Seminars & Internal Meetings

Seminars are usually held on Thursdays afternoon. Fill this form if you whish to be included in the mailing list.

2024.10.14, 14:15 - 15:00, Forskningsparken A289

Speaker: Yoshihiro Yokoyama

Affiliation: Swedish Institute of Space Physics (IRF)

Title: The BROR experiment, a Swedish rocket mission: the behaviours of artificial plasma clouds at different altitudes in the low-altitude ionosphere

It is also possible to join the seminar remotely.
Join the mailing list to get the link to the Teams meeting.

2024.09.26, 13:15 - 14:00, Forskningsparken A289

Speaker: Lunjin Chen

Affiliation: The University of Texas at Dallas

Title: Modeling electron microburst induced by chorus waves

Abstract:
During magnetospheric storms, radiation belt electrons are produced and then removed on varying timescales. An efficient loss process is microbursts, strong, transient precipitation of electrons into the lower atmosphere over a wide energy range, from tens of keV to sub-relativistic and relativistic energies (100s keV and above). However, the detailed generation mechanism of microbursts, especially over sub-relativistic and relativistic energies, remains unknown. Here, we show that these energetic electron microbursts may be caused by ducted whistler-mode lower-band chorus waves. Using combined observations of equatorial chorus waves from Van Allen Probes and electron precipitation from low-altitude ELFIN, our data-driven simulations demonstrate that the observed microbursts are the result of resonant interaction of electrons with ducted chorus waves rather than nonducted ones. Revealing the physical mechanism behind the microbursts advances our understanding of radiation belt dynamics and its impact on the lower atmosphere and space weather.

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2024.09.03, 13:00 - 14:00, Teknologibygget 1.022

Speaker: Jeffrey Plaut

Affiliation: NASA Jet Propulsion Laboratory, Pasadena, CA, USA

Title: Radar sounding of ice sheets and glaciers on Mars

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2024.06.27, 13:15 - 14:00, Forskningsparken A289

Speaker: Liliana Macotela

Affiliation: NORCE

Title: The VLF technique to study the lower ionosphere

Abstract:
One of the very few techniques that is used to study both the lower boundary of the ionosphere, also known as the D-region, and the magnetosphere is the propagation of Very Low Frequency (VLF: 3-30 kHz) radio waves. To monitor the ionospheric D-region, the VLF waves propagate inside a natural waveguide formed between the Earth surface and the lower boundary of the ionosphere, also known as the Earth-ionosphere waveguide. If in this system the electrical conductivity of its boundaries is disturbed, the propagation of VLF waves is also disrupted, which is observed as phase and amplitude variations of VLF waves with respect to their quiescent levels. There is a diversity of physical phenomena that are able to alter significantly the conductivity of this waveguide upper boundary. These phenomena can have their origin at the Earth (e.g., lightning), in the solar system (e.g., solar flares) or even much farther away (e.g., galactic gamma-ray bursts). This talk presents solar flare, galactic gamma-ray bursts, and atmospheric activity.

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2024.06.13, 13:15 - 14:00, Forskningsparken A289 / Remotely

Speaker: Shreedevi P. R.

Affiliation: Institute for Space-Earth Environmental Research (ISEE), Nagoya University

Title: Recent advances in modeling the EMIC wave-particle interaction

Abstract:
Both solar radiation and particle precipitation are important sources for ionizing the upper atmosphere in the high-mid latitude regions. It is commonly accepted that, electrons compared to ions are the major source of energy deposition in the sub-auroral upper atmosphere. However, the origin of localized ion precipitation in the sub-auroral regions and its relative contribution to the total energy flux deposited into the ionosphere is not well understood. Statistical and case studies relate the EMIC wave-particle scattering in the inner magnetosphere to the loss of ring current ions into the ionosphere. We implemented this loss mechanism in a kinetic ring current model (RAM-SCBE) as a diffusion process aided with the associated pitch angle diffusion coefficients. To understand the role of EMIC wave-particle scattering in causing ion precipitation into the ionosphere, we conducted two simulations using the Space Weather Modeling Framework (SWMF) (BATSRUS+RAMSCBE) with and without EMIC waves included. We validated the simulation results by examining the temporal and spatial evolution of the proton precipitation into the ionosphere and its correspondence to the EMIC wave activity observed by the Arase and the RBSP-A satellite during geomagnetic storms. Results indicate that the RAM-SCBE model is able to capture the EMIC wave activity fairly well. The simulation with EMIC waves reproduces the precipitating fluxes in the pre-midnight sector, and is found to be in good agreement with the DMSP and MetOp satellite observations. The results suggest that the EMIC wave scattering of ring current ions gives rise to the proton precipitation in the pre-midnight sector at sub-auroral latitudes.

