On Flare-CME Characteristics from Sun to Earth Combining Remote-Sensing Image Data with <Emphasis Type="Italic">In Situ</Emphasis> Measurements Supported by Modeling     

Manuela Temmer  Julia K. Thalmann  Karin Dissauer  Astrid M. Veronig  Johannes Tschernitz  Jürgen Hinterreiter  Luciano Rodriguez 《Solar physics》2017,292(7):93

We analyze the well-observed flare and coronal mass ejection (CME) from 1 October 2011 (SOL2011-10-01T09:18) covering the complete chain of effects – from Sun to Earth – to better understand the dynamic evolution of the CME and its embedded magnetic field. We study in detail the solar surface and atmosphere associated with the flare and CME using the Solar Dynamics Observatory (SDO) and ground-based instruments. We also track the CME signature off-limb with combined extreme ultraviolet (EUV) and white-light data from the Solar Terrestrial Relations Observatory (STEREO). By applying the graduated cylindrical shell (GCS) reconstruction method and total mass to stereoscopic STEREO-SOHO (Solar and Heliospheric Observatory) coronagraph data, we track the temporal and spatial evolution of the CME in the interplanetary space and derive its geometry and 3D mass. We combine the GCS and Lundquist model results to derive the axial flux and helicity of the magnetic cloud (MC) from in situ measurements from Wind. This is compared to nonlinear force-free (NLFF) model results, as well as to the reconnected magnetic flux derived from the flare ribbons (flare reconnection flux) and the magnetic flux encompassed by the associated dimming (dimming flux). We find that magnetic reconnection processes were already ongoing before the start of the impulsive flare phase, adding magnetic flux to the flux rope before its final eruption. The dimming flux increases by more than 25% after the end of the flare, indicating that magnetic flux is still added to the flux rope after eruption. Hence, the derived flare reconnection flux is most probably a lower limit for estimating the magnetic flux within the flux rope. We find that the magnetic helicity and axial magnetic flux are lower in the interplanetary space by ～?50% and 75%, respectively, possibly indicating an erosion process. A CME mass increase of 10% is observed over a range of \({\sim}\,4\,\mbox{--}\,20~\mathrm{R}_{\odot }\). The temporal evolution of the CME-associated core-dimming regions supports the scenario that fast outflows might supply additional mass to the rear part of the CME.  相似文献   

Observations of a Radio-Quiet Solar Preflare     

Arnold O. Benz  Marina Battaglia  Manuel Güdel 《Solar physics》2017,292(10):151

The preflare phase of the flare SOL2011-08-09T03:52 is unique in its long duration, in that it was covered by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Nobeyama Radioheliograph, and because it showed three well-developed soft X-ray (SXR) peaks. No hard X-rays (HXR) are observed in the preflare phase. Here we report that no associated radio emission at 17 GHz was found either, despite the higher sensitivity of the radio instrument. The ratio between the SXR peaks and the upper limit of the radio peaks is higher by more than one order of magnitude than the ratio in regular flares. The result suggests that the ratio between acceleration and heating in the preflare phase was different than in regular flares. Acceleration to relativistic energies, if any, occurred with lower efficiency.  相似文献   

Franz-Ludwig Deubner (1934 – 2017)     

Bernhard Fleck  Oskar von der Lühe 《Solar physics》2017,292(12):178

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Snow carrots after the Chelyabinsk event and model implications for highly porous solar system objects          下载免费PDF全文

Robert Luther  Natalia Artemieva  Marina Ivanova  Cyril Lorenz  Kai Wünnemann 《Meteoritics & planetary science》2017,52(5):979-999

After the catastrophic disruption of the Chelyabinsk meteoroid, small fragments formed funnels in the snow layer covering the ground. We constrain the pre‐impact characteristics of the fragments by simulating their atmospheric descent with the atmospheric entry model. Fragments resulting from catastrophic breakup may lose about 90% of their initial mass due to ablation and reach the snow vertically with a free‐fall velocity in the range of 30–90 m s^?1. The fall time of the fragments is much longer than their cooling time, and, as a consequence, fragments have the same temperature as the lower atmosphere, i.e., of about ?20 °C. Then, we use the shock physics code iSALE to model the penetration of fragments into fluffy snow, the formation of a funnel and a zone of denser snow lining its walls. We examine the influence of several material parameters of snow and present our best‐fit model by comparing funnel depth and funnel wall characteristics with observations. In addition, we suggest a viscous flow approximation to estimate funnel depth dependence on the meteorite mass. We discuss temperature gradient metamorphism as a possible mechanism which allows to fill the funnels with denser snow and to form the observed “snow carrots.” This natural experiment also helps us to calibrate the iSALE code for simulating impacts into highly porous matter in the solar system including tracks in the aerogel catchers of the Stardust mission and possible impact craters on the 67P/Churyumov‐Gerasimenko comet observed recently by the Rosetta mission.  相似文献   

Experiments on the effect of inflow and outflow sequences on suspended sediment exchange rates     

Michael M&#;ller  Giovanni De Cesare  Anton J. Schleiss 《国际泥沙研究》2017,32(2)

