Nomenclature and resolution in Holocene glacial chronologies

Most Quaternary research in Canada during the first half of the twentieth century focused on Pleistocene glaciation. Given the dramatic shifts in climate during the Pleistocene, it is not surprising that the Holocene was viewed as a time of benign climate. Holocene climate variability was first recognized around the middle of the century when paleoecologists found evidence that the early part of the epoch was warmer and drier than the later part. In 1970s and 1980s, another generation of geologists, geographers, and botanists began to recognize more complexity in Holocene climate and vegetation in western Canada. Several millennial-scale glacier “advances” postdating the early Holocene warm interval were defined, including the Garibaldi Phase (6.9–5.6 ka), the Tiedemann–Peyto Advance (3.5–1.9 ka), and the Little Ice Age (AD 1200–1900). Subsequently, application of dendrochronological techniques and stratigraphic studies in glacier forefields showed that the Little Ice Age was itself more complex than previously thought. During that 700-year period, glaciers repeatedly advanced and retreated in response to climatic variability on time scales ranging from centuries to decades. Recent work shows that the glacier record of the Garibaldi Phase and the Tiedemann and Peyto advances are similar in complexity to the Little Ice Age, with multiple advances of glaciers separated by intervals of more restricted ice cover. Researchers have also identified other times in the Holocene when glaciers expanded from restricted positions – 8.20, 4.90–3.80, and 1.70–1.40 ka. Continued research undoubtedly will reveal additional complexities, but with what is currently known the appropriateness of terms such as “Tiedemann Advance,” “Peyto Advance,” and “Little Ice Age” can be questioned. Only short periods of time separate these episodes as currently defined, and it seems likely that intervals of restricted glacier cover within each of these millennial-length intervals are just as long as the intervals separating them.     

Comparison of groundwater recharge estimation methods for the semi-arid Nyamandhlovu area, Zimbabwe

The Nyamandhlovu aquifer is the main water resource in the semi-arid Umguza district in Matebeleland North Province in Zimbabwe. The rapid increase in water demand in the city of Bulawayo has prompted the need to quantify the available groundwater resources for sustainable utilization. Groundwater recharge estimation methods and results were compared: chloride mass balance method (19–62 mm/year); water-table fluctuation method (2–50 mm/year); Darcian flownet computations (16–28 mm/year); ¹⁴C age dating (22–25 mm/year); and groundwater modeling (11–26 mm/year). The flownet computational and modeling methods provided better estimates for aerial recharge than the other methods. Based on groundwater modeling, a final estimate for recharge (from precipitation) on the order of 15–20 mm/year is believed to be realistic, assuming that part of the recharge water transpires from the water table by deep-rooted vegetation. This recharge estimate (2.7–3.6% of the annual precipitation of 555 mm/year) compares well with the results of other researchers. The advantages/disadvantages of each recharge method in terms of ease of application, accuracy, and costs are discussed. The groundwater model was also used to quantify the total recharge of the Nyamandhlovu aquifer system (20?×?10⁶–25?×?10⁶ m³/year). Groundwater abstractions exceeding 17?×?10⁶ m³/year could cause ecological damage, affecting, for instance, the deep-rooted vegetation in the area.     

