Tuesday, 30 October 2012

Science Tuesday: Recent Papers

Tuesday is the science day on the EISCAT_3D blog. For the science feature, you can submit your research to the blog with an image, photo, or graph, and a short text explaining the study and the key result. We will then publish your work here. For the time being, please send any input to the blog's editor Thomas Ulich (thu -at- sgo -dot- fi). Thanks!
  • Ionization effect of nuclei with solar and galactic origin in the Earth atmosphere during GLE 69 on 20 January 2005, by A.L. Mishev, P.I.Y. Velinov, L. Mateev, Y. Tassev, J. Atm. Sol.-Terr. Phys., 89, 1-7, 2012, (link).
  • Estimating high-energy electron fluxes by intercalibrating Reimei optical and particle measurements using an ionospheric model, by D.K. Whiter, B.S. Lanchester, T. Sakanoi, K. Asamura, J. Atm. Sol.-Terr. Phys., 89, 8-17, 2012, (link).
  • Mesospheric temperature estimation from meteor decay times of weak and strong meteor trails, by Jeong-Han Kim, Yong Ha Kim, Geonhwa Jee, Changsup Lee, J. Atm. Sol.-Terr. Phys., 89, 18-26, 2012, (link).
  • Temporal variations of short- and mid-term periodicities in solar wind parameters and cosmic ray intensity, by Y.P. Singh, Shweta Gautam, Badruddin, J. Atm. Sol.-Terr. Phys., 89, 48-53, 2012, (link).
  • Experimental evidence of a stratospheric circulation influence on mesospheric temperatures and ice-particles during the 2010–2011 austral summer at 69°S, by Ray J. Morris, Josef Höffner, Franz-Josef Lübken, Timo P. Viehl, Bernd Kaifler, Andrew R. Klekociuk, J. Atm. Sol.-Terr. Phys., 89, 54-61, 2012, (link).
  • Analysis of diurnal double maxima observed above Italy during 1975–1991, by Z.T. Katamzi, N.D. Smith, C.N. Mitchell, P. Spalla, J. Atm. Sol.-Terr. Phys., 89, 67-75, 2012, (link).
  • An adaptive information technology for the operative diagnostics of the tropical cyclones; solar–terrestrial coupling mechanisms, by Vladimir F. Krapivin, Vladimir Yu. Soldatov, Costas A. Varotsos, Arthur P. Cracknell, J. Atm. Sol.-Terr. Phys., 89, 83-89, 2012, (link).
Source: ScienceDirect Message Center.

Friday, 26 October 2012

UHF-to-VHF Conversion completed

A while ago we reported, that the remote EISCAT UHF receivers in Kiruna and Sodankylä will be converted to the VHF frequency of 224 MHz in order to continue tristatic operations despite the interferences from mobile communication networks around the old frequency of 930 MHz.

This week, on Tuesday, 23rd October 2012, the conversion work was completed with the replacement of the small mirror with a dipole ring feed. The feed system is shown in the photo above while still loaded on the trailer on which it was brought over from Kiruna, where it was built.

With the new feed installed at Sodankylä, the conversion of the remote sites is complete – pending testing of the new setup using the Tromsø VHF transmitter. This is planned for next week.

The photo above shows the small mirror being lowered into the yard of the Sodankylä Geophysical Observatory (SGO) after having been unbolted. Two cranes were needed: one for lifting the mirror, and the other holding a basket as a platform for doing the work.

The second photo shows the new VHF feed being lifted into position. It is secured by two ropes to the ground in order to ensure the right orientation. At the same time, the mounting crew is getting ready in the basket of the other crane, ready to install the feed.

These two photos are part of a series of thousands of images taken by a time-lapse camera on the roof of the EISCAT station. A time-lapse movie (Full HD 1080p) of the operation has been made available on-line. The movie is 7'34" long, based on images every 2 seconds and running at 25 fps. However, it failed to capture the action in the centre of the radar dish since it was pointed just a little too low. This unfortunate mistake is down to this specific camera not having a view finder allowing for exact aim. Well, we learnt something again: download test images before running all day.

See also the photos of the Sodankylä conversion, which were published on the KAIRA blog earlier this week.

Time-lapse images were a collaboration between Thomas Ulich, Toivo Iinatti, and Derek McKay-Bukowski. Photo of the feed on trailer by Thomas Ulich.

