Tuesday, 31 May 2011

First Polar Mesospheric Summer Echos seen at Svalbard

Last Friday, 27th May 2011, the SOUSY Svalbard radar observed the first Polar Mesospheric Summer Echos (PMSE) of the season. SOUSY is a MST radar, which is co-located with the EISCAT Svalbard Radar (ESR) outside Longyearbyen, Svalbard, and it is operated by the University of Tromsø, Norway.

In summer, the polar mesopause region is extremely cold. Interesting phenomena are observed in that region, namely so-called noctilucent clouds (NLC) and strong radar echos (PMSE) between 80 and 95 km altitude. PMSE have first been observed by Ecklund and Balsley (J. Geophys. Res., 86, 7775–7780, 1981).

In the cold mesopause region, ice particles form and create noctilucent clouds. The surrounding atmosphere, i.e. the lower ionosphere, is ionised and free electrons attach to the ice particles. At the same time, gravity waves propagate upwards in the atmosphere. The part of the atmosphere where the ice particles occur coincides with the region in which these gravity waves become unstable and thereby produce turbulence. This turbulence leads to small-scale structures in the distribution of the charged ice particles, which, in turn, can be seen by radars as strong, coherent echos (PMSE).

The EISCAT_3D radar will not only be able to see these echos, but it will provide three-dimensional, high time-resolution images of PMSE. These and other Atmospheric Science topics were discussed at the recent 3rd EISCAT_3D User Meeting in Uppsala, Sweden. Most of the presentations are available for download now at the EISCAT_3D project site.


You can watch the measurements of the SOUSY radar in real-time on-line.

Monday, 30 May 2011

Inverse Problems Africa 2012

An inverse problems school and conference will be organised in Bahir Dar, Ethiopia, in October 2012. The events will have a strong emphasis on incoherent scatter radars and EISCAT_3D techniques.

The school will take place 15th to 20th October 2012, and the conference will follow immediately afterwards 22nd to 26th October 2012.

The lecturers for the school thus far are
  1. Markku Lehtinen, University of Oulu, Finland — Statistical Inversion and Incoherent Scatter Radar
  2. Heikki Haario, Lappeenranta University of Technology, Finland — Epidemiology Models and MarkovChain Monte Carlo Methods
  3. Wilson Mahera, University of Dar es Salaam, Tanzania — Stochastic Differential Equations and their Applications to Pollutant Dispersion in Shallow Waters
  4. Samuli Siltanen, University of Helsinki, Finland — Tomographic Imaging
The conference will cover, among others, the following topics:
  1. Statistical and Classical Inversion
  2. Numerical Methods and Software
  3. Partial Differential Equations and Stochastic Differential Equations
  4. Mathematical Finance and Insurance
  5. Applications: Radar, Tomography, Imaging, Epidemiology
The conference will be organised as thematic days. Every day will be opened by a keynote speech by an internationally known expert.
  • Monday — Matti Lassas, University of Helsinki, Finland — Thematic day in statistical and classical inversion
  • Tuesday — Tony van Eyken, SRI International, USA — Thematic day in incoherent scatter radars
  • Wednesday — N.N. — Thematic day in differential equations
  • Thursday — Joseph Mugisha, Makerere University, Uganda — Thematic day in epidemiology
  • Friday — Baylie Damtie, Bahir Dar University, Ethiopia — Conclusion of the conference, planning of future activities
More information at www.inverse-problems.org.

Friday, 27 May 2011

The Mighty VHF Radar

It's Friday and time to end the week with an interesting picture. This time we will feature the mighty EISCAT VHF incoherent scatter radar. If you have any interesting, beautiful, inspiring photos or graphs you want to share, please let us know and they will be included in a future Friday image feature.

The VHF radar, or simply the VHF as it is known, is the biggest of the EISCAT radars. It is located at Ramfjordmoen near Tromsø, Norway, at 69° 35'11"N, 19° 13'38" E. It is co-located with the transmitter of the tri-static EISCAT UHF radar.

The VHF is huge: its shape is a parabolic cyclinder, which is 120 m wide and 40 m high. It consists of four panels, each of which is 30 m wide. In the photo above, the westernmost panel is upright, i.e. it's pointing northward, while the other three panels are tilted back so that they point to zenith. It takes typically about 20 min for the huge electrical motors to tilt the antenna by 90°.

The photo was taken from what is called the feeder bridge. It features a total of 128 crossed dipoles for transmission and reception mounted on the outside of a fully-enclosed hallway big enough to walk around in. These dipoles are connected by coaxial cables and high-power wave guides to the transmitter and receiver systems. The transmitter is a 1.6-MW klystron, and the radar operates in the frequency range of 222.8 to 225.4 MHz.

Technical specifications as well as the locations of all EISCAT radars are available on the EISCAT website.

Have a good weekend everyone!

Photo: Thomas Ulich.

