A Standard for Exchangeable Magnetotelluric Metadata

Author

Working Group for Data Handling and Software - PASSCAL Magnetotelluric Program

Date

Version 0.0.16 – July 2020 1

Introduction

Researchers using magnetotelluric (MT) methods lack a standardized format for storing time series data and metadata. Commercially available MT instruments produce data in formats that range from proprietary binary to ASCII, whereas recent datasets from the U.S. MT community have utilized institutional formats or heavily adapted formats like miniSEED. In many cases, the available metadata for MT time series are incomplete and loosely standardized; and overall, these datasets are not “user friendly”. This lack of a standardized resource impedes the exchange and broader use of these data beyond a small community of specialists.

The IRIS PASSCAL MT facility maintains a pool of MT instruments that are freely available to U.S. Principal Investigators (PIs). Datasets collected with these instruments are subject to data sharing requirements, and an IRIS working group advises the development of sustainable data formats and workflows for this facility. Following in the spirit of the standard created for MT transfer function datasets, this document outlines a new metadata standard for level 0,1,and 2 MT time series data (Data Levels). Following community approval of these standards, MTH5 (an HDF5 MT specific format) will be developed later in 2020.

The Python 3 module written for these standards and MTH5 is being developed at https://github.com/kujaku11/MTarchive/tree/tables.

General Structure

The metadata for a full MT dataset are structured to cover details from single channel time series to a full survey. For simplicity, each of the different scales of an MT survey and measurements have been categorized starting from largest to smallest (Figure 1). These categories are: Survey, Station, Run, DataLogger, Electric Channel, Magnetic Channel, and Auxiliary Channel. Each category is described in subsequent sections. Required keywords are labeled as and suggested keywords are labeled as . A user should use as much of the suggested metadata as possible for a full description of the data.

../_images/example_mt_file_structure.png

Schematic of a MT time series file structure with appropriate metadata. The top level is the Survey that contains general information about who, what, when, where, and how the data were collected. Underneath Survey are the Station and Filter. Filter contains information about different filters that need to be applied to the raw data to get appropriate units and calibrated measurements. Underneath Station are Run, which contain data that were collected at a single sampling rate with common start and end time at a single station. Finally, Channel describes each channel of data collected and can be an Auxiliary, Electric, or Magnetic. Metadata is attributed based on the type of data collected in the channel.

Metadata Keyword Format

The metadata key names should be self-explanatory and are structured as follows:

  • {category}.{name}, or can be nested

  • {category1}.{categroy2}.{name} where:
    • category refers to a metadata category or level that has common parameters, such as location, which will have a latitude, longitude, and elevation \longrightarrow location.latitude, location.longitude, and location.elevation. These can be nested, for example, station.location.latitude

    • name is a descriptive name, where words should be separated by an underscore. Note that only whole words should be used and abbreviations should be avoided, e.g. data_quality.

A ‘.’ represents the separator between different categories. The metadata can be stored in many different forms. Common forms are XML or JSON formats. See examples below for various ways to represent the metadata.

Formatting Standards

Specific and required formatting standards for location, time and date, and angles are defined below and should be adhered to.

Time and Date Format

All time and dates are given as an ISO formatted date-time String in the UTC time zone. The ISO Date Time format is YYYY-MM-DDThh:mm:ss.ms+00:00, where the UTC time zone is represented by +00:00. UTC can also be denoted by Z at the end of the date-time string YYYY-MM-DDThh:mm:ss.msZ. Note that Z can also represent Greenwich Mean Time (GMT) but is an acceptable representation of UTC time. If the data requires a different time zone, this can be accommodated but it is recommended that UTC be used whenever possible to avoid confusion of local time and local daylight savings. Milliseconds can be accurate to 9 decimal places. ISO dates are formatted YYYY-MM-DD. Hours are given as a 24 hour number or military time, e.g. 4:00 PM is 16:00.

Location

All latitude and longitude locations are given in decimal degrees in the well known datum specified at the Survey level. NOTE: The entire survey should use only one datum that is specified at the Survey level.

  • All latitude values must be <|90| and all longitude values must be <|180|.

  • Elevation and other distance values are given in meters.

  • Datum should be one of the well known datums, WGS84 is preferred, but others are acceptable.