Multi‐Messenger Cosmic Particles

A54 Cosmic Ray Acceleration in Galactic Wind Shocks A71 Detection of Ultra‐High Energy Cosmic Rays and Neutrinos with LOFAR A80 Status of the gravitational‐wave detector GEO600 A87 Recent Results and Future of the MAGIC gamma‐ray telescope A92 Cosmic ray detection with the radio technique A93 Cosmic Ray Physics with IceCube A94 The resonance‐like gamma‐ray absorption processes for use in astrophysics A97 Geometry reconstruction of air shower fluorescence detectors revisited A102 Supermassive Binary Black Holes & Radio Jets A108 Muonic Component of Air Showers Measured by KASCADE‐Grande A110 Towards new frontiers: observation of photons with energies above 10¹⁸ eV A112 The IceCube Neutrino Telescope A114 The ground‐based gamma‐ray observatory CTA A116 IceCube: Recent Results and Prospects A117 Particle Physics with AMANDA and IceCube A118 Altitude dependence of fluorescence light emission by extensive air showers A120 Neutrino‐induced cascades in AMANDA & IceCube A122 Enhancement Telescopes for the Pierre Auger Southern Observatory in Argentina A123 Proton spectra from relativistic shock environments in AGN and GRBs A124 The Baikal Neutrino Telescope – Physics Results A127 Searches for point‐like sources of cosmic neutrinos with IceCube A128 The MAGIC/IceCube Target of Opportunity Programtest run A131 Supernova detection with IceCube: from low to high energy neutrinos A132 Measurement of the UHECR energy spectrum from hybrid data of the Pierre Auger Observatory A133 Extension of IceCube at Lower Energy: the Use of AMANDA as Nested Array and the Future Prospectives A135 Searching for neutrinos with the Pierre Auger Observatory A138 Search for Transient Emission of Neutrinos in IceCube A140 Acoustic Neutrino Detection in Antarctic Ice A159 AMANDA limits on the diffuse muon‐neutrino flux: physics implications A164 Investigation of the Radio Emission of Cosmic Ray Air Showers with LOPES A168 The Northern Site of the Pierre Auger Observatory A170 Shower reconstruction and size spectra with KASCADE‐Grande data A171 Neutrinos from Gamma Ray Bursts: predictions and limits from AMANDA‐II data A172 Simulation study of shower profiles from ultra‐high energy cosmic rays A174 Upper limit to the photon fraction in cosmic rays above 10¹⁹ eV from the Pierre Auger Observatory A176 Astrophysics at MeV energies A180 Study of the Cosmic Ray Composition above 0.4 EeV using the Longitudinal Profiles of Showers observed at the Pierre Auger Observatory A185 Backgrounds for UHE horizontal neutrino showers A186 The Front‐End Cards of the Pierre Auger Surface Detectors: Test Results and Performance in the Field A187 Monte Carlo Studies for MAGIC‐II A194 Measuring the proton‐air cross section from logitudinal air shower profiles A195 The UHECR energy spectrummeasured at the Pierre Auger Observatory A203 Highlights of Observations of Galactic Sources with the MAGIC telescope A207 Adesign study for a 12.5 m ∅︁ Imaging Air Cherenkov Telescope for ground‐based γ ‐ray astronomy A210 The Future of Long‐Wavelengths Radio‐Astronomy in Germany: LOFAR and GLOW A211 Online Monitoring of the Pierre Auger Observatory A216 OPTIMA‐Burst – Catching GRB Afterglows (and other Transients) with High Time Resolution A227 JEM‐EUSO mission A232 Rapid Variations in AGN: Clues on Particle Accelerators A235 Systematic search forVHEgamma‐ray emission from X‐ray bright high‐frequency peaked BL Lac objects A237 Prospects for GeV Astronomy in the Era of GLAST A241 Improvements of the energy reconstruction for the MAGIC telescope by means of analysis and Monte Carlo techniques A265 Discovery of VHE γ ‐rays from BL Lacertae with the MAGIC telescope A266 Results of two observation cycles of LS I+61°303 with the MAGIC telescope A267 Wide Range Multifrequency Observations of Northern TeV Blazars A269 Diffusive and convective cosmic ray transport in elliptical galaxies     

Vegetation as a major conductor of geomorphic changes on the Earth surface: toward evolutionary geomorphology

Earth surface processes and landforms may have coadjusted^? with plant morphology, biomechanics and life‐history. We suggest that the colonization of land by plants at the early Silurian, and their propagation inside continents, represent critical phases of the coupling between geomorphic and biological processes on the Earth at a global scale. The consideration of this coupling involving geomorphic‐biological feedback mechanisms at the scales of ecological succession and organisms' evolution may promote the emergence of an evolutionary^? geomorphology. Copyright © 2009 John Wiley & Sons, Ltd.     

Mechanisms controlling the air–sea flux in the North Sea

The mechanisms driving the air–sea exchange of carbon dioxide (CO₂) in the North Sea are investigated using the three-dimensional coupled physical–biogeochemical model ECOHAM (ECOlogical-model, HAMburg). We validate our simulations using field data for the years 2001–2002 and identify the controls of the air–sea CO₂ flux for two locations representative for the North Sea's biogeochemical provinces. In the seasonally stratified northern region, net CO₂ uptake is high () due to high net community production (NCP) in the surface water. Overflow production releasing semi-labile dissolved organic carbon needs to be considered for a realistic simulation of the low dissolved inorganic carbon (DIC) concentrations observed during summer. This biologically driven carbon drawdown outcompetes the temperature-driven rise in CO₂ partial pressure (pCO₂) during the productive season. In contrast, the permanently mixed southern region is a weak net CO₂ source (). NCP is generally low except for the spring bloom because remineralization parallels primary production. Here, the pCO₂ appears to be controlled by temperature.     

