A5051937940- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- GNSS positioning and interference
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Spacecraft Design and Technology
- Planetary Science and Exploration
- Seismic Waves and Analysis
- Radar Systems and Signal Processing
- Atomic and Subatomic Physics Research
- Solar Radiation and Photovoltaics
- Space exploration and regulation
- Lightning and Electromagnetic Phenomena
- Satellite Image Processing and Photogrammetry
- Magnetic Field Sensors Techniques
- Geophysics and Sensor Technology
- Ocean Waves and Remote Sensing
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Underwater Acoustics Research
- Magnetic confinement fusion research
- Radio Astronomy Observations and Technology
- Target Tracking and Data Fusion in Sensor Networks
University of Oulu
2015-2024
Swedish Institute of Space Physics
2023
Democritus University of Thrace
2023
South African National Space Agency
2022
KTH Royal Institute of Technology
1993
The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the UHF and VHF systems) Svalbard electronically scanning ESR (EISCAT Radar) for studies high-latitude ionised upper atmosphere ionosphere). radars were constructed about 30 years ago, based technological solutions that time. science drivers today, however, require a more flexible instrument, which allows measurements to be...
Abstract. The lower-thermosphere–ionosphere (LTI) system consists of the upper atmosphere and lower part ionosphere as such comprises a complex coupled to both below space above. atmospheric LTI is dominated by laws continuum fluid dynamics chemistry, while plasma controlled electromagnetic forces driven magnetosphere, solar wind, well wind dynamo. hence domain many different physical processes. However, systematic in situ measurements within this region are severely lacking, although...
The lower thermosphere-ionosphere (LTI) is a key transition region between Earth’s atmosphere and space. Interactions ions neutrals maximize within the LTI in particular at altitudes from 100 to 200 km, which least visited of near-Earth environment. lack situ co-temporal co-spatial measurements all relevant parameters their elusiveness most remote-sensing methods means that complex interactions its neutral charged constituents remain poorly characterized this date. This measurements,...
Abstract Derivation of the auroral ionospheric currents from magnetic field measurements can produce drastically different results depending on data and method used. We have cross tested several methods for obtaining instantaneous field‐aligned horizontal Swarm satellite International Monitor Auroral Geomagnetic Effects (IMAGE) ground measurements. found that yield latitude profiles east‐west component divergence‐free current density at most ∼200 km resolution, typically resolving...
Abstract. The Daedalus mission has been proposed to the European Space Agency (ESA) in response call for ideas Earth Observation program's 10th Explorer. It was selected 2018 as one of three candidates a phase-0 feasibility study. goal is quantify key electrodynamic processes that determine structure and composition upper atmosphere, gateway between Earth's atmosphere space. An innovative preliminary design allows access electrodynamics down altitudes 150 km below. will perform situ...
Abstract The time delay from an interplanetary driver arriving at the magnetopause to response in ionosphere has never been quantified separately for different types of storm drivers. This study investigates storms driven by high‐speed streams and associated stream interaction regions (HSS/SIR), or coronal mass ejection sheaths magnetic clouds (MC). total field‐aligned current (FAC) SME index lag Newell coupling function (NCF) 40 ± 10 min during HSS/SIR sheaths, 60 MCs. correlation...
Abstract Solar cycles 24–25 were quiet until a geomagnetic storm with Sym‐H index of −170 nT occurred in late March 2023. On 23–24, Fabry‐Perot interferometer (FPI; 630 nm) Tromsø, Norway, recorded the highest thermospheric wind speed over 500 m/s since 2009. Comparisons magnetometer readings Scandinavia showed that large amount electromagnetic energy was transferred to ionosphere‐thermosphere system. Total electron content maps suggested an enlarged auroral oval and revealed FPI observed...
In May 2024, the most intense geomagnetic storm since 2003 was caused by coronal mass ejections from Sun. It has triggered a surge of interest within international space science community with dedicated workshops and planned special issues. Our study focuses on ionosphere-thermosphere responses in northern polar region based multiple observations ground-based instruments (including EISCAT incoherent scatter radar Svalbard, GNSS TEC receivers, SuperMAG magnetometers, SuperDARN coherent...
The mass density scale height in the upper atmosphere gives vertical distance over which neutral decreases by a factor of e (the base natural logarithms). change may depend on changes temperature and/or composition. This study uses simultaneous measurements from coplanar low-Earth-orbit satellites to derive and analyses variations during quiet time geomagnetic storms. events are found satellite missions 2014 2023, including Swarm, GRACE, GRACE-FO.Our shows several interesting findings....
Understanding both the spatial and temporal dynamics of near-Earth space environment is important for successful forecasting weather. One example auroral Joule heating which causes thermal expansion upper atmosphere, increasing thermospheric density causing low Earth orbiting (LEO) satellites to experience more drag. This chain events often begins when geoeffective solar wind transients such as high-speed stream/stream interaction regions (HSS/SIR) or interplanetary coronal mass ejections...
