the University of Hawaii (UH) and the Lamont-Doherty Earth Observatory (LDEO) serve as the conduit to integrate LADCP data from international sources into a common database in support of GO-SHIP. LADCP data in this collection begin in 2015 with 1-2 cruises per year, which revisit World Ocean Circulation Experiment (WOCE) transect lines across the major ocean basins. Files within each granule of the collection consist of either ASCII text or NetCDF formats for the science-ready data, though there are some proprietary formats for the raw data directories, which are included to give advanced users the opportunity to reprocess the set. 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 distances from the transducer head. In this application, the ADCP is mounted on a Conductivity-Temperature-Depth (CTD) rosette frame and lowered along with the rest of the package, hence called Lowered ADCP ("LADCP"). 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. Lowered ADCP data requires ancillary information to calculate ocean velocities and turbulence parameters. Ancillary measurements included in the submission package include Conductivity, Temperature, Depth, at 24Hz, with 1Hz position, and shipboard ADCP data. For the NCEI archive of GO-SHIP LADCP, 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. 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.

This dataset contains the Lowered Acoustic Doppler Current Profile (LADCP) estimates of ocean currents and shear as well as water temperature, salinity, and others taken by CTD in a profile to deep waters from the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). 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 R.Revelle for cruise TN390 on World Ocean Circulation Experiment lines A22 from 2022-04-30 to 2022-06-10. This cruise is part of the NCEI collection for GO-SHIP LADCP. The finalized datasets have been assembled and submitted to NCEI by the LADCP data management staff of University of Hawaii and the Lamont-Doherty Earth Observatory. The originators of each LADCP set are defined within the accession documentation. Data files for the processed set are in ASCII text, PDF, and NetCDF. Raw data are given in proprietary binary files and made available in case a user prefers to reprocess the set from “level-0” status.

This dataset contains the Lowered Acoustic Doppler Current Profile (LADCP) estimates of ocean currents and shear, as well as water temperature, salinity and others taken by CTD in a profile to deep waters from the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). 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 R.Revelle for cruise TN390 on World Ocean Circulation Experiment lines A22 from 2022-06-13 to 2022-07-16. This cruise is part of the NCEI collection for GO-SHIP LADCP. The finalized datasets have been assembled and submitted to NCEI by the LADCP data management staff of University of Hawaii and the Lamont-Doherty Earth Observatory. The originators of each LADCP set are defined within the accession documentation. Data files for the processed set are in ASCII text, PDF, and NetCDF. Raw data are given in proprietary binary files and made available in case a user prefers to reprocess the set from “level-0” status.

This collection holds the lowered Acoustic Doppler Current Profiler (LADCP) data collected from annual cruises within October to December on the RVIB Nathaniel B. Palmer as part of the cDrake Experiment 2007-2011. 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.

Current meter data from the ADCP instruments of BE/335 and BW/333 from January 3, 1991 to November 26, 1992 collected as part of the World Ocean Circulation Experiment (WOCE).

This dataset includes ADCP data collected aboard NOAA Ship Ronald H. Brown in the South Pacific Ocean from 2008-10-20 to 2008-11-02 during originator cruise RB0806STRATUS9VOCALS1. These data include CURRENT SPEED - EAST/WEST COMPONENT (U) and CURRENT SPEED - NORTH/SOUTH COMPONENT (V). The instruments used to collect these data include ADCP and GPS. These ADCP data represent the raw dataset. Post processed quality assessed data are not available in this accession.

This dataset includes ADCP data collected aboard NOAA Ship Ronald H. Brown in the South Atlantic Ocean from 2011-10-06 to 2011-10-14 during originator cruise RB1102B. These data include CURRENT SPEED - EAST/WEST COMPONENT (U) and CURRENT SPEED - NORTH/SOUTH COMPONENT (V). The instruments used to collect these data include ADCP and GPS. These ADCP data represent the raw dataset. Post processed quality assessed data are not available in this accession.

This dataset includes ADCP data collected aboard NOAA Ship Ronald H. Brown in the South Atlantic Ocean from 2011-10-05 to 2011-10-30 during originator cruise RB1102B. These data include CURRENT SPEED - EAST/WEST COMPONENT (U) and CURRENT SPEED - NORTH/SOUTH COMPONENT (V). The instruments used to collect these data include ADCP and GPS. These ADCP data represent the raw dataset. Post processed quality assessed data are not available in this accession.