Antarctic Temperatures Over the Past Two Centuries from Ice Cores

We present a reconstruction of Antarctic mean surface temperatures over the past two centuries based on water stable isotope records from high-resolution, precisely dated ice cores. Both instrumental and reconstructed temperatures indicate large interannual to decadal scale variability, with the dominant pattern being anti-phase anomalies between the main Antarctic continent and the Antarctic Peninsula region. Comparative analysis of the instrumental Southern Hemisphere (SH) mean temperature record and the reconstruction suggests that at longer timescales, temperatures over the Antarctic continent vary in phase with the SH mean. Our reconstruction suggests that Antarctic temperatures have increased by about 0.2 degrees C since the late nineteenth century. The variability and the long-term trends are strongly modulated by the SH Annular Mode in the atmospheric circulation.

The role of brand marketing in snowboarding: A comparative study of Switzerland and New Zealand

Introduction: Brands play an essential role in the organizational structure of snowboarding by sponsoring athletes, arranging events, contributing to product development and developing long-term partnerships with other key actors. However, the specialities of their role in scene sports, such as creating identities, networking and brand marketing strategies, have not been extensively researched. This study aims to provide an analysis of the function of brands within the snowboarding subculture by comparing how the sport is organized in Switzerland and New Zealand. Sociological theories of subcultures (Hitzler & Niederbacher, 2010) and social networks (Stegbauer, 2008) are used to defi ne the structures of the sport, whereas marketing and branding theories (Adjouri & Stastny, 2006) help to understand the role of the brands. Snowboarding will be defi ned as an alternative sports subculture based on characteristics such as aesthetics, adventure and new resources of performance (Schwier, 2006). Such a defi nition also begs for a novel form of analyzing its organization. Unlike more conventional structures, the organization of snowboarding allows a variety of actors to get involved in leading the sport. By portraying and encouraging differentiated identities and lifestyles, athletes provide a space for other actors to fi nd their place within the sport (Wheaton, 2005). According to Stegbauers network theory, individual actors are able to obtain high positions and defi ne their identity depending on their ties to actors and networks within the subculture (Stegbauer, 2008). For example, social capital, contacts within the sport and insider knowledge on subculture-related information enable actors to get closer to the core (Hitzler & Niederbacher, 2010). Actors who do not have close networks and allies within the subculture are less likely to engage successfully in the culture, whether as an individual or as a commercial actor (Thorpe, 2011). This study focuses on the organizational structure of snowboarding by comparing the development of the sport in Switzerland and New Zealand. An analysis of snowboarding in two nations with diverse cultures and economic systems allows a further defi nition of the structural organization of the sport and explains how brands play an important role in the sport. Methods: The structural organization of the sport will be analyzed through an ethnographic approach, using participant observation at various leading events in Switzerland (Freestyle.ch, European Open) and New Zealand (World Heli Challenge, New Zealand Open, New Zealand Winter Games). The data is analyzed using grounded theory (Glaser & Strauss 1967) and gives an overview of the actors that are playing an important role in the local development of snowboarding. Participant observation was also used as a tool to get inside the sport culture and opened up the possibility to make over 40 semi-structured qualitative expert interviews with international core actors from 11 countries. Obtaining access to one actor as a partner early on helped to get inside the local sport culture. The ‘snowball effect’ allowed the researcher to acquire access, build trust and conduct interviews with experts within the core scene. All the interviewed actors have a direct infl uence on the sport in one or both countries, which permit a cross-analysis. The data of the interviews was evaluated through content analysis (Mayring 2010). The two methods together provided suffi cient data to analyze the organizational structure and discuss the role of brand marketing within snowboarding. Results: An actors mapping by means of a center-periphery framework has identifi ed fi ve main core groups: athletes, media representatives, brand-marketing managers, resort managers and event organizers. In both countries the same grouping of actors were found. Despite possessing different and frequently multiple roles and responsibilities, core actors appear to have a strong common identifi cation as ‘snowboarders’, are considered to be part of the organizational elite of the sport and tend to advocate similar goals. The author has found that brands in Switzerland tend to have a larger impact on the broader snowboarding culture due to a number of factors discussed below. Due to a larger amount of snowboarders and stronger economic power in Europe, snowboarders are making attempts to differentiate themselves from other winter sports, while competing with each other to develop niche markets. In New Zealand, on the other hand, the smaller market enables more cooperation and mutual respect within snowboarders. Further they are more closely linked to other winter sports and are satisfi ed with being lumped together. In both