MPI‐ESM is a new version of the global Earth system model developed at the Max Planck Institute for Meteorology. This paper describes the ocean state and circulation as well as basic aspects of ...variability in simulations contributing to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The performance of the ocean/sea‐ice model MPIOM, coupled to a new version of the atmosphere model ECHAM6 and modules for land surface and ocean biogeochemistry, is assessed for two model versions with different grid resolution in the ocean. The low‐resolution configuration has a nominal resolution of 1.5°, whereas the higher resolution version features a quasiuniform, eddy‐permitting global resolution of 0.4°. The paper focuses on important oceanic features, such as surface temperature and salinity, water mass distribution, large‐scale circulation, and heat and freshwater transports. In general, these integral quantities are simulated well in comparison with observational estimates, and improvements in comparison with the predecessor system are documented; for example, for tropical variability and sea ice representation. Introducing an eddy‐permitting grid configuration in the ocean leads to improvements, in particular, in the representation of interior water mass properties in the Atlantic and in the representation of important ocean currents, such as the Agulhas and Equatorial current systems. In general, however, there are more similarities than differences between the two grid configurations, and several shortcomings, known from earlier versions of the coupled model, prevail.
Key Points
documentation the performance of MPIOM in the new MPI‐ESM coupled system
Assessment of impact of ocean resolution
Specific investigation of the Agulhas region
The clumped isotopic composition of carbonate‐derived CO2 (denoted Δ47) is a function of carbonate formation temperature and in natural samples can act as a recorder of paleoclimate, burial, or ...diagenetic conditions. The absolute abundance of heavy isotopes in the universal standards VPDB and VSMOW (defined by four parameters: R13VPDB, R17VSMOW, R18VSMOW, and λ) impact calculated Δ47 values. Here, we investigate whether use of updated and more accurate values for these parameters can remove observed interlaboratory differences in the measured T‐Δ47 relationship. Using the updated parameters, we reprocess 14 published calibration data sets measured in 11 different laboratories, representing many mineralogies, bulk compositions, sample types, reaction temperatures, and sample preparation and analysis methods. Exploiting this large composite data set (n = 1,253 sample replicates), we investigate the possibility for a “universal” clumped isotope calibration. We find that applying updated parameters improves the T‐Δ47 relationship (reduces residuals) within most labs and improves overall agreement but does not eliminate all interlaboratory differences. We reaffirm earlier findings that different mineralogies do not require different calibration equations and that cleaning procedures, method of pressure baseline correction, and mass spectrometer type do not affect interlaboratory agreement. We also present new estimates of the temperature dependence of the acid digestion fractionation for Δ47 (Δ*25‐X), based on combining reprocessed data from four studies, and new theoretical equilibrium values to be used in calculation of the empirical transfer function. Overall, we have ruled out a number of possible causes of interlaboratory disagreement in the T‐Δ47 relationship, but many more remain to be investigated.
Plain Language Summary
Measured stable and clumped isotope values are fundamentally tied to established compositions of international standard materials. When these standard compositions are updated, it impacts previously published isotope measurements such as those used to define the clumped isotope calibration relationship (the foundation for use of this isotopic proxy as a paleothermometer, recorder of burial history or past diagenetic conditions). Here we reprocess 14 published clumped isotope calibration studies using updated international standard compositions and identical data processing procedures to see if these changes would eliminate previously observed interlaboratory discrepancies in clumped isotope calibration relationships. We find that this update tightens the clumped isotope calibration relationship within most laboratories and improves overall agreement between laboratories but does not eliminate all interlaboratory differences. We also propose “best practices” for data processing and dissemination going forward. This study makes progress toward resolving discrepancies in clumped isotope calibration relationships between laboratories by eliminating a number of possible causes and moves the clumped isotope community closer toward our ultimate goal of applying this powerful new proxy routinely to exciting science questions.