Angles

All angles of orientation are given in decimal degrees. Orientation of channels should be given in a geographic or a geomagnetic reference frame where the right-hand coordinates are assumed to be North = 0, East = 90, and vertical is positive downward (Figure 2). The coordinate reference frame is given at the station level station.orientation.reference_frame. Two angles to describe the orientation of a sensor is given by channel.measurement_azimuth and channel.measurement_tilt. In a geographic or geomagnetic reference frame, the azimuth refers to the horizontal angle relative to north positive clockwise, and the tilt refers to the vertical angle with respect to the horizontal plane. In this reference frame, a tilt angle of 90 points downward, 0 is parallel with the surface, and -90 points upwards.

Archived data should remain in measurement coordinates. Any transformation of coordinates for derived products can store the transformation angles at the channel level in channel.transformed_azimuth and channel.transformed_tilt, the transformed reference frame can then be recorded in station.orientation.transformed_reference_frame.

../_images/reference_frame.svg

Diagram showing a right-handed geographic coordinate system. The azimuth is measured positive clockwise along the horizontal axis and tilt is measured from the vertical axis with positive down = 0, positive up = 180, and horizontal = 90.

Units

Acceptable units are only those from the International System of Units (SI). Only long names in all lower case are acceptable. Table 1 summarizes common acceptable units.

Acceptable Units

Measurement Type

Unit Name

Angles

decimal degrees

Distance

meter

Electric Field

millivolt

Latitude/Longitude

decimal degrees

Magnetic Field

nanotesla

Resistance

ohms

Resistivity

ohm-meter

Temperature

celsius

Time

second

Voltage

volt

String Formats

Each metadata keyword can have a specific string style, such as date and time or alpha-numeric. These are described in Table 2. Note that any list should be comma separated.

:class: tight-table :widths: 30 45 15

Style

Description

Example

Free Form

An unregulated string that can contain {a-z, A-Z, 0-9} and special characters

This is Free Form!

Alpha Numeric

A string that contains no spaces and only characters {a-z, A-Z, 0-9, -, /, _}

WGS84 or GEOMAG-USGS

Controlled Vocabulary

Only certain names or words are allowed. In this case, examples of acceptable values are provided in the documentation as [ option01 | option02 | … ]. The … indicates that other options are possible but have not been defined in the standards yet

reference_frame = geographic

List

List of entries using a comma separator

Ex, Ey, Bx, By, Bz, T

Number

A number according to the data type; number of decimal places has not been implemented yet

10.0 (float) or 10 (integer)

Date

ISO formatted date YYYY-MM-DD in UTC

2020-02-02

Date Time

ISO formatted date time YYYY-MM- DDThh:mm:ss.ms+00:00 in UTC

2020-02-02T1 2:20:45.123456+00:00

Email

A valid email address

person@mt.or g

URL

A full URL that a user can view in a web browser

https:// www.passcal.nmt.edu/

Survey

A survey describes an entire data set that covers a specific time span and region. This may include multiple PIs in multiple data collection episodes but should be confined to a specific experiment or project. The Survey metadata category describes the general parameters of the survey.

Survey Attributes

acquired_by.author

acquired_by.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of the person or persons who acquired the data. This can be different from the project lead if a contractor or different group collected the data.

person name

acquired_by.comments

acquired_by.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about aspects of how the data were collected or any inconsistencies in the data.

Lightning strike caused a time skip at 8 am UTC.

fdsn.network

fdsn.network

Description

Example

Required: False

Units: None

Type: String

Style: Alpha Numeric

Network code given by PASSCAL/IRIS/FDSN. This will be a two character String that describes who and where the network operates.

EM

citation_dataset.doi

citation_dataset.doi

Description

Example

Required: True

Units: None

Type: String

Style: URL

The full URL of the doi Number provided by the archive that describes the raw data

http://doi.10.adfabe

citation_journal.doi

citation_journal.doi

Description

Example

Required: False

Units: None

Type: String

Style: URL

The full URL of the doi Number for a journal article(s) that uses these data. If multiple journal articles use these data provide as a comma separated String of urls.

http://doi.10.xbsfs2

comments

comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about the survey that are important for any user to know.

Solar activity low.

country

country

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Country or countries that the survey is located in. If multiple input as comma separated names.