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2024.05.23, 13:15 - 14:00, Forskningsparken A289 / Remotely

Speaker: Ruchi Pandey

Affiliation: Physical Research Laboratory, Ahmedabad

Title: Shock-induced dust formation in nova V2891 Cyg: A phenomenological approach

Abstract:
Novae are fascinating objects which have enabled the direct observation of the various aspects of astrophysical dust formation on a frequent basis. Since the timescale of dust formation in novae typically ranges from 30 to 100 days following an outburst, these environments can serve as test beds for studying the formation and evolution of astrophysical dust in real time scale. However, dust formation in the hostile environment of novae ejecta has been an open question for many decades. Several attempts have been made to understand the physical and chemical conditions required for this phenomenon and its relationship with the observable parameters. Numerous hypotheses have been developed in order to explain the mechanisms that underlie the process of dust formation. An intriguing proposition is put forth, suggesting the possibility of shock-induced dust formation in novae. A recent study of Nova V2891 Cyg by a team of astronomers at Physical Research Laboratory, India has provided, most likely, the first observational evidence of such a method of dust formation in novae ejecta. In this seminar, I will commence with a concise introduction to the phenomenon of dust formation in novae, highlighting its significance and the current gaps in understanding the same. Subsequently, I will shed insights into the phenomenological modelling of Nova V2891 Cyg and bring out its relevance in illustrating the origin of some observational signatures of shock-induced dust formation.

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2024.04.25, 13:15 - 14:00, Forskningsparken A289 / Remotely

Speaker: Rahul Rathi

Affiliation: Indian Institute of Technology Roorkee

Title: Investigations of MSTIDs and the dynamics behind their generation during geomagnetic quiet and active nights

Abstract:
Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are one of the most prominent plasma structures in the mid-latitude ionospheric F region. These are the propagating bands of high and low plasma density, which appear as bright and dark bands in the O(1D) 630.0 nm airglow images and have been investigated extensively with other datasets as well. Overall seasonal variation and propagation characteristics of MSTIDs are widely reported in literature. However, the mechanism behind their generation is not well understood.

Using O(1D) 630.0 nm airglow data obtained from an all-sky airglow imager installed at Hanle (32.7°N, 78.9°E; Mlat. ~24.1°N), Ladakh, India, I have investigated quite a few unique MSTID events during geomagnetic quiet and active nights. In these events I have observed simultaneously existing different types of MSTIDs (electrified MSTID and non-electrified MSTID) and investigated their coexistence, properties, and generation mechanisms. I have also explored the role of polarization electric field associated with electrified MSTIDs (EMSTIDs) on the various phenomena during geomagnetic quiet nights. Whereas, on a moderately active night, I have investigated the role of the externally imposed electric fields on the evolution and decay of an EMSTID during two consecutive substorms. These studies helped in better understanding of the influence of these electric fields on the evolution/decay of EMSTIDs and their interaction with other mid-latitude plasma structures during geomagnetic quiet as well as active condition.

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2024.02.22, 13:00 - 14:00, Forskningsparken A289 / Remotely

Speaker: Tobias Stein

Affiliation: University of Göttingen

Title: Solar Radiation Sweeping Dust through the Solar System: A peculiar asymmetry

Abstract:
When the dust particles in the cloud of dust around the Sun collide, the resulting smaller particles get blown away by the Sun's radiation. But where do they get blown away to? When analyzing this, a highly unexpected result is seen: We observe many of these particles over the Sun's ecliptic north pole, but none over its south pole. In this talk, we will try to make sense of an asymmetric Solar System, while also learning about the physics of dust and how we detect it.

