Tuesday, 7 February 2017

Northern Lights 31st January / 1st February 2017

[Helsingin Sanomissa 7.2.2017: "Revontulet sykkivät mystisesti" -artikkeli SGO:n ja Japanilaistutkijoiden välisestä tutkimusyhteistyöstä.]

Last week beautiful northern lights were seen across large parts of Northern Finland and Scandinavia. Already early in the evening after 19:00 EET (17:00 UTC), the lights appeared and by 21:00 EET the sky was filled with what we call "pulsating aurora". This form of aurora displays large patches of diffuse green light, which are flickering at various speeds, some flicker very fast. Pulsating aurora is very much a topic of active research, and our Japanese colleagues just launched the ARASE (ERG) satellite to study these specific lights from space. These efforts are combined with optical studies on the ground, and just in time for last week's northern lights, a special high-speed camera was installed at SGO, which can take up to 100 photos of the aurora per second!

From Sodankylä, four films of the aurora during the night of 31st January / 1st February have recently been published, two of which are from SGO:

The video above was made by taking all of the images of the regular all-sky camera of SGO, which are black-and-white images taken through filters for the auroral green, red, and blue lines, and combine these to create RGB (false) colour images. Images are taken every 20 seconds, and thus the video linked above is a time-lapse of the whole night, which is just 1min 30 sec long. (©2017 by SGO)

The video linked here is a result of a collaboration between SGO and Site-Eye Ltd., UK. Site-Eye have installed two long-term time-lapse cameras at SGO, one looking at the sky at a northerly direction, the other looking west across the river Kitinen. This video combines images from both cameras. (©2017 by SGO and Site-Eye Ltd)

The video above was taken by SGO's Thomas Ulich, who placed a camera looking almost straight up, with a slight tilt towards the south. This is the best direction to see what is called the auroral corona, a display, where the auroral rays all seem to originate from the same point in space. This is, however, just a result of perspective: the rays are in fact parallel. Images taken over 9 hours at a rate of four photos per minute were combined into a time-lapse film of about one minute duration. (©2017 by Thomas Ulich, see his blog post)

In the final video of this series, which was taken by SGO's Esa Turunen using a fish-eye lens to cover as much sky as possible, you can see the shapes of pulsating aurora especially well. They are patches drifting across the sky and flickering at the same time. The images were taken at a rate of approximately one per second. (©2017 by Esa Turunen)

Please note that in all videos linked here, the flickering of the aurora is aliased by the number of time per minute the images were taken as well as by the frames-per-second rate of the final time-lapse films.

Tuesday, 20 December 2016

ERG/Epsilon-2 Launch Live Broadcast starts today!

Launch window of the Japanese ERG-satellite on-board the Epsilon-2 rocket will be opened today at 10:40 UTC (= 12:40 Finnish time).  Follow the potential launch online HERE!

Copyright: ERG project
Science objective of the ERG mission is to study acceleration and loss mechanisms of relativistic electrons around Earth during geospace storms.

SGO supports the mission by its ground-based measurement networks and collaborates closely with Nagoya University in interpretation of the satellite measurements by means of atmospheric modelling.

Recent joint study by Turunen et al., 2016 suggests that the so-called pulsating aurorae may associate energetic electron precipitation that is capable of remarkable ozone destruction in the mesosphere. By means of the ERG datasets, combined with the ground-based observations, we wish to study more closely this potentially important space weather influence on the upper atmosphere.

ERG/Epsilon-2 laukaisu tänään 20.12. klo 13

JAXA, (Japan Aerospace Exploration Agency) laukaisee ERG-tutkimussatelliitin 20.12.2016. Live-streamia laukaisusta voi seurata osoitteessa:


ERG-satelliitti tutkii Maan säteilyvyöhykkeiden suurienergisiä hiukkasia ja niiden käyttäytymistä magneettisten myrskyjen aikana. SGO:n, Ilmatieteen laitoksen ja Nagoyan yliopiston tutkijoiden yhteistyössä selvitetään sykkivien revontulien syntymekanismeja ja mitataan suurienergisen hiukkassateen aiheuttamaa pakotetta ilmakehään. Nagoyan yliopisto ja SGO ovat sijoittaneet Sodankylään uuden 100 kuvaa sekunnissa kuvaavan  revontulikameran tutkimuksia varten.