Canada

datum

datum

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

The reference datum for all geographic coordinates throughout the survey. It is up to the user to be sure that all coordinates are projected into this datum. Should be a well-known datum: [ WGS84 ; NAD83 ; OSGB36 ; GDA94 ; ETRS89 ; PZ-90.11 ]

WGS84

geographic_name

geographic_name

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Geographic names that encompass the survey. These should be broad geographic names. Further information can be found at https://w ww.usgs.gov/core-science- systems/ngp/board-on- geographic-names

Southwestern, USA

name

name

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Descriptive name of the survey

MT Characteriza tion of Yukon Terrane

northwest_corner.latitude

northwest_corner.latitude

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Latitude of the northwest corner of the survey in the datum specified.

23.134

northwest_corner.longitude

northwest_corner.longitude

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Longitude of the northwest corner of the survey in the datum specified.

14.23

project

project

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Alphanumeric name for the project. This is different than the fdsn.identifier in that it describes a project with a common project lead and source of funding. There may be multiple surveys within a project. For example if the project is to estimate geomagnetic hazards that project = GEOMAG but the fdsn.identifier = YKN20.

GEOMAG

project_lead.author

project_lead.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of the project lead. This should be a person who is responsible for the data.

Magneto

project_lead.email

project_lead.email

Description

Example

Required: True

Units: None

Type: String

Style: Email

Email of the project lead. This is in case there are any questions about data.

mt.guru@em.org

project_lead.organization

project_lead.organization

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Organization name of the project lead.

MT Gurus

release_license

release_license

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

How the data can be used. The options are based on Creative Commons licenses. Options –> [CC-0; CC-BY; CC-BY-SA; CC-BY-ND; CC-BY-NC-SA; CC-BY-NC-ND] For details visit,

https://creativecommons.org/licenses/

CC-0

southeast_corner.latitude

southeast_corner.latitude

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Latitude of the southeast corner of the survey in the datum specified.

23.134

southeast_corner.longitude

southeast_corner.longitude

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Longitude of the southeast corner of the survey in the datum specified.

14.23

summary

summary

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Summary paragraph of the survey including the purpose; difficulties; data quality; summary of outcomes if the data have been processed and modeled.

Long project of characterizing mineral resources in Yukon

time_period.end_date

time_period.end_date

Description

Example

Required: True

Units: None

Type: String

Style: Date

End date of the survey in UTC.

2020-02-01

time_period.start_date

time_period.start_date

Description

Example

Required: True

Units: None

Type: String

Style: Date

Start date of the survey in UTC.

1995-06-21

Example Survey XML Element

<?xml version="1.0" ?>
<survey>
    <acquired_by>
        <author>MT Graduate Students</author>
        <comments>Multiple over 5 years</comments>
    </acquired_by>
    <fdsn>
        <identifier>SAM1990</identifier>
        <network>EM</network>
    </fdsn>
    <citation_dataset>
        <doi>https://doi.###</doi>
    </citation_dataset>
    <citation_journal>
        <doi>https://doi.###</doi>
    </citation_journal>
    <comments>None</comments>
    <country>USA, Canada</country>
    <datum>WGS84</datum>
    <geographic_name>Yukon</geographic_name>
    <name>Imaging Gold Deposits of the Yukon Province</name>
    <northwest_corner>
        <latitude type="Float" units="decimal degrees">-130</latitude>
        <longitude type="Float" units="decimal degrees">75.9</longitude>
    </northwest_corner>
    <project>AURORA</project>
    <project_lead>
        <Email>m.tee@mt.org</Email>
        <organization>EM Ltd.</organization>
        <author>M. Tee</author>
    </project_lead>
    <release_license>CC0</release_license>
    <southeast_corner>
        <latitude type="Float" units="decimal degrees">-110.0</latitude>
        <longitude type="Float" units="decimal degrees">65.12</longitude>
    </southeast_corner>
    <summary>This survey spanned multiple years with graduate students
             collecting the data.  Lots of curious bears and moose,
             some interesting signal from the aurora.  Modeled data
             image large scale crustal features like the
             "fingers of god" that suggest large mineral deposits.
    </summary>
    <time_period>
        <end_date>2020-01-01</end_date>
        <start_date>1995-01-01</start_date>
    </time_period>
</survey>

Station

A station encompasses a single site where data are collected. If the location changes during a run, then a new station should be created and subsequently a new run under the new station. If the sensors, cables, data logger, battery, etc. are replaced during a run but the station remains in the same location, then this can be recorded in the Run metadata but does not require a new station entry.

