EOT11a - Global Empirical Ocean Tide model from multi-mission satellite altimetry, with links to model results

EOT11a is a global (E)mpirical (O)cean (T)ide model derived in 2011 by residual analysis of multi-mission satellite (a)ltimeter data. EOT11a includes amplitudes and phases of the main astronomical tides M2, S2, N2, K2, 2N2, O1, K1, P2, and Q1, the non-linear constituent M4, the long period tides Mm and Mf, and the radiational tide S1. Ocean tides as well as loading tides are provided. EOT11a was computed by means of residual tidal analysis of multi-mission altimeter data from TOPEX/Poseidon, ERS-2, ENVISAT, and Jason-1/2, as far as acquired between September 1992 and April 2010. The resolution of 7.5'x7.5' is identical with FES2004 which was used as reference model for the residual tide analysis. The development of EOT11a was funded by the Deutsche Forschungsgemeinschaft (DFG) under grant BO1228/6-2.

Marine Isotope Stage (MIS) 11 results of model data with Community Climate System Model version 3 including the Dynamic Global Vegetation Model (CCSM3-DGVM) in NetCDF format at global and regional scale

The climate of Marine Isotope Stage (MIS) 11, the interglacial roughly 400,000 years ago, is investigated for four time slices, 416, 410, 400, and 394 ka. The overall picture is that MIS 11 was a relatively warm interglacial in comparison to preindustrial, with Northern Hemisphere (NH) summer temperatures early in MIS 11 (416-410 ka) warmer than preindustrial, though winters were cooler. Later in MIS 11, especially around 400 ka, conditions were cooler in the NH summer, mainly in the high latitudes. Climate changes simulated by the models were mainly driven by insolation changes, with the exception of two local feedbacks that amplify climate changes. Here, the NH high latitudes, where reductions in sea ice cover lead to a winter warming early in MIS 11, as well as the tropics, where monsoon changes lead to stronger climate variations than one would expect on the basis of latitudinal mean insolation change alone, are especially prominent. The results support a northward expansion of trees at the expense of grasses in the high northern latitudes early during MIS 11, especially in northern Asia and North America.

Model-based changes in global annual mean surface temperature change (Delta T_g) and radiative forcing due to land ice albedo changes (Delta R_[LI]) over the last 5 Myr, supplementary material

It is still an open question how equilibrium warming in response to increasing radiative forcing - the specific equilibrium climate sensitivity S - depends on background climate. We here present palaeodata-based evidence on the state dependency of S, by using CO2 proxy data together with a 3-D ice-sheet-model-based reconstruction of land ice albedo over the last 5 million years (Myr). We find that the land ice albedo forcing depends non-linearly on the background climate, while any non-linearity of CO2 radiative forcing depends on the CO2 data set used. This non-linearity has not, so far, been accounted for in similar approaches due to previously more simplistic approximations, in which land ice albedo radiative forcing was a linear function of sea level change. The latitudinal dependency of ice-sheet area changes is important for the non-linearity between land ice albedo and sea level. In our set-up, in which the radiative forcing of CO2 and of the land ice albedo (LI) is combined, we find a state dependence in the calculated specific equilibrium climate sensitivity, S[CO2,LI], for most of the Pleistocene (last 2.1 Myr). During Pleistocene intermediate glaciated climates and interglacial periods, S[CO2,LI] is on average ~ 45 % larger than during Pleistocene full glacial conditions. In the Pliocene part of our analysis (2.6-5 Myr BP) the CO2 data uncertainties prevent a well-supported calculation for S[CO2,LI], but our analysis suggests that during times without a large land ice area in the Northern Hemisphere (e.g. before 2.82 Myr BP), the specific equilibrium climate sensitivity, S[CO2,LI], was smaller than during interglacials of the Pleistocene. We thus find support for a previously proposed state change in the climate system with the widespread appearance of northern hemispheric ice sheets. This study points for the first time to a so far overlooked non-linearity in the land ice albedo radiative forcing, which is important for similar palaeodata-based approaches to calculate climate sensitivity. However, the implications of this study for a suggested warming under CO2 doubling are not yet entirely clear since the details of necessary corrections for other slow feedbacks are not fully known and the uncertainties that exist in the ice-sheet simulations and global temperature reconstructions are large.

