The Borok INTERMAGNET magnetic observatory

Introduction

[2] There is a long history of magnetic observations in Borok. Since the establishment of the Borok Geophysical Observatory (BGO) by the Schmidt's Institute of Physics of the Earth of the Russian Academy of Sciences (IPERAS) in 1957, ultra-low-frequency (ULF) geomagnetic pulsations have been recorded in Borok. From 1976 to 2001, a magnetic observatory was in operation on the BGO campus, under the responsibility of the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN). The geomagnetic field was recorded on photographic paper by a three-component Bobrov-type magnetometer. Since 1998, geomagnetic variations have been recorded by a triaxial fluxgate magnetometer belonging to SAMNET, the UK Sub-Auroral Magnetometer Network.

[3] In 2002, IPERAS and BGO started a collaboration with the Institute of Physics of the Earth in Paris (IPGP) to install and operate an INTERMAGNET magnetic observatory in Borok. INTERMAGNET is the global network of digital magnetic observatories adopting modern standard specifications for measuring and recording the Earth's magnetic field variations on long time scales. Data from INTERMAGNET observatories are transmitted in quasi-real time via Geomagnetic Information Nodes to the scientific community and are available at www.intermagnet.org. INTERMAGNET has regularly expanded since its foundation in the late 1980s and now comprises more than hundred observatories throughout the world (107 in 2007). In April 2004, BGO and IPGP installed new magnetometers in Borok, after which the observatory gained official INTERMAGNET magnetic observatory (IMO) status.

Figure 1

[4] One of the main goals of INTERMAGNET is to aid in the establishment of new observatories or the upgrade of existing facilities in areas where the density of IMOs is low, in order to obtain a more homogeneous distribution of IMOs at the Earth's surface. From this point of view, the Borok IMO is a very valuable addition to the global network, since the closest IMO in the West direction is Nurmajarvi (Finland), located 1403 km from Borok, while the closest IMOs in the East direction are Alma Ata (Kazakhstan) and Novosibirsk (Russia), located 3602 km and 4086km from Borok, respectively (Figure 1). Also, Borok is one of only three magnetic observatories in Russia having the IMO status, and the only one in the European part of Russia.

[5] The present paper describes the layout and instruments of the Borok INTERMAGNET observatory. It presents the data acquired since 2004 and assesses their quality. Finally, the future of ground magnetic observatories such as Borok in the magnetic satellite era is briefly discussed.