Key Points
Updates to 17O correction parameters and international standard compositions affect clumped isotopic compositions
Reprocessing published calibration data using new parameters and consistent methodology slightly improves interlaboratory agreement
There is no evidence (within error) for mineral‐specific offsets in calibration equation or temperature dependence of acid digestion fractionation
Decadal and bi-decadal climate responses to tropical strong volcanic eruptions (SVEs) are inspected in an ensemble simulation covering the last millennium based on the Max Planck Institute—Earth ...system model. An unprecedentedly large collection of pre-industrial SVEs (up to 45) producing a peak annual-average top-of-atmosphere radiative perturbation larger than −1.5 Wm
−2
is investigated by composite analysis. Post-eruption oceanic and atmospheric anomalies coherently describe a fluctuation in the coupled ocean–atmosphere system with an average length of 20–25 years. The study provides a new physically consistent theoretical framework to interpret decadal Northern Hemisphere (NH) regional winter climates variability during the last millennium. The fluctuation particularly involves interactions between the Atlantic meridional overturning circulation and the North Atlantic gyre circulation closely linked to the state of the winter North Atlantic Oscillation. It is characterized by major distinctive details. Among them, the most prominent are: (a) a strong signal amplification in the Arctic region which allows for a sustained strengthened teleconnection between the North Pacific and the North Atlantic during the first post-eruption decade and which entails important implications from oceanic heat transport and from post-eruption sea ice dynamics, and (b) an anomalous surface winter warming emerging over the Scandinavian/Western Russian region around 10–12 years after a major eruption. The simulated long-term climate response to SVEs depends, to some extent, on background conditions. Consequently, ensemble simulations spanning different phases of background multidecadal and longer climate variability are necessary to constrain the range of possible post-eruption decadal evolution of NH regional winter climates.
Oceanic heat transport variations, carried by the northward-flowing Atlantic Water, strongly influence Arctic sea-ice distribution, ocean-atmosphere exchanges, and pan-Arctic temperatures. ...Palaeoceanographic reconstructions from marine sediments near Fram Strait have documented a dramatic increase in Atlantic Water temperatures over the 20th century, unprecedented in the last millennium. Here we present results from Earth system model simulations that reproduce and explain the reconstructed exceptional Atlantic Water warming in Fram Strait in the 20th century in the context of natural variability during the last millennium. The associated increase in ocean heat transfer to the Arctic can be traced back to changes in the ocean circulation in the subpolar North Atlantic. An interplay between a weakening overturning circulation and a strengthening subpolar gyre as a consequence of 20th-century global warming is identified as the driving mechanism for the pronounced warming along the Atlantic Water path toward the Arctic. Simulations covering the late Holocene provide a reference frame that allows us to conclude that the changes during the last century are unprecedented in the last 1150 years and that they cannot be explained by internal variability or natural forcing alone.
Young loggerhead sea turtles (Caretta caretta) from eastern Florida undertake a transoceanic migration in which they gradually circle the north Atlantic Ocean before returning to the North American ...coast. Here we report that hatchling loggerheads, when exposed to magnetic fields replicating those found in three widely separated oceanic regions, responded by swimming in directions that would, in each case, help keep turtles within the currents of the North Atlantic gyre and facilitate movement along the migratory pathway. These results imply that young loggerheads have a guidance system in which regional magnetic fields function as navigational markers and elicit changes in swimming direction at crucial geographic boundaries.
The Nordic Seas and the Barents Sea is the Atlantic Ocean’s gateway to the Arctic Ocean, and the Gulf Stream’s northern extension brings large amounts of heat into this region and modulates climate ...in northwestern Europe. We have investigated the predictive skill of initialized hindcast simulations performed with three state-of-the-art climate prediction models within the CMIP5-framework, focusing on sea surface temperature (SST) in the Nordic Seas and Barents Sea, but also on sea ice extent, and the subpolar North Atlantic upstream. The hindcasts are compared with observation-based SST for the period 1961–2010. All models have significant predictive skill in specific regions at certain lead times. However, among the three models there is little consistency concerning which regions that display predictive skill and at what lead times. For instance, in the eastern Nordic Seas, only one model has significant skill in predicting observed SST variability at longer lead times (7–10 years). This region is of particular promise in terms of predictability, as observed thermohaline anomalies progress from the subpolar North Atlantic to the Fram Strait within the time frame of a couple of years. In the same model, predictive skill appears to move northward along a similar route as forecast time progresses. We attribute this to the northward advection of SST anomalies, contributing to skill at longer lead times in the eastern Nordic Seas. The skill at these lead times in particular beats that of persistence forecast, again indicating the potential role of ocean circulation as a source for skill. Furthermore, we discuss possible explanations for the difference in skill among models, such as different model resolutions, initialization techniques, and model climatologies and variance.
