ENSO suppression due to weakening of the North Atlantic thermohaline circulation

Changes of the North Atlantic thermohaline circulation (THC) excite wave patterns that readjust the thermocline globally. This paper examines the impact of a freshwater-induced THC shutdown on the depth of the Pacific thermocline and its subsequent modification of the El Niño–Southern Oscillation (ENSO) variability using an intermediate-complexity global coupled atmosphere–ocean–sea ice model and an intermediate ENSO model, respectively. It is shown by performing a numerical eigenanalysis and transient simulations that a THC shutdown in the North Atlantic goes along with reduced ENSO variability because of a deepening of the zonal mean tropical Pacific thermocline. A transient simulation also exhibits abrupt changes of ENSO behavior, depending on the rate of THC change. The global oceanic wave adjustment mechanism is shown to play a key role also on multidecadal time scales. Simulated multidecadal global sea surface temperature (SST) patterns show a large degree of similarity with previous climate reconstructions, suggesting that the observed pan-oceanic variability on these time scales is brought about by oceanic waves and by atmospheric teleconnections

Pairing and duality of algebraic quantum groupoids

Algebraic quantum groupoids have been developed by two of the authors (AVD and SHW) of this note in a series of papers. Regular multiplier Hopf algebroids are obtained also by two authors (TT and AVD). Integral theory and duality for those have been studied by one author here (TT). Finally, again two authors of us (TT and AVD) have investigated the relation between weak multiplier Hopf algebras and multiplier Hopf algebroids. In the paper 'Weak multiplier Hopf algebras III. Integrals and duality' (by AVD and SHW), one of the main results is that the dual of an algebraic quantum groupoid, admits a dual of the same type. In the paper 'On duality of algebraic quantum groupoids' (by TT), a result of the same nature is obtained for regular multiplier Hopf algebroids with a single faithful integral. The duality of regular weak multiplier Hopf algebras with a single integral can be obtained from the duality of regular multiplier Hopf algebroids. That is however not the obvious way to obtain this result. It is more difficult and less natural than the direct way. We will discuss this statement further in the paper. Nevertheless, it is interesting to investigate the relation between the two approaches to duality in greater detail. This is what we do in this paper. We build further on the intimate relation between weak multiplier Hopf algebras and multiplier Hopf algebroids. We now add the presence of integrals. That seems to be done best in a framework of dual pairs. It is in fact more general than the duality of these objects coming with integrals

On the freshening of the northwestern Weddell Sea continental shelf

12 páginas, 10 figuras, 2 tablas.We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.Una parte de la financiación de esta investigación se debe a los proyectos ATOS (POL2006-00550/CTM) y ESASSI (POL2006-11139-C02-01/CGL), subvencionados por el Subprograma de Investigación Polar del Ministerio de Ciencia e Innovación y el por el Fondo Europeo de Desarrollo Regional de la Unión Europea.Peer reviewe

Globally clustered chimera states in delay--coupled populations

We have identified the existence of globally clustered chimera states in delay coupled oscillator populations and find that these states can breathe periodically, aperiodically and become unstable depending upon the value of coupling delay. We also find that the coupling delay induces frequency suppression in the desynchronized group. We provide numerical evidence and theoretical explanations for the above results and discuss possible applications of the observed phenomena.Comment: Accepted in Phys. Rev. E as a Rapid Communicatio

Why so few Nobel Prizes for cancer researchers?:An analysis of Nobel Prize nominations for German physicians with a focus on Ernst von Leyden and Karl Heinrich Bauer

Purpose!#!To date, 11 scientists have received the Nobel Prize for discoveries directly related to cancer research. This article provides an overview of cancer researchers nominated for the Nobel Prize from 1901 to 1960 with a focus on Ernst von Leyden (1832-1910), the founder of this journal, and Karl Heinrich Bauer (1890-1978).!##!Methods!#!We collected nominations and evaluations in the archive of the Nobel committee of physiology or medicine in Sweden to identify research trends and to analyse oncology in a Nobel Prize context.!##!Results!#!We found a total of 54 nominations citing work on cancer as motivation for 11 candidates based in Germany from 1901 to 1953. In the 1930s, the US became the leading nation of cancer research in a Nobel context with nominees like Harvey Cushing (1869-1939) and George N. Papanicolaou (1883-1962).!##!Discussion!#!The will of Alfred Nobel stipulates that Nobel laureates should have 'conferred the greatest benefit to mankind'. Why were then so few cancer researchers recognized with the Nobel medal from 1901 to 1960? Our analysis of the Nobel dossiers points at multiple reasons: (1) Many of the proposed cancer researchers were surgeons, and surgery has a weak track record in a Nobel context; (2) several scholars were put forward for clinical work and not for basic research (historically, the Nobel committee has favoured basic researchers); (3) the scientists were usually not nominated for a single discovery, but rather for a wide range of different achievements

Is the wind-stress forcing essential for the meridional overturning circulation?

We use a global coupled atmosphere‐ocean sea‐ice model of intermediate complexity to demonstrate that wind‐forcing is a crucial element to sustain meridional overturning flow in the Atlantic. Neglecting wind‐stress in our multi‐century‐long simulations leads to a complete shutdown of the conveyor belt circulation. This result may have tremendous impacts for an assessment of the sensitivity of 2‐d climate models which typically do not capture wind‐driven gyres. It is argued that wind effects may be a key element in determining the fate and length of a collapsed THC state. Possible paleo implications will be discussed

Is the windstress essential for the global meridional overturning circulation

We use a global coupled atmosphere-ocean sea-ice model of intermediate complexity to demonstrate that wind-forcing is a crucial element to sustain meridional overturning flow in the Atlantic. Neglecting wind-stress in our multi-century-long simulations leads to a complete shutdown of the conveyor belt circulation. This result may have tremendous impacts for an assessment of the sensitivity of 2-d climate models which typically do not capture wind-driven gyres. It is argued that wind effects may be a key element in determining the fate and length of a collapsed THC state. Possible paleo implications will be discussed