Written by Jaša Čalogović Saturday, 13 July 2013 16:36
Written by Jaša Čalogović Tuesday, 12 March 2013 14:04This is the second announcement for the International Study for Earth-Affecting Solar Transients (ISEST) Workshop in Hvar, Croatia, June 17-20, 2013. ISEST is intended to bring together scientists from different countries to interact and establish collaborations that can effectively address the physical mechanisms of the origin and propagation of coronal mass ejections (CMEs), toward the goal of developing the prediction capability of solar transients' arrival and potential impact on the Earth. This is a newly established program under SCOSTEP CAWSES-II. The workshop engages coordinated international activities in observation, theory and modeling, and involves scientists in both developed and developing countries, and provides an online platform for both research and educational opportunities for students.
Written by Jaša Čalogović Tuesday, 29 January 2013 10:20COMESEP 2nd Year Progress Meeting will be organized by Hvar Observatory and take place at Zagreb Observatory from 15 to 19 April, 2013 in Zagreb, Croatia.
>> more information about COMESEP Meeting
Written by Jaša Čalogović Friday, 25 January 2013 18:21The purpose of the basic form of the model is to provide a prediction of the arrival time and impact speed at the Earth. Calculations are based on the assumption that the dominant force in the heliospheric dynamics of ICMEs is the magnetohydrodynamical equivalent of the aerodynamic drag. For a given set of input parameters it provides the ICME Sun-Earth transit time, the arrival time, and the impact speed.
The new version of DBM now includes the advanced DBM which provides this output for any target in the heliosphere and takes into account also the shape of ICME employing the so-called cone-geometry. Plots showing the impact speed depending on the distance from the Sun (v-R) and CME geometry are added to the model outputs.
>> link to Drag-Based Model
Written by Jaša Čalogović Friday, 05 October 2012 10:30We would like to remind that the deadline for submitting the manuscripts for the proceedings of 12th Hvar Astrophysical Colloquium "The Sun and Heliosphere" is November 30, 2012.
The following page limits apply for the proceedings: reviews = 18 pages, invited talks = 14 pages, contributed talks = 12 pages, posters = 6 pages.
Manuscripts should be prepared in LaTeX, preferably using the Cent. Eur. Astrophys. Bull. style file which is available here.
Written by Jaša Čalogović Tuesday, 10 July 2012 18:45Pictures from XIth Hvar Astrophysical Colloquium (2.-6.7.2012) you can find under the links here:
Photos by LOC
Photos by participants
We would like to remind you that the deadline for submitting the manuscripts for Proceedings of XIth HAC (special volume of the Central European Astrophysical Bulletin) is October 30, 2012.
Written by Jaša Čalogović Wednesday, 06 June 2012 16:37During the morning hours of 6.6.2012, Hvar Observatory double solar telescope was able to observe and record the last Venus transit in this century. Photospheric and chromosperic telescope were used from the sunrise (3:44 UTC) till the end of transit (4:55 UTC). Unfortunately for those who missed it, the next Venus transit will not occur until December 2117. Observer was Nikša Novak and data were processed by Jaša Čalogović.
Written by Jaša Čalogović Sunday, 01 April 2012 23:02
All those interested in solar influences on climate and especially in the contended topic about link between the cosmic rays and clouds can now online access the talk of Jaša Čalogović held on IAC, La Laguna on 15. March 2012.
Cosmic ray modulation by different types of solar wind disturbances
Written by Mateja Dumbovic Tuesday, 20 December 2011 00:00
The amount of the galactic cosmic rays (primarily protons) that hit the Earth is greatly influenced by the solar activity. On the short time scales it can be substantially reduced by the passing of solar wind disturbances, such as interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs). The resulting short-term cosmic ray depressions are generally denoted as Forbush decreases. We present a systematic statistical study of various aspects of Forbush decreases. The analysis is based on ground-based neutron monitor data and the in-situ solar wind data recorded by the Advanced Composition Explorer (ACE) satellite and provides empirical background for physical interpretations of short-term cosmic ray modulations.
Solar irradiance, cosmic rays and cloudiness over daily timescales
Written by Jaša Čalogović Tuesday, 20 December 2011 00:00
Although over centennial and greater timescales solar variability may be one of the most influential climate forcing agents, the extent to which solar activity influences climate over shorter time periods is poorly understood. If a link exists between solar activity and climate, it is likely via a mechanism connected to one (or a combination) of the following parameters: total solar irradiance (TSI), ultraviolet (UV) spectral irradiance, or the galactic cosmic ray (GCR) flux. We present an analysis based around a superposed epoch (composite) approach focusing on the largest TSI increases and decreases (the latter occurring in both the presence and absence of appreciable GCR reductions) over daily timescales...
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