ERG-mission tieteellinen kuvaus löytyy täältä: https://ergsc.isee.nagoya-u.ac.jp/

Oulun yliopiston tiedote: ERG-satelliitti selvittämään magneettimyrskyjen vaikutusta otsoniin

Tiedetuubissa: Video: Japani lähetti avaruuteen revontulivakoojan 

Sykkivät revontulet tuhoavat yläilmakehän otsonia. Uusin tutkimustulos aiheesta löytyy täältä:


Launched right on time – congratulations to our Japanese colleagues

Screen shot from JAXA's live stream. Watch again here.

Wednesday, 7 December 2016

PhD Candidate in Radio Science and Ionospheric Physics

PhD Candidate in Radio Science and Ionospheric Physics at UiT The Arctic University of Norway

University of Tromsø - The Arctic University of Norway, Faculty of Science and Technology, has a PhD student position vacant for applicants who wish to obtain the degree of Philosophiae Doctor (PhD). The appointment is for a period of four years.

The successful candidate will participate in the development and use of novel high power large aperture radar observational techniques in combination with other relevant instruments, with the goal of advancing the state of knowledge of ionospheric phenomena. Examples of potential topics of research include: ionospheric modification, characterisation of auroral energetic particle precipitation, and magnetosphere-ionosphere coupling. The final scope of the thesis project will be determined based on the background and interests of the candidate.

The position is attached to the Space Physics group at the Department of Physics and Technology, which is located on the Tromsø campus of UiT. The Space Physics group has a long tradition in using the radar instruments of the EISCAT Scientific Association in Northern Scandinavia and plays an important role in preparing for the new advanced atmospheric radar facility EISCAT_3D. Scientists in the group also conduct research on topics including: auroral ionosphere, ionospheric modification, space weather, laboratory plasmas, space debris, planetary radar, dusty plasma in the mesosphere, and long-term trends in the ionosphere. The Space Physics group consists of eight faculty members and six PhD students. The group will be expanded by four PhD students and one postdoctoral scientist during the next year.

Further information about the position and project details is available by contacting:

Associate Professor Juha Vierinen, email juha-pekka.vierinen -at- uit.no or tel. +47 981 72 827.

Please read also the full announcement of this vacancy.

Photo: Thomas Ulich.

Monday, 7 November 2016

EISCAT Peer-Review Programme: Call for Proposals

The EISCAT Scientific Association invites applications for observing time on the EISCAT facilities in 2017, by individual scientists, research groups, and consortia throughout the world on equal, competitive basis. This means that anyone can apply, independent of whether or not the applicant is from an EISCAT associate country.

While evaluations are merit based, in the case of two applications having similar merits in evaluation, preference will be given either to those applicants who are new to the EISCAT facilities, in order to enlarge the EISCAT user community and further more open access to the facilities, or to the applicant showing stronger educational impact in their proposal.

The present call is the first one for 2017. In total, 200 hours of experiment time are open for international, peer-reviewed competition, and are available for the use of any of the current EISCAT facilities. Roughly half of this time has been allocated in the first call.

Please refer to the details of the call at http://www.eiscat.se/PeerReviewProgram/eiscatppexp for more information.

The deadline for proposals is 21st November 2016 at 24:00 UTC.

Text: EISCAT; photo: Th.Ulich.

Saturday, 29 October 2016

Study of TEC Fluctuation via Stochastic Models and Bayesian Inversion

Our study on GPS total electron content modelling has been published in Radio Science:

Bires, A.L. RoininenB. D. YeshitaM. Nigussie, and H. Vanhamäki (2016), Study of TEC Fluctuation via Stochastic Models and Bayesian InversionRadio Sci.51, doi:10.1002/2016RS005959.