The effect of climate change on extreme waves in front of the Dutch coast

Coastal safety may be influenced by climate change, as changes in wave conditions (height, period, direction) may increase the vulnerability of dunes and other coastal defences. Dune erosion depends on mean water level, storm surge height and wave conditions. In this paper, we investigate the change in wave conditions in the North Sea in a changing climate. Until now, the effect of climate change on annual maximum wave conditions has been investigated, while events with higher return periods are actually most damaging for the coast (e.g. severe dune erosion). Here, we use the 17-member Ensemble SimulationS of Extreme weather under Non-linear Climate changeE (ESSENCE) change of climate change simulations, to analyse A1b-induced changes in the mean wave climate, the annual maxima and wave conditions with return periods of up to 1:10,000?years in front of the Dutch coast. The mean wave climate is not projected to differ between 1961–1990 and 2071–2100, with both wave height (H _s) and wave period (T _m) remaining unaltered. In the annual maximum conditions, a decrease is projected; especially, the annual T _m maximum decreases significantly by 0.3 to 0.6?s over the whole study area. Furthermore, we find that the direction of the annual maximum wave conditions shifts from north and north-west to west and south-west for both H _s and T _m. This is induced by a similar shift in the direction of the extreme wind speeds. Despite the decrease in annual maximum conditions, the return H _s and T _m are not projected to change significantly as a result of climate change in front of the Dutch coast for the period 2071–2100 relative to 1961–1990.     

Recent climatic trends and linkages to river discharge in Central Vietnam

In this study, change in rainfall, temperature and river discharge are analysed over the last three decades in Central Vietnam. Trends and rainfall indices are evaluated using non‐parametric tests at different temporal levels. To overcome the sparse locally available network, the high resolution APHRODITE gridded dataset is used in addition to the existing rain gauges. Finally, existing linkages between discharge changes and trends in rainfall and temperature are explored. Results are indicative of an intensification of rainfall (+15%/decade), with more extreme and longer events. A significant increase in winter rainfall and a decrease in consecutive dry days provides strong evidence for a lengthening wet season in Central Vietnam. In addition, trends based on APHRODITE suggest a strong orographic signal in winter and annual trends. These results underline the local variability in the impacts of climatic change at the global scale. Consequently, it is important that change detection investigations are conducted at the local scale. A very weak signal is detected in the trend of minimum temperature (+0.2°C/decade). River discharge trends show an increase in mean discharge (31 to 35%/decade) over the last decades. Between 54 and 74% of this increase is explained by the increase in precipitation. The maximum discharge also responds significantly to precipitation changes leading to a lengthened wet season and an increase in extreme rainfall events. Such trends can be linked with a likely increase in floods in Central Vietnam, which is important for future adaptation planning and management and flood preparedness in the region. Copyright © 2012 John Wiley & Sons, Ltd.     

History of anthropogenic nitrogen input to the German Bight/SE North Sea as reflected by nitrogen isotopes in surface sediments,sediment cores and hindcast models

The German Bight/SE North Sea is considered a hot-spot of river-induced eutrophication, but the scarce observational data of river nitrate loads prior to the 1970s complicate the assessment of target conditions for environmental management and legislation. Stable nitrogen isotope ratios (δ¹⁵N) in sediment records can be used to decipher historical river nitrate contributions. To better constrain pre-1970s conditions, we determined δ¹⁵N in archive sediment samples (1950–1969) and dated cores from the Helgoland depositional area. We also modeled the δ¹⁵N in past situations (1960 and 1860) using an N-isotope-tracking ecosystem model. The modeled spatial distribution of δ¹⁵N in sediments for 1960 conditions and the observed spatial pattern of δ¹⁵N in archive sediment samples (1950–1969) represent a period of moderate eutrophication. The modeled spatial distribution of δ¹⁵N in sediments for 1860 conditions (pre-industrial) showed a moderate δ¹⁵N gradient from the Elbe river mouth (δ¹⁵N<4‰) to the open sea (δ¹⁵N∼5‰). This pattern contrasts with the δ¹⁵N pattern in modern surface sediments, which exhibits a steep and inverted δ¹⁵N gradient from the Elbe river mouth (δ¹⁵N>9‰) to the open sea (δ¹⁵N<7‰). Modeled δ¹⁵N for 1860 conditions are consistent with δ¹⁵N values observed in dated sediment cores that span the last 900 years. Value of δ¹⁵N in sediment cores increased from approximately 1860 to 2000 by 2.5‰. The increasing trend reflects changes in the abundance and isotopic composition of riverine nitrate loads caused by anthropogenic activities. Sensitivity tests suggest that loads and isotopic ratios of nitrogen forms other than nitrate (ammonium and organic nitrogen) have minor impact on the modeled surface sediments, despite their higher abundance in the riverborne loads in the past. Our results suggest that eutrophication of the German Bight predates the 1960 period of documented rapidly increasing river loads. Pre-industrial levels of δ¹⁵N modeled with 28% of the modern annual (1990–1999) atmospheric loads and 10% of the modern annual river loads agree best with levels of δ¹⁵N (∼6‰) observed in sediments of the cores dated to 1860.     