countries, brands have taken up the role of supporting young athletes, organizing competitions and feeding media with subculture-related content. Brands build their image and identity through the collaboration with particular athletes who can represent the values of the brand. Local and global communities with similar lifestyles and interests are being built around brands that share a common vision of the sport. The dominance of brands in snowboarding has enabled them with the power to organize and rule the sport through its fan base and supporters. Brands were defi ned by interviewees as independent institutions led by insiders who know the codes and symbols of the sport and were given trust and credibility. The brands identify themselves as the engines of the sport by providing the equipment, opportunities for athletes to get exposure, allowing media to get exclusive information on activities, events and sport-related stories. Differences between the two countries are more related to the economic system. While Switzerland is well integrated in the broader European market, New Zealand’s geographical isolation and close proximity to Australia tends to limit its market. Further, due to different cultural lifestyles, access to resorts and seasonal restrictions, to name a few, the amount of people practicing winter sports in New Zealand is much smaller than in Switzerland. However, this also presents numerous advantages. For example, the short southern hemisphere winter season in New Zealand enables them to attract international sports athletes, brands and representatives in a period when Europe and North America is in summer. Further, the unique snow conditions in New Zealand and majestic landscape is popular for attracting world renowned photo- and cinematographers. Another advantage is the less populated network as it provides the opportunity for individuals to gain easier access to the core of the sport, obtain diverse positions and form a unique identity and market. In Switzerland, on the other hand, the snowboarding network is dense with few positions available for the taking. Homegrown brands with core recognition are found in both countries. It was found that the Swiss brands tend to have a larger impact on the market, whereas in New Zealand, the sport is more dependent on import products by foreign brands. Further, athletes, events and resorts in New Zealand are often dependent on large brand sponsorships from abroad such as from brand headquarters in the Unites States. Thus, due to its location in the centre of Europe, Swiss brands can take advantage of brands which are closer in proximity and culture to sponsor athletes and events. In terms of media coverage, winter sports in New Zealand tend to have a minor coverage and tradition in local mass media, which leads to less exposure, recognition and investment into the sport. This is also related to how snowboarding is more integrated into other winter sports in New Zealand. Another difference is the accessibility of the ski resort by the population. While in Switzerland the resorts are mostly being visited by day-travelers, ‘weekend warriors’ and holiday makers, the location of the resorts in New Zealand make it diffi cult to visit for one day. This is in part due to the fact that Swiss ski resorts and villages are usually the same location and are accessible through public transportation, while the ski resorts in New Zealand have been built separately from the villages. Further, the villages have not been built to accommodate to high tourist arrivals. Thus, accommodation and food facilities are limited and there is a lack of public transportation to the resorts. Discussion: The fi ndings show that networks and social relations combined with specifi c knowledge on scene-related attributes are crucial in obtaining opportunities within the sport. Partnerships as well as competition between these different actors are necessary for core acceptance, peer credibility and successful commercial interests. Brands need to maintain effective marketing strategies and identities which incorporate subcultural forms of behavior and communication. In order to sustain credibility from its fans, athletes and other snowboarding actors, brands need to maintain their insider status through social networks and commercial branding strategies. The interaction between all actors is a reciprocated process, where social capital, networks and identities are being shared. While the overall structure of snowboard subcultures in Europe and New Zealand are similar, there are some distinct characteristics which make each one unique. References Adjouri, N. & Stastny, P. (2006). Sport-Branding: Mit Sport-Sponsoring zum Markenerfolg. Wiesbaden: Gabler. Glaser, B. & Strauss, K. (1967). The discovery of grounded theory: Strategies for qualitative research. Chicago: Aldine. Hebdige, D. (2009). Subculture; The meaning of style. New York: Routledge. Hitzler, R. & Niederbacher, A. (2010). Leben in Szenen: Formen juveniler Vergemeinschaftung heute. Wiesbaden: Verlag für Sozialwissenschaften. Mayring, P. (2010). Qualitative Inhaltsanalyse: Grundlagen und Techniken. Weinheim: Beltz. Schwier, J. (2006). Repräsentationen des Trendsports. Jugendliche Bewegungskulturen, Medien und Marketing. In: Gugutzer, R. (Hrsg.). body turn. Perspektiven der Soziologie des Körpers und des Sports. Bielefeld: transcript (S. 321-340). Stegbauer, C. (2008). Netzwerkanalyse und Netzwerktheorie. Ein neues Paradigma in den Sozialwissenschaften. Wiesbaden: VS Verlag für Sozialwissenschaften. Thorpe, H. (2011). Snowboarding bodies in theory and practice. Basingstoke: Palgrave Macmillan. Wheaton, B. (2005). Understanding lifestyle sports; consumption, identity and difference. New York: Routledge.

