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Featured researches published by Anke Schneider.
Geophysical Research Letters | 2007
Anke Schneider; Douglas W.R. Wallace; Arne Körtzinger
Total alkalinity (AT) was measured during the Meteor 51/2 cruise, crossing the Mediterranean Sea from west to east. AT concentrations were high (∼2600 μmol kg−1) and alkalinity-salinity-correlations had negative intercepts. These results are explained by evaporation coupled with high freshwater AT inputs into coastal areas. Salinity adjustment of AT revealed excess alkalinity throughout the water column compared to mid-basin surface waters. Since Mediterranean waters are supersaturated with respect to calcite and aragonite, the excess alkalinity likely reflects alkalinity inputs to coastal areas close to regions of deep and intermediate water formation. An alkalinity budget shows that main alkalinity inputs come from the Black Sea and from rivers, whereas the Strait of Gibraltar is a net sink. The major sink appears to be carbonate sedimentation. The basin-average net calcification rate and CaCO3 sedimentation was estimated to be 0.38 mol m−2 yr−1. The estimated residence time of AT is ∼160 yr.
Journal of Geophysical Research | 2012
Donata Banyte; Toste Tanhua; Martin Visbeck; Douglas W.R. Wallace; Johannes Karstensen; Gerd Krahmann; Anke Schneider; Lothar Stramma; Marcus Dengler
A deliberate tracer release experiment in 2008–2010 was used to study diapycnal mixing in the tropical northeastern Atlantic. The tracer (CF3SF5) was injected on the isopycnal surface σΘ = 26.88 kg m−3, which corresponds to about 330 m depth. Three surveys, performed 7, 20, and 30 months after the release, sampled the vertically and laterally expanding tracer patch. The mean diapycnal mixing estimate over the entire region occupied by the tracer and the period of 30 months was found to be (1.19 ± 0.18) × 10−5 m2 s−1, or, alternatively, (3.07 ± 0.58) × 10−11 (kg m−3)2 s−1 as computed from the advection-diffusion equation in isopycnal coordinates with the thickness-weighted averaging. The latter method is preferable in the regions of different stratification for it yields local diapycnal mixing estimates varying less with stratification than their Cartesian coordinate counterparts. Results of this study are comparable to the results of the North Atlantic tracer release experiment (NATRE). However, the internal wave-wave interaction models predict reduced mixing from the breaking of internal waves at low latitudes. Thus, the diapycnal diffusivity found in this study is higher than parameterized by the low latitude of the site (4°N–12°N).
Meteor-Berichte, M80/1 . Leitstelle Deutsche Forschungsschiffe, Inst. f. Meereskunde, Hamburg, Germany, 49 pp. | 2011
Peter Brandt; D. Brownell; Marcus Dengler; Sven-Helge Didwischus; Sandra Fehsenfeld; Sebastian Fessler; Jürgen Fischer; Andreas Funk; Tobias Großkopf; Johannes Hahn; H. Halm; Verena Hormann; Uwe Koy; Gerd Krahmann; A. Krupke; V. Melo; Mario Müller; Gerd Niehus; Uwe Papenburg; Andreas Pinck; Anke Schneider; Tobias Steinhoff; Tim Stöven; T. Truscheit; N. Viera; H. von Neuhoff; Thibaut Wagener; Kathrin Wuttig; Rainer J. Zantopp
METEOR cruise 80/1 was a contribution to the SFB 754 “Climate-Biogeochemistry Interactions in the Tropical Ocean”. Shipboard, glider and moored observations are used to study the temporal and spatial variability of physical and biogeochemical parameters within the oxygen minimum zone (OMZ) of the tropical North Atlantic. As part of the BMBF “Nordatlantik” project, it further focuses on the equatorial current system including the Equatorial Undercurrent (EUC) and intermediate currents below. During the cruise, hydrographic station observations were performed using a CTD/O2 rosette, including water sampling for salinity, oxygen, nutrients and other biogeochemical tracers. Underway current measurements were successfully carried out with the 75 kHz ADCP borrowed from R/V POSEIDON during the first part of the cruise, and R/V METEOR’s 38 kHz ADCP during the second part. During M80/1, an intensive mooring program was carried out with 8 mooring recoveries and 8 mooring deployments. Right at the beginning of the cruise, a multidisciplinary mooring near the Cape Verde Islands was recovered and redeployed. Within the framework of SFB 754, two moorings with CTD/O2 profilers were recovered and redeployed with other instrumentation in the center and at the southern rim of the OMZ of the tropical North Atlantic. The equatorial mooring array as part of BMBF “North Atlantic” project consists of 5 current meter moorings along 23°W between 2°S and 2°N. It is aimed at quantifying the variability of the thermocline water supply toward the equatorial cold tongue which develops east of 10°W during boreal summer. Several glider missions were performed during the cruise. One glider was recovered that was deployed two months earlier. Another glider was deployed for two short term missions, near the equator for about 8 days and near 8°N for one day. This glider was equipped with a new microstructure probe in addition to standard sensors, i.e. CTD/O2, chlorophyll and turbidity.
Journal of Geophysical Research | 2010
Anke Schneider; Toste Tanhua; Arne Körtzinger; Douglas W.R. Wallace
Ocean Science | 2013
Anke Schneider; Toste Tanhua; Wolfgang Roether; Reiner Steinfeldt
Schneider, Anke, Tanhua, Toste, Körtzinger, Arne and Wallace, Douglas W.R. (2012) An evaluation of tracer fields and anthropogenic carbon in the equatorial and the tropical North Atlantic Deep Sea Research Part I: Oceanographic Research Papers, 67 . pp. 85-97. DOI 10.1016/j.dsr.2012.05.007 <http://dx.doi.org/10.1016/j.dsr.2012.05.007>. | 2012
Anke Schneider; Toste Tanhua; Arne Körtzinger; Douglas W.R. Wallace
Journal of Geophysical Research | 2012
Donata Banyte; Toste Tanhua; Martin Visbeck; Douglas W.R. Wallace; Johannes Karstensen; Gerd Krahmann; Anke Schneider; Lothar Stramma; Marcus Dengler
Banyte, Donata, Tanhua, Toste, Visbeck, Martin, Wallace, Douglas W.R., Karstensen, Johannes, Krahmann, Gerd, Schneider, Anke and Stramma, Lothar (2011) Diapycnal diffusivity at the upper boundary of the North Tropical Atlantic Oxygen Minimum Zone [Poster] In: WCRP OSC Climate Research in Service to Society, 24.-28.10.2011, Denver, USA. | 2011
Donata Banyte; Toste Tanhua; Martin Visbeck; Douglas W.R. Wallace; Johannes Karstensen; Gerd Krahmann; Anke Schneider; Lothar Stramma
Geophysical Research Letters | 2007
Anke Schneider; Douglas W.R. Wallace; Arne Körtzinger
[Talk] In: CIESM Congress, 28.10.-01.11.2013, Marseille, France . | 2013
Tim Stöven; Toste Tanhua; Anke Schneider; Wolfgang Roether