Abstract We use the EISCAT incoherent scatter radar data measured in years 2001–2021 to study statistical characteristics of 1–100 keV electron precipitation at 66.7° MLAT over Tromsø. Peak energies, auroral powers and number fluxes precipitating electrons are derived from density altitude profiles along geomagnetic field line during periods no photoionization. The method allows us include energetic 30–100 electrons, which poorly covered earlier satellite‐based studies. Locations within oval...
The spatial distribution of electric fields, conductances, and currents steadily drifting medium‐scale (15–50 km) arcs in the evening sector (20–23 magnetic local time (MLT)) is obtained from European Incoherent Scatter Radar (EISCAT) optical ground‐based measurements. current systems stable residing northward convection field region show a consistent pattern: flow downward on equatorward side arcs, then poleward, upward arcs. In one event where are located reversals, pattern more...
Abstract We present a statistical investigation of the seasonal effect on hemispheric asymmetry in auroral currents during low (Kp < 2) and high ≥ geomagnetic activity. Five years magnetic data from Swarm satellites has been analyzed by applying spherical elementary current system (SECS) method. Bootstrap resampling used to remove differences between hemispheres set. In general, are larger Northern Hemisphere (NH) than Southern (SH). Asymmetry is Kp local winter autumn summer spring. For...
Abstract Energetic particle precipitation is the major source of electron production that controls ionospheric Pedersen and Hall conductances at high latitudes. Many studies use empirical formulas to estimate conductances. The spectra measured by Defense Meteorological Satellite Program (DMSP) Special Sensor J are often used as input formulas. In this study, we evaluate during four different types auroral conditions based on 63 conjugate events observed DMSP EISCAT. calculated from data with...
Abstract. Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made EISCAT incoherent scatter radar Tromsø (66.6 cgmlat) from 6 March to April 2006. The data same season (close vernal equinox) similar sunspot conditions (about 1.5 years before minimum) providing an excellent set study MLT Kp dependence parameters with temporal spatial resolution. All show clear variation, which is different...
[1] A new method utilizing stochastic inversion in determining the electric field and neutral wind from monostatic beam swing incoherent scatter measurements is described. The consists of two stages. In first stage, beam-aligned ion velocities a chosen F region height interval set subsequent directions are taken as measurements. unknowns components field-aligned velocity profile. solution gives most probable values with error estimates. second consist E region, fields given by problem also...
Abstract. We report observations of a sequence quiet-time Earthward bursty bulk flows (BBFs) measured by the Cluster spacecraft in near-tail plasma sheet (XGSM ~ −12 to −14 RE) evening sector, and simultaneous high-resolution measurements northern conjugate ionosphere EISCAT radars, MIRACLE all-sky camera magnetometers, as well meridian-scanning photometer (MSP) Scandinavian sector on 17 October 2005. The BBFs at show signatures that are consistent with "bubble" model (Chen Wolf, 1993,...
The EISCAT radar in Tromsø (67° cgmLat) has been used to estimate statistics of electromagnetic (EM) energy transfer rates by utilizing calculated electric fields, conductivities and E‐region neutral winds. It was found that the magnetospheric EM input is slightly larger evening than morning sector, but due winds, Joule heating rate largest values sector. duskside subauroral region contains large northward fields a site significant heating. For quiet conditions (Kp: 0–2 + ), wind major...
The statistical properties of the altitude profiles different energy transfer rates in auroral ionosphere are studied by using European Incoherent Scatter radar measurements Tromsø (67° cgmLat). Aikio et al. (2012) found that during active conditions, winds reduce height‐integrated Joule heating evening but enhance them morning. Here we show reduction takes place close to and above peak heating, so descends from Pedersen conductivity maximum at 120 km down about 115 km. Values reduced also...
We study the properties and geoeffectiveness of solar wind high-speed streams (HSSs) emanating from coronal holes associated with stream interaction regions (SIRs). This paper presents a statistical 588 SIR/HSS events speed at 1 AU exceeding 500 km/s during 1995-2017, encompassing decline cycle 22 to 24. Events are detected using measurements interplanetary magnetic field (IMF). misidentified as or interacting mass ejections (ICMEs) removed by comparison an existing ICME list. Using this...
Daedalus MASE (Mission Assessment through Simulation Exercise) is an open-source package of scientific analysis tools aimed at research in the Lower Thermosphere-Ionosphere (LTI). It was created with purpose to assess performance and demonstrate closure mission objectives Daedalus, a concept targeting perform in-situ measurements LTI. However, its successful usage as mission-simulator toolset, has evolved encompass numerous capabilities related LTI science modeling. Inputs are geophysical...
We present a comprehensive study of sequence two substorms and multiple pseudobreakups using optical, magnetic incoherent scatter radar measurements, energetic particles from geosynchronous satellites particle field data the Geotail spacecraft located at X gsm ∼ −86 R E . Following conventional nomenclature, we classified as those auroral breakups which did not exhibit significant poleward expansion (< 2° latitude). Auroral intensifications following substorm were also observed,...
Abstract. The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 RE in the post-midnight sector. When mapped along geomagnetic field lines, separation spacecraft ionosphere was confined within 110km latitude and 50km longitude. This constellation allowed us study temporal evolution plasma with time scale few minutes. Ground-based instrumentation used involved two all-sky cameras, magnetometers EISCAT radar....