Lutetia׳s lineaments

The European Space Agency׳s Rosetta spacecraft flew by asteroid (21) Lutetia on July 10, 2010. Observations through the OSIRIS camera have revealed many geological features. Lineaments are identified on the entire observed surface of the asteroid. Many of these features are concentric around the North Pole Crater Cluster (NPCC). As observed on (433) Eros and (4) Vesta, this analysis of Lutetia assesses whether or not some of the lineaments could be created orthogonally to observed impact craters. The results indicate that the orientation of lineaments on Lutetia׳s surface could be explained by three impact craters: the Massilia and the NPCC craters observed in the northern hemisphere, and candidate crater Suspicio inferred to be in the southern hemisphere. The latter has not been observed during the Rosetta flyby. Of note, is that the inferred location of the Suspicio impact crater derived from lineaments matches locations where hydrated minerals have been detected from Earth-based observations in the southern hemisphere of Lutetia. Although the presence of these minerals has to be confirmed, this analysis shows that the topography may also have a significant contribution in the modification of the spectral shape and its interpretation. The cross-cutting relationships of craters with lineaments, or between lineaments themselves show that Massilia is the oldest of the three impact feature, the NPCC the youngest, and that the Suspicio impact crater is of intermediate age that is likely occurred closer in time to the Massilia event.

Backscattered energetic neutral atoms from the Moon in the Earth's plasma sheet observed by Chandarayaan-1/Sub-keV Atom Reflecting Analyzer instrument

We present the observations of energetic neutral atoms (ENAs) produced at the lunar surface in the Earth's magnetotail. When the Moon was located in the terrestrial plasma sheet, Chandrayaan-1 Energetic Neutrals Analyzer (CENA) detected hydrogen ENAs from the Moon. Analysis of the data from CENA together with the Solar Wind Monitor (SWIM) onboard Chandrayaan-1 reveals the characteristic energy of the observed ENA energy spectrum (the e-folding energy of the distribution function) ∼100 eV and the ENA backscattering ratio (defined as the ratio of upward ENA flux to downward proton flux) <∼0.1. These characteristics are similar to those of the backscattered ENAs in the solar wind, suggesting that CENA detected plasma sheet particles backscattered as ENAs from the lunar surface. The observed ENA backscattering ratio in the plasma sheet exhibits no significant difference in the Southern Hemisphere, where a large and strong magnetized region exists, compared with that in the Northern Hemisphere. This is contrary to the CENA observations in the solar wind, when the backscattering ratio drops by ∼50% in the Southern Hemisphere. Our analysis and test particle simulations suggest that magnetic shielding of the lunar surface in the plasma sheet is less effective than in the solar wind due to the broad velocity distributions of the plasma sheet protons.

SMARTnet: A Sensor for Monitoring the Geostationary Ring

As the number of space debris is increasing in the geostationary ring, it becomes mandatory for any satellite operator to avoid any collisions. Space debris in geosynchronous orbits may be observed with optical telescopes. Other than radar, that requires very large dishes and transmission powers for sensing high-altitude objects, optical observations do not depend on active illumination from ground and may be performed with notably smaller apertures. The detection size of an object depends on the aperture of the telescope, sky background and exposure time. With a telescope of 50 cm aperture, objects down to approximately 50 cm may be observed. This size is regarded as a threshold for the identification of hazardous objects and the prevention of potentially catastrophic collisions in geostationary orbits. In collaboration with the Astronomical Institute of the University of Bern (AIUB), the German Space Operations Center (GSOC) is building a small aperture telescope to demonstrate the feasibility of optical surveillance of the geostationary ring. The telescope will be located in the southern hemisphere and complement an existing telescope in the northern hemisphere already operated by AIUB. These two telescopes provide an optimum coverage of European GEO satellites and enable a continuous monitoring independent of seasonal limitations. The telescope will be operated completely automatically. The automated operations should be demonstrated covering the full range of activities including scheduling of observations, telescope and camera control as well as data processing.