Tuesday, 23 October 2012

Science Tuesday: Recent Papers

Tuesday is the science day on the EISCAT_3D blog. For the science feature, you can submit your research to the blog with an image, photo, or graph, and a short text explaining the study and the key result. We will then publish your work here. For the time being, please send any input to the blog's editor Thomas Ulich (thu -at- sgo -dot- fi). Thanks!
  • Electron loss and meteoric dust in the mesosphere, by M. Friedrich, M. Rapp, T. Blix, U.-P. Hoppe, K. Torkar, S. Robertson, S. Dickson, and K. Lynch, ANGEO, 2012, Vol.30, pp. 1495-1501, SRef-ID: 1432-0576/angeo/2012-30-1495, http://direct.sref.org/1432-0576/angeo/2012-30-1495.
  • Collisionless reconnection: magnetic field line interaction, by R. A. Treumann, W. Baumjohann, and W. D. Gonzalez, ANGEO, 2012, Vol.30, pp. 1515-1528, SRef-ID: 1432-0576/angeo/2012-30-1515, http://direct.sref.org/1432-0576/angeo/2012-30-1515.
  • Interball-1 observations of flux transfer events, by G. I. Korotova, D. G. Sibeck, and V. I. Petrov, ANGEO, 2012, Vol.30, pp. 1451-1462, SRef-ID: 1432-0576/angeo/2012-30-1451, http://direct.sref.org/1432-0576/angeo/2012-30-1451.
  • Characteristics of mid-latitude planetary waves in the lower atmosphere derived from radiosonde data, by R. Wang, S. D. Zhang, H. G. Yang, and K. M. Huang, ANGEO, 2012, Vol.30, pp. 1463-1477, SRef-ID: 1432-0576/angeo/2012-30-1463, http://direct.sref.org/1432-0576/angeo/2012-30-1463.
  • The equatorial ionospheric response over Tirunelveli to the 15 January 2010 annular solar eclipse: observations, by C. K. Nayak, D. Tiwari, K. Emperumal, and A. Bhattacharyya, ANGEO, 2012, Vol.30, pp. 1371-1377, SRef-ID: 1432-0576/angeo/2012-30-1371, http://direct.sref.org/1432-0576/angeo/2012-30-1371.
  • The unusual persistence of an ozone hole over a southern mid-latitude station during the Antarctic spring 2009: a multi-instrument study, by E. A. Wolfram, J. Salvador, F. Orte, R. D'Elia, S. Godin-Beekmann, J. Kuttippurath, A. Pazmiño, F. Goutail, C. Casiccia, F. Zamorano, N. Paes Leme, and E. J. Quel, ANGEO, 2012, Vol.30, pp. 1435-1449, SRef-ID: 1432-0576/angeo/2012-30-1435, http://direct.sref.org/1432-0576/angeo/2012-30-1435.
  • Planetary waves in the upper stratosphere and lower mesosphere during 2009 Arctic major stratospheric warming, by P. Kishore, I. Velicogna, M. Venkat Ratnam, J. H. Jiang, and G. N. Madhavi, ANGEO, 2012, Vol.30, pp. 1529-1538, SRef-ID: 1432-0576/angeo/2012-30-1529, http://direct.sref.org/1432-0576/angeo/2012-30-1529.
Source: COSIS.net Alert Service Subscriptions.

Friday, 19 October 2012

EISCAT_3D – SKA Technical Meeting Report

At the end of September, a number of participants in the EISCAT_3D project visited the Cavendish Laboratory of Cambridge University, UK, for discussions with one of the key groups involved in the design of the Square Kilometre Array (SKA). The two projects have a large number of common issues, since the SKA will contain an aperture array covering the frequency range from 70 to 450 MHz, due to be deployed in Western Australia. This frequency range includes the EISCAT_3D band, and the EISCAT_3D team were therefore interested to see the developments in antenna and signal processing technology, with which the Cambridge team were working. The two projects established a good working relationship and identified a number of issues where future collaboration would be desirable.

The picture shows some of the meeting participants at the Lord’s Bridge field site of Cambridge University, where a small test array of “Christmas Tree” log-periodic antennas has been built as a test for the SKA Aperture Array. From left to right: Johan Borg (Luleå Technical University, E3D); Ian McCrea (Rutherford Appleton Laboratory, E3D) ; Björn Gustafsson (EISCAT, E3D); Nima Razavi-Ghods (Cambridge, SKA); Leif Johansson (National Instruments, E3D); Eloy de Lera Acedo (Cambridge, SKA); Markku Lehtinen (Sodankylä Geophysical Observatory, E3D); Frank Lind (MIT Haystack, E3D TAC chair) and Andy Faulkner (Cambridge, SKA).

Text: Ian McCrea (RAL); photo: Colin Lonsdale (MIT Haystack).

Wednesday, 17 October 2012

Winter in EISCAT Land

This morning the southernmost EISCAT site at Sodankylä awoke to a beautiful winter scene: overnight fell about 5 cm of wet snow. Perfect for making a snowman, but not ideal for working outside. Hopefully the winter weather will not cause problems to next week's (Tuesday, 23rd October 2012) replacement of the small mirror in the UHF antenna by a dipole ring feed, which will complete the conversion of the UHF remote antennae to VHF frequency.

