Towards improved management of coastal submersion crises - CRISMA-WAVE solution as an example of CRISMA Framework application

Coping with various types of natural or man-made hazards the FP7 SECURITY CRISMA project (http://www.crisrnaprojecteu) has designed and developed an experimental software framework allowing building crisis management simulation application. One of the five pilot applications of CRISMA dealing with preparedness to the coastal submersions was developed and implemented using return of experience of the reference Xynthia storm surge event in the Charente Maritime County in France. The paper addresses the generic CRISMA Framework applicability to simulate mitigation effects of a coastal submersion through CRISMA-Wave implementation of a full modelling cycle. The CRISMA-Wave paradigm reflects user needs for simulation of "what-if" scenarios for short and long-term actions and the paper describes in particular its different components : *Simulation of submersion effects at a range of temporal and spatial scales, *Preparedness Planning, *Assessment of impacts depending on scenarios based on options for managing the inundation risks, *Cascading effects and *Evaluation of damages with comparison of submersion defence scenarios based on cost-benefit and multi criteria analysis

Zn, Cu, Cd and Hg binding to metallothioneins in harbour porpoises <i>Phocoena phocoena</i> from the southern North Sea

Background: Harbour porpoises Phocoena phocoena from the southern North Sea are known to display high levels of Zn and Hg in their tissues linked to their nutritional status (emaciation). The question arises regarding a potential role of metallothioneins (MTs) with regard to these high metal levels. In the present study, metallothionein detection and associated Zn, Cd, Cu and Hg concentrations were investigated in the liver and kidney of 14 harbour porpoises collected along the Belgian coast. Results: Metallothioneins seemed to play a key role in essential metal homeostasis, as they were shown to bind 50% of the total hepatic Zn and 36% of the total hepatic Cu concentrations. Renal MTs also participated in Cd detoxification, as they were shown to bind 56% of the total renal Cd. Hg was mainly found in the insoluble fraction of both liver and kidney. Concomitant increases in total Zn concentration and Zn bound to MTs were observed in the liver, whereas Zn concentration bound to high molecular weight proteins remained constant. Cu, Zn and Cd were accumulated preferentially in the MT fraction and their content in this fraction increased with the amount in the hepatocytosol. Conclusion: MTs have a key role in Zn and Cu homeostasis in harbour porpoises. We demonstrated that increasing hepatic Zn concentration led to an increase in Zn linked to MTs, suggesting that these small proteins take over the Zn overload linked to the poor body condition of debilitated harbour porpoises

Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15

We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on time scale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) channels in the range 25-100 keV lead all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and the Extreme Ultra-Violet (EUV) channels of the Euv SpectroPhotometer (ESP) onboard the Solar Dynamic Observatory (SDO). The Zirconium and Aluminum filter channels of the Large Yield Radiometer (LYRA) onboard the Project for On-Board Autonomy (PROBA2) satellite and the SXR channel of ESP follow. The largest lags occur in observations from the Geostationary Operational Environmental Satellite (GOES), where the channel at 1-8 {\AA} leads the 0.5-4 {\AA} channel by several seconds. The time lags between the first and last channels is up to 9 s. We identified at least two distinct time intervals during the flare impulsive phase, during which the QPPs were associated with two different sources in the Nobeyama RadioHeliograph at 17 GHz. The radio as well as the hard X-ray channels showed different lags during these two intervals. To our knowledge, this is the first time that time lags are reported between EUV and SXR fluctuations on these time scales. We discuss possible emission mechanisms and interpretations, including flare electron trapping

Numerical simulation of the internal plasma dynamics of post-flare loops

We integrate the MHD ideal equations of a slender flux tube to simulate the internal plasma dynamics of coronal post-flare loops. We study the onset and evolution of the internal plasma instability to compare with observations and to gain insight into physical processes and characteristic parameters associated with flaring events. The numerical approach uses a finite-volume Harten-Yee TVD scheme to integrate the 1D1/2 MHD equations specially designed to capture supersonic flow discontinuities. We could reproduce the observational sliding down and upwardly propagating of brightening features along magnetic threads of an event occurred on October 1st, 2001. We show that high--speed downflow perturbations, usually interpreted as slow magnetoacoustic waves, could be better interpreted as slow magnetoacoustic shock waves. This result was obtained considering adiabaticity in the energy balance equation. However, a time--dependent forcing from the basis is needed to reproduce the reiteration of the event which resembles observational patterns -commonly known as quasi--periodic pulsations (QPPs)- which are related with large scale characteristic longitudes of coherence. This result reinforces the interpretation that the QPPs are a response to the pulsational flaring activity.Comment: Accepted MNRAS, 10 pages, 14 figures, 1 tabl

The SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing

The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV solar telescope on board ESA's Project for Onboard Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm and provides images of the low solar corona over a 54x54 arcmin field-of-view with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is designed to monitor all space-weather-relevant events and features in the low solar corona. Given the limited resources of the PROBA2 microsatellite, the SWAP telescope is designed with various innovative technologies, including an off-axis optical design and a CMOS-APS detector. This article provides reference documentation for users of the SWAP image data.Comment: 26 pages, 9 figures, 1 movi

The SWAP Filter: A Simple Azimuthally Varying Radial Filter for Wide-Field EUV Solar Images

We present the SWAP Filter: an azimuthally varying, radial normalizing filter specifically developed for EUV images of the solar corona, named for the Sun Watcher with Active Pixels and Image Processing (SWAP) instrument on the Project for On-Board Autonomy 2 spacecraft. We discuss the origins of our technique, its implementation and key user-configurable parameters, and highlight its effects on data via a series of examples. We discuss the filter's strengths in a data environment in which wide field-of-view observations that specifically target the low signal-to-noise middle corona are newly available and expected to grow in the coming years.Comment: Contact D. B. Seaton for animations referenced in figure caption

Stability and mode analysis of solar coronal loops using thermodynamic irreversible energy principles

We study the modes and stability of non - isothermal coronal loop models with different intensity values of the equilibrium magnetic field. We use an energy principle obtained via non - equilibrium thermodynamic arguments. The principle is expressed in terms of Hermitian operators and allow to consider together the coupled system of equations: the balance of energy equation and the equation of motion. We determine modes characterized as long - wavelength disturbances that are present in inhomogeneous media. This character of the system introduces additional difficulties for the stability analysis because the inhomogeneous nature of the medium determines the structure of the disturbance, which is no longer sinusoidal. Moreover, another complication is that we obtain a continuous spectrum of stable modes in addition to the discrete one. We obtain a unique unstable mode with a characteristic time that is comparable with the characteristic life-time observed for loops. The feasibility of wave-based and flow-based models is examined.Comment: 29 pages 10 figure

Torsional Alfven waves in stratified and expanding magnetic flux tubes

The effects of both density stratification and magnetic field expansion on torsional Alfven waves in magnetic flux tubes are studied. The frequencies, the period ratio P1/P2 of the fundamental and its first-overtone, and eigenfunctions of torsional Alfven modes are obtained. Our numerical results show that the density stratification and magnetic field expansion have opposite effects on the oscillating properties of torsional Alfven waves.Comment: 13 pages, 7 figures, Accepted for publication in Astrophysics and Space Scienc

On-disk coronal rain

Small and elongated, cool and dense blob-like structures are being reported with high resolution telescopes in physically different regions throughout the solar atmosphere. Their detection and the understanding of their formation, morphology and thermodynamical characteristics can provide important information on their hosting environment, especially concerning the magnetic field, whose understanding constitutes a major problem in solar physics. An example of such blobs is coronal rain, a phenomenon of thermal non- equilibrium observed in active region loops, which consists of cool and dense chromospheric blobs falling along loop-like paths from coronal heights. So far, only off-limb coronal rain has been observed and few reports on the phenomenon exist. In the present work, several datasets of on-disk H{\alpha} observations with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish 1-m Solar Telescope (SST) are analyzed. A special family of on-disk blobs is selected for each dataset and a statistical analysis is carried out on their dynamics, morphology and temperatures. All characteristics present distributions which are very similar to reported coronal rain statistics. We discuss possible interpretations considering other similar blob-like structures reported so far and show that a coronal rain interpretation is the most likely one. Their chromospheric nature and the projection effects (which eliminate all direct possibility of height estimation) on one side, and their small sizes, fast dynamics, and especially, their faint character (offering low contrast with the background intensity) on the other side, are found as the main causes for the absence until now of the detection of this on-disk coronal rain counterpart.Comment: 18 pages, 10 figures. Accepted for Solar Physic

Dynamics of solar coronal loops II. Catastrophic cooling and high-speed downflows

This work addresses the problem of plasma condensation and ``catastrophic cooling'' in solar coronal loops. We have carried out numerical calculations of coronal loops and find several classes of time-dependent solutions (static, periodic, irregular), depending on the spatial distribution of a temporally constant energy deposition in the loop. Dynamic loops exhibit recurrent plasma condensations, accompanied by high-speed downflows and transient brightenings of transition region lines, in good agreement with features observed with TRACE. Furthermore, these results also offer an explanation for the recent EIT observations of De Groof et al. (2004) of moving bright blobs in large coronal loops. In contrast to earlier models, we suggest that the process of catastrophic cooling is not initiated by a drastic decrease of the total loop heating but rather results from a loss of equilibrium at the loop apex as a natural consequence of heating concentrated at the footpoints of the loop, but constant in time.Comment: 13 pages, 15 figure