It is also possible to join the seminar remotely.
Meeting ID: 651 2505 4729

2023.12.06, 15:00 - 16:00, Forskningsparken A289

Speaker:  Hans Pecseli

Affiliation: UiO/UiT

Title: Kinetically unstable ion velocity distributions formed via charge exchange collisions by E×B-drifts in magnetized plasmas

Abstract:
The stability of ion velocity distributions in magnetized plasmas is studied under conditions where the plasma has an E × B-drift with respect to a neutral background. Charge–exchange collisions can give rise to velocity distributions in the form of a ring or a loss-cone, being linearly unstable. Simple arguments can explain the process. Usually the distributions have distorted forms, and a stability analysis is not straightforward. Numerical simulations offer the most convenient method of a stability analysis in such cases. A particle-in-cell code that includes collisional interactions shows the formation of such velocity distributions and the instabilities associated with them. We observe the saturation of the linear instability by quasi-linear velocity space diffusion. The parameter dependence of the instability conditions is illustrated by examples. The results may be relevant for explaining some of the low-frequency oscillations observed in the lower parts of the Earth’s ionosphere (E- and F-regions), where collisions with neutrals are abundant. The results can be important for laboratory experiments as well.

It is also possible to join the seminar remotely. Just know that the quality won't be as good as usual as we are not able to use the microphone and the camera of the room due to a new hardware incompatible with zoom.
Meeting ID: 651 2505 4729

2023.11.23, 14:30 - 15:30, Forskningsparken A289

Speaker:  Tomotaka Tanaka

Affiliation: SOKENDAI/NIPR

Title: How effective is the mirror force for the altitude profile of electron density?

Abstract:
We will show simulation results of electron density profiles by electron precipitation in the altitudes between 70 km and 85 km. We used data of electron fluxes obtained with the ELFIN satellites and a simulation code of ionization rate developed by Katoh et al.(2023). The simulation code enables us to investigate mirror force effects. We compared the electron density profiles from the ELFIN data and the simulation code with those from EISCAT observations.

It is also possible to join the seminar remotely. Just know that the quality won't be as good as usual as we are not able to use the microphone and the camera of the room due to a new hardware incompatible with zoom.
Meeting ID: 651 2505 4729

2023.11.09, 14:30 - 16:00, Teknologibygget 2.018

Speaker: Hervé Dole

Affiliation: Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS

Title: The search for galaxy protoclusters : the rise of the large scale structure in the Universe (including results from JWST and Euclid missions)

It is also possible to join the seminar remotely:
Meeting ID: 364 317 846 326 (Teams)

2023.10.26, 13:30 - 14:30, Forskningsparken A289

Speaker: Daniel Kastinen

Affiliation: IRF Swedish Institute of Space Physics

Title: Meteors and space objects research at IRF

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.09.22, 14:00 - 15:00, Forskningsparken A289

Speaker: Peter Berthelemy

Affiliation: Department of Electronic & Electrical Engineering, University of Bath, UK

Title: Gravity Waves (and how to find them)

Abstract:
Atmospheric gravity waves are prevalent all throughout the atmosphere, with various important effects depending on the layer. But one major problem has always been, how do you extract them from the surrounding noise?

This seminar will briefly go over the basics of gravity waves and airglow, and some of the methods used to gather useable data. It will then explain the new method for the extraction of gravity waves using Aqua-AIRS satellite data, and airglow imager data, and then will compare against the older data.

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.09.21, 13:00 - 14:00, Forskningsparken A289

Speaker: Sophie Maguire

Affiliation: Space Environment and Radio Engineering (SERENE) Research Group, School of Engineering, University of Birmingham, United Kingdom

Title: Evolution of large-scale structures in the high-latitude ionosphere

Abstract:
The terrestrial ionosphere is a highly variable medium that has the ability to affect the propagation of radio waves. Within the ionosphere, large-scale structures, such as polar cap patches, auroral forms, blobs and polar holes, have been observed. Small-scale irregularities associated with these large-scale structures result from instability processes which can lead to scintillation of trans-ionospheric radio signals, such as those used for Global Navigation Satellite Systems (GNSS).

In order to test the relationship between large-scale structures and scintillation, an experiment named Scintillation and Plasma Density Gradients (SGRAD) was conducted on the European Incoherent Scatter (EISCAT) radars. The experiment aimed to observe different large-scale structures under varying geomagnetic conditions and to determine which of these are related to the scintillation of GNSS signals. It has previously been demonstrated that scintillation effects are not always observed in the presence of large-scale structures (Jenner et al., 2020). Therefore, the experiment was designed to explore whether a minimum electron density gradient and/or value is required at the edge of large-scale structures for scintillation to occur. The results from the SGRAD run on the 5th of January 2023 are presented. A polar cap patch was observed exiting the polar cap and becoming a boundary blob. We present the first direct observations of multiple plasma structuring mechanisms acting simultaneously to create a blob. Additionally, the scintillation data is in the process of being analysed.

