Type II and IV radio bursts in the active period October-November 2003

In this report we present the Type II and IV radio bursts observed and analyzed by the radio spectrograph ARTEMIS IV1, in the 650-20MHz frequency range, during the active period October-November 2003. These bursts exhibit very rich fine structures such fibers, pulsations and zebra patterns which is associated with certain characteristics of the associated solar flares and CMEs.Comment: Recent Advances in Astronomy and Astrophysics: 7th International Conference of the Hellenic Astronomical Society. AIP Conference Proceedings, Volume 848, pp. 199-206 (2006

Ten Years of the Solar Radiospectrograph ARTEMIS-IV

The Solar Radiospectrograph of the University of Athens (ARTEMIS-IV) is in operation at the Thermopylae Satellite Communication Station since 1996. The observations extend from the base of the Solar Corona (650 MHz) to about 2 Solar Radii (20 MHz) with time resolution 1/10-1/100 sec. The instruments recordings, being in the form of dynamic spectra, measure radio flux as a function of height in the corona; our observations are combined with spatial data from the Nancay Radioheliograph whenever the need for 3D positional information arises. The ARTEMIS-IV contribution in the study of solar radio bursts is two fold- Firstly, in investigating new spectral characteristics since its high sampling rate facilitates the study of fine structures in radio events. On the other hand it is used in studying the association of solar bursts with interplanetary phenomena because of its extended frequency range which is, furthermore, complementary to the range of the WIND/WAVES receivers and the observations may be readily combined. This reports serves as a brief account of this operation. Joint observations with STEREO/WAVES and LOFAR low frequency receivers are envisaged in the future

Type II Shocks Characteristics: Comparison with associated CMEs and Flares

A number of metric (100-650 MHz) typeII bursts was recorded by the ARTEMIS-IV radiospectrograph in the 1998-2000 period; the sample includes both CME driven shocks and shocks originating from flare blasts. We study their characteristics in comparison with characteristics of associated CMEs and flares.Comment: Recent Advances in Astronomy and Astrophysics: 7th International Conference of the Hellenic Astronomical Society. AIP Conference Proceedings, Volume 848, pp. 238-242 (2006

New records of aphid species (Hemiptera: Aphididae) in Greece

Τις τελευταίες δυο δεκαετίες έχουν δημοσιευθεί αρκετές εργασίες σχετικές με την αφιδοπανίδα της Ελλάδας. Ωστόσο, ο αριθμός των καταγεγραμμένων ειδών αφίδων είναι αρκετά μικρότερος από άλλες Ευρωπαϊκές χώρες, συμπεριλαμβανομένων αυτών στη λεκάνη της Μεσογείου. Στην παρούσα εργασία συλλέξαμε δείγματα αφίδων από διάφορους ξενιστές και περιοχές της νότιας, κεντρικής και βόρειας Ελλάδας. Συνολικά συλλέχθηκαν 128 είδη αφίδων, που ανήκουν σε 55 γένη και έξι υποοικογένειες, από 200 είδη φυτών-ξενιστών. Τα περισσότερα είδη αφίδων ανήκαν στην υποοικογένεια Aphidinae (ειδικά στις φυλές Macrosiphini και Aphidini). Δεκαοκτώ από τα συλλεχθέντα είδη είναι νέες αναφορές για την Ελλάδα. Τα αποτελέσματα της παρούσας εργασίας αυξάνουν τη γνώση μας σχετικά με την αφιδοπανίδα της Ελλάδας και δείχνουν ότι ο αριθμός των καταγεγραμμένων ειδών στην Ελλάδα μπορεί να αυξηθεί σημαντικά αν πραγματοποιηθούν επιπλέον σχετικές μελέτες. Several papers have been published on aphid fauna in Greece during the last two decades, but the number of recorded species is still low compared to other European countries, including some from the Mediterranean basin. In this context, we collected aphids from various host-plants and regions in southern, central and northern Greece characterized by diverse flora, climatic conditions and ecological habitats. In total, 128 aphid species belonging to 55 genera and six subfamilies were collected on 200 host-species. Most of the species dominated the subfamily Aphidinae (especially tribes Macrosiphini and Aphidini). Among the species collected, 18 were new records in Greece. The present work improves our knowledge regarding the aphid fauna of Greece and suggests that the number of recorded species could increase further if additional studies were undertaken