Station Attributes

acquired_by.author

acquired_by.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of person or group that collected the station data and will be the point of contact if any questions arise about the data.

person name

acquired_by.comments

acquired_by.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about who acquired the data.

Expert diggers.

channel_layout

channel_layout

Description

Example

Required: False

Units: None

Type: String

Style: Controlled Vocabulary

How the dipoles and magnetic channels of the station were laid out. Options: [“L”; “+”]

“+”

channels_recorded

channels_recorded

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

List of components recorded by the station. Should be a summary of all channels recorded dropped channels will be recorded in Run. Options: [ Ex; Ey; Hx; Hy; Hz; T Battery; other ]

T

comments

comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on the station that would be important for a user.

Pipeline near by.

data_type

data_type

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

All types of data recorded by the station. If multiple types input as a comma separated list. Options –> [RMT; AMT; BBMT; LPMT]

BBMT

fdsn.identifier

fdsn.identifier

Description

Example

Required: True

Units: None

Type: String

Style: Alpha Numeric

Station name that is archived {a-z;A-Z;0-9. For IRIS this is a 5 character String.

MT201

geographic_name

geographic_name

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Closest geographic name to the station, or a location description unique to the station

Kelly, YK or Three Elms

id

id

Description

Example

Required: True

Units: None

Type: String

Style: Alpha Numeric

Station ID name. This should be an alpha numeric name that is typically 5-6 characters long. Commonly the project name in 2 or 3 letters and the station number.

MT001

location.declination.comments

location.declination.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on declination that are important to an end user.

Different than recorded declination from data logger.

location.declination.model

location.declination.model

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Name of the geomagnetic reference model as model_name-YYYY. Model options -> [EMAG2; EMM; HDGM; IGRF; WMM]

WMM-2016

location.declination.value

location.declination.value

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Declination angle relative to geographic north positive clockwise estimated from location and geomagnetic model.

12.3

location.elevation

location.elevation

Description

Example

Required: True

Units: meters

Type: Float

Style: Number

Elevation of station location in datum specified at survey level.

123.4

location.latitude

location.latitude

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Latitude of station location in datum specified at survey level.

23.134

location.longitude

location.longitude

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Longitude of station location in datum specified at survey level.

14.23

orientation.method

orientation.method

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Method for orienting station channels. Options: [compass; GPS; theodolite; electric_compass ]

compass

orientation.reference_frame

orientation.reference_frame

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Reference frame for station layout. There are only 2 options geographic and geomagnetic. Both assume a right-handed coordinate system with North=0

geomagnetic

orientation.transformed_reference_frame

orientation.transformed_reference_frame

Description

Example

Required: False

Units: None

Type: Float

Style: Number

Reference frame rotation angel relative to orientation.reference_frame assuming positive clockwise. Should only be used if data are rotated.

10

provenance.comments

provenance.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on provenance of the data.

From a graduated graduate student.

provenance.creation_time

provenance.creation_time

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

Date and time the file was created.

2020-02-08 T12: 23:40.324600 +00:00

provenance.log

provenance.log

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

A history of any changes made to the data.

2020-02-10 T14:24:45+00:00 updated station metadata.

provenance.software.author

provenance.software.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Author of the software used to create the data files.

programmer 01

provenance.software.name

provenance.software.name

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of the software used to create data files

mtrules

provenance.software.version

provenance.software.version

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Version of the software used to create data files

12.01a

provenance.submitter.author

provenance.submitter.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of the person submitting the data to the archive.

person name

provenance.submitter.email

provenance.submitter.email

Description

Example

Required: True

Units: None

Type: String

Style: Email

Email of the person submitting the data to the archive.

mt.guru@em.org

provenance.submitter.organization

provenance.submitter.organization

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of the organization that is submitting data to the archive.

MT Gurus

time_period.end

time_period.end

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

End date and time of collection in UTC.

2020-02-04 T16: 23:45.453670 +00:00

time_period.start

time_period.start

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

Start date and time of collection in UTC.