Thursday, 26 May 2011

Vacancy: PhD Student in Antenna and Array Design and Simulation

EISLAB at the Department of Computer Science, Space and Electrical Engineering at Luleå university of technology is taking part in the design of the EISCAT_3D radar. The system will consist of several large, active phased-array antenna transmitter/receiver sites and multiple passive sites located in Norway, Finland and Sweden, each comprising tens of thousands of individual antenna elements. When it will have been built, EISCAT_3D will be capable of making measurements from the upper stratosphere to the magnetosphere and beyond, contributing to basic, environmental and applied science that underpins the use of space by contemporary society.

Project Description

The aim of this research effort is to develop design methods for robust antenna arrays suitable for the harsh conditions in Northern Scandinavia. The project will have a system level approach which means that the antenna elements, the array layout, and the associated calibration systems all will need to be studied. The results will be used to design the antenna arrays for the EISCAT_3D radar. The project is a collaboration between several parties, which means that travel and interaction will be a part of the work.

Qualifications

Applicants must have excellent academic credentials and recently completed their M.Sc. or equivalent degree in Engineering Physics, Electrical Engineering, Space Engineering or any other closely related subject. Prior knowledge and experience in electromagnetic simulations, signal processing, antenna array design, and antenna measurements is desirable. Good knowledge in Matlab is required. The applicants must possess excellent skills in written and spoken English. The applicant should be self-driven and possess good social competence.

Contact Information

Dr Tore Lindgren, +46 (0)920-49 11 42, tore [dot] lindgren [at] ltu [dot] se, or
Dr Jonny Johansson +46 (0)920-49 17 03, +46 (0)70-7261703, jonny [dot] johansson [at] ltu [dot] se

Application

Please send your application along with CV, copies of transcripts, certificates and degrees attained, marked with reference no. 1085-11 to: Registrator, Luleå University of Technology, SE-971 87 Luleå, Sweden or by e-mail: registrator [at] ltu [dot] se

Deadline for application: 9th June 2011. (This call is now closed.)

Image: EISCAT Scientific Association.

Wednesday, 25 May 2011

Requests for World Day Observations with Incoherent Scatter Radars

The global network of incoherent scatter radars (ISR) provides observations of fundamental properties of the atmosphere, ionosphere, and magnetosphere. Use of these radars is open to all qualified scientists, and the data are freely disseminated to a broad community of users for research and in the development and validation of models and instrumentation.

Radar observing time is allocated (1) to individuals or groups through either formal or informal requests to the institutions responsible for operating the facilities, and (2) for World Day observations co-ordinated through a plan developed annually by the URSI Incoherent Scatter Working Group (ISWG).

The ISWG will have its usual planning meeting at the CEDAR Workshop to co-ordinate the World Day experiments involving the world's upper atmospheric observatories. The planning meeting is for ISWG and UAF staff to review all the proposals submitted and determine how the global network of ISRs can best satisfy the approved observational requests. The proposer's presence during this discussion is not required, but all are welcome, especially students.

Written proposals are requested for meeting specific research needs using the World Day observations. Please refer to the procedures for scheduling World Day observations,which include other links referenced therein which include a sample proposal (.doc).

The CEDAR Workshop will take place from 26th June to 1st July, 2011 at Santa Fe Convention Center and Eldorado Hotel in New Mexico, USA.

These proposals should be submitted by 5th June 2011.

Please feel free to consult with any facility staff member or the ISWG Chair Ingemar Häggström (ingemar [at] eiscat [dot] se) for clarification on the process for requesting ISR observing time within the World Day program.

Tuesday, 24 May 2011

Solar Activity Dependence of Ion Upflow Observed with EISCAT UHF Radar

Today our Science Tuesday post deals with the phenomenon of ion upflow in the polar ionosphere, where the geomagnetic field lines are very steep, almost vertical to the surface of the Earth. Charged particles travel along these lines, and given the right conditions, even heavy ions flow upwards, i.e. away from Earth.

The influence of solar activity upon ion upflow in the polar ionosphere was investigated using data obtained by the European Incoherent Scatter (EISCAT) Tromsø UHF radar between 1984 and 2008. In agreement with other work we find that the upward ion flux is generally higher at high solar activity than at low solar activity. However, the frequency of ion upflow events is higher at low solar activity and also the upward velocity is higher at low solar activity.

In any year about 30–40% of ion upflow is accompanied by ≈500 K above-background electron temperature at 400 km altitude. Electron and ion heating in connection with upflow is nearly twice as prevalent during high solar activity as it is at low activity. The acceleration of ions by pressure gradients and ambipolar electric field becomes larger at low solar activity than at high solar activity. This variation of the average acceleration is caused by the different shapes of electron density profiles for low and high solar activities. While ions start to flow up at above 450 km altitude when solar activity is high, at low solar activity this happens at 300–500 km altitude. It is suggested that the solar activity influences long-term variations of the ion upflow occurrence because it modulates the density of neutral particles, the formation of the F2-density peak, and ion-neutral collision frequencies in the thermosphere and ionosphere.