A 600 years warm-season temperature record from varved sediments of Lago Plomo, Northern Patagonia, Chile (47°S)

High-resolution records of calibrated proxy data for the past millennium are fundamental to place current changes into the context of pre-industrial natural forced and unforced variability. Although the need for regional spatially-explicit comprehensive reconstructions is widely recognized, the proxy data sources are still scarce, particularly for the Southern Hemisphere and especially for South America. We present a 600-year long warm season temperature record from varved sediments of Lago Plomo, a proglacial lake of the Northern Patagonian Ice field in Southern Chile (46°59′S, 72°52′W, 203 m a.s.l.). The thickness of the bright summer sediment layer relative to the dark winter layer (measured as total brightness; % reflectance 400–730 nm) is calibrated against warm season SONDJF temperature (1900–2009; r = 0.58, p(aut) = 0.056, RE = 0.52; CE = 0.15, RMSEP = 0.28 °C; five-year triangular filtered data). In Lago Plomo, warm summer temperatures lead to enhanced glacier melt and suspended sediment transport, which results in thicker light summer layers and to brighter sediments. Although Patagonia shows pronounced regional differences in decadal temperature trends and variability, the 600 years temperature reconstruction from Lago Plomo compares favourably with other regional/continental temperature records, but also emphasizes significant regional differences for which no data and information existed so far. These regional differences seem to be real as they are also reflected in modern climate data sets (1900–2010). The reconstruction shows pronounced subdecadal – multidecadal variability with cold phases during parts of the Little Ice Age (16th and 18th centuries) and in the beginning of the 20th century. The most prominent warm phase is the 19th century which is as warm as the second half of the 20th century. The exceptional summer warmth AD 1780–1810 is also found in other archives of Northern Patagonia and Central Chile. Our record shows the delayed 20th century warming in the Southern Hemisphere. The comparison between winter precipitation and summer temperature (inter-seasonal coupling) from Lago Plomo reveals alternating phases with parallel and contrasting decadal trends of winter precipitation and summer temperature (positive and negative running correlations Rwinter PP; summer TT). This observation from the sediment proxy data is also confirmed by two sets of reanalysis data for the 20th century. Reanalysis data show that phases with negative correlations between winter precipitation and summer temperature (e.g., dry winters and warm summers) at Lago Plomo are characteristic for periods when circumpolar Westerly flow is displaced southward and enhanced around 60°S.

Extratropical fronts in the lower troposphere-global perspectives obtained from two automated methods

In this study two commonly used automated methods to detect atmospheric fronts in the lower troposphere are compared in various synoptic situations. The first method is a thermal approach, relying on the gradient of equivalent potential temperature (TH), while the second method is based on temporal changes in the 10 m wind (WND). For a comprehensive objective comparison of the outputs of these methods of frontal identification, both schemes are firstly applied to an idealised strong baroclinic wave simulation in the absence of topography. Then, two case-studies (one in the Northern Hemisphere (NH) and one in the Southern Hemisphere (SH)) were conducted to contrast fronts detected by the methods. Finally, we obtain global winter and summer frontal occurrence climatologies (derived from ERA-Interim for 1979–2012) and compare the structure of these. TH is able to identify cold and warm fronts in strong baroclinic cases that are in good agreement with manual analyses. WND is particularly suited for the detection of strongly elongated, meridionally oriented moving fronts, but has very limited ability to identify zonally oriented warm fronts. We note that the areas of the main TH frontal activity are shifted equatorwards compared to the WND patterns and are located upstream of regions of main WND front activity. The number of WND fronts in the NH shows more interseasonal variations than TH fronts, decreasing by more than 50% from winter to summer. In the SH there is a weaker seasonal variation of the number of observed WND fronts, however TH front activity reduces from summer (DJF) to winter (JJA). The main motivation is to give an overview of the performance of these methods, such that researchers can choose the appropriate one for their particular interest.