The improved ARTEMIS IV multichannel solar radio spectrograph of the University of Athens

We present the improved solar radio spectrograph of the University of Athens operating at the Thermopylae Satellite Telecommunication Station. Observations now cover the frequency range from 20 to 650 MHz. The spectrograph has a 7-meter moving parabola fed by a log-periodic antenna for 100 650 MHz and a stationary inverted V fat dipole antenna for the 20 100 MHz range. Two receivers are operating in parallel, one swept frequency for the whole range (10 spectrums/sec, 630 channels/spectrum) and one acousto-optical receiver for the range 270 to 450 MHz (100 spectrums/sec, 128 channels/spectrum). The data acquisition system consists of two PCs (equipped with 12 bit, 225 ksamples/sec ADC, one for each receiver). Sensitivity is about 3 SFU and 30 SFU in the 20 100 MHz and 100 650 MHz range respectively. The daily operation is fully automated: receiving universal time from a GPS, pointing the antenna to the sun, system calibration, starting and stopping the observations at preset times, data acquisition, and archiving on DVD. We can also control the whole system through modem or Internet. The instrument can be used either by itself or in conjunction with other instruments to study the onset and evolution of solar radio bursts and associated interplanetary phenomena.Comment: Experimental Astronomy, Volume 21, Issue 1, pp.41-5

Solar flares with and without SOHO/LASCO coronal mass ejections and type II shocks

We analyse of a set of radio rich (accompanied by type IV or II bursts) solar flares and their association with SOHO/LASCO Coronal Mass Ejections in the period 1998 2000. The intensity, impulsiveness and energetics of these events are investigated. We find that, on the average, flares associated both with type IIs and CMEs are more impulsive and more energetic than flares associated with type IIs only (without CME reported), as well as flares accompanied by type IV continua but not type II shocks. From the last two classes, flares with type II bursts (without CMEs reported) are the shortest in duration and the most impulsive.Comment: Advances in Space Research, Volume 38, Issue 5, p. 1007-101

Radio Observations of the January 20, 2005 X-Class Event

We present a multi-frequency and multi-instrument study of the 20 January 2005 event. We focus mainly on the complex radio signatures and their association with the active phenomena taking place: flares, CMEs, particle acceleration and magnetic restructuring. As a variety of energetic particle accelerators and sources of radio bursts are present, in the flare-ejecta combination, we investigate their relative importance in the progress of this event. The dynamic spectra of {Artemis-IV-Wind/Waves-Hiras with 2000 MHz-20 kHz frequency coverage, were used to track the evolution of the event from the low corona to the interplanetary space; these were supplemented with SXR, HXR and gamma-ray recordings. The observations were compared with the expected radio signatures and energetic-particle populations envisaged by the {Standard Flare--CME model and the reconnection outflow termination shock model. A proper combination of these mechanisms seems to provide an adequate model for the interpretation of the observational data.Comment: Accepted for publication in Solar Physic

Centaur database: an information system for aphid surveys and pest control

The development and the use of an information system (Centaur) including aphid trapping data from suction and yellow traps are described. Centaur is a client-server database on an NT server and the interface is in Windows. The system allows users to enter and retrieve data of aphid captures and to produce summaries of data at various time levels (daily, weekly, yearly) for specific sites. The data can be illustrated graphically and they can be exported or printed. In addition, the system allows the incorporation of biological data and morphological images, and maps which estimate the spatial distribution of aphids. The information retrieval is fast and user-friendly. The system can be of considerable value for research, community ecology, plant protection, public and private authorities, plant protection specialists, agronomists, agrochemical companies, farmers and the agricultural industry as it can be used for decision support. The data can be used to make forecasts for risk and/or to give advice for timely interventions. The system is currently operated in Greece and includes data from 1993 but it can be applied to other European countries and can be used for other insect pests