The effect of misleading surface temperature estimations on the sensible heat fluxes at a high Arctic site – the Arctic Turbulence Experiment 2006 on Svalbard (ARCTEX-2006)

The observed rapid climate warming in the Arctic requires improvements in permafrost and carbon cycle monitoring, accomplished by setting up long-term observation sites with high-quality in-situ measurements of turbulent heat, water and carbon fluxes as well as soil physical parameters in Arctic landscapes. But accurate quantification and well adapted parameterizations of turbulent fluxes in polar environments presents fundamental problems in soil-snow-ice-vegetation-atmosphere interaction studies. One of these problems is the accurate estimation of the surface or aerodynamic temperature T<sub>(0)</sub> required to force most of the bulk aerodynamic formulae currently used. Results from the Arctic-Turbulence-Experiment (ARCTEX-2006) performed on Svalbard during the winter/spring transition 2006 helped to better understand the physical exchange and transport processes of energy. The existence of an atypical temperature profile close to the surface in the Arctic spring at Svalbard could be proven to be one of the major issues hindering estimation of the appropriate surface temperature. Thus, it is essential to adjust the set-up of measurement systems carefully when applying flux-gradient methods that are commonly used to force atmosphere-ocean/land-ice models. The results of a comparison of different sensible heat-flux parameterizations with direct measurements indicate that the use of a hydrodynamic three-layer temperature-profile model achieves the best fit and reproduces the temporal variability of the surface temperature better than other approaches

Langzeit-Datenreihe (2007 - 2017) von Eddy-Kovarianz CO2- und Energieflüssen der arktischen Bayelva-Station, Spitzbergen

Die Messung von ganzjährigen CO2-, Wasser- und Energieflüssen zwischen Erdoberfläche und Atmosphäre in arktischen Regionen wird bisher nur an wenigen Standorten durchgeführt. Derartige Messungen sind aber insbesondere insofern relevant, als dass arktische Tundren bedeutende CO2-Senken darstellen, unter einem sich erwärmenden Klima möglicherweise aber zukünftig im Permafrost gespeicherten Kohlenstoff freisetzen. Durch den Einsatz bodengebundener in situ Messungen können Kohlenstoff- und Energiedynamik bilanziert werden. Des Weiteren sind die gemessenen Gas- und Energieflüsse wertvoll für die Kalibration und Validierung globaler Klimamodelle. Eine Messstation in der europäischen Arktis ist die Bayelva-Messstation (78� 55‘ N, 11� 50‘ O) nahe Ny Ålesund auf Spitzbergen. Der starke Einfluss des Nordatlantikstroms führt dort zu einem maritimen Klima mit kühlen Sommertemperaturen von durchschnittlich 5 °C im Juli und relativ milden Wintertemperaturen von -13 °C im Januar. Es handelt sich somit um eine vergleichsweise warme Permafrostregion mit Jahresmitteltemperaturen von etwa -2.5 °C. Der Jahresniederschlag liegt bei etwa 400 mm und die schneefreie Zeit beträgt typischerweise drei Monate. An der Bayelva-Station fanden von 2007 bis 2017 Messungen von Wasserdampf- und CO2-Konzentrationen (mittels open-path LiCor LI-7500 CO2 und H2O Gasanalysierer) sowie dreidimensionale Messungen der Windgeschwindigkeit (mittels Campbell CSAT 3D sonic anemometer) mit einer Messfrequenz von 20 Hz statt. Mithilfe der Eddy-Kovarianz-Software TK3 ermitteln wir hieraus halbstündliche Gas- und Energieflüsse und führen Qualitätsprüfungen durch. Erste Ergebnisse für das Jahr 2008/2009 zeigen, dass die jährliche CO2-Bilanz des Standortes nahezu bei null liegt, was durch die lange, winterliche Freisetzung von CO2 in die Atmosphäre zu erklären ist. Allerdings sind die Prozesse, welche diese winterliche CO2-Emission bedingen bisher nicht untersucht. Unser Ziel besteht daher nun darin, die Analyse der Gas- und Energieflüsse auf den gesamten Messzeitraum von 2007 bis 2017 auszuweiten. Insbesondere für die Zeiträume Oktober 2012 bis August 2014 sowie Januar 2015 bis September 2016 sind die Messreihen nahezu komplett mit Datenlücken von nur wenigen Tagen pro Zeitraum. Auf der Grundlage der entstehenden Langzeit-Datenreihe können wir durch den Klimawandel bedingte Änderungen der CO2-Flüsse von zwischenjährlicher Variabilität unterscheiden sowie saisonale und jahreszeitliche Schwankungen bilanzieren. Außerdem ermöglicht es uns der mehrjährige Datensatz die Umstände der ablaufenden Prozesse genauer zu beschreiben und dadurch möglicherweise Rückschlüsse auf deren Auslöser zu ziehen. Im weiteren Verlauf ist es zudem vorstellbar Wechselwirkungen zwischen den beobachteten Gas- und Energieflüssen und weiteren Eigenschaften verschiedener Komponenten des Klimasystems wie zum Beispiel Wolkeneigenschaften zu untersuchen