Nitrogen and carbon cycling in the North Sea and exchange with the North Atlantic—A model study,Part II: Carbon budget and fluxes

The 3-d coupled physical–biogeochemical model ECOHAM (version 3) was applied to the Northwest-European Shelf (47°41′–63°53′N, 15°5′W–13°55′E) for the years 1993–1996. Carbon fluxes were calculated for the years 1995 and 1996 for the inner shelf region, the North Sea (511,725 km²). This period was chosen because it corresponds to a shift from a very high winter-time North Atlantic Oscillation Index (NAOI) in 1994/1995, to an extremely low one in 1995/1996, with consequences for the North Sea physics and biogeochemistry. During the first half of 1996, the observed mean SST was about 1 °C lower than in 1995; in the southern part of the North Sea the difference was even larger (up to 3 °C). Due to a different wind regime, the normally prevailing anti-clockwise circulation, as found in winter 1995, was replaced by more complicated circulation patterns in winter 1996. Decreased precipitation over the drainage area of the continental rivers led to a reduction in the total (inorganic and organic) riverine carbon load to the North Sea from 476 Gmol C yr⁻¹ in 1995 to 340 Gmol C yr⁻¹ in 1996. In addition, the North Sea took up 503 Gmol C yr⁻¹ of CO₂ from the atmosphere. According to our calculations, the North Sea was a sink for atmospheric CO₂, at a rate of 0.98 mol C m⁻² yr⁻¹, for both years. The North Sea is divided into two sub-systems: the shallow southern North Sea (SNS; 190,765 km²) and the deeper northern North Sea (NNS; 320,960 km²). According to our findings the SNS is a net-autotrophic system (net ecosystem production NEP>0) but released CO₂ to the atmosphere: 159 Gmol C yr⁻¹ in 1995 and 59 Gmol C yr⁻¹ in 1996. There, the temperature-driven release of CO₂ outcompetes the biological CO₂ drawdown. In the NNS, where respiratory processes prevail (NEP<0), 662 and 562 Gmol C yr⁻¹ were taken up from the atmosphere in 1995 and 1996, respectively. Stratification separates the productive, upper layer from the deeper layers of the water column where respiration/remineralization takes place. Duration and stability of the stratification are determined by the meteorological conditions, in relation to the NAO. Our results suggest that this mechanism controlling the nutrient supply to the upper layer in the northern and central North Sea has a larger impact on the carbon fluxes than changes in lateral transport due to NAOI variations. The North Sea as a whole imports organic carbon and exports inorganic carbon across the outer boundaries, and was found to be net-heterotrophic, more markedly in 1996 than in 1995.     

Kohlendioxid-Messungen in einem Durchfluß-Meßsystem mit einem neu entwickelten CO2-Sensor am Beispiel eines Hartwassersees (Willersinnweiher, Ludwigshafen am Rhein)

The concentrations of free dissolved carbon dioxide in lake water were measured with a newly developed CO₂ sensor, which was installed in a through-flow measurement system. The results of measurements demonstrate the CO₂ dynamics in lake Willersinnweiher. The CO₂ concentrations showed a correlation with the oxidation of CH₄ in the metalimnion and caused shifts in the carbonate system, thus affecting the autochthonous precipitation and dissolution of calcite.

From the results of measurement appears that the CO₂ sensor is capable of very exact measurements of dissolved free CO₂ in lake water. At the same time, the parameter is easily determined in the field without large expenditures.