Figure: (a) Occurrence frequency of ion upflow starting between 200 and 550 km altitude at nighttime between 1900 and 0500 MLT is shown between 1984 and 2008: 1 year average (black line) and 3 month average (gray circles). (b) Average field-aligned ion velocity at 400 km altitude. Red circles: average flux in upflow events; blue circles: average flux of all samples (upflow, no-flow, and downflow events). (c) Average field-aligned flux at 400 km altitude; circles every 3 months.

Original article: Y. Ogawa, S. C. Buchert, A. Sakurai, S. Nozawa, and R. Fujii, Solar activity dependence of ion upflow in the polar ionosphere observed with the EISCAT Tromsø UHF radar, J. Geophys. Res., 115, A07310, doi:10.1029/2009JA014766, 2010.

Monday, 23 May 2011

15th International EISCAT Workshop

Biennial EISCAT International Workshops have been organized since 1983. The 15th International EISCAT Workshop will be held in Qingdao, China, 5th - 9th September 2011, hosted by the China Research Institute of Radiowave Propagation (CRIRP). The year 2011 marks 30 years of EISCAT incoherent scatter radar measurements. We will celebrate this anniversary with a dedicated ceremony.

The workshop sessions will cover new results from areas including space weather, solar-magnetosphere-ionosphere-atmosphere coupling, high-latitude ionosphere, mesosphere and thermosphere, meteors and space debris, ionospheric modification, and especially both traditional and novel applications of the EISCAT and other incoherent scatter radars in the world. In addition to the sessions concerning scientific progress there will be sessions on new radar plans and techniques (e.g. EISCAT_3D, the new Antarctic radar, the 3rd antenna for the EISCAT Svalbard Radar, collaboration with satellites).

Suggested sessions
  1. Overview of the IS Research by EISCAT- 30 Years of Measurements
  2. Space Weather and Solar Wind-Magnetosphere-Ionosphere-Atmosphere Coupling
  3. High-Latitude Ionospheres
  4. Mesosphere and Thermosphere
  5. The EISCAT-3D and the Future
  6. The Global ISR Network
  7. Meteors and Space Debris
  8. New Techniques and Areas of Research
  9. Ionospheric Modification
  10. Poster session
Deadlines

We welcome scientists and students all over the world to attend the workshop presenting the latest research achievements. Oral or poster contributions are both welcome. The invitation letters will be sent together with the acceptance notification of abstract to each contributor for application of visa to China.

— Submission of abstracts: 31st May 2011; extended to 30th June 2011!
— Acceptance notification and invitation letter: 30th June 2011
— Pre-registration: 31st July 2011
— Registration: 4th-5th September 2011

For more information, please visit the workshop pages.

Post updated: 2011-06-09, thu. Abstract deadline extended!

Friday, 20 May 2011

EISCAT UHF and the Northern Lights

It's Friday, and it's soon going to be summer in the Arctic, which is a very beautiful time. A lot of the nature has been dormant during the long winter, and now it's wake-up time: the white of the snow is gone, and it is rapidly replaced by a lush green of new leaves. The birds are returning to the Arctic, and the almost complete silence of the winter is replaced by bird song and the sound of warm winds in the boreal forest.

The polar day has started, and for optical observations the nights have been too bright to see any aurora since about mid-April. However, this will not stop us from enjoying the Northern Lights.

We wish all of you a very good weekend with a photo of diffuse aurora and the Sodankylä receiver of the tri-static EISCAT UHF system.

Photo: Thomas Ulich.

Wednesday, 18 May 2011

EISCAT_3D User Meeting: Science Case Work Package (WP3)

The EISCAT_3D Preparatory Phase Project includes a work package (WP3) on "Science Planning and User Engagement," which is lead by Anita Aikio of the University of Oulu. The work package has, together with invited experts, discussed the Science Case in the area of "Atmospheric Science." The first day of the current 3rd EISCAT_3D User Meeting in Uppsala, Sweden, is dedicated to discussion about this topic. Please refer to the meeting programme for more information.

