524 research outputs found
A compilation of current and temperature data from moored instruments during INDEX 1979, RRS "Discovery"
No full text
Intraseasonal variability in the southwestern Arabian Sea and its relation to the seasonal circulation
No full textAn analysis of TOPEX/POSEIDON altimeter data and in situ current and temperature data obtained between April 1995 and October 1996 from a moored array shows strong intraseasonal fluctuations in the southwestern Arabian Sea, an oceanic region where the Great Whirl (GW), a predominantly wind-generated, very energetic anticyclone, is present during the Southwest Monsoon. Fluctuation periods between 30 and 50 days, up to 100 days during some years, are observed in the 8-year altimetric dataset, mostly during late summer and fall. These fluctuations are largest in a 1000 km-wide region off the Somali, Omani and Yemeni coasts north of 5°N, suggesting a local generation mechanism. The in situ data at different moorings show strong and coherent fluctuations that are characterized by southwestward phase propagation and northward energy propagation. Their periods range from 30 to 60 days and increase steadily from July 1995 to January 1996. In the first stage, these periods are at and below the cut-off period of freely propagating, first baroclinic mode Rossby waves, but approach this theoretical limit later in the year. Instabilities of the flow in the transition region between the Southern Gyre and the GW are likely sources of these fluctuations
Multibeam bathymetry raw data (Kongsberg EM710 entire dataset) of RV METEOR during cruise M104
No full textMultibeam bathymetry raw data using the ship's own Kongsberg EM 710 multibeam echosounder was not continuously recorded during RV METEOR cruise M104. Data was recorded on 4 days between 2014-02-23 and 2014-02-27. This dataset contains a survey west of Namibia in the South Atlantic Ocean. The approximate average depth of the entire dataset is around 600m, covering parts of the the continental shelf and parts of the continental slope.
The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. No ancillary sound velocity profiles (SVP) files from the cruise are archived at the BSH, thus no SVP files are added to this dataset. Data analysis of the multibeam raw data revealed that SVP has not been changed during the survey.
This publication is conducted within the efforts of the German Marine Research Alliance in the core area 'Data management and Digitalization' (Deutsche Allianz Meeresforschung, DAM).
Data are unprocessed and therefore contains incorrect depth measurements (artifacts) without further processing. Note that refraction errors can be expected due to the lack of proper SVP. Overall, it appears that the data quality is rather moderate in the shelf area since the gridded hillshade data showed relatively few obstacles. However, in the deeper areas at the continental slope the data quality is really bad. The reason for this is unknown.
Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2022)
Microstructure measurements and estimates of entrainment in the Denmark Strait overflow plume
No full textTo examine processes controlling the entrainment of ambient water into the Denmark Strait overflow (DSO) plume/gravity current, measurements of turbulent dissipation rate were carried out by a quasi-free-falling (tethered) microstructure profiler (MSP). The MSP was specifically designed to collect data on dissipation-scale turbulence and fine thermohaline stratification in an ocean layer located as deep as 3500 m. The task was to perform microstructure measurements in the DSO plume in the lower 300 m depth interval including the bottom mixed layer and the interfacial layer below the non-turbulent ambient water. The MSP was attached to a Rosette water sampler rack equipped with a SeaBird CTDO and an RD Instruments lowered acoustic Doppler current profiler (LADCP). At a chosen depth, the MSP was remotely released from the rack to perform measurements in a quasi-free-falling mode. Using the measured vertical profiles of dissipation, the entrainment rate as well as the bottom and interfacial stresses in the DSO plume were estimated at a location 200 km downstream of the sill at depths up to 1771 m. Dissipation-derived estimates of entrainment were found to be much smaller than bulk estimates of entrainment calculated from the downstream change of the mean properties in the plume, suggesting the lateral stirring due to mesoscale eddies rather than diapycnal mixing as the main contributor to entrainment. Dissipation-derived bottom stress estimates are argued to be roughly one third the magnitude of those derived from log velocity profiles. In the interfacial layer, the Ozmidov scale calculated from turbulence dissipation rate and buoyancy frequency was found to be linearly proportional to the overturning scale extracted from conventional CTD data (the Thorpe scale), with a proportionality constant of 0.76, and a correlation coefficient of 0.77
Evidence for the influence of Atlantic-Ionian Stream fluctuations on the tidally induced internal dynamics in the Strait of Messina
No full textÜber den Monsunresponse der Zirkulation im westlichen äquatorialen Indischen Ozean
No full textTIB: RN 3292 (99) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Multibeam bathymetry raw data (Kongsberg EM 122 entire dataset) of RV METEOR during cruise M86/1c
No full textMultibeam bathymetry raw data using the ship's own Kongsberg EM 122 multibeam echosounder was almost continuously recorded during RV METEOR cruise M86/1c. Data were recorded on 11 days between 2011-12-12 and 2011-12-23. The approximate average depth of the entire dataset is around 3700m.
The cruise took place between 2011-12-06 and 2011-12-23 in the eastern North Atlantic Ocean. The main aim of this cruise was the calibration of the multibeam systems of RV METEOR at Gettysburg seamount.
The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. Ancillary sound velocity profiles (SVP) from the cruise are archived at the BSH, thus added to this dataset. Data analysis of the mulitbeam raw data reveled that SVP has been changed on several occasions during the cruise.
This publication is conducted within the efforts of the German Marine Research Alliance in the core area "Data management and Digitalization" (Deutsche Allianz Meeresforschung, DAM).
Data are unprocessed and therefore may contain incorrect depth measurements (artifacts) without further processing.
Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2021)
Faroe Bank Channel Overflow: Mesoscale Variability
No full textThe Faroe Bank Channel is the deepest connection through the Greenland–Scotland Ridge, where dense water formed north of the ridge flows southward over the sill crest, contributing to the formation of North Atlantic Deep Water. The overflow region is characterized by high mesoscale variability and energetic os- cillations, accompanied by a high degree of sea surface level variability. Here, 2-month-long time series of velocity and temperature from 12 moorings deployed in May 2008 are analyzed to describe the oscillations and explore their generation and propagation. The observed 2.5–5-day oscillations in velocity and temper- ature are highly coherent both horizontally and vertically, and they are associated with 100–200-m-thick boluses of cold plume water flowing along the slope. A positive correlation between temperature and relative vorticity and the distribution of clockwise/counterclockwise rotation across the slope suggest a train of al- ternating warm cyclonic and cold anticyclonic eddies, where the maximum plume thickness is located downslope of the eddy center. The along-slope phase velocity is found to be 25–60 cm s-1, corresponding to a wavelength of 75–180 km, while the vertical phase propagation is downward. The oscillations are present already in the sill region. The observations do not match predictions for eddies generated either by vortex stretching or baroclinic instability but agree broadly with properties of topographic Rossby waves
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