Caroline Blockx

Dayside and nightside reconnection rates inferred from IMAGE FUV and Super Dual Auroral Radar Network data

The spectrographic imager at 121.8 nm (SI12) of the far ultraviolet (FUV) experiment onboard the IMAGE spacecraft produces global images of the Doppler-shifted Lyman α emission of the proton aurora. This emission is solely due to proton precipitation and is not contaminated by dayglow, allowing us to monitor the auroral oval on the dayside as well as on the nightside. Remote sensing of the polar aurora can be advantageously supplemented by use of ground-based data from the Super Dual Auroral Radar Network (SuperDARN) that monitors the ionospheric convective flow pattern in the polar region. In the present study, the SI12 images are used to determine the location of the open/closed field line boundary and to monitor its movement. The SuperDARN data are then used to compute the ionospheric electric field at the location of the open/closed boundary. The total electric field is then computed along the boundary accounting for its movement via Faradays law so that the dayside and nightside reconnection voltages can be derived. This procedure is applied to several substorm intervals observed simultaneously with IMAGE FUV and SuperDARN. The dayside reconnection voltage feeds the magnetosphere with open flux, which is later closed by nightside reconnection. The calculated dayside reconnection rate is consistent with the solar wind properties measured by the Geotail, Wind, and ACE satellites. We identify the presence of nightside reconnection due to pseudobreakups taking place during the growth phase. In several cases, we establish that the nightside reconnection rate is maximum at the time of the substorm expansion phase onset or shortly after, reaching ∼120 kV, and then slowly returns to undisturbed values of ∼30 kV. The flux closure rate can also start intensifying prior to expansion phase onset, producing pseudobreakups.

PEGASE, an integrated river/basin model dedicated to surface water quality assessment: application to cocaine

Abstract The scientists of the Aquapôle of the University of Liège have been involved in environmental modeling for more than 20 years. Among other, its current R&D unit focuses on the compartment of surface water, and – for modeling processes – is specialized on the water quality. One of its environmental models, called PEGASE (Planification Et Gestion de l’ASsainissement des Eaux), French acronym for “Planning and management of water purification” is devoted to the modeling of the environmental state of surface water, at different scales from small watersheds (10 km2) and basins up to entire transnational Districts (more than 100.000 km2). The software is used operationally by several administrations (Agencies and Ministries) mainly through Europe (France and Benelux, Germany …), and several calculations have also been performed at international District levels for international commissions (Scheldt, Meuse, Moselle …). Recently, the PEGASE model has been adapted to describe the cocaine’s behavior (using a stable metabolite of the cocaine in the environment: the benzoylecgonine) in waste water, waste water treatment plants (WWTP) and surface water. The cocaine is newly described in the model as an additional micropollutant (Pegase already treats numerous heavy metals), thanks to the implementation of new state variable equations and their specific parameterizations. At a first stage, only the urban sources (releases associated to the consumption by inhabitants) were considered as the industrial releases and the soil loads are assumed to be negligible. Simulations of benzoylecgonine have been done in the Walloon and Flemish regions, where many measurements from the COWAT project were available. These first results are showing a good agreement between calculated and measured values. This ability of the model to simulate the fate of the cocaine derivatives in surface waters should be continued and extended to other metabolites.