Study of TEC Fluctuation via Stochastic Models and Bayesian Inversion

We propose stochastic processes to be used to model the total electron content (TEC) observation. Based on this, we model the Rate of change of TEC (ROT) variation during ionospheric quiet conditions with stationary processes. During ionospheric disturbed conditions, for example when irregularity in ionospheric electron density distribution occurs, stationarity assumption over long time periods is no longer valid. In these cases, we make the parameter estimation for short time scales, during which we can assume stationarity. We show the relationship between the new method and commonly used TEC characterization parameters ROT and the ROT Index (ROTI). We construct our parametric model within the framework of Bayesian statistical inverse problems and hence give the solution as an a posteriori probability distribution. Bayesian framework allows us to model measurement errors systematically. Similarly, we mitigate variation of TEC due to factors which are not of ionospheric origin, like due to the motion of satellites relative to the receiver, by incorporating a priori knowledge in the Bayesian model. In practical computations, we draw the so-called maximum a posteriori estimates, which are our ROT and ROTI estimates, from the posterior distribution. Because the algorithm allows to estimate ROTI at each observation time, the estimator does not depend on the period of time for ROTI computation. We verify the method by analyzing TEC data recorded by GPS receiver located in Ethiopia (11.6°N, 37.4°E). The results indicate that the TEC fluctuations caused by the ionospheric irregularity can be effectively detected and quantified from the estimated ROT and ROTI values.

Thursday, 27 October 2016

Reply to Comment by Pätzold et al. on “Mars Express radio-occultation data: A novel analysis approach”

A paper was recently accepted for publication in the Journal of Geophysical Research Space Physics. It is a Reply to a Comment on the Grandin et al. (2014) article introducing a new method to analyse radio-occultation data for Mars Express.

The early view of this Reply can be accessed from the Wiley Online Library here.

Grandin, M., P.-L. Blelly, O. Witasse, and A. Marchaudon (2016), Reply to Comment by Pätzold et al. on “Mars Express radio-occultation data: A novel analysis approach”, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA022229.

Below is the abstract of the Reply.
We reply to the Comment by Pätzold et al. on our paper presenting a new analysis approach for Mars Express radio-occultation data. We address each of the main comments, showing that none of them invalidates the method itself, but rather, they underline aspects which could be considered to improve the model. One major issue raised by the Comment is the computation of the frequency residual values, as our model did not take into account the change in frequency between the uplink and the downlink. This problem has been given full consideration, and the corresponding part of the model has been corrected accordingly. The dayside profile analyzed in the original article has been reanalyzed with the updated version of the model, and the results are presented, which show overall improvements.
©2016. American Geophysical Union.

Tuesday, 25 October 2016

EISCAT Campaign in Tromsø

Time for the traditional Finnish autumn EISCAT campaign! Ilkka Virtanen and I have been running radar experiments since last Friday evening, from the control room of the Ramfjord site near Tromsø, Norway. This is the site where the EISCAT transmitters are located: the VHF – which may be used alongside the Sodankylä and Kiruna receivers for tri-static measurements –, the UHF, and the ionospheric heating system (among other instruments).

Four experiments from the Finnish EISCAT user community were scheduled for this campaign. A first experiment consisted in a continuous 48-hour run of the EISCAT Svalbard Radar (ESR) during a solar wind high-speed stream. It was run in the beginning of this month, separately from the rest of the campaign. The second experiment aimed at using the UHF radar in a 3-position scanning mode to study neutral wind acceleration during auroral activity. The third experiment was supposed to use UHF, VHF, remote VHF receivers, ESR and the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) to cover SWARM satellite overpasses during two nights. The fourth experiment was supposed to study the lower ionosphere during pulsating aurora, using the VHF system.

Unfortunately, as this is often the case, reality reserves some surprises. In our case, these were not particularly good ones, since the KAIRA clock experiences some time drift, probably because its rubidium atomic clock needs to be replaced. Just to make sure that we have no regrets about it, the VHF is also down due to problems with a coaxial cable. As a consequence, the experiments using the VHF system could not be run as planned: the SWARM experiment only used field-aligned UHF measurements and ESR, and the pulsating aurora experiment had to be totally cancelled.

As a form of compensation, we have been granted exceptional weather here in Tromsø – while on the Finnish side of the border, thick clouds offer an uninterrupted display of medium-grey and dark-grey. And at night, the aurora gave us several nice displays during the previous nights. Some form of compensation, indeed.

The UHF radar, the aurora, and a mysterious beam of light.
Photo: M. Grandin