The following Key Science Questions in Atmospheric Science were identified and presented by Ian McCrea:
  1. Dynamical coupling in the atmosphere
    • What is the three-dimensional structure of the wave fields propagating upwards from the troposphere?  How do their characteristics change as they move upwards to thermospheric heights?
    • How does atmospheric turbulence form and evolve? How is this process different in the different atmospheric layers?
    • What is the relationship between changes in chemistry and changes in dynamics?
    • How do waves and turbulence interact to modify the global-scale circulation of the middle atmosphere?  What effects are seen when the normal circulation is disrupted?
    • What is the relationship between the waves generated in the upper atmosphere and the processes which cause them?
  2. Solar-terrestrial effects on chemistry
    • What are the durations and extents of the energetic particle events which modulate chemistry?
    • How does the wave and tidal climatology change when the heat balance of the middle atmosphere is modulated, for example by changes in chemistry?
    • What processes link these changes to apparent effects at lower altitudes?
    • Can high-resolution continuous observations help validate chemical/dynamical models of the D region?
    • Can we improve our models through targeted active experiments?
  3. Dynamical and chemical coupling in the mesosphere (mesospheric thin layers)
    • How much small-scale structure is contained in mesospheric thin layers? Is this linked to wave activity, or plasma physics, or both?
    • What explains the aspect sensitivity of PMSE and PMWE layers?
    • What is the horizontal and vertical structure of the dust size in PMSE layers, and how does this vary?
    • Are PMWE layers linked to both dust and turbulence, or only to turbulence? How do they form, and what determines when they appear?
    • Are mesospheric thin layers signs of global change, connected to human activity?
    • Turbulence and vorticity effects
    • Heterogenuous chemistry on particles in mesosphere incl ice and meteoritic material
    • Charging processes, how are particles charged in the mesosphere
  4. Stratosphere and troposphere
    • How does turbulence form and develop?
    • How do stratospheric warming events affect the atmosphere at other heights and latitudes?
    • What are the effects of turbulence and wave dissipation on energy exchange between atmospheric layers?
    • Can the upper atmosphere exert a downward control on troposphere? How?
    • How do solar irradiance variability affect the stratosphere
  5. Short-term and long-term change
    • How does long-term change in the troposphere affect its energy exchange with the other atmospheric layers?
    • Is greenhouse warming of the lower atmopshere resulting in long-term cooling of the upper atmopsher? If so, what effect does that have?
    • What are the problems of our current models of the upper atosphere, and what implications might these have for predicatabilty?
    • Can we use EISCAT_3D data as a basis to make improved predictions of shorter-term variations in the Earth's upper atmopshere, such as those connected to the solar cycle?

Note, that this is a draft list! Please consider the following questions:

1. Are the section headings correct?
2. Are there major areas or important questions missing?
3. Are the Key Science Questions appropriate?
4. Have some questions been answered already?
5. Will EISCAT_3D really be able to make a contribution?

Get involved now! Please send your comments to Ian McCrea or Anita Aikio.

EISCAT_3D — It's your radar!

Tuesday, 17 May 2011

Wind Fluctuations During Pulsating Aurora at Tromsø

It's Tuesday, and time for another blog post about EISCAT-related science results. This time we look at a study combining radar measurements with a rocket campaign and optical observations. If you want to increase visibility for your science results, please let us know!

Simultaneous observations were conducted with a Fabry-Perot Interferometer (FPI) and an all-sky camera, both at a wavelength of 557.7 nm, as well as the EISCAT UHF radar during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA-2) rocket campaign in January 2009. This paper concentrates on two events during periods of pulsating aurora. The lower-thermospheric wind velocity measured with the FPI showed obvious fluctuations in both vertical and horizontal components. Of particular interest is that the location of the fluctuations was found to be in a darker area that appeared within the pulsating aurora.

During the same time period, the EISCAT radar observed sporadic enhancements in the backscattered power from the F region, which suggests the presence of low-energy electron precipitation (<=1 keV) coinciding with the increase of the amplitude of the electromagnetic wave (order of 10 Hz or higher). While we have not yet identified the dominant mechanism causing the fluctuations in FPI-derived wind velocity during pulsating aurora, the frictional heating energy dissipated by the electric-field perturbations may be responsible for the increase in ionospheric thermal energy thus modifying the local wind dynamics in the lower thermosphere.

Figure: Top panels show the temporal variations in vertical wind speed and fringe peak count at zenith, respectively, measured with the FPI (557.7 nm) on 26 January 2009. Vertical bars are 2σ uncertainty. Bottom panels show images taken with the ASC at 557.7 nm during pulsating aurora, which are mapped in geographic co-ordinates at a height of 110 km. Black dots and red crosses indicate the location of the FPI and the EISCAT UHF observation positions, respectively. Black arrows correspond to the horizontal component of the FPI-derived neutral wind velocity (scale in image of 01:15 UTC).

Original article: S. Oyama, K. Shiokawa, J. Kurihara, T. T. Tsuda, S. Nozawa, Y. Ogawa, Y. Otsuka, and B. J. Watkins, Lower-thermospheric wind fluctuations measured with an FPI in pulsating aurora at Tromsoe, Norway, Ann. Geophys.28, 1847-1857, 2010.

Monday, 16 May 2011

General Assembly of the EISCAT_3D project

It is time to continue our series on EISCAT_3D project internals. Today we are looking at the ultimate decision making body of the EISCAT_3D Preparatory Phase project.

