4:00pm - 4:20pm
Keynote: Magnetic Field Turbulence and Scaling Features in the Polar Ionosphere: Results from Swarm Mission
1INAF-Istituto di Astrofisica e Planetologia Spaziali, Italy; 2Istituto Nazionale di Geofisica e Vulcanologia, Italy
The characterization of ionospheric turbulence plays an important role for all those communication systems affected by the ionospheric medium, such as, for instance, the Global Navigation Satellite Systems (GNSS). Swarm measurements of the Earth's magnetic field allow a precise characterization of ionospheric turbulence and scaling features through magnetic field fluctuations, using a set of scaling indices derived from structure function analysis. This work focuses on some recent results dealing with the analysis of the scaling properties of magnetic field increments/fluctuations as measured by Swarm in the polar regions of the Northern Hemisphere. We discuss the obtained results in the framework of magnetic field turbulence, investigating also the variability of the observed turbulence features in relation to different IMF conditions and ionospheric polar convection patterns.
4:20pm - 4:35pm
Diagnosing the Electrodynamics of Magnetosphere-Ionosphere Coupling Using the Swarm Satellite Constellation: The Role of Alfven Waves?
1Unversity of Alberta, Edmonton, Alberta, Canada.; 2Mullard Space Science Laboratory, University College London, London, UK;; 3University of Calgary, Calgary, Alberta, Canada.; 4NASA Goddard Space Flight Center, Greenbelt, MD, USA.; 5John Hopkins University Applied Physics Laboratory, Laurel, MD,USA.; 6National Observatory of Athens, Athens, Greece; 7National and Kapodistrian University of Athens, Athens, Greece
We use data from the Swarm satellite constellation to examine the role of Alfven waves in magnetosphere-ionosphere coupling (MIC), including the potential impact of the ionospheric Alfven resonator (IAR). Exploiting the unique capabilities of the SWARM constellation, including multi-point measurements and the combination of high cadence and high resolution electric and magnetic field data, we investigate the impacts of the incidence, reflection and interference of Alfven waves on magnetosphere-ionosphere coupling. The multi-point Swarm magnetic field data reveals a remarkable non-stationarity on ~10 second timescales, with contemporaneous E- and B-field measurements from single satellites additionally indicating the characterization of such disturbances as Alfven waves. Moreover, statistical analysis of the magnetic fluctuations and the related single spacecraft field-aligned current (FAC) data product reveal that the stationarity assumption implicit in deriving such FAC estimates is frequently not valid. Whilst the large scale FAC profiles at spatial scales larger than ~150km are typically characteristic of the standard Iijima and Potemra region 1 and region 2 current systems, smaller scale presumably Alfvenic structures appear to behave differently and to have energetically significant consequences for MIC. We use the Swarm dataset to investigate the consequences of these Alfven waves for potentially changing the standard paradigms for magnetosphere-ionosphere energy transport.
4:35pm - 4:50pm
Ion Energization Processes Observed by ePOP, DMSP, and SWARM
1University of Colorado, United States of America; 2NOAA, Boulder Colorado, USA; 3University of Calgary, Alberta, CA
One of the outstanding problems in magnetosphere / ionosphere coupling is a detailed understanding of the processes energizing oxygen and other heavy ions to escape velocity in the top-side ionosphere. We present magnetic conjunction data from ePOP, DMSP, and SWARM taken at different altitudes that can begin to put constraints on the temporal and spatial extent of these processes.
4:50pm - 5:05pm
Statistical Analysis of the Field-Aligned Currents in the Cusp with Swarm
1Institut de Recherche en Astrophysique et Planétologie (IRAP), France; 2Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences; 3RAL Space, Rutherford Appleton Laboratory, STFC, Oxfordshire, UK; 4Swedish Institute of Space Physics, Uppsala, Sweden
The cusp connects the dayside magnetosphere and the polar ionosphere region through the open field lines. Particles from the solar wind directly precipitate into the ionosphere and may form various field-aligned current structures. Our goal is to study the distribution and variation of the field-aligned currents in the cusp, driven by the solar wind-magnetosphere-ionosphere interactions. In this work, we have analyzed Swarm data in the early phase of the mission, when the three satellites were still on the same orbit (as a string of pearl) and overflying Earth’s polar regions a couple of minutes apart. We have identified all cusp crossings according geometric considerations (magnetic latitude and MLT sector) and plasma signatures. We have statistically studied the characteristics of the currents and searched for possible correlations with solar wind/IMF parameters.
5:05pm - 5:20pm
FLR Event Studies With SWARM-SuperDARN Conjunctions
University of Calgary, Canada
Field line resonances (FLRs) are standing shear Alfven waves along Earth’s magnetic field lines. They play an important role in solar wind-magnetosphere-ionosphere coupling and are known to be associated with discrete auroral arcs, substorm onset, and radiation belt dynamics. The large spatial coverage of SuperDARN and the orbital tracks of the SWARM spacecraft provide a great opportunity for conjunction event studies of FLRs. Intervals of conjunction between SuperDARN and SWARM during FLR wave activity will be identified and analyzed. SuperDARN backscattered velocities will be used to calculate the FLR wave plasma flows and electric fields which will then be used to estimate field aligned currents associated with the FLR. These wave parameters will be compared to simultaneous SWARM measurements of electric fields, plasma flows and field aligned currents as SWARM passes through the region of the FLR. The aim is to find numerous event conjunctions which will allow comparison of FLR wave parameters for a variety of wave frequencies and wavelengths. These comparisons will lead to new knowledge of FLRs and may provide new insight into the role that FLRs play in auroral arc generation.
5:20pm - 5:35pm
Coordinated Swarm In Situ and THEMIS All Sky Imager (ASI) Observations of the Motion of Patchy Pulsating Aurora
University of Calgary, Canada
Patchy pulsating aurora (PPA) is a common ionospheric phenomenon and as such offers a unique opportunity to study the inner magnetosphere. Patchy Pulsating Aurora (PPA) patches typically preserve the shape over several minutes. Although it has yet to be proven, structures of PPA patches are believed to move with ionospheric convection. In this presentation, we show observations of auroral structures from THEMIS All Sky Imagers during two PPA events and simultaneous Swarm EFI observations of convection in the topside ionosphere over those structures. We demonstrate that the latitudinal variation of velocity from Swarm EFI is consistent with the motion of the PPA structures from the auroral images. Given that the processes that define the shape of PPA patches occur near the magnetospheric equator, our results indicate that cold magnetospheric plasma plays a key role in determining patch shape and evolution.