RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 11, RE1008, doi:10.2205/2009ES000355, 2009

Global Access to Geomagnetic data – Concept and Implementation of a Virtual Observatory

Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation of Russian Academy of Sciences (IZMIRAN), Troitsk, Moscow region, Russia

V. O. Papitashvili

University of Michigan, Michigan, USA

Abstract

The traditional concept of a virtual observatory assumes the establishment of a World Wide Web server (Portal) which (upon data inquiries) connects to those data provider sites that are known to the server. Upon establishing such connection(s), the Portal downloads requested data, reformats them to the required data format, and submits back to the user. The main advantage of such approach is a simplicity of the client-side software and easiness in maintaining the service. At the same time, there are some disadvantages – the network traffic increases and the HTTP protocol has some limitations that do not allow achieving real effectiveness in the data processing and visualization.

Often special codes (applets) are created and downloaded to the client computers to improve efficiency of a virtual observatory. Further development of this approach is presented by Papitashvili at al, [2003, 2006] where two possible ways for the remote data access are offered utilizing the same code – the Web-based VGMO and the stand-alone VGMO. The former utilizes the standard approach uploading a Java applet to the client computer; the latter works directly with the data provider (client) Web sites (or with data provider computer which are set in the Internet). Two versions of the stand-alone VGMO are developed to be run under the Windows and MacOS X operation systems. Our experience in using the Web-based Portal VGMO shows two distinctive problems when working with the remote data sources:

1. There are currently about 20–25 sources (sites) providing access to the ground-based geomagnetic data (not counting individual observatories), but only 1/3 of these sites allow the anonymous access to the stored data; thus, only these sites can be accessed via the Web-based VGMO.
2. Because of significant restrictions imposed by local network managers for safety of their sites, any specially designed protocols and applets for the remote data access would not work in many cases.

In addition, our stand-alone VGMO is written in Fortran and Java, which requires recompilation of the codes during regular updates or exporting the VGMO software to a new platform. This is time-consuming task requiring significant efforts in the software tracking and maintenance.

Here we suggest developing a new version of the stand-alone VGMO – Personal Virtual GeoMagnetic Observatory (PVGMO) using the open source programming language Python. This is a high-level programming language which can substitute Matlab or IDL, and it is free and available for all computational platforms and Operational Systems. Python is a part of the Unix-based OS, and for Microsoft's Windows the language modules can be easily downloaded from many sources. Python is completely OS-independent – the same code can be executed everywhere, and there is a huge number of ready-to-use free-distributed libraries. The Python codes are easily readable and, therefore, they can be easily supported and/or modified. Our stand-alone VGMO where some procedures are already written in Python can be utilized as a prototype for the PVGMO development.

The Web-based PVGMO server software can be used as a kernel for the development and support of the entire system. The server allows the users to download the codes, supports updates, and keeps the list of known data sources (providers). Those users who modify or develop new codes for the data processing and visualization initially for their own needs can then share their products with other users via the Web-based PVGMO server. As a result of the collective PVGMO software development, the entire network of geomagnetic data providers could become an open source system.

Received 22 October 2009; accepted 28 October 2009; published 30 November 2009.

Keywords: geomagnetic data, virtual observatories; magnetic observatories

Citation: Petrov V. G., V. O. Papitashvili (2009), Global Access to Geomagnetic data – Concept and Implementation of a Virtual Observatory, Russ. J. Earth Sci., 11, RE1008, doi:10.2205/2009ES000355.