INTERMAGNET Terminology

ADJUSTED Data

Each observatory or its parent institute is allowed to modify REPORTED data files to produce ADJUSTED data, with a goal of 7 days after transmission. These adjustments may be to modify baselines, remove spikes, fill gaps etc. on any day file. When data are missing from an ADJUSTED data file, these data may be input to a GIN in a later message. This new message file can be transmitted to a GIN with the data type set to ADJUSTED (See APPENDIX E1 ). ADJUSTED data are maintained online until the annual INTERMAGNET Reference Data Set (IRDS) is available. They are then archived by the GIN and only available thereafter by special arrangement.

DEFINITIVE Data

This describes the final publication stage of observatory data. DEFINITIVE data have been corrected for baseline variations, have had spikes removed and gaps filled where possible. DEFINITIVE data are recorded and transmitted in files with the data type set to DEFINITIVE ( APPENDIX E1 , APPENDIX E5 ). The quality of DEFINITIVE data is such that in this form they would be used for inclusion into Observatory Year Books, input to World Data Centers and included in the INTERMAGNET Reference Data Set (IRDS).

Flags

Flags are reserved data values that are typically used to indicate that a data sample is missing. This can be the result of a fault with an instrument; where data have been removed due to poor quality; or where a particular component is not observed when the necessary instrument is not operated. The value of a data flag is specific to the data format. See ( APPENDIX E1, APPENDIX E5 ).

GIN

Geomagnetic Information Nodes are data centers, organized on a regional basis, which INTERMAGNET observatories send their provisional data to. GINs forward this data to the INTERMAGNET web site. GIN managers will help INTERMAGNET observatories with the technical details of establishing reliable data flow. GINs do not distribute data to users – this task is done by the INTERMAGNET web site.

IMO

An INTERMAGNET Magnetic Observatory (IMO) is a magnetic observatory equipped with magnetometers, clock, control electronics, transmitting equipment and a data collection platform (DCP), residing at the magnetic observatory site. The operation and equipment must meet INTERMAGNET standards and specifications.

IPM

INTERMAGNET Physical Media, this term collectively describes the INTERMAGNET CDs, INTERMAGNET DVDs and INTERMAGNET USBs.

IRDS

INTERMAGNET Reference Data Set contains all definitive data and metadata from the first Intermagnet publication in 1991 up to the current year, including any corrections that have been made. Published with a DOI, for example the INTERMAGNET Reference Data Set, 2015: https://doi.org/10.5880/INTERMAGNET.1991.2015.

Magnetic observatory

A permanent installation of magnetometers capable of providing magnetic field values with an absolute accuracy of better than 5 nT over a period ranging from DC to approximately 1 Sec.

NESS binary

This term is specific to the data transmission format used by the GOES satellite. For GOES transmissions, each 16-bit binary word is encoded as 3 pseudo ASCII bytes, so that the 126 bytes of IMFV2.83 data are encoded as 189 bytes NESS binary (see APPENDIX E2).

Offset

A fixed-value change applied to an instrument or data set. An offset can be inherent in an instrument but is often used to bring an instrument into its operating range, or to reduce the magnitude of a data point for storage or transmission. For example, offsets are used to reduce the size of data blocks where bandwidth is limited, such as in satellite telemtery. The IMFV2.83 format has provisions for offset values for one-minute data per component ( APPENDIX E1 ).

QUASI-DEFINITIVE Data

As the name implies, the data should be close to the expected definitive value, but is to be delivered more rapidly than an observatory’s annual definitive data. This initiative will be useful for a number of scientific activities, where timely and close-to-definitive data is essential. For example, quasi-definitive data will be particularly useful in joint analyses of geomagnetic and other phenomena, together with data measured by satellites. Quasi-definitive data are 1-minute or 1-second data (observatories are encouraged to produce both minute and second data) that can be submitted to INTERMAGNET as (H, D, Z) or (X, Y, Z) and have the following properties:

Corrected using temporary baselines

Made available less than 3 months after their acquisition

Such that the difference between the quasi-definitive and definitive (X, Y, Z) monthly means are less than 5 nT in any component for every month of the year

Point C is checked a posteriori by comparing quasi-definitive and definitive data from the previous year. Observatories are strongly encouraged to submit quasi-definitive data that is thoroughly controlled, i.e. de-spiked, free from corrupted data, data gaps filled in from back-up systems, and with the best possible baseline at the time of submission. Submission of quasi-definitive data should not be seen as having satisfied the requirements for definitive data. The annual definitive data, again thoroughly controlled and with a baseline based on a full year of absolute measurements, shall be submitted in the formats for definitive data at latest by the deadline agreed by INTERMAGNET.

Reference Measurement (RM)

RMs are optional values provided by an IMO as additional quality control information. RM values have historically been derived automatically from variometer data and an independent, stable vector instrument, often sampling at a slower cadence. RMs transmitted in data formats such as IMFV2.83 ( APPENDIX E1 ) can be applied to reported data to produce adjusted data and to supplement baseline control.

REPORTED Data

Data as output by an observatory, transmitting through a satellite or using email. REPORTED data have not had any baseline corrections applied, may contain spikes and may have missing values. When ADJUSTED data are available, REPORTED data are removed from online access.

Time stamp

The precise date and time of acquisition of a data sample. Timestamp are recorded and transmitted alongside the data. In the IMFV2.83 format, a timestamp is recorded for the first sample of each 12-minute data block only due to bandwidth constraints (see APPENDIX E1 and APPENDIX E2 ).