The next stage of this work involves investigating plasma structuring at multiple scale sizes. The proposed Scales of Ionospheric Plasma Structuring (SIPS) experiment is discussed.

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.09.15, 13:15 - 14:15, Forskningsparken A289

Speaker: Lakshmi Narayanan Viswanathan

Affiliation: Department of Electronic & Electrical Engineering, University of Bath, UK

Title: On the relationship between PMSE power and spectral width in the VHF and UHF frequencies

Abstract:
Polar mesospheric summer echoes (PMSE) are strong radar echoes due to the variation of the refractive index caused by modification of the electron density distribution through turbulence in the presence of ice crystals under the extreme low temperatures of summer polar mesosphere. Active experiments using powerful radio waves to heat the ionosphere indicated that the charged ice crystals might play a role in generation of PMSE thereby adding further evidence that it is a dusty plasma phenomenon. In this work, we study the relationship between the peak power of the PMSE echoes and the spectral widths obtained with three EISCAT radars operating in the frequencies 223.4 MHF, 500.3 MHz and 929.6 MHz. We have fitted Gaussian curves to the PMSE spectra and obtained the peak power of the echo and corresponding spectral width. We have also considered the possibility of contribution from incoherent scattering from the free electrons by means of fitting a Lorentzian curve to the spectra. The results reveal that most intense echoes almost always contain spectral widths in the range of 5 - 8 m/s. Interestingly, wider spectral widths do not cause intense PMSE echoes in vast majority of cases and broadening due to the incoherent scattering is not a cause for the observed wider spectral widths in those cases. The pattern exists irrespective of magnetically quiet periods, particle precipitation periods and active ionospheric heating periods. We also show rare cases wherein active turbulence generates stronger PMSE echoes, which appears to be more important for UHF frequencies. We discuss these results based on present understanding of PMSE and attempt to understand the observations.

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.06.22, 13:15 - 14:15, Forskningsparken A289

Speaker: Yasunobu Ogawa

Affiliation: National Institue of Polar Research, Tachikawa, Japan

Title: Statistical study of high energy electron precipitation based on ERG (Arase) satellite - EISCAT collaborative observation data

Abstract:
In this seminar, we report statistical results of the relationship between wave and particle data observed by the Arase satellite and ionospheric electron density data obtained with the EISCAT Tromsø radar. Their results are based on more than 150 collaborative observations (~600 hours in total) between the Arase satellite and EISCAT radar since March 2017, and summarized as follows: (1) When the amplitude of the lower-band chorus (LBC) waves is above ~18 pT, magnetospheric electrons with energies above ~160 keV undergo pitch angle scattering, and become significantly ionized at altitudes between 65-100 km. (2) The relationship between resonance energies of pitch angle scattering and electron density increases due to energetic electron precipitation suggests that pitch-angle scattering of energetic electrons by LBC waves propagating at higher latitudes (~20 deg) rather than in the magnetic equatorial plane occurs frequently.

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.06.15, 13:15 - 14:15, Forskningsparken B284

Speaker: Lindis Merete Bjoland

Affiliation: Department of Physics and Technology, UiB

Title: Space weather with EISCAT_3D

Abstract:
Severe space weather events pose a risk to human technologies and infrastructure. To mitigate the effect of these events, it is important to understand and monitor the solar wind-magnetosphere-ionosphere interactions and dynamics. The ESA Space Weather Service Network provides a wide range of products for such monitoring of the space weather, and we are currently working on an ESA project to assess how EISCAT_3D can be utilized within this context to enhance existing space weather products and potentially develop new products. We will present preliminary results from this study where we highlight the space weather products to which we think data from EISCAT_3D potentially could contribute, and show a few examples of how we envision these products.

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.05.26, 11:00 - 12:00, Forskningsparken B281

Speaker: Fabio Del Sordo

Affiliation: Institute of Space Sciences (ICE-CSIC), Barcelona, Spain

Title: On the possibility of observing magnetic star-planet interaction in exoplanetary systems.