2020-02-01 T09: 23:45.453670 +00:00

Example Station JSON

{    "station": {
        "acquired_by": {
            "author": "mt",
            "comments": null},
        "channel_layout": "L",
        "channels_recorded": "Ex, Ey, Bx, By",
        "comments": null,
        "data_type": "MT",
        "geographic_name": "Whitehorse, Yukon",
        "id": "MT012",
        "location": {
            "latitude": 10.0,
            "longitude": -112.98,
            "elevation": 1234.0,
            "declination": {
                "value": 12.3,
                "comments": null,
                "model": "WMM-2016"}},
        "orientation": {
            "method": "compass",
            "reference_frame": "geomagnetic"},
        "provenance": {
            "comments": null,
            "creation_time": "1980-01-01T00:00:00+00:00",
            "log": null,
            "software": {
                "author": "test",
                "version": "1.0a",
                "name": "name"},
            "submitter": {
                "author": "name",
                "organization": null,
                "email": "test@here.org"}},
        "time_period": {
            "end": "1980-01-01T00:00:00+00:00",
            "start": "1982-01-01T16:45:15+00:00"}
         }
}

Run

A run represents data collected at a single station with a single sampling rate. If the dipole length or other such station parameters are changed between runs, this would require adding a new run. If the station is relocated then a new station should be created. If a run has channels that drop out, the start and end period will be the minimum time and maximum time for all channels recorded.

Run Attributes

acquired_by.author

acquired_by.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of the person or persons who acquired the run data. This can be different from the station.acquired_by and survey.acquired_by.

M.T. Nubee

acquired_by.comments

acquired_by.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about who acquired the data.

Group of undergraduates.

channels_recorded_auxiliary

channels_recorded_auxiliary

Description

Example

Required: True

Units: None

Type: String

Style: name list

List of auxiliary channels recorded.

battery

channels_recorded_electric

channels_recorded_electric

Description

Example

Required: True

Units: None

Type: String

Style: name list

List of electric channels recorded.

Ey

channels_recorded_magnetic

channels_recorded_magnetic

Description

Example

Required: True

Units: None

Type: String

Style: name list

List of magnetic channels recorded.

Hz

comments

comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on the run that would be important for a user.

Badger attacked Ex.

data_logger.firmware.author

data_logger.firmware.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Author of the firmware that runs the data logger.

instrument engineer

data_logger.firmware.name

data_logger.firmware.name

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Name of the firmware the data logger runs.

mtrules

data_logger.firmware.version

data_logger.firmware.version

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Version of the firmware that runs the data logger.

12.01a

data_logger.id

data_logger.id

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Instrument ID Number can be serial Number or a designated ID.

mt01

data_logger.manufacturer

data_logger.manufacturer

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Name of person or company that manufactured the data logger.

MT Gurus

data_logger.model

data_logger.model

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Model version of the data logger.

falcon5

data_logger.power_source.comments

data_logger.power_source.comments

Description

Example

Required: False

Units: None

Type: String

Style: Name

Any comment about the power source.

Used a solar panel and it was cloudy.

data_logger.power_source.id

data_logger.power_source.id

Description

Example

Required: False

Units: None

Type: String

Style: name

Battery ID or name

battery01

data_logger.power_source.type

data_logger.power_source.type

Description

Example

Required: False

Units: None

Type: String

Style: name

Battery type

pb-acid gel cell

data_logger.power_source.voltage.end

data_logger.power_source.voltage.end

Description

Example

Required: False

Units: volts

Type: Float

Style: Number

End voltage

12.1

data_logger.power_source.voltage.start

data_logger.power_source.voltage.start

Description

Example

Required: False

Units: volts

Type: Float

Style: Number

Starting voltage

14.3

data_logger.timing_system.comments

data_logger.timing_system.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comment on timing system that might be useful for the user.

GPS locked with internal quartz clock

data_logger.timing_system.drift

data_logger.timing_system.drift

Description

Example

Required: False

Units: seconds

Type: Float

Style: Number

Estimated drift of the timing system.

0.001

data_logger.timing_system.type

data_logger.timing_system.type

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Type of timing system used in the data logger.

GPS

data_logger.timing_system.uncertainty

data_logger.timing_system.uncertainty

Description

Example

Required: False

Units: seconds

Type: Float

Style: Number

Estimated uncertainty of the timing system.