In laboratory experiments, the influence of inflow and outflow sequences on the behavior of fine sedi-ment was investigated. The experimental set-up consisted of two interconnected rectangular basins, between which water was moved back and forth. Suspended sediment concentration in the main basin as well as the sediment exchange rates were derived from turbidity measurements.The suspended sediment ratio, SSR, and sediment exchange rates (influx sediment rate, ISR, and evacuated sediment rate, ESR) were measured. In twenty test runs, a parametric study on the magnitude and frequency of inflow and outflow cycles, the relative duration between inflow and outflow sequences, the initial sediment concentration, and the intake position was done. An initial test with stagnant water described the set-tling behavior of fine sediment and served as a reference scenario.The test results show that settling of fine particles near the intake/outlet structure can be considerably reduced by the nature of the inflow and outflow sequences. High cycle magnitude and frequency lead to maximum suspended sediment ratio in the system. For low discharges, the evolution of suspended sediment concentration cannot be directly correlated to the inflow and outflow cycles. However, compared to"no operation"conditions, the suspended sediment ratio could be increased by 10%to 40%locally. For high discharge, the evolution of suspended sediment concentration correlated with discharge cycles and suspended sediment ratios between 50%and 80%higher than for stagnant water could be achieved. Similar ratios could be obtained when the intake is located closer to the bottom or to the free water surface.Meanwhile, the overall sediment balance remained in equilibrium over the test period, indicating that the influx and evacuated sediment rates are not significantly influenced by the inflow and outflow cycles.  相似文献   

Real-time envelope cross-correlation detector: application to induced seismicity in the Insheim and Landau deep geothermal reservoirs   总被引：1，自引：0，他引：1  

Margarete Vasterling  Ulrich Wegler  Jan Becker  Andrea Brüstle  Monika Bischoff 《Journal of Seismology》2017,21(1):193-208

We develop and test a real-time envelope cross-correlation detector for use in seismic response plans to mitigate hazard of induced seismicity. The incoming seismological data are cross-correlated in real-time with a set of previously recorded master events. For robustness against small changes in the earthquake source locations or in the focal mechanisms we cross-correlate the envelopes of the seismograms rather than the seismograms themselves. Two sequenced detection conditions are implemented: After passing a single trace cross-correlation condition, a network cross-correlation is calculated taking amplitude ratios between stations into account. Besides detecting the earthquake and assigning it to the respective reservoir, real-time magnitudes are important for seismic response plans. We estimate the magnitudes of induced microseismicity using the relative amplitudes between master event and detected event. The real-time detector is implemented as a SeisComP3 module. We carry out offline and online performance tests using seismic monitoring data of the Insheim and Landau geothermal power plants (Upper Rhine Graben, Germany), also including blasts from a nearby quarry. The comparison of the automatic real-time catalogue with a manually processed catalogue shows, that with the implemented parameters events are always correctly assigned to the respective reservoir (4 km distance between reservoirs) or the quarry (8 km and 10 km distance, respectively, from the reservoirs). The real-time catalogue achieves a magnitude of completeness around 0.0. Four per cent of the events assigned to the Insheim reservoir and zero per cent of the Landau events are misdetections. All wrong detections are local tectonic events, whereas none are caused by seismic noise.  相似文献   

Binding characteristics of Pb<Superscript>2+</Superscript> to natural fulvic acid extracted from the sediments in Lake Wuliangsuhai,Inner Mongolia plateau,P. R. China     

Jinghua Wang  Changwei Lü  Jiang He  Boyi Zhao 《Environmental Earth Sciences》2016,75(9):768

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Groundwater – the disregarded component in lake water and nutrient budgets. Part 2: effects of groundwater on nutrients          下载免费PDF全文

Jörg Lewandowski  Karin Meinikmann  Gunnar Nützmann  Donald O. Rosenberry 《水文研究》2015,29(13):2922-2955

Lacustrine groundwater discharge (LGD) transports nutrients from a catchment to a lake, which may fuel eutrophication, one of the major threats to our fresh waters. Unfortunately, LGD has often been disregarded in lake nutrient studies. Most measurement techniques are based on separate determinations of volume and nutrient concentration of LGD: Loads are calculated by multiplying seepage volumes by concentrations of exfiltrating water. Typically low phosphorus (P) concentrations of pristine groundwater often are increased due to anthropogenic sources such as fertilizer, manure or sewage. Mineralization of naturally present organic matter might also increase groundwater P. Reducing redox conditions favour P transport through the aquifer to the reactive aquifer‐lake interface. In some cases, large decreases of P concentrations may occur at the interface, for example, due to increased oxygen availability, while in other cases, there is nearly no decrease in P. The high reactivity of the interface complicates quantification of groundwater‐borne P loads to the lake, making difficult clear differentiation of internal and external P loads to surface water. Anthropogenic sources of nitrogen (N) in groundwater are similar to those of phosphate. However, the environmental fate of N differs fundamentally from P because N occurs in several different redox states, each with different mobility. While nitrate behaves essentially conservatively in most oxic aquifers, ammonium's mobility is similar to that of phosphate. Nitrate may be transformed to gaseous N₂ in reducing conditions and permanently removed from the system. Biogeochemical turnover of N is common at the reactive aquifer‐lake interface. Nutrient loads from LGD were compiled from the literature. Groundwater‐borne P loads vary from 0.74 to 2900 mg PO₄‐P m^?2 year^?1; for N, these loads vary from 0.001 to 640 g m^?2 year^?1. Even small amounts of seepage can carry large nutrient loads due to often high nutrient concentrations in groundwater. Large spatial heterogeneity, uncertain areal extent of the interface and difficult accessibility make every determination of LGD a challenge. However, determinations of LGD are essential to effective lake management. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

GUP assisted Hawking radiation of rotating acoustic black holes     

I. Sakalli  A. Övgün  K. Jusufi 《Astrophysics and Space Science》2016,361(10):330

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Rapid subglacial streamlined bedform formation at a calving bay margin          下载免费PDF全文

Thomas P. F. Dowling  Per Möller  Matteo Spagnolo 《第四纪科学杂志》2016,31(8):879-892

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