OR/16/030 UK and overseas observatories
| Thomson, Alan W P. 2016. Geomagnetism review 2015. British Geological Survey Internal Report, OR/16/030. |
BGS operates three absolute geomagnetic observatories in the UK and six observatories overseas to supply high quality, real-time measurements for research and services. We also take a leading role in the expansion of the global observatory network, to improve global magnetic field modelling and for local and global applications. The UK observatories achieved 100% continuous data supply in 2015.
Technical developments
New low-power, solid state data recorders running the updated QNX6.5 operating system have been operating at all observatories for over a year and have proven to be secure and reliable. Recorded data resolution has been modified to 1pT at all observatories in anticipation of the roll out of new magnetometers to meet updated INTERMAGNET data standards.
The Lemi-025 fluxgate magnetometer is the first of these new instruments to undergo long-term testing at a BGS observatory, with initial analysis showing good quality data that meets most aspects of the new INTERMAGNET one-second data standard. However these magnetometers have been susceptible to lightning damage and had to be removed for repair in July 2015. The instruments have now been upgraded to be more resilient and will be re-installed in early 2016.
New scalar Overhauser magnetometers have been purchased to allow a faster sampling of the full field vector. In acquiring data at a rate of 1Hz, these magnetometers will allow greater quality control, particularly so at high geomagnetic latitude observatories.
Electric field monitors have now been running at the three UK observatories since early 2013. In 2015, the signal conditioning hardware was redesigned to include a low-pass filter amplifier. All three observatories are now sampling filtered and amplified data at a rate of 10Hz, improving the quality of recorded measurements.
Magnetic observatories
The new observatory at Fort McMurray, Alberta, came online in early 2015, supplying real-time IIFR data to the local directional drilling industry in partnership with Halliburton-Sperry Drilling.
Service visits were made to remote observatories on Ascension Island, Sable Island and in Northern Alaska. With JCO Observatory (Alaska) being accepted as BGS’s eighth INTERMAGNET observatory, these visits are essential for routine calibrations, as well as for infrastructure and instrument improvements in order that data quality continues to meet INTERMAGNET standards. Such visits can also provide collaboration opportunities, an example being the refurbishment in 2015 of the British Antarctic Survey’s VLF receiver on Ascension Island, which is part of the World Wide Lightning Location Network.
In the UK, BGS worked with local planners, developers and power companies to ensure that the pristine measurement environment of Lerwick observatory for magnetic and seismic monitoring was preserved during the development of nearby land for housing.
Hartland Observatory has regularly been used as a calibration facility by third-party magnetometer manufacturers and as a training facility for Royal Navy personnel conducting magnetic surveys in and around the Antarctic Peninsula.
Training was given throughout the year on instrumentation and observing practice to staff from Environment Canada, British Antarctic Survey, Royal Navy and the Met Office.
The global network
BGS continues to be active on INTERMAGNET committees and in the INDIGO project. The objective of INDIGO is to increase the number of INTERMAGNET-quality digital observatories around the world, particularly in developing countries. BGS continues to develop data processing software that is made freely available to overseas observatories. This software is designed to facilitate the production of definitive data meeting the INTERMAGNET standard. BGS staff also visited the INTERMAGNET observatory at Cheongyang, South Korea, to exchange data processing knowledge and further assistance in observatory operation and data publication was provided to institutes in China, Russia and Syria.
UK repeat station network
The 2015 magnetic repeat station programme covered thirteen measurement sites in the West of Scotland, the Western Isles, South West England and the Midlands. 2015 saw a feasibility study carried out to ensure the future viability of the repeat station network, with one recommendation being the upgrade of the azimuth determining hardware. To this end a tender has been placed for a new differential GPS system, with delivery expected in early 2016.
The UK repeat station network and measurement techniques were presented at the MagnetE 2015 workshop, Budapest, Hungary.