According to the "Description of Work" document, the General Assembly "consists of one representative from each of the participating entities [...]."

"The General Assembly will have an ordinary meeting at least once per year, and additional meetings can be requested by the Executive Board or by General Assembly members. The representative from the Co-ordinator chairs all meetings of the General Assembly, unless decided otherwise for a particular meeting."

The members of the General Assembly are:
  • Esa Turunen (EISCAT Scientific Association; Co-ordinator)
  • Henrik Andersson (EISCAT Scientific Association; Co-ordinator)
  • Cesar La Hoz (University of Tromsø)
  • Jerker Delsing (Luleå Technical University)
  • Lars Eliasson (Swedish Institute for Space Physics)
  • Anita Aikio (University of Oulu)
  • Tomas Andersson (Vetenskapsrådet)
  • Leif Johansson (National Instruments)
  • Richard Harrison (Science and Technology Facilities Council, Rutherford Appleton Laboratory)
"The General Assembly is able to make decisions regarding the contents of the Work Packages, finances, intellectual property rights and the evolution of the consortium. The decisions of the General Assembly should be accepted by all members of the EISCAT_3D consortium. [...] The General Assembly shall be free to act on its own initiative to formulate proposals and take decisions. In addition, all proposals made by the Executive Board shall also be considered and decided upon by the General Assembly."

Friday, 13 May 2011

EISCAT Svalbard Radar


The EISCAT Scientific Association, which by the way will celebrate 30 years since the first incoherent scatter radar measurements were made at EISCAT, operates altogether three large radar systems. These are the UHF and VHF radars located on continental Northern Fenno-Scandinavia, and the newest installation, the EISCAT Svalbard Radar (ESR), which is located outside Longyearbyen on Svalbard, at 78° 09' 11" N, 16° 01' 44" E.

Inaugurated in 1996, the 500-MHz ESR initially had one fully steerable 32-metre parabolic dish antenna, which is the left antenna in the photograph above. In 1999, the fixed 42-metre antenna on the right was added. The 42-m antenna looks almost straight up, but not quite. The pointing direction is called "field-aligned," which means that the radar beam is tangential to the Earth's magnetic field at a certain altitude. The magnetic field lines in the very high latitudes are almost vertical.

The ESR has made a huge contribution to the recent International Polar Year (IPY) 2007/08. The radar operated almost continuously during this time, the only major interruption of one month being due to the Longyearbyen power station, which was not able to provide enough power to run the radar. Such a long, continuous run is highly remarkable for an incoherent scatter radar, which requires high power of typically a megawatt or more, and permanent presence of personnel.

The so-called IPY-run resulted in a fantastic data set giving a unique view of the polar ionosphere at very low solar activity and at all seasons and times of day. This data set will be the topic of a later post.

EISCAT_3D will have long-term monitoring modes, and the goal is to have it run automatically all the time.

With this photograph we wish all of you a very good weekend. Next week we will be blogging directly from the EISCAT_3D User Meeting in Uppsala.

Photo: Thomas Ulich, 9th August 2010.

Thursday, 12 May 2011

8th European Space Weather Week

One of the objectives of the future EISCAT_3D radar is to have continuous operation modes, which will, among others, serve Space Situational Awareness operations, which include, e.g., space weather and space debris monitoring. Last year, EISCAT_3D took the opportunity of the European Space Weather Week to present the project at the meeting's Space Weather Fair featuring the EISCAT_3D video and stunning 3D footage of the aurora and the Sun.

The European Space Weather Week will be held in the town of Namur, Belgium, from 28th November to 2nd December 2011. The meeting is being jointly organised by the Belgian Solar-Terrestrial Centre of Excellence (STCE), ESA, the Space Weather Working Team and the COST ES0803 communities. The local organisation is done by the STCE and the Royal Observatory of Belgium (ROB). This event will build on the advances made during previous European Space Weather Weeks and preceding ESA Space Weather Applications Workshops.

Now in its 8th year, the ESWW has grown into the main annual event in the European Space Weather calendar. This year's event will highlight key innovations in space weather research, applications and services. The meeting will also focus on current challenges and actions necessary in moving towards a sustainable Space Weather infrastructure in Europe able to meet the requirements of a diverse end-user community.

Recent Space Weather related activities in the framework of the ESA Space Situational Awareness programme and the EC's 7th Framework Programme will be a key topic, and next steps will be presented with the opportunity for technical discussion. Community input is welcome and encouraged in particular via the SWWT plenary meeting on Wednesday afternoon.

In order to meet the needs of a growing community, for the first time parallel sessions on focussed topics will be organised on two days of the meeting. Furthermore, it is expected that the main sessions will again be complemented by a diverse range of splinter and business meetings covering a range of topical themes.

For more information, please visit http://sidc.oma.be/esww8/.

