99 research outputs found
One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity
Methane and carbon dioxide were measured with
an autonomous and continuous running system on a ferry line crossing the Baltic Sea on a 2â3 day interval from the Mecklenburg Bight to the Gulf of Finland in 2010. Surface methane saturations show great seasonal differences in shallow regions like the Mecklenburg Bight (103â507 %) compared to deeper regions like the Gotland Basin (96â161 %).
The influence of controlling parameters like temperature, wind, mixing depth and processes like upwelling, mixing of the water column and sedimentary methane emissions on methane oversaturation and emission to the atmosphere are investigated. Upwelling was found to influence methane surface concentrations in the area of Gotland significantly during
the summer period. In February 2010, an event of elevated methane concentrations in the surface water and water column of the Arkona Basin was observed, which could be linked to a wind-derived water level change as a potential
triggering mechanism. The Baltic Sea is a source of methane to the atmosphere throughout the year, with highest fluxes occurring during the winter season. Stratification was found
to promote the formation of a methane reservoir in deeper regions like Gulf of Finland or Bornholm Basin, which leads to long lasting elevated methane concentrations and enhanced
methane fluxes, when mixed to the surface during mixed layer deepening in autumn and winter. Methane concentrations and fluxes from shallow regions like the Mecklenburg
Bight are predominantly controlled by sedimentary production and consumption of methane, wind events and the change in temperature-dependent solubility of methane in the surface water. Methane fluxes vary significantly in shallow regions (e.g. Mecklenburg Bight) and regions with a temporal
stratification (e.g. Bornholm Basin, Gulf of Finland).
On the contrary, areas with a permanent stratification like the Gotland Basin show only small seasonal fluctuations in methane fluxes
The D-Grid Integration Project: How to Build a Grid for Different Communities
The Grid world is highly dynamic due to the appearance of new resources, easier access and new Grid applications. Moreover, an increasing number of scientific communities begins to realize that Grids will become an indispensable tool for modern science. However, the requirements of those communities often differ significantly from each other. Therefore, it is a particularly di±cult challenge to establish a national Grid infrastructure that serves as many communities as possible. To address this challenge, the German D-Grid has developed a concept that is based on development of independent Community Grids that are connected with a single integration project. Further, the process will involve several steps to consider dependencies between the various projects and their tasks. Presently, we are still at the beginning of the realization of a German Grid. Therefore in this paper, we first briefly explain this concept in this paper. Then we focus on the integration project and describe its tasks in more detail. This includes some first results and experiences that were achieved within the first year of the project. Finally, some plans for future steps are presented
Distribution of methane in the water column of the Baltic Sea
The distribution of dissolved methane in the water column of the Baltic Sea was extensively investigated. A strong correlation between the vertical density stratification, the distribution of oxygen, hydrogen sulfide, and methane has been identified. A widespread release of methane from the seafloor is indicated by increasing methane concentrations with water depth. The deep basins in the central Baltic Sea show the strongest methane enrichments in stagnant anoxic water bodies (max. 1086 nM and 504 nM, respectively), with a pronounced decrease towards the pelagic redoxcline and slightly elevated surface water concentrations (saturation values of 206% and 120%, respectively). In general the more limnic basins in the northern part of the Baltic are characterized by lower water column methane concentrations and surface water saturation values close to the atmospheric equilibrium (between 106% and 116%). In contrast, the shallow Western Baltic Sea is characterized by high saturation values up to 746%
Perspectives and Integration in SOLAS Science
Why a chapter on Perspectives and Integration in SOLAS Science in this book? SOLAS science by its nature deals with interactions that occur: across a wide spectrum of time and space scales, involve gases and particles, between the ocean and the atmosphere, across many disciplines including chemistry, biology, optics, physics, mathematics, computing, socio-economics and consequently interactions between many different scientists and across scientific generations. This chapter provides a guide through the remarkable diversity of cross-cutting approaches and tools in the gigantic puzzle of the SOLAS realm.
Here we overview the existing prime components of atmospheric and oceanic observing systems, with the acquisition of oceanâatmosphere observables either from in situ or from satellites, the rich hierarchy of models to test our knowledge of Earth System functioning, and the tremendous efforts accomplished over the last decade within the COST Action 735 and SOLAS Integration project frameworks to understand, as best we can, the current physical and biogeochemical state of the atmosphere and ocean commons. A few SOLAS integrative studies illustrate the full meaning of interactions, paving the way for even tighter connections between thematic fields. Ultimately, SOLAS research will also develop with an enhanced consideration of societal demand while preserving fundamental research coherency.
The exchange of energy, gases and particles across the air-sea interface is controlled by a variety of biological, chemical and physical processes that operate across broad spatial and temporal scales. These processes influence the composition, biogeochemical and chemical properties of both the oceanic and atmospheric boundary layers and ultimately shape the Earth system response to climate and environmental change, as detailed in the previous four chapters. In this cross-cutting chapter we present some of the SOLAS achievements over the last decade in terms of integration, upscaling observational information from process-oriented studies and expeditionary research with key tools such as remote sensing and modelling.