Abstract:
Exoplanetary discoveries of the last 30 years provided us with a large number of diverse planetary systems. Nowadays more than 5000 exoplanets have been discovered, and none of the systems observed so far is similar to our Solar System. One of the main tasks in exoplanetary science is now to provide a deeper characterization of these new world.
In this talk I will discuss the possibility of understanding one of the most elusive features of exoplanets, that is their magnetization. This is a key ingredient for allowing life as we know it to develop on the Earth, therefore it is natural to ask whether it is common, or not, that exoplanets too are magnetized.
I will briefly introduce the basics of what we know about exoplanets, and of what we believe to be the mechanism able to sustain their magnetization, namely a dynamo.
The most direct way to prove the magnetization of an exoplanet is to observe aurora-like emission triggered by the magnetic interaction with the winds of their host star. Conversely, planets orbiting on a very short time scale, if magnetized, may also be able to influence some features connected with stellar magnetism. I will discuss the theoretical basis of both scenarios, and present the first proposed observational evidence for both cases.

It is also possible to join the seminar remotely:
Meeting ID: 682 8360 3792

2023.04.13, 14:15 - 15:00, Forskningsparken A289

Speaker: Florian Günzkofer

Affiliation: Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), Neustrelitz, Germany

Title: Coupling of ionosphere plasma and neutral atmosphere in the ionospheric dynamo region

Abstract:
The ionospheric dynamo/transition region at∼90−150 km altitude is determined by the collisionality of neutral atmosphere and ionosphere plasma. At these altitudes, the two gases undergo a transition from being highly collisional to non-collisional. Pedersen and Hall conductivities maximize in the dynamo region and their vertical profiles strongly depend on the coupling of neutral and plasma particles. Atmospheric processes in this region (e.g. tides, gravity waves, etc.) significantly impact the ionospheric variability. Combined observations of neutral atmosphere and ionosphere plasma in the transition region are essential to understand these processes and the plasma-neutral coupling. Incoherent Scatter Radars (ISR) are capable to measure basic plasma parameters across the whole dynamo region and also allow us to infer information about the neutral atmosphere under certain assumptions. We present combined measurements of atmosphere-ionosphere coupling processes in the transition region with the EISCAT ISR located in Northern Scandinavia and other instruments in the area. Such measurements can be applied to assess the ionospheric variability caused by atmospheric processes like the mixing of tidal modes or atmospheric gravity waves. The possibility to infer additional atmosphere-ionosphere parameters is demonstrated as well

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

2023.03.23, 13:15 - 14:00, Forskningsparken A289

Speaker: Hans Pécseli

Affiliation:
Department of Physics and Technology, Arctic University of Norway, 9037 Tromsø, Norway
Department of Physics, University of Oslo, Boks 1048 Blindern, 0316 Oslo, Norway

Title: Minute time-scale oscillations of the magnetopause

Abstract:
It is argued that a simple model based on magnetic image arguments suffices to give a convincing insight into both the basic static as well as some transient dynamic properties of the near-Earth's magnetosphere, particularly accounting for damped oscillations being excited in response to impulsive perturbations. The parameter variations of the frequency are given. Qualitative results can also be obtained for heating due to the compression of the radiation belts. The properties of this simple dynamic model for the solar wind–magnetosphere interaction are discussed and compared to observations. In spite of its simplicity, the model gives convincing results concerning the magnitudes of the near-Earth's magnetic and electric fields. The database contains ground-based results for magnetic field variation in response to shocks in the solar wind. Here, the observations also include data from the two Van Allen satellites.

It is also possible to join the seminar remotely:
Meeting ID: 651 2505 4729

 __________________________________________________________________________________________________________________

Seminars from 2020 and earlier are listed below ↓↓↓
 __________________________________________________________________________________________________________________

2020.10.01 13:15-14:00

Speaker: Andres Spicher (with contributions from a long list of co-authors)

Title: High latitude ionospheric density irregularities

Abstract:

Plasma density irregularities with scale-sizes ranging from hundreds of kilometers down to a few meters are common in the high-latitude ionosphere. The irregularities generally peak around the cusp and auroral regions, and can have significant space weather impacts, as they can degrade Global Navigation Satellite System (GNSS) radio signals by causing amplitude and phase scintillations. As the physical causes and detailed formation are still unresolved, characterizing density irregularities and their sources is of significant interest, and will be essential to develop models for predicting scintillations. In this seminar, we briefly review the physical processes generally regarded as dominant for causing macro-scale density irregularities at F region altitudes. We then present selected studies (based on both in situ and ground-based instruments) examining different sources of free energy and the applicability and relevance of different instability modes. Finally, observations and analysis necessary to advance the fields will be discussed.