Wednesday, 11 May 2011

TRANSMIT: Mitigating Ionospheric Threats

Global navigation satellite systems (GNSS) are now fully embedded in modern society, from in-car navigation to the timing of the world’s financial transactions. GNSS technology has taken the world by storm and we have come to rely on this multi-billion pound industry.

One of the major threats to our ever increasing dependence on GNSS comes from the sun. Solar related phenomena and their effect on the Earth's ionosphere, such as ionospheric scintillation, can be very disruptive, with serious consequential effects. The concern is that GNSS has little or no protection from them.

We are approaching the next solar maximum around 2013, when ionospheric effects will be at their greatest. At worst solar flares can black out satellite signals altogether. They can also create positioning errors and rapid signal fading. These intermittent problems are hindering the full development of mission-critical and high-precision applications for air, rail and marine transport, even autonomous machinery in areas such as agriculture.

TRANSMIT — Training Research and Applications Network to Support the Mitigation of Ionospheric Threats — is a 4M€ Marie Curie Initial Training Network (ITN) funded by the European Commission as part of the FP7 People Programme. The programme aims to improve the career perspectives of researchers who are in the first five years of their research career in both public and private sectors.

TRANSMIT is currently inviting applications for 13 posts of Early Stage Researchers and 1 post of Experienced Researcher. See also: TRANSMIT press release, TRANSMIT Facebook page.

TRANSMIT is made up of a consortium of leading universities, research centres and industry across Europe and as far afield as Brazil and Canada. The host institutions for researchers are the University of Nottingham, UK, Politecnico di Torino, Italy, the Space Research Center, Poland, Technische Universität Berlin, Germany, the University of Bath, UK, the University of Nova Gorica, Slovenia, the University of Zagreb, Croatia, and the Instituto Nazionale di Geofisica e Vulcanologia, Italy.

Also the EISCAT Scientific Association is part of TRANSMIT. Researchers employed by any of the host institutions will be able to spend extended amounts of time with EISCAT in order to gain from the experience of EISCAT personnel and to use the EISCAT facilities.

Deadline for applications is Monday, 30th May 2011.

Tuesday, 10 May 2011

PhD thesis: Solitary Waves and Enhanced Ion Lines

Jonas Ekeberg of the Dept of Physics, Faculty of Science and Technology, University of Umeå, Sweden, will defend his PhD thesis entitled "Solitary Waves and Enhanced Incoherent Scatter Ion Lines" on Friday, 13th May 2011, at 10.00 h at the Swedish Institute for Space Physics in Kiruna, Sweden. The opponent will be Prof. Jan Trulsen of the Institute for Theoretical Astrophysics of the University of Oslo, Norway.

Abstract

This thesis addresses solitary waves and their significance for auroral particle acceleration, coronal heating and incoherent scatter radar spectra. Solitary waves are formed due to a balance of nonlinear and dispersive effects. There are several non-linearities present in ideal magnetohydrodynamics (MHD) and dispersion can be introduced by including the Hall term in the generalised Ohm's law. The resulting system of equations comprise the classical ideal MHD waves, whistlers, drift waves and solitary wave solutions. The latter reside in distinct regions of the phase space spanned by the speed and the angle (to the magnetic field) of the propagating wave. Within each region, qualitatively similar solitary structures are found. In the limit of neglected electron intertia, the solitary wave solutions are confined to two regions of slow and fast waves, respectively. The slow (fast) structures are associated with density compressions (rarefactions) and positive (negative) electric potentials. Such negative potentials are shown to accelerate electrons in the auroral region (solar corona) to tens (hundreds) of keV. The positive electric potentials could accelerate solar wind ions to velocities of 300–800 km/s. The structure widths perpendicular to the magnetic field are in the Earth's magnetosphere (solar corona) of the order of 1–100 km (m). This thesis also addresses a type of incoherent scatter radar spectra, where the ion line exhibits a spectrally uniform power enhancement with the up- and downshifted shoulder and the spectral region in between enhanced simultaneously and equally. The power enhancements are one order of magnitude above the thermal level and are often localised to an altitude range of less than 20 km at or close to the ionospheric F-region peak. The observations are well-described by a model of ion-acoustic solitary waves propagating transversely across the radar beam. Two cases of localised ion line enhancements are shown to occur in conjunction with auroral arcs drifting through the radar beam. The arc passages are associated with large gradients in ion temperature, which are shown to generate sufficiently high velocity shears to give rise to growing Kelvin-Helmholtz instabilities. The observed ion-line enhancements are interpreted in the light of the low-frequency turbulence associated with these instabilities.