Global distributions of picophytoplankton abundance and biomass - Gridded data product (NetCDF) - Contribution to the MAREDAT World Ocean Atlas of Plankton Functional Types

The smallest marine phytoplankton, collectively termed picophytoplankton, have been routinely enumerated by flow cytometry since the late 1980s, during cruises throughout most of the world ocean. We compiled a database of 40,946 data points, with separate abundance entries for Prochlorococcus, Synechococcus and picoeukaryotes. We use average conversion factors for each of the three groups to convert the abundance data to carbon biomass. After gridding with 1° spacing, the database covers 2.4% of the ocean surface area, with the best data coverage in the North Atlantic, the South Pacific and North Indian basins. The average picophytoplankton biomass is 12 ± 22 µg C L-1 or 1.9 g C m-2. We estimate a total global picophytoplankton biomass, excluding N2-fixers, of 0.53 - 0.74 Pg C (17 - 39 % Prochlorococcus, 12 - 15 % Synechococcus and 49 - 69 % picoeukaryotes). Future efforts in this area of research should focus on reporting calibrated cell size, and collecting data in undersampled regions.

Global cooling during the Eocene Oligocene Transition

About 34 million years ago, Earth's climate shifted from a relatively ice-free world to one with glacial conditions on Antarctica characterized by substantial ice sheets. How Earth's temperature changed during this climate transition remains poorly understood, and evidence for Northern Hemisphere polar ice is controversial. Here, we report proxy records of sea surface temperatures from multiple ocean localities and show that the high-latitude temperature decrease was substantial and heterogeneous. High-latitude (45 degrees to 70 degrees in both hemispheres) temperatures before the climate transition were ~20°C and cooled an average of ~5°C. Our results, combined with ocean and ice-sheet model simulations and benthic oxygen isotope records, indicate that Northern Hemisphere glaciation was not required to accommodate the magnitude of continental ice growth during this time.

ETOPO1 Global Relief Model converted to PanMap layer format

ETOPO1 is a 1 arc-minute global relief model of Earth's surface that integrates land topography and ocean bathymetry. It was built from numerous global and regional data sets. Data were converted to the PanMap layer format in 14 contour lines from 500 to 7000 meter in steps of 500 m. The link provides a zip-archive (1.1 MB) with *.lay files. The PanMap Mini-GIS software is published at doi:10.1594/PANGAEA.104840.

"En el monumento Resuçitest, fust alos ynfiernos" : ¿Error del poeta o influencia de una fuente en el Cantar de Mio Cid?

El presente trabajo vuelve a los vv. 358-361 del Cantar de Mio Cid sobre un tema que ha perturbado a la crítica: el texto conservado en el Códice de Vivar refiere que Jesús resucitó primero, y luego descendió a los Infiernos, lo cual implica una inversión del orden tradicional de los acontecimientos. En consecuencia, se revisan aquí las distintas opiniones sobre el particular, que en general pueden dividirse básicamente en dos grupos -aquellas que sostienen que el poeta cometió un error, y otras que afirman que el autor del poema adhirió a un determinado modelo, proveniente ya de la épica francesa, ya de la liturgia-, y se intenta arribar a una solución que considere más satisfactoriamente la especificidad del texto manuscrito.

Global habitat suitability of deep-water Antipatharia

Antipatharia are a diverse group of corals with many species found in deep water. Many Antipatharia are habitat for associates, have extreme longevity and some species can occur beyond 8500 m depth. As they are major constituents of 'coral gardens', which are Vulnerable Marine Ecosystems (VMEs), knowledge of their distribution and environmental requirements is an important pre-requisite for informed conservation planning particularly where the expense and difficulty of deep-sea sampling prohibits comprehensive surveys. This study uses a global database of Antipatharia distribution data to perform habitat suitability modelling using the Maxent methodology to estimate the global extent of black coral habitat suitability. The model of habitat suitability is driven by temperature but there is notable influence from other variables of topography, surface productivity and oxygen levels. This model can be used to predict areas of suitable habitat, which can be useful for conservation planning. The global distribution of Antipatharia habitat suitability shows a marked contrast with the distribution of specimen observations, indicating that many potentially suitable areas have not been sampled, and that sampling effort has been disproportionate to shallow, accessible areas inside marine protected areas (MPAs). Although 25% of Antipatharia observations are located in MPAs, only 7-8% of predicted suitable habitat is protected, which is short of the Convention on Biological Diversity target to protect 10% of ocean habitats by 2020.