2020.09.24 13:15-14:00

2020.09.17 13:15-14:00

Margareta Myrvang and Johann Stamm

Title: Sopp

Abstract:

Dette foredraget handler opp soppens spennende verden. Hensikten med foredraget er å gjøre dere til potensielt litt mer selvsikre og selvstendige sopplukkere. Vi vil blant annet snakke om hvor det er lurt å lete etter sopp, noe som varierer mellom de ulike artene. Noen sopper foretrekker barskog, andre løvskog og noen vokser på enger. Et par arter er ikke så kresne og vokser både her og der. I foredraget nevner vi også hva dere bør ta med av utstyr på sopptur. Vi vil i tillegg snakke om hvordan man unngår giftige sopper. Selvfølgelig nevner vi noen gode matsopper. Til slutt en liten quiz!

2020.09.10 13:15-14:00

Markus Floer

Title: Svalbard - a hot-zone within space physics. You can/should also go there and study.

Abstract:

Longyearbyen, situated at the Svalbard archipelago is a hot spot for researchers and aspiring space physicists. In terms of space physics, it is uniquely located within the cusp region of the magnetosphere which makes it an ideal place for observing cusp dynamics – an area of ongoing research; the importance of which is emphasized by the Grand Challenge Initiative. Because of this, Svalbard houses several observatory facilities, some of which are The EISCAT Svalbard radar, the Kjell Henriksen Observatory and a sounding rocket range. Here you also find the University Centre in Svalbard (UNIS), which is an educational facility owned by the 5 main universites of Norway. At UNIS you can take courses within space physics, write your thesis and become an expert on arctic geophysics. You will also become acquainted with researches from all over the world, both within the field of space physics and without. In this talk I present to you why Svalbard is such an interesting place, and argue why you should utilize the opportunity to go there.

2020.09.03 13:15-14:00 

Björn Gustavsson

Title: Dynamic aurora - how to calculate the ionospheric responses when things happen quickly (Part 2/2)

2020.08.27 13:15-14:00 

Björn Gustavsson

Title: Dynamic aurora - how to calculate the ionospheric responses when things happen quickly (Part 1/2)

Abstract: In dynamic aurora the intensity can vary at sub-second
time-scales. The ionospheric response to the different types of
rapidly varying aurora share some characteristics that are different to
the case of stable auroral arcs. In this talk examples of such auroras
will be presented. To calculate the auroral brightness for such fast
variations it is necessary to take into account the time it takes
high-energy electrons to move from the source-altitude (typically a
few thousand kilometres) down to and through the upper atmosphere (down
to about 100 km altitude), and the time it takes for these electrons to
lose their energy. A new "auroral electron-transport" model
that takes these effects into account have been developed. Previous
steady-state electron-transport models could not resolve
time-variations of the precipitation. This novel model allows us to
determine time-variations in electron-fluxes which makes it possible
to predict small time-shifts between auroral emission. Comparisons
with optical data show the prediction to be consistent with
observations.

Friday 22 November 13:15 - Seminar room FPARK 289 - Forskningsparken

Adrien Pineau

University of Bordeaux, France 

Modeling the electron collision frequency during solid-to-plasma transition of polystyrene for direct-drive inertial confinement fusion applications

 Wednesday 13 November 14:00 - Seminar room - Forskningsparken

Professor T. W. Hartquist

School of Physics and Astronomy, University of Leeds, United Kingdom

Astronanophysics and Astromicrophysics – Dust in the Cosmos

The talk will provide examples of the variety of cosmic environments in which dust exists and plays roles in governing the physical and chemical properties. It will also contain a review of work done in Leeds on the effects of dust on the dynamics of shocks in dusty star forming regions and on methods for treating the evolution of the grain size distribution in a region where destruction and agglomeration occur. It will cover: the basic properties of interstellar dust; the formation and role of dust in stellar outflows; surface chemistry and dusty magnetohydrodynamics in star forming regions; protoplanetary disc formation; presolar grains and meteoroids; dust near the terrestrial mesopause; some dust dynamics in Saturn’s rings.