Reference

Ekeberg, J., Solitary Waves and Enhanced Incoherent Scatter Ion Lines, IRF Scientific Report, URI: urn:nbn:se:umu:diva-42955, ISBN 978-91-977255-7-6, IRF, Umeå University, Sweden. (permanent url)

Monday, 9 May 2011

HEPPA 2011, Granada, Spain

From today until Wednesday, the Workshop on High-Energy Particle Precipitation in the Atmosphere (HEPPA) is taking place in Granada, Spain. It is the third workshop of its kind. The first meeting took place in Helsinki, Finland, and the second workshop was held at NCAR in Boulder, Colorado. In Finnish language, "heppa" is what (young) children call a horse, thus it can be translated as "horsey."

Energetic particle precipitation from space can penetrate deep into the atmosphere. In the case of galactic cosmic rays even down to ground level. Energetic auroral precipitation routinely enters the mesosphere where it creates odd nitrogen. In the absence of sunlight at nighttime, or in the polar regions during the long polar nights, odd nitrogen lives long enough to be transported into the stratosphere where it contributes to the destruction of ozone.

Studies of these processes have been conducted for a number of years, but in 2007 it was recognised that in general particle precipitation effects in the atmosphere are not well enough understood. It was decided to arrange a workshop to discuss these topics, and HEPPA was born.

Since EISCAT is a very powerful tool for measuring the ionised part of the atmosphere down to altitudes of 60 km or so, EISCAT-related studies are well represented at the current workshop. Moreover, EISCAT Director Esa Turunen will present the status and plans for the future EISCAT_3D radar system.

  • EISCAT_3D Incoherent scatter facility -status of the project; Turunen, E., and the EISCAT 3D Project Team.
  • Atmospheric signatures of REP; Clilverd, M. A., C. J. Rodger, P. T. Verronen, A. Seppälä, E. Turunen, C.-F. Enell, Th.Ulich, J. Tamminen.
  • Global observations of thermospheric temperature and nitric oxide from MIPAS spectra; López-Puertas, M., B. Funke, D. Bermejo-Pantaleón, M. García-Comas, G. P. Stiller, T. von Clarmann, N. Glatthor, U. Grabowski, M. Kiefer, G. Lu.
  • The response of an incoherent scatter radar and riometer to the precipitation of MeV electrons; Kavanagh, A. J., C. J. Rodger, M. A. Clilverd, C-F. Enell and F. Honary.
  • Anomalous variations in the quiet daytime D-region ionosphere during the 1-year IPY experiment at the EISCAT Svalbard radar; Kero, A., C.-F. Enell, L. Roininen, Th.Ulich, E. Turunen, I. Häggström, P. T. Verronen, S.-M. Salmi.
  • ISSI project: Geospace Coupling to Polar Atmosphere; Seppälä, A., M. A. Clilverd, Th. Ulich, C.-F. Enell, A. Kero, D. Marsh, C. J. Rodger, E. Rozanov, T. Egorova, P. T. Verronen, S.-M. Salmi, E. Turunen.
  • Atmospheric Ionization Module OSnabrück (AIMOS)-Reliability analysis of AIMOS/- HAMMONIA in comparison to incoherent scatter observations; Wissing, J. M., M.-B. Kallenrode, J. Kieser, H. Schmidt, M. T. Rietveld, A. Strømme, P. J. Erickson.
For more information, please refer to the HEPPA web site at http://heppa2011.iaa.es/.

Credit: The beautiful poster for the meeting was created by Andrés Alonso-Herrero, and last Friday's picture feature is a part of this poster.

Friday, 6 May 2011

Unusual setting for Northern Lights

It's Friday and time to end a busy week with a beautiful picture. The picture today features one of the most beautiful phenomena of the Earth's atmosphere, the Northern Lights or aurora borealis. These majestic lights can be seen also on the southern hemisphere where they are called Southern Lights or aurora australis.

The setting of this stunning image, however, is very unusual. The picture seemingly taken though a window, which has distinctly Arabic features. So where was it taken?

We'll leave it to you to ponder over the weekend, and we will solve the puzzle on Monday.

Have a good weekend!

PS: Click on the picture to get a bigger version.

Credit: Andrés Alonso-Herrero.

Thursday, 5 May 2011

Co-ordinator of the EISCAT_3D project

On 2nd May we introduced the Executive Board of the EISCAT_3D Preparatory Phase project. In this series of blog posts of "project internals," we shall continue to introduce the different committees that run the project. Next in line is the Co-ordinator.

The EISCAT Scientific Association takes the role as Co-ordinator during the EISCAT_3D Preparatory Phase.

According to the "Description of Work", the "Co-ordinator acts [as] the intermediary between the parties of the consortium and the European Commission. In particular, the Co-ordinator is responsible for monitoring compliance by the consortium parties with their obligations and keeping the contact details of the members of the consortium management bodies and other contact persons updated and available. The role of the Co-ordinator also includes collecting the results of the project activities, reviewing them to verify consistency and submitting reports and other deliverables (including financial statements and related certifications) to the European Commission."

"The Co-ordinator is responsible for transmitting documents and information connected with EISCAT_3D to, and between, Work Package leaders and any other parties concerned."