Minimising the impact of disturbances in future highly-distributed power systems

It is expected that future power systems will require radical distributed control approaches to accommodate the significant expansion of renewable energy sources and other flexible grid devices. It is important to rapidly and efficiently respond to disturbances by, for example: utilising adaptive, wide-area protection schemes; proactive control of available grid resources (such as managing the fault level contribution from converter-interfaced generation) to optimise protection functionality; and taking post-fault action to ensure protection stability and optimal system operation. This paper analyses and highlights the protection functions which will be especially important to minimising the impact of disturbances in future power systems. These functions include: fast-acting wide-area protection methods using Phasor Measurement Units (PMUs); adaptive and “self-organising” protection under varying system conditions; protection with distributed Intelligent Electronic Devices (IEDs); enhanced fault ride-through; and pattern recognition based schemes. In particular, the paper illustrates how the increased availability of measurements and communications can enable improved protection functionality within distribution systems, which is especially important to accommodate the connection of highly-distributed generation at medium- and low-voltages

Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

The following authors were omitted from the original version of this Data Descriptor: Markus Reichstein and Nicolas Vuichard. Both contributed to the code development and N. Vuichard contributed to the processing of the ERA-Interim data downscaling. Furthermore, the contribution of the co-author Frank Tiedemann was re-evaluated relative to the colleague Corinna Rebmann, both working at the same sites, and based on this re-evaluation a substitution in the co-author list is implemented (with Rebmann replacing Tiedemann). Finally, two affiliations were listed incorrectly and are corrected here (entries 190 and 193). The author list and affiliations have been amended to address these omissions in both the HTML and PDF versions

The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data.

The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible

A three-step numerical approximant based on block hybrid backward differentiation formula for stiff system of ordinary differential equation

We present results of an analysis of the reaction $γγ→ωϱ$ in the two-photon process $e^+e^−→ϵ^+e^−2π^+2π^−π^0$ in the untagged mode. The cross section is largely compatible with previous determinations; however, we do not confirm the enhancement claimed at 1.9 GeV. All observed ω's are accompanied by ϱ's in the recoiling ππ spectrum. An angular correlation analysis shows that the data is not dominated by a single spin-parity state, thus establishing severe constraints on $qqqq$ models which predict $JP= 2^+$

Алгоритм сжатия на основе вычисления скорости изменения ультразвукового сигнала

The intermittency structure of multihadronic e+e- annihilation is analyzed by evaluating the factorial moments F2-F5 in three-dimensional Lorentz invariant phase space as a function of the resolution scale. We interpret our data in the language of fractal objects. It turns out that the fractal dimension depends on the resolution scale in a way that can be attributed to geometrical resolution effects and dynamical effects, such as the pi-O Dalitz decay. The LUND 7.2 hadronization model provides an excellent description of the data. There is no indication of unexplained multiplicity fluctuations in small phase space regions

Разработка модульного стенда физического подобия для изучения гидротехнических систем

В рамках данной работы проведен обзор и анализ образовательных стендов, сформулирована концепция модульного стенда физического подобия, разработаны функциональные схемы двух модулей, в соответствии с которыми подобраны основные элементы. Для первого модуля предоставлены принципиальная схема и демонстрационный алгоритм работы.In this work, a review and analysis of educational booths, formulated the concept of modular stand physical similarity, developed functional diagrams of the two modules, in accordance with which the selected basic elements. For the first module, a schematic diagram and a demonstration algorithm are provided