Mutations in the PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine–threonine kinase, and Parkin, an E3 ubiquitin ligase, are associated with autosomal-recessive forms of Parkinson ...disease (PD). Both are involved in the maintenance of mitochondrial integrity and protection from multiple stressors. Recently, Parkin was demonstrated to be recruited to impaired mitochondria in a PINK1-dependent manner, where it triggers mitophagy. Using primary human dermal fibroblasts originating from PD patients with various PINK1 mutations, we showed at the endogenous level that (i) PINK1 regulates the stress-induced decrease of endogenous Parkin; (ii) mitochondrially localized PINK1 mediates the stress-induced mitochondrial translocation of Parkin; (iii) endogenous PINK1 is stabilized on depolarized mitochondria; and (iv) mitochondrial accumulation of full-length PINK1 is sufficient but not necessary for the stress-induced loss of Parkin signal and its mitochondrial translocation. Furthermore, we showed that different stressors, depolarizing or non-depolarizing, led to the same effect on detectable Parkin levels and its mitochondrial targeting. Although this effect on Parkin was independent of the mitochondrial membrane potential, we demonstrate a differential effect of depolarizing versus non-depolarizing stressors on endogenous levels of PINK1. Our study shows the necessity to introduce an environmental factor, i.e. stress, to visualize the differences in the interaction of PINK1 and Parkin in mutants versus controls. Establishing human fibroblasts as a suitable model for studying this interaction, we extend data from animal and other cellular models and provide experimental evidence for the generally held notion of PD as a condition with a combined genetic and environmental etiology.
Juvenile and adult sea turtles often navigate to specific feeding areas during long-distance migrations, and adults periodically return to particular geographic areas for mating and nesting. In ...addition, turtles displaced from feeding or nesting areas often home to the site of capture. Relatively little is known, however, about how turtles navigate to particular goal areas.
Both juvenile and adult turtles use the Earth's magnetic field as a source of navigational information. Laboratory experiments have provided evidence that juvenile green turtles learn the magnetic topography of their feeding grounds and acquire a “magnetic map” that facilitates navigation toward particular locations. Adult green turtles displaced from nesting beaches on an island in the Indian Ocean showed diminished homing ability when magnets were attached to their heads, implying that mature turtles also exploit magnetic cues when navigating to islands or other specific destinations.
Although geomagnetic information appears to be an important component of sea turtle navigation, it is unlikely to be the only cue used. Additional experiments in which nesting green turtles were displaced from islands have highlighted the possible involvement of local, non-magnetic cues in the final phase of island-finding. Thus, a reasonable hypothesis is that turtles use multiple cues to navigate in the marine environment, perhaps relying on a magnetic map to navigate into the vicinity of a distant target and then using non-magnetic cues to guide themselves to the final goal.
In recent years, mass spectrometry has become the method of choice for high-sensitivity glycan identification. Currently, only a few tools assisting mass spectra interpretation are available. The web ...application GlycoFragment (www.dkfz.de/spec/projekte/fragments/) calculates all theoretically possible fragments of complex carbohydrates and aims to support the interpretation of mass spectra. GlycoSearchMS (www.dkfz.de/spec/glycosciences.de/sweetdb/ms/) compares each peak of a measured mass spectrum with the calculated fragments of all structures contained in the SweetDB database. The best-matching spectra and the associated structures are displayed in order of decreasing similarity. Since both algorithms work very efficiently, they are well suited to be used for automatic identification of series of mass spectra of complex carbohydrates.
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