"En el monumento Resuçitest, fust alos ynfiernos" : ¿Error del poeta o influencia de una fuente en el Cantar de Mio Cid?

El presente trabajo vuelve a los vv. 358-361 del Cantar de Mio Cid sobre un tema que ha perturbado a la crítica: el texto conservado en el Códice de Vivar refiere que Jesús resucitó primero, y luego descendió a los Infiernos, lo cual implica una inversión del orden tradicional de los acontecimientos. En consecuencia, se revisan aquí las distintas opiniones sobre el particular, que en general pueden dividirse básicamente en dos grupos -aquellas que sostienen que el poeta cometió un error, y otras que afirman que el autor del poema adhirió a un determinado modelo, proveniente ya de la épica francesa, ya de la liturgia-, y se intenta arribar a una solución que considere más satisfactoriamente la especificidad del texto manuscrito.

Stratigraphy of the Campanian-Maastrichtian boundary in ODP Hole 122-762C

An integrated framework of magnetostratigraphy, calcareous microfossil bio-events, cyclostratigraphy and d13C stratigraphy is established for the upper Campanian-Maastrichtian of ODP Hole 762C (Exmouth Plateau, Northwestern Australian margin). Bulk-carbonate d13C events and nannofossil bio-events have been recorded and plotted against magnetostratigraphy, and provided absolute ages using the results of the cyclostratigraphic study and the recent astronomical calibration of the Maastrichtian. Thirteen carbon-isotope events and 40 nannofossil bio-events are recognized and calibrated with cyclostratigraphy, as well as 14 previously published foraminifer events, thus constituting a solid basis for large-scale correlations. Results show that this site is characterized by a nearly continuous sedimentation from the upper Campanian to the K-Pg boundary, except for a 500 kyr gap in magnetochron C31n. Correlation of the age-calibrated d13C profile of ODP Hole 762C to the d13C profile of the Tercis les Bains section, Global Stratotype Section and Point of the Campanian-Maastrichtian boundary (CMB), allowed a precise recognition and dating of this stage boundary at 72.15 ± 0.05 Ma. This accounts for a total duration of 6.15 ± 0.05 Ma for the Maastrichtian stage. Correlation of the boundary level with northwest Germany shows that the CMB as defined at the GSSP is ~800 kyr younger than the CMB as defined by Belemnite zonation in the Boreal realm. ODP Hole 762C is the first section to bear at the same time an excellent recovery of sediments throughout the upper Campanian-Maastrichtian, a precise and well-defined magnetostratigraphy, a high-resolution record of carbon isotope events and calcareous plankton biostratigraphy, and a cyclostratigraphic study tied to the La2010a astronomical solution. This section is thus proposed as an excellent reference for the upper Campanian-Maastrichtian in the Indian Ocean.

(Table 2) Stratigraphic position of midpoints of reddish and beige layers of lithologic cycles in the Loulja-A Section and their astronomical ages after tuning to the ETP and Summer Insolation Curves of the La2004 solution

An integrated high-resolution stratigraphy and orbital tuning is presented for the Loulja sections located in the Bou Regreg area on the Atlantic side of Morocco. The sections constitute the upward continuation of the upper Messinian Ain el Beida section and contain a well-exposed, continuous record of the interval straddling the Miocene-Pliocene (M-P) boundary. The older Loulja-A section, which covers the interval from ~5.59 to 5.12 Ma, reveals a dominantly precession-controlled color cyclicity that allows for a straightforward orbital tuning of the boundary interval and for detailed cyclostratigraphic correlations to the Mediterranean; the high-resolution and high-quality benthic isotope record allows us to trace the dominantly obliquity-controlled glacial history. Our results reveal that the M-P boundary coincides with a minor, partly precession-related shift to lighter "interglacial" values in d18O. This shift and hence the M-P boundary may not correlate with isotope stage TG5, as previously thought, but with an extra (weak) obliquity-controlled cycle between TG7 and TG5. Consequently, the M-P boundary and basal Pliocene flooding of the Mediterranean following the Messinian salinity crisis are not associated with a major deglaciation and glacio-eustatic sea level rise, indicating that other factors, such as tectonics, must have played a fundamental role. On the other hand, the onset of the Upper Evaporites in the Mediterranean marked by hyposaline conditions coincides with the major deglaciation step between marine isotope stage TG12 and TG11, suggesting that the associated sea level rise is at least partly responsible for the apparent onset of intermittently restricted marine conditions following the main desiccation phase. Finally, the Loulja-A section would represent an excellent auxiliary boundary stratotype for the M-P boundary as formally defined at the base of the Trubi marls in the Eraclea Minoa section on Sicily.

