Date (Creation)

2021

Identifier

http://data.bgs.ac.uk/id/dataHolding/13607915

Maintenance and update frequency

notPlanned Not planned

GEMET - INSPIRE themes, version 1.0

• Geology

BGS Thesaurus of Geosciences

• Magnetic fields
• data.gov.uk (non-INSPIRE)
• Ionosphere

dataCentre

• data.gov.uk (non-INSPIRE)

Keywords

• NERC_DDC

Access constraints

otherRestrictions Other restrictions

Other constraints

licenceOGL

Other constraints

Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

Use constraints

otherRestrictions Other restrictions

Other constraints

The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused.

Other constraints

Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

Metadata language

EnglishEnglish

Topic category

• Geoscientific information

Begin date

2021-01-01

End date

2021-01-01

Distribution format

• ASCII text file ()

• ASCII text file ()

OnLine resource

Data

OnLine resource

Digital Object Identifier (DOI)

Hierarchy level

nonGeographicDataset Non geographic dataset

Other

non geographic dataset

Statement

There are two induction coils located in the Eskdalemuir Observatory. • They oriented in the following directions: North-South (CH1) and East-West (CH2). • The data are sampled at 100 Hz. • The raw ASCII data are given in 24 one-hour files starting at the 00:00:00.00 UT for each day. • Each hour file contains 60 * 60 * 100 Hz = 360000 ASCII values. • The last value of the day is for the time 23:59.59.99 UT. The hourly files for each year have been tarred together and then gzipped up into a single file for year e.g. ESKINDCOIL_2015.tar.gz Within the annual files the names of each data file for each hour are given as CH{1,2}_{year}_{month}_{day}_{hour}.dat e.g. CH1_2015_01_01_22.dat This is the data for Channel 1 (CH1) for the 1st January 2015, hour 22 (22:00:00.00 – 22:59:59.99 UT) Each hourly file, when unzipped, has a size of 3.6 Mb. Calibration information on the data and the manufacturer and model of the magnetic sensors: The coils are French-built from around the 1970s (CM11E1) which came from the NERC Geophysical pool to BGS in 2003. They are connected to 24-bit Guralp digitizer previously used for seismology applications. The data are converted from an analogue voltage by the digitizer, sent to a computer located in a vault around 150m away, recorded onto the disk and retrieved once per hour back to the Edinburgh office The raw data in the files are given in digitizer units (with an arbitrary offset of ~-570,000) which can be converted back to Volts. The induction coils output an analogue signal which is calibrated by Volts per nT in the frequency domain (not the time domain). However, the time-series can be approximately converted to SI units of Tesla (see below) • The frequency dependence of the coils is around 50.1 mV per nT between 0.1 – 100 Hz. • The digitizer has a conversion factor of 3.491*10^-6 Volts per count for Channel 1 and 3.475*10^-6 Volts per count for Channel 2. Thus, the easiest way to convert to (approximate SI units) in the time domain is to Butterworth filter the time series data between 0.1 and 50Hz frequencies, to get a filtered digitizer signal. Multiply the filtered signal by the Volts per count ratio of the digitizer (e.g. 3.491*10^-6 for Channel 1) to get the value in Volts. Then multiply the time series by 1/50100 nT/Volt to get the values in nT. There is some example Matlab code (ProcessInductionCoilData.m and the exact frequency response in CoilCalibration_CM11E1.m) available.

File identifier

d9b26690-cbf4-40b0-e054-002128a47908 XML

Metadata language

EnglishEnglish

Hierarchy level

nonGeographicDataset Non geographic dataset

Hierarchy level name

non geographic dataset

Date stamp

2025-05-07

Metadata standard name

UK GEMINI

Metadata standard version

2.3

Dataset URI

http://data.bgs.ac.uk/id/dataHolding/13607915