Monday 5 August 2019, 14:00 - Realfagbygget, room B203

Dr. Katherine Rosenfeld

MIT Lincoln Laboratories, USA

Katherine talks about her PhD project: Applications of High-Resolution Observations of Millimeter Wavelengths

Interferometric observations at millimeter wavelengths provide a precious, detailed view of certain astrophysical objects. This thesis is composed of studies that both rely on and enable this technique to study the structure of planet-forming disks and soon image the closest regions around super-massive black holes. Young stars form out of a cloud of gas and dust that, before its eventual dissipation, flattens to a disk. However the disk population is diverse and recent high-resolution images have revealed a wide variety of interesting features. To understand these observations we use detailed radiative transfer models to motivate various physical scenarios. First we identify a set of traits in the disk around V4046 Sgr that marks the coupled progression of the gas and dust distributions in the presence of at least one embedded companion. Next, we investigate how the vertical temperature structure of a disk can be spatially resolved and apply our framework to observations of the disk around HD163296. Lastly, we show how large-scale radial flows of gas may be observable and question how this phenomenon might be distinguished from other scenarios such as warps or outflows. The last chapter summarizes the APHIDS project which changes the sampling rate of data taken at the SMA so that it may be used for VLBI campaigns.

Tuesday 7 May 2019, 14:00 - Teknologiebygget, room 3.028

Professor J. P. Rozelot

Université de la Côte d'Azur, Nice, France

How big is the Sun ? A critical assessment of the diameter data over the centuries

The measurement of the solar diameter has a rich history extending well back into the past. Tackled by Greek astronomers from a geometric point of view, an estimate, although incorrect, has been first determined, not truly called into question for several centuries. A canonical value was adopted by Auwers in 1891. In spite of  considerable efforts during the second half of the XXth century, involving dedicated space instruments, no consensus has been reached on this issue. However, a shrinking or an expanding shape is ultimately linked to solar activity, as gravitational or magnetic fields, which are existing mechanisms for storing energy during a solar cycle, lead to distinct perturbations in the equilibrium solar structure and changes in the diameter. We will here give a brief review of some of the most remarkable techniques used in the past, emphasizing the advent of high sensibility instruments on board satellites, such as SDO, which allows accurate determination of the shape of the Sun. Furthermore, notable features of the Near Sub-Surface Layer (NSSL), called the leptocline, can be established in relation to the solar limb variations, mainly through the shape asphericities coefficients. Recent studies encourage further in-depth investigations of the solar subsurface dynamics, observationally through SDO: we will show the latest results on such solar limb shape asphericities. It turns out that such modern measurements are one of the ways we have now for peering into the solar interior, learning empirically about flows and motions there that would otherwise only be guessed from theoretical considerations. 

Friday 15 March 2019, 14:00 - Realfagbygget, room will be announced 

Professor J. M. C. Plane

School of Chemistry, University of Leeds, United Kingdom

Cosmic Dust in Planetary Atmospheres (including Earth)

Cosmic dust particles are produced in the solar system from the sublimation of comets as they orbit close to the sun, and also from asteroidal collisions between Mars and Jupiter. Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. 

In this seminar I will describe the results of a large study designed to determine the input rate of cosmic dust to the terrestrial atmosphere, using a self-consistent treatment of cosmic dust from the outer solar system to the Earth’s surface. An astronomical model which tracks the evolution of dust from various sources into the inner solar system was combined with a chemical ablation model to determine the rate of injection of metallic vapours into the atmosphere. Constraining these coupled models with observations of IR emission from the Zodiacal Cloud, lidar measurements of the vertical fluxes of Na and Fe in the terrestrial mesosphere, and the rate of accretion of cosmic spherules at the South Pole, indicates that about 30 tonnes of dust enters the Earth’s atmosphere each day. Having fitted the astronomical model to the terrestrial input, the same model can be used to predict the dust inputs into the atmospheres of Venus and Mars. A separate outer solar system model has also been used to determine the dust input into Titan’s atmosphere. The Chemical Ablation Model (CABMOD), which is central to quantifying planetary impacts, has recently been tested using a novel experimental system developed at Leeds: a Meteor Ablation Simulator, which measures the evaporation of metals from meteoritic particles that are flash heated to over 2800 K with a time-resolved temperature profile simulating atmospheric entry.