"The Co-ordinator also administers the Community financial contribution and provides, upon request, the consortium parties with official copies or originals of documents which are in the sole possession of the Co-ordinator when such copies or originals are necessary for the parties to present claims."

Tuesday, 3 May 2011

EISCAT Observations of the Quiet-Time Ionospheric Trough

It is Science Tuesday and we are happy to present the first science result in this series. If you are interested in seeing your results on-line on the EISCAT_3D blog, please send us a short text explaining the main result, one image or graph with caption, and the original article's reference. Also, please send the PDF of the article in its final layout, because that will clarify possible questions.

As an introdution to this work, the ionospheric trough is a gap of lower-than-elsewhere ionisation between the sunlit and night-time ionosphere. The solar terminator is the great-circle line on the globe, which is the separator of the sunlit and the dark hemispheres.

Data from a combined azimuth-scan and overhead-scan UHF radar experiments were used to determine the behaviour of the eveningside F-region trough on 9th November 1987. The MLT and CGMlat dependence of various ionospheric parameters at a set of F-region altitudes was determined. It was found that both ion and electron temperatures have minima within the trough region and increase at the poleward wall. The most important result was obtained by comparing the observed ion velocity and electron density to the respective parameters given by the LiMIE model (see Figure). The results suggest that the density depletion within the trough is due to recombination of F-region plasma convecting for a long time in the dusk convection cell beyond the terminator. The northern edge of the trough is associated with soft particle precipitation. The southern edge is steeper than the northern edge, and is built by sunlit plasma brought to the trough region by corotation. The trough is thus a result of a combination of transport and precipitation processes rather than stagnation.


Figure: (left) Zonal ion velocity and (right) electron density at 345 km together with the convection pattern given by the LiMIE model, positive potentials are indicated by continuous and negative potentials by dashed lines. Shown is also the position of the solar terminator as a line of different colours, chosen for the sake of a good contrast with the background.

Original article: Voiculescu, M., T. Nygrén, A. Aikio, and R. Kuula, An olden but golden EISCAT observation of a quiet-time ionospheric trough, J. Geophys. Res., 115, A10315, doi:10.1029/2010JA015557, 2010.

Thanks to Tuomo Nygrén for providing the text and the figure.

Monday, 2 May 2011

Executive Board of EISCAT_3D project

Marking the completion of the first two quarter-years of the project, the Executive Board of the EISCAT_3D Preparatory Phase project will have its third meeting in Sigtuna, Sweden, on the 3rd and 4th of May, 2011. Sigtuna is a convenient location very close to the main airport of Stockholm, Arlanda.

According to the document "Description of Work, Part B", which is part of the Consortium Agreement, the "Executive Board acts as the supervisory body for the execution of the EISCAT_3D Preparatory Phase. It consists of two members from the Co-ordinator and up to three members from the other members of the consortium. The Co-ordinator appoints its own members and the General Assembly appoints the other members of the Executive Board, ..."

The Co-ordinator of the project is EISCAT. The members of the Executive Board are:
  • Esa Turunen, EISCAT Headquarters
  • Henrik Andersson, EISCAT Headquarters
  • Ian McCrea, STFC/RAL, U.K.
  • Jonny Johansson, University of Luleå, Sweden
  • Thomas Ulich, Sodankylä Geophysical Observatory, Finland
The Executive Board is in constant contact. It meets every week in a telephone conference, which is currently held on Fridays at 1100 UTC. In addition to that, the Board meets every three months to conclude the quarterly reporting intervals. Typically the meetings are held about one month after the quarter is concluded. Because the EISCAT_3D project began in October 2010, the project quarters coincide with calendar quarters.

Tasks of the Executive Board

The aforementioned Description of Work details the tasks of the Executive Board: "The Executive Board prepares the meetings, proposes decisions and prepares the agenda of the General Assembly, and it seeks a consensus among the members of the consortium. It is responsible for the proper execution and implementation of the decisions of the General Assembly and it monitors the effective and efficient implementation of EISCAT_3D Preparatory Phase project. In addition, the Executive Board collects information at least every six months on the progress of the Preparatory Phase, examines that information to assess the compliance of EISCAT_3D with the activity plan and, if necessary, proposes modifications of the activity plan to the General Assembly. Furthermore, the Executive Board initiates, coordinates and organises the Sub Project(s) whenever such are needed. It agrees on the members of the Management Support Team upon a proposal from the Coordinator, and supports the Coordinator in preparing meetings with the European Commission and in preparing related data and deliverables. It also prepares the content and timing of press releases and joint publications by the consortium. In the case of abolished tasks as a result of a decision of the General Assembly, the Executive Board shall advise the General Assembly on ways to rearrange the tasks and budgets of the consortium members concerned. Such rearrangement shall take into consideration the legitimate commitments taken prior to the decisions, which cannot be cancelled."