A5021945474- Ionosphere and magnetosphere dynamics
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Solar and Space Plasma Dynamics
- Atmospheric chemistry and aerosols
- Earthquake Detection and Analysis
- GNSS positioning and interference
- Atmospheric aerosols and clouds
- Calibration and Measurement Techniques
- Lightning and Electromagnetic Phenomena
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Planetary Science and Exploration
- Research Data Management Practices
- Plant responses to elevated CO2
- Seismic Waves and Analysis
- Atomic and Subatomic Physics Research
- Geophysics and Sensor Technology
- Scientific Computing and Data Management
- Climate variability and models
- Vacuum and Plasma Arcs
- Image Processing and 3D Reconstruction
- Arctic and Antarctic ice dynamics
- Space exploration and regulation
- Meteorological Phenomena and Simulations
European Incoherent Scatter Scientific Association
2014-2023
Swedish Institute of Space Physics
1999-2021
University of Oulu
2007-2014
We have studied the short‐term effect of October–November 2003 series solar proton events on middle atmosphere. Using flux measurements from GOES–11 satellite as input, we modeled precipitating particles between 26 October and 6 November with a one–dimensional ion neutral chemistry model. Then compared results ground‐based radio propagation measurements, well NO 2 ozone profiles made by GOMOS instrument. The very low frequency signal experiences up to −7 dB absorption during largest event,...
The paper reviews recent advances in studies of electric discharges the stratosphere and mesosphere above thunderstorms, their effects on atmosphere. primary focus is sprite discharge occurring mesosphere, which most commonly observed high altitude by imaging cameras from ground, but upper atmosphere electromagnetic radiation lightning are also considered. During past few years, co-ordinated observations over Southern Europe have been made a wide range parameters related to sprites causative...
Stratospheric bromine originates partly from natural and anthropogenic sources. After the Montreal protocol following amendments, emissions (halons methyl bromide) were largely reduced. This reduction was not only seen in tropospheric situ measurements, but also a of stratospheric levels (estimated BrO measurements) after about 2002.Here, we report on ground-based observations carried out between 1995 present Kiruna (northern Sweden). The (slant) column density is analysed UV spectra zenith...
The Magnetometers Ionospheric Radars All-sky Cameras Large Experiment (MIRACLE) network monitors auroral activity in the Fennoscandian sector. Network stations cover range of 55° to 57° magnetic latitude north and span two hours local time. Seven MIRACLE include digital all-sky cameras (ASCs). Up recent years, type ASC used consisted an optical system, a charged coupled device (CCD) image intensifier enabling short exposure times. This system is referred as intensified CCD (ICCD) camera. As...
Abstract. This work investigates the influence of meteoric smoke particles (MSP) on charge balance in D-region ionosphere. Both experimental situ measurements and a one-dimensional ionospheric model reveal clear impact MSP composition D-region. The study reviews rocket-borne electron positive ion density, which show distinct deficit electrons comparison to ions between 80 95 km. can be explained by ambient negatively charged measured simultaneously with Faraday cup. is addressed simplified...
The Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) is a dual array of omnidirectional VHF radio antennas located near Kilpisjärvi, Finland. It operated by the Sodankylä Geophysical Observatory. makes extensive use proven LOFAR antenna and digital signal-processing hardware, can act as stand-alone passive receiver, receiver for European Incoherent Scatter (EISCAT) very high frequency (VHF) incoherent scatter radar in Tromsø, or conjunction with other Fenno-Scandinavian experiments. In...
Abstract We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at Earth accompanied enhancements of MeV‐range energetic particle flux both solar wind (SEP event) inner magnetosphere, an AL < −2,000 substorm took place. (1) Both X caused enhancement electron density for...
Ground‐based zenith sky UV–visible measurements of stratospheric bromine monoxide (BrO) slant column densities are compared with simulations from the SLIMCAT three‐dimensional chemical transport model. The observations have been obtained a network 11 sites, covering high and midlatitudes both hemispheres. This data set gives for first time near‐global picture distribution BrO ground‐based is used to test our current understanding chemistry. In order allow direct comparison between model...
The local chemical impact of sprites is investigated for the first time. This study motivated by current understanding streamer nature sprites: streamers are known to produce NO x , thus expected lead a enhancement background abundances, and possibly ozone. We adopted following strategy: middle atmosphere MIPAS/GMTR 2 satellite measurements were correlated with ground‐based WWLLN detections large tropospheric thunderstorms as proxy sprite activity. found no evidence any significant at global...
Abstract. Transient luminous events, such as red sprites, occur in the middle atmosphere electric field above thunderstorms. We here address question whether these processes may be a significant source of odd nitrogen and affect ozone or other important trace species. A well-established coupled ion-neutral chemical model has been extended for this purpose applied together with estimated rates ionisation, excitation dissociation based on spectroscopic ratios from ISUAL FORMOSAT-2. This...