Photo: Thomas Ulich.

Tuesday, 16 October 2012

Science Tuesday: Recent Papers

Tuesday is the science day on the EISCAT_3D blog. For the science feature, you can submit your research to the blog with an image, photo, or graph, and a short text explaining the study and the key result. We will then publish your work here. For the time being, please send any input to the blog's editor Thomas Ulich (thu -at- sgo -dot- fi). Thanks!
  • Sources of plasma in the high altitude cusp, by W.K. Peterson, K.J. Trattner, J. Atm. Sol.-Terr. Phys., 87–88, 1-10, 2012, (link).
  • Multi-scale features of solar terrestrial coupling in the cusp ionosphere, by J. Moen, H.C. Carlson, Y. Rinne, Å. Skjæveland, J. Atm. Sol.-Terr. Phys., 87–88, 11-19, 2012, (link).
  • Flux transfer events: Motion and signatures, by D.G. Sibeck, N. Omidi, J. Atm. Sol.-Terr. Phys., 87–88, 20-24, 2012, (link).
  • Observations of a broad and dynamic region of radiation in geospace, by Jiasheng Chen, Ling-Hsiao Lyu, J. Atm. Sol.-Terr. Phys., 87–88, 25-38, 2012, (link).
  • The cusp as a source of magnetospheric particles, by T.A. Fritz, B.M. Walsh, M. Klida, J. Chen, J. Atm. Sol.-Terr. Phys., 87–88, 39-46, 2012, (link).
  • Simultaneous observations of the exterior cusp region, by B.M. Walsh, T.A. Fritz, J. Chen, J. Atm. Sol.-Terr. Phys., 87–88, 47-55, 2012, (link).
  • Investigating the relationship between cusp energetic particle events and cusp diamagnetic cavities, by K.J. Trattner, S.M. Petrinec, S.A. Fuselier, R. Friedel, J. Atm. Sol.-Terr. Phys., 87–88, 56-64, 2012, (link).
  • Energetic ions near the dayside magnetopause reconnection site: Implications for energization sources, by S.M. Petrinec, K.J. Trattner, S.A. Fuselier, T.D. Phan, V. Angelopoulos, J. Atm. Sol.-Terr. Phys., 87–88, 65-69, 2012, (link).
  • On the origin of high-energy particles in the cusp diamagnetic cavity, by K. Nykyri, A. Otto, E. Adamson, E. Kronberg, P. Daly, J. Atm. Sol.-Terr. Phys., 87–88, 70-81, 2012, (link).
  • Auroral precipitation/ion upwelling as a driver of neutral density enhancement in the cusp, by F. Brent Sadler, Marc Lessard, Eric Lund, Antonius Otto, Hermann Lühr, J. Atm. Sol.-Terr. Phys., 87–88, 82-90, 2012, (link).
Source: COSIS.net Alert Service Subscriptions.

Tuesday, 9 October 2012

PhD Thesis: On Statistical Theory of Radar Measurements

On 1st October 2013, Juha Vierinen defended his PhD thesis entitled "On Statistical Theory of Radar Measurements" (pdf, 6.4MB) at the Sodankylä Geophysical Observatory. Dr Jorge L. Chau of the Jicamarca Radio Observatory near Lima, Perú, served as the opponent, and prof. Erkki Oja chaired the defence. Juha Vierinen, who has worked extensively with the EISCAT radars and has contributed to the EISCAT_3D development, will shortly graduate as Doctor of Science (Technology) from the Dept of Information and Computer Science, School of Science, Aalto-University of Finland.

During the defence ceremony, Juha Vierinen showed the latest results from the KAIRA facility, which has had a tremendously successful first month of operation receiving echoes from the Tromsø VHF radar as well as interplanetary and ionospheric scintillation.

Abstract

Statistical treatment of radar measurements is important as most radar measurements are corrupted by random receiver noise. In addition to this, many radar targets themselves have to be modeled as random processes. It is therefore not a coincidence that this thesis uses the framework of statistical inverse problems for modeling radar measurements.

The introductory part of this thesis first goes through some important mathematical and numerical methods that can be used to model radar measurements and to apply these models in practice. We then describe several different types of radar measurements, with emphasis on high power large aperture radars. After this, we go through several useful radar measurement models. Finally, with the help of these models, we discuss optimal experiment design -- which typically amounts to radar transmission waveform optimization.

The publications included in this thesis contain practical applications of the topics described in the introduction, including amplitude domain estimation of incoherent scatter signals, radar transmission code optimization, inverse synthetic aperture radar, and measurements of space debris.

Photo

The photo shows Juha Vierinen inside the receiver cabin of the Sodankylä EISCAT UHF antenna, where he had installed his version of the cantenna radar for testing, trying to get it to work using a Big Dish. Photo Thomas Ulich.