Examples of the impacts of meteoric ablation will then be described. For Earth: mesospheric metal layers; noctilucent cloud nucleation; freezing of polar stratospheric clouds; and deposition of bio-available Fe to the Southern Ocean. For Venus: oxidation of CO and removal of O₂on meteoric smoke particles in the hot troposphere. For Mars: production of an Mg⁺layer which has recently been observed by the MAVEN spacecraft. And for Titan: the production of benzene in the troposphere by the cyclo-trimerization of acetylene on dust particles.

Thursday 23 August 2018, 13:00 - Realf.bygget, B203
Dr. Philip Erickson
(Massachusetts Institute of Technology Haystack Observatory Westford, Massachusetts, USA) 
Auroral Emissions Radio Explorer (AERO): Science and technical overview, and collaborations

Thursday 23 August 2018, 13:30 - Realf.bygget, B203
Dr. Andrew Kavanagh
(British Antarctic Survey, Cambridge, UK)
Radiation Belt slot-region filling events: sustained energetic precipitation into the mesosphere

Thursday 16 August 2018, 14:00-15:00, Teknologibygget: Rom 1.017
Professor Meers Oppenheim
(Boston University, USA) 
Studying Meteor Plasma Physics with Massively Parallel Particle-in-Cell Simulations

Thursday, 26 April - 10:15 Teknologibygget 1.016

Professor Burkhard Wrenger

Ostwestfalen-Lippe University of Applied Sciences (OWL UAS), Germany,

Drone Based Environmental Monitoring

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Tuesday 17 April  2018  - 12:00 Teknologibygget 3.028

Dr. Joan Stude 
(Institute of Atmospheric Research, German Space Center, DLR, Pfaffenhofen, German) 
The PMWE rocket campaign from Andøya on Friday 13 April 

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Wednesday 7 March 2018  - 14:00 Teknologibygget 3.028

Monday 27. November - Tuesday 28. November

Visit from Murmansk Arctic State University, Murmansk, Russia

Monday 27 November

14:15 - 16:00 at Teknologibygget 3.028 Seminar

Computer modeling of physical processes in the near-Earth environment

Prof. Alexandr Namgaladze 

Wednesday 1. November 2017 - 14:15 - 16:00 at Teknologibygget 2.017
Björn Gustavsson, UiT
EISCAT observation campaign October 2017

Wednesday 7. December 2016 - 14:15 location to be announced

Stein Haaland

University of Bergen, Department of Physics and Technology

Cold ion outflow from the polar caps: Combining satellite and radar measurements 

Wednesday 30. November 2016 - 14:15 - 15:00 at Teknologibygget 3.028 

Satonori Nozawa

Solar-Terrestrial Environment Laboratory, Nagoya University, Japan

Multi-beam sodium LIDAR observations at Ramfjordmoen 

In-Situ Detection and Analysis of Cosmic Dust Particles: from the Upper Atmosphere to Distant Worlds

It is in the form of dust particles that heavy elements recycle from dying stars into freshly forming planetary systems. Today, in our solar system, dust particles are still continually generated, processed, and destroyed/expelled with a range of dynamical processes governing their fate. The in-situ detection and analysis of dust particles, including their trajectories and elemental/chemical makeup, thus allows insight into the formation and currect state of the solar system, including Earth. Cosmic dust particles available for in-situ detection can be broadly sorted into four categories: interplanetary dust, interstellar dust, circum-planetary dust, and ejecta dust clouds around airless planetary objects. The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado is one of the few institutes engaged in the development of dust detector and analyzer instruments; and is equipped with unique laboratory calibration facilities. The latter includes a 3 MV electrostaic dust accelerator that allows the study of impact processes at the hypervelocity range commonly encoutered in space. In this presentation I will review the instrument development efforts of the past decade at LASP, starting with the detection of meteoirc smoke particles in the upper atmosphere, and ending with the capabilites of the state-of-the art dust analyzer currently under development for the upcoming Europa Mission (NASA) to characterize the habitability of this distant icy world.

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Thursday 18. August 2016

Antti Kero 

Sodankylä Geophysical Observatory / University of Oulu, Finland 

D-region ionisation characteristics inverted from ground based measurements