Composition-dependent outgassing of comet 67P/Churyumov-Gerasimenko from ROSINA/DFMS

Context. Early measurements of Rosetta’s target comet, 67P/Churyumov-Gerasimenko (67P), showed a strongly heterogeneous coma in H2O, CO, and CO2. Aims. The purpose of this work is to further investigate the coma heterogeneity of 67P, and to provide predictions for the near-perihelion outgassing profile based on the proposed explanations. Methods. Measurements of various minor volatile species by ROSINA/DFMS on board Rosetta are examined. The analysis focuses on the currently poorly illuminated winter (southern) hemisphere of 67P. Results. Coma heterogeneity is not limited to the major outgassing species. Minor species show better correlation with either H2O or CO2. The molecule CH4 shows a different diurnal pattern from all other analyzed species. Such features have implications for nucleus heterogeneity and thermal processing. Conclusions. Future analysis of additional volatiles and modeling the heterogeneity are required to better understand the observed coma profile.

Insolation, erosion, and morphology of comet 67P/Churyumov-Gerasimenko

Context. The complex shape of comet 67P and its oblique rotation axis cause pronounced seasonal effects. Irradiation and hence activity vary strongly. Aims. We investigate the insolation of the cometary surface in order to predict the sublimation of water ice. The strongly varying erosion levels are correlated with the topography and morphology of the present cometary surface and its evolution. Methods. The insolation as a function of heliocentric distance and diurnal (spin dependent) variation is calculated using >10(5) facets of a detailed digital terrain model. Shading, but also illumination and thermal radiation by facets in the field of view of a specific facet are iteratively taken into account. We use a two-layer model of a thin porous dust cover above an icy surface to calculate the water sublimation, presuming steady state and a uniform surface. Our second model, which includes the history of warming and cooling due to thermal inertia, is restricted to a much simpler shape model but allows us to test various distributions of active areas. Results. Sublimation from a dirty ice surface yields maximum erosion. A thin dust cover of 50 pm yields similar rates at perihelion. Only about 6% of the surface needs to be active to match the observed water production rates at perihelion. A dust layer of 1 mm thickness suppresses the activity by a factor of 4 to 5. Erosion on the south side can reach more than 10 m per orbit at active spots. The energy input to the concave neck area (Hapi) during northern summer is enhanced by about 50% owing to self-illumination. Here surface temperatures reach maximum values along the foot of the Hathor wall. Integrated over the whole orbit this area receives the least energy input. Based on the detailed shape model, the simulations identify "hot spots" in depressions and larger pits in good correlation with observed dust activity. Three-quarters of the total sublimation is produced while the sub-solar latitude is south, resulting in a distinct dichotomy in activity and morphology. Conclusions. The northern areas display a much rougher morphology than what is seen on Imhotep, an area at the equator that will be fully illuminated when 67P is closer to the Sun. Self-illumination in concave regions enhance the energy input and hence erosion. This explains the early activity observed at Hapi. Cliffs are more prone to erosion than horizontal, often dust covered, areas, which leads to surface planation. Local activity can only persist if the forming cliff walls are eroding. Comet 67P has two lobes and also two distinct sides. Transport of material from the south to the north is probable. The morphology of the Imhotep plain should be typical for the terrains of the yet unseen southern hemisphere.

A Noachian source region for the "Black Beauty" meteorite, and a source lithology for Mars surface hydrated dust?

The Martian surface is covered by a fine-layer of oxidized dust responsible for its red color in the visible spectral range (Bibring et al., 2006; Morris et al., 2006). In the near infrared, the strongest spectral feature is located between 2.6 and 3.6 mu m and is ubiquitously observed on the planet (Jouglet et al., 2007; Milliken et al., 2007). Although this absorption has been studied for many decades, its exact attribution and its geological and climatic implications remain debated. We present new lines of evidence from laboratory experiments, orbital and landed missions data, and characterization of the unique Martian meteorite NWA 7533, all converging toward the prominent role of hydroxylated ferric minerals. Martian breccias (so-called "Black Beauty" meteorite NWA7034 and its paired stones NWA7533 and NWA 7455) are unique pieces of the Martian surface that display abundant evidence of aqueous alteration that occurred on their parent planet (Agee et al., 2013). These dark stones are also unique in the fact that they arose from a near surface level in the Noachian southern hemisphere (Humayun et al., 2013). We used IR spectroscopy, Fe-XANES and petrography to identify the mineral hosts of hydrogen in NWA 7533 and compare them with observations of the Martian surface and results of laboratory experiments. The spectrum of NWA 7533 does not show mafic mineral absorptions, making its definite identification difficult through NIR remote sensing mapping. However, its spectra are virtually consistent with a large fraction of the Martian highlands. Abundant NWA 7034/7533 (and paired samples) lithologies might abound on Mars and might play a role in the dust production mechanism. (C) 2015 Elsevier B.V. All rights reserved.