"En el monumento Resuçitest, fust alos ynfiernos" : ¿Error del poeta o influencia de una fuente en el Cantar de Mio Cid?

El presente trabajo vuelve a los vv. 358-361 del Cantar de Mio Cid sobre un tema que ha perturbado a la crítica: el texto conservado en el Códice de Vivar refiere que Jesús resucitó primero, y luego descendió a los Infiernos, lo cual implica una inversión del orden tradicional de los acontecimientos. En consecuencia, se revisan aquí las distintas opiniones sobre el particular, que en general pueden dividirse básicamente en dos grupos -aquellas que sostienen que el poeta cometió un error, y otras que afirman que el autor del poema adhirió a un determinado modelo, proveniente ya de la épica francesa, ya de la liturgia-, y se intenta arribar a una solución que considere más satisfactoriamente la especificidad del texto manuscrito.

Microcharcoal concentration and elongation, and age model of sediment core MD96-2098

Although grassland and savanna occupy only a quarter of the world's vegetation, burning in these ecosystems accounts for roughly half the global carbon emissions from fire. However, the processes that govern changes in grassland burning are poorly understood, particularly on time scales beyond satellite records. We analyzed microcharcoal, sediments, and geochemistry in a high-resolution marine sediment core off Namibia to identify the processes that have controlled biomass burning in southern African grassland ecosystems under large, multimillennial-scale climate changes. Six fire cycles occurred during the past 170,000 y in southern Africa that correspond both in timing and magnitude to the precessional forcing of north-south shifts in the Intertropical Convergence Zone. Contrary to the conventional expectation that fire increases with higher temperatures and increased drought, we found that wetter and cooler climates cause increased burning in the study region, owing to a shift in rainfall amount and seasonality (and thus vegetation flammability). We also show that charcoal morphology (i.e., the particle's length-to-width ratio) can be used to reconstruct changes in fire activity as well as biome shifts over time. Our results provide essential context for understanding current and future grassland-fire dynamics and their associated carbon emissions.

Biostratigraphy and Sr isotopic composition of sediments from DSDP Legs 12, 14, 15, 17, 20-22, and 30

We present the data used to construct the Cenozoic and Cretaceous portion of the Phanerozoic curve of seawater 87Sr/86Sr that had been given in summary form by W.H. Burke co-workers. All Cenozoic samples (128) and 22 Cretaceous samples are foram-nannofossil oozes and limestones from DSDP cores distributed among 13 sites in the Atlantic, Pacific and Indian Oceans, and the Caribbean Sea. Non-DSDP Cretaceous samples (126) include limestone, anhydrite and phosphate samples from North America, Europe and Asia. Determination of the 87Sr/86Sr value of seawater at particular times in the past is based on comparison of ratios derived from coeval marine samples from widely separated geographic areas. These samples are characterized by a wide variety of diagenetic and burial histories. The large size and cosmopolitan nature of the data set decreases the likelihood that, among coeval data, systematic error has been introduced by a similar pattern of diagenetic alteration of the ratios. There is good clustering of data points throughout the Cenozoic and Cretaceous curve. The consistency of data is illustrated by Cenozoic and Cretaceous data plots that include a separate symbol for each DSDP site and non-DSDP sample location. More than 98% of the data points are enclosed by upper and lower lines that define a narrow band. For any given time, the correct seawater ratio probably lies within this band. A line drawn within the band represents our estimate of the actual seawater ratio as a function of time. The general configuration of the Cenozoic and Cretaceous curve appears to be strongly influenced by the history of plate interactions and sea-floor spreading. Specific rises and falls in the 87Sr/86Sr of seawater, however, may be caused by a variety of factors such as variation in lithologic composition of the crust exposed to weathering, configuration and topographic relief of continents, volcanic activity, rate of sea-floor spreading, extent of continental inundation by epeiric seas, and variations in both climate and paleooceanographic conditions. Many or all of these factors are probably related to global tectonic processes, yet their combined effect on the temporal variation of seawater 87Sr/86Sr can complicate a direct platetectonic interpretation for portions of the seawater curve.