Here we do not pretend to encompass the entire legacy of SOLAS efforts but rather offer a selective view of some of the major integrative SOLAS studies that combined available pieces of the immense jigsaw puzzle. These include, for instance, COST efforts to build up global climatologies of SOLAS relevant parameters such as dimethyl sulphide, interconnection between volcanic ash and ecosystem response in the eastern subarctic North Pacific, optimal strategy to derive basin-scale CO2 uptake with good precision, or significant reduction of the uncertainties in sea-salt aerosol source functions. Predicting the future trajectory of Earthâs climate and habitability is the main task ahead. Some possible routes for the SOLAS scientific community to reach this overarching goal conclude the chapter
The role of the dentate gyrus and adult neurogenesis in hippocampal-basal ganglia associated behaviour
The ability of the brain to continually generate new neurons throughout life is one of the most intensely researched areas of modern neuroscience. While great advancements in understanding the biochemical mechanisms of adult neurogenesis have been made, there remain significant obstacles and gaps in connecting neurogenesis with behavioural and cognitive processes such as learning and memory. The purpose of the thesis was to examine by review and laboratory experimentation the role of the dentate gyrus and of adult neurogenesis within the hippocampus in the performance of cognitive tasks dependent on the hippocampal formation and hippocampal-basal ganglia interactions. Advancement in understanding the role of neurogenesis in these processes may assist in improving treatments for common brain injury and cognitive diseases that affect this region of the brain.
Mild chronic stress reduced the acquisition rate of a stimulus-response task (p=0.043), but facilitated the acquisition of a discrimination between a small and a large reward (p=0.027). In locomotor activity assays, chronic stress did not shift the dose-response to methamphetamine. Analysis of 2,5-bromodeoxyuridine incorporation showed that, overall, chronic mild stress did not effect survival of neuronal progenitors . However, learning of the tasks had a positive influence on cell survival in stressed animals (p=0.038). Microinjections of colchicine produced significant lesions of the dentate gyrus and surrounding CA1-CA3 and neocortex. Damage to these regions impaired hippocampal-dependent reference memory (p=0.054) while preserving hippocampal independent simple discrimination learning. In a delay discounting procedure, the lesions did not induce impulsive-like behaviour when delay associated with a large reward was introduced. The experiments uphold a current theory that learning acts as a buffer to mitigate the negative effects of stress on neurogenesis
The Pierre Auger Observatory Open Data
The Pierre Auger Collaboration has embraced the concept of open access to
their research data since its foundation, with the aim of giving access to the
widest possible community. A gradual process of release began as early as 2007
when 1% of the cosmic-ray data was made public, along with 100% of the
space-weather information. In February 2021, a portal was released containing
10% of cosmic-ray data collected from 2004 to 2018, during Phase I of the
Observatory. The Portal included detailed documentation about the detection and
reconstruction procedures, analysis codes that can be easily used and modified
and, additionally, visualization tools. Since then the Portal has been updated
and extended. In 2023, a catalog of the 100 highest-energy cosmic-ray events
examined in depth has been included. A specific section dedicated to
educational use has been developed with the expectation that these data will be
explored by a wide and diverse community including professional and
citizen-scientists, and used for educational and outreach initiatives. This
paper describes the context, the spirit and the technical implementation of the
release of data by the largest cosmic-ray detector ever built, and anticipates
its future developments.Comment: 19 pages, 8 figure
Radio Measurements of the Depth of Air-Shower Maximum at the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA), part of the Pierre Auger
Observatory, is currently the largest array of radio antenna stations deployed
for the detection of cosmic rays, spanning an area of km with 153
radio stations. It detects the radio emission of extensive air showers produced
by cosmic rays in the MHz band. Here, we report the AERA measurements
of the depth of the shower maximum (), a probe for mass
composition, at cosmic-ray energies between to eV,
which show agreement with earlier measurements with the fluorescence technique
at the Pierre Auger Observatory. We show advancements in the method for radio
reconstruction by comparison to dedicated sets of CORSIKA/CoREAS
air-shower simulations, including steps of reconstruction-bias identification
and correction, which is of particular importance for irregular or sparse radio
arrays. Using the largest set of radio air-shower measurements to date, we show
the radio resolution as a function of energy, reaching a
resolution better than g cm at the highest energies, demonstrating
that radio measurements are competitive with the established
high-precision fluorescence technique. In addition, we developed a procedure
for performing an extensive data-driven study of systematic uncertainties,
including the effects of acceptance bias, reconstruction bias, and the
investigation of possible residual biases. These results have been
cross-checked with air showers measured independently with both the radio and
fluorescence techniques, a setup unique to the Pierre Auger Observatory.Comment: Submitted to Phys. Rev.
Demonstrating Agreement between Radio and Fluorescence Measurements of the Depth of Maximum of Extensive Air Showers at the Pierre Auger Observatory
We show, for the first time, radio measurements of the depth of shower
maximum () of air showers induced by cosmic rays that are
compared to measurements of the established fluorescence method at the same
location. Using measurements at the Pierre Auger Observatory we show full
compatibility between our radio and the previously published fluorescence data
set, and between a subset of air showers observed simultaneously with both
radio and fluorescence techniques, a measurement setup unique to the Pierre
Auger Observatory. Furthermore, we show radio resolution as a
function of energy and demonstrate the ability to make competitive
high-resolution measurements with even a sparse radio array.
With this, we show that the radio technique is capable of cosmic-ray mass
composition studies, both at Auger and at other experiments.Comment: Submitted to Phys. Rev. Let
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