Benthic foraminiferal stable isotope record from ODP Site 138-849 on the East Pacific Rise

Benthic foraminifer and delta13C data from Site 849, on the west flank of the East Pacific Rise (0°11 'N, 110°31'W; 3851 m), give relatively continuous records of deep Pacific Ocean stable isotope variations between 0 and 5 Ma. The mean sample spacing is 4 k.y. Most analyses are from Cibicides wuellerstorfi, but isotopic offsets relative to Uvigerina peregrina appear roughly constant. Because of its location west of the East Pacific Rise, Site 849 yields a suitable record of mean Pacific Ocean delta13C, which approximates a global oceanic signal. The ~100-k.y.-period climate cycle, which is prevalent in delta18O does not dominate the long-term delta13C record. For delta13C, variations in the ~400- and 41-k.y. periods are more important. Phase lags of delta13C relative to ice volume in the 41- and 23-k.y. bands are consistent with delta13C as a measure of organic biomass. A model-calculated exponential response time of 1-2 k.y. is appropriate for carbon stored in soils and shallow sediments responding to glacial-interglacial climate change. Oceanic delta13C leads ice volume slightly in the 100-k.y. band, and this suggests another process such as changes in continental weathering to modulate mean river delta13C at long periods. The delta13C record from Site 849 diverges from that of Site 677 in the Panama Basin mostly because of decay of 13C-depleted organic carbon in the relatively isolated Panama Basin. North Atlantic to Pacific delta13C differences calculated using published data from Sites 607 and 849 reveal variations in Pliocene deep water within the range of those of the late Quaternary. Maximum delta13C contrast between these sites, which presumably reflects maximum influx of high-delta13C northern source water into the deep North Atlantic Ocean, occurred between 1.3 and 2.1 Ma, well after the initiation of Northern Hemisphere glaciation. Export of high-delta13C North Atlantic Deep Water from the Atlantic to the circumpolar Antarctic, as recorded by published delta13C data from Subantarctic Site 704, appears unrelated to the North Atlantic-Pacific delta13C contrast. To account for this observation, we suggest that deep-water formation in the North Atlantic reflects northern source characteristics, whereas export of this water into the circumpolar Antarctic reflects Southern Hemisphere wind forcing. Neither process appears directly linked to ice-volume variations.

Granulometry of two sediment cores from Maxwell Bay, South Shetland Islands, West Antarctica

The climate evolution of the South Shetland Islands during the last c. 2000 years is inferred from the multiproxy analyses of a long (928 cm) sediment core retrieved from Maxwell Bay off King George Island. The vertical sediment flux at the core location is controlled by summer melting processes that cause sediment-laden meltwater plumes to form. These leave a characteristic signature in the sediments of NE Maxwell Bay. We use this signature to distinguish summer and winter-dominated periods. During the Medieval Warm Period, sediments are generally finer which indicates summer-type conditions. In contrast, during the Little Ice Age (LIA) sediments are generally coarser and are indicative of winter-dominated conditions. Comparison with Northern and Southern Hemisphere, Antarctic, and global temperature reconstructions reveals that the mean grain-size curve from Maxwell Bay closely resembles the curve of the global temperature reconstruction. We show that the medieval warming occurred earlier in the Southern than in the Northern Hemisphere, which might indicate that the warming was driven by processes occurring in the south. The beginning of the LIA appears to be almost synchronous in both hemispheres. The warming after the LIA closely resembles the Northern Hemisphere record which might indicate this phase of cooling was driven by processes occurring in the north. Although the recent rapid regional warming is clearly visible, the Maxwell Bay record does not show the dominance of summer-type sediments until the 1970s. Continued warming in this area will likely affect the marine ecosystem through meltwater induced turbidity of the surface waters as well as an extension of the vegetation period due to the predicted decrease of sea ice in this area.