In this paper, we explain the HNO 3 observations made with MIPAS/Envisat instrument in northern polar region at time of October‐November 2003 solar proton event. Increases 0.5–5.5 ppbv are seen altitudes 35–58 km after onset Results from Sodankylä Ion and Neutral Chemistry model good agreement MIPAS observations, except around 58 where modeled mixing ratios about a factor two larger. According to results, production above 35 is almost entirely due ion‐ion recombination between NO − H +...
Abstract The first implementation of the so‐called spectral riometer technique for ionospheric electron density profile estimation is presented. In contrast to traditional operating at a single frequency, this experiment monitors cosmic radio noise 244 frequencies, ranging between 10 and 80 MHz, by using new Kilpisj rvi Atmospheric Imaging Receiver Array telescope. received power each time frequency compared corresponding quiet‐day value, resulting in absorption spectrum as measurement...
Abstract. This paper presents a comparison between standard ionospheric parameters manually and automatically scaled from ionograms recorded at the high-latitude Sodankylä Geophysical Observatory (SGO, ionosonde SO166, 64.1° geomagnetic latitude), located in vicinity of auroral oval. The study is based on 2610 during period June–December 2013. automatic scaling was made by means Autoscala software. A few typical examples are shown to outline method, statistics presented regarding differences...
Abstract The Antarctic and Arctic regions are Earth's open windows to outer space. They provide unique opportunities for investigating the troposphere–thermosphere–ionosphere–plasmasphere system at high latitudes, which is not as well understood mid- low-latitude mainly due paucity of experimental observations. In addition, different neutral ionised atmospheric layers latitudes much more variable compared lower their variability mechanisms yet fully understood. Fortunately, in this new...
Abstract. Lightning-generated whistlers lead to coupling between the troposphere, Van Allen radiation belts and lower-ionosphere through Whistler-induced electron precipitation (WEP). Lightning produced interact with cyclotron resonant belt electrons, leading pitch-angle scattering into bounce loss cone atmosphere. Here we consider relative significance of WEP lower ionosphere atmosphere by contrasting ionisation rate changes those from Galactic Cosmic Radiation (GCR) solar photoionisation....
Abstract. A new incoherent scatter (IS) diagnostic technique for the actively heated D-region ionosphere is presented. In this approach, an exponential autocorrelation function (ACF) was fitted to data by using a Markov Chain Monte Carlo (MCMC) inversion and Sodankylä Ion Chemistry model (SIC). The method applied set of combined EISCAT heating VHF radar experiments carried out in November 2006. newly designed experiment, sippi, based on optimised phase codes direct sampling transmitted...
Recent research on sprites shows these and other transient luminous events can exert a local impact atmospheric chemistry, although with minor effects at global scales. In particular, both modelling remote sensing work suggest perturbations to the background NOx up few tens of per cent occur above active sprite-producing thunderstorms. this study we present detailed investigation MIPAS/ENVISAT satellite measurements middle NO2 in regions high likelihood sprite occurrence during period August...
Abstract Transient luminous events affect Earth's atmosphere between thunderstorm tops and the lower ionosphere through ion‐neutral chemistry reactions. Particular emphasis has been given to sprites, with models observations suggesting a capability of perturbing atmospheric nitrogen oxides at local level, as it is known occur for tropospheric lightning laboratory air discharges. However, yet unknown whether sprites can be relevant source upper atmosphere. In this paper, we study sensitivity...
Abstract. Understanding the altitude distribution of particle precipitation forcing is vital for assessment its atmospheric and climate impacts. However, proportion electron proton around mesopause region during solar events not always clear due to uncertainties in satellite-based flux observations. Here we use concentration observations European Incoherent Scatter Scientific Association (EISCAT) incoherent scatter radars located at Tromsø (69.58° N, 19.23° E) investigate contribution...
Abstract. Here we present a new retrieval algorithm of the slant column densities (SCDs) chlorine dioxide (OClO) by differential optical absorption spectroscopy (DOAS) from measurements performed TROPOspheric Monitoring Instrument (TROPOMI) on board Sentinel-5P satellite. To achieve substantially improved accuracy, which is especially important for OClO observations, accounting absorber and pseudo structures in depth even order 10−4 important. Therefore, comparison to existing retrievals,...
The mechanism behind the modulation of polar mesospheric winter echoes (PMWE) observed in active HF heating experiments is considered. We propose that negative ion chemistry plays a role heater‐induced PMWEs. In mesosphere, an increased electron temperature leads to higher rate neutral attachment, and therefore decreased density. To first‐order approximation, scattering from Bragg‐scale gradients caused by turbulence can be considered proportional density squared. Under this assumption,...
Abstract. Polar stratospheric clouds (PSCs) are often observed in the Kiruna region northern Sweden, east of Scandinavian mountain range, during wintertime. PSC occurrence can be detected by ground-based optical instruments. Most these require clear tropospheric weather. By applying zenith-sky colour index technique, which works under most weather conditions, data availability extended. The observations suggest that events, especially type II (water PSCs) may indeed more common than...