Global distributions of pteropods (Gymnosomata, Thecosomata, Pseudothecosomata) abundance and biomass - Gridded data product (NetCDF) - Contribution to the MAREDAT World Ocean Atlas of Plankton Functional Types

Pteropods are a group of holoplanktonic gastropods for which global biomass distribution patterns remain poorly resolved. The aim of this study was to collect and synthesize existing pteropod (Gymnosomata, Thecosomata and Pseudothecosomata) abundance and biomass data, in order to evaluate the global distribution of pteropod carbon biomass, with a particular emphasis on its seasonal, temporal and vertical patterns. We collected 25 902 data points from several online databases and a number of scientific articles. The biomass data has been gridded onto a 360 x 180° grid, with a vertical resolution of 33 WOA depth levels. Data has been converted to NetCDF format. Data were collected between 1951-2010, with sampling depths ranging from 0-1000 m. Pteropod biomass data was either extracted directly or derived through converting abundance to biomass with pteropod specific length to weight conversions. In the Northern Hemisphere (NH) the data were distributed evenly throughout the year, whereas sampling in the Southern Hemisphere was biased towards the austral summer months. 86% of all biomass values were located in the NH, most (42%) within the latitudinal band of 30-50° N. The range of global biomass values spanned over three orders of magnitude, with a mean and median biomass concentration of 8.2 mg C l-1 (SD = 61.4) and 0.25 mg C l-1, respectively for all data points, and with a mean of 9.1 mg C l-1 (SD = 64.8) and a median of 0.25 mg C l-1 for non-zero biomass values. The highest mean and median biomass concentrations were located in the NH between 40-50° S (mean biomass: 68.8 mg C l-1 (SD = 213.4) median biomass: 2.5 mg C l-1) while, in the SH, they were within the 70-80° S latitudinal band (mean: 10.5 mg C l-1 (SD = 38.8) and median: 0.2 mg C l-1). Biomass values were lowest in the equatorial regions. A broad range of biomass concentrations was observed at all depths, with the biomass peak located in the surface layer (0-25 m) and values generally decreasing with depth. However, biomass peaks were located at different depths in different ocean basins: 0-25 m depth in the N Atlantic, 50-100 m in the Pacific, 100-200 m in the Arctic, 200-500 m in the Brazilian region and >500 m in the Indo-Pacific region. Biomass in the NH was relatively invariant over the seasonal cycle, but more seasonally variable in the SH. The collected database provides a valuable tool for modellers for the study of ecosystem processes and global biogeochemical cycles.

A refined Pliocene to early Pleistocene chronostratigraphic frame at ODP Hole 653A (West Mediterranean)

Two planktonic foraminiferal oxygen isotope records of ODP Hole 653A (Tyrrhenian Sea) are presented for the time period extending from approximately 0.8 to 3.0 Ma. Six, generally accepted, synchronous bioevents were used to precise the oxygen isotope chronology and to identify the oxygen isotope stages 22 down to 114. Subsequently, this oxygen isotope chronology was used to determine the synchronism or diachronism of various other biostratigraphic events with those recorded in the Singa and Ficarazzi land sections (Italy) and those in other DSDP/ODP sites. New results concern the diachronity of the FOD of the planktonic foraminiferal species N. atlantica, G.truncatulinoides truncatulinoides and G. inflata between ODP Hole 653A and the Italian landsections. Because many species entered the Mediterranean in short term fluxes, strongly related to the southward migration of cool North Atlantic surface waters, their time distribution through the Pliocene-Pleistocene generally corresponds to alternated intervals of presence and absence. This should explain most of the apparently diachronous appearances and disappearances. Alternating presence-absence patterns are of less importance for the various nannofossil events. The LOD of D. surculus occurs during the transition of stage 100 to 101 in both ODP Hole 653A and the Singa section, which is in perfect agreement with the disappearance of this species from the open ocean. The LOD of D. pentaradiatus in the Mediterranean occurs in stages 100-99, which seems to be consistent with the extinction of this species in the southern Hemisphere. G. oceanica, which corresponds to the 4 µm < Gephyrocapsa spp <5.5 µm is recorded in stages 65 to 64 at ODP Hole 653A. The Gephyrocapsa spp. >5.5 µm first occurred in stage 51 at Hole 653A, which fits within the uncertainty interval for this event stretching from stage 51 to 47 in the open ocean and seems therefore a useful tool for conventional biostratigraphy in the Mediterranean.