0.0002

data_logger.type

data_logger.type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Type of data logger

broadband 32-bit

data_type

data_type

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Type of data recorded for this run. Options -> [RMT; AMT; BBMT; LPMT]

BBMT

fdsn.new_epoch

data_type

Description

Example

Required: False

Units: None

Type: String

Style: Controlled Vocabulary

Boolean if a new epoch should be made. An epoch is a run and if parameters of the run changes set to True

False

id

id

Description

Example

Required: True

Units: None

Type: String

Style: Alpha Numeric

Name of the run. Should be station name followed by an alphabet letter for the run.

MT302b

metadata_by.author

metadata_by.author

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Person who input the metadata.

Metadata Zen

metadata_by.comments

metadata_by.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about the metadata that would be useful for the user.

Undergraduate did the input.

provenance.comments

provenance.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on provenance of the data that would be useful to users.

all good

provenance.log

provenance.log

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

A history of changes made to the data.

2020-02-10 T14:24:45 +00:00 updated metadata

sampling_rate

sampling_rate

Description

Example

Required: True

Units: samples per second

Type: Float

Style: Number

Sampling rate for the recorded run.

100

time_period.end

time_period.end

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

End date and time of collection in UTC.

2020-02-04 T16: 23:45.453670 +00:00

time_period.start

time_period.start

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

Start date and time of collection in UTC.

2020-02-01 T09: 23:45.453670 +00:00

Example Run JSON

{
    "run": {
        "acquired_by.author": "Magneto",
        "acquired_by.comments": "No hands all telekinesis.",
        "channels_recorded_auxiliary": ["temperature", "battery"],
        "channels_recorded_electric": ["Ex", "Ey"],
        "channels_recorded_magnetic": ["Bx", "By", "Bz"],
        "comments": "Good solar activity",
        "data_logger.firmware.author": "Engineer 01",
        "data_logger.firmware.name": "MTDL",
        "data_logger.firmware.version": "12.23a",
        "data_logger.id": "DL01",
        "data_logger.manufacturer": "MT Gurus",
        "data_logger.model": "Falcon 7",
        "data_logger.power_source.comments": "Used solar panel but cloudy",
        "data_logger.power_source.id": "Battery_07",
        "data_logger.power_source.type": "Pb-acid gel cell 72 Amp-hr",
        "data_logger.power_source.voltage.end": 14.1,
        "data_logger.power_source.voltage.start": 13.7,
        "data_logger.timing_system.comments": null,
        "data_logger.timing_system.drift": 0.000001,
        "data_logger.timing_system.type": "GPS + internal clock",
        "data_logger.timing_system.uncertainty": 0.0000001,
        "data_logger.type": "Broadband 32-bit 5 channels",
        "data_type": "BBMT",
        "fdsn.new_epoch": "False",
        "id": "YKN201b",
        "metadata_by.author": "Graduate Student",
        "metadata_by.comments": "Lazy",
        "provenance.comments": "Data found on old hard drive",
        "provenance.log": "2020-01-02 Updated metadata from old records",
        "sampling_rate": 256,
        "time_period.end": "1999-06-01T15:30:00+00:00",
        "time_period.start": "1999-06-5T20:45:00+00:00"
    }
}

Electric Channel

Electric channel refers to a dipole measurement of the electric field for a single station for a single run.

Electric Channel Attributes

ac.end

ac.end

Description

Example

Required: False

Units: volts

Type: Float

Style: Number

Ending AC value; if more than one measurement input as a list of Number [1 2 …]

49.5

ac.start

ac.start

Description

Example

Required: False

Units: volts

Type: Float

Style: Number

Starting AC value; if more than one measurement input as a list of Number [1 2 …]

55.8

channel_number

channel_number

Description

Example

Required: True

Units: None

Type: Integer

Style: Number

Channel number on the data logger of the recorded channel.

1

comments

comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about the channel that would be useful to a user.

Lightning storm at 6pm local time

component

component

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Name of the component measured. Options: [ Ex; Ey ]

Ex

contact_resistance.end

contact_resistance.end

Description

Example

Required: False

Units: ohms

Type: Float

Style: Number list

Starting contact resistance; if more than one measurement input as a list [1

1.8

contact_resistance.start

contact_resistance.start

Description

Example

Required: False

Units: ohms

Type: Float

Style: Number list

Starting contact resistance; if more than one measurement input as a list [1

1.4

data_quality.rating.author

data_quality.rating.author

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Name of person or organization who rated the data.

graduate student ace

data_quality.rating.method

data_quality.rating.method

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

The method used to rate the data. Should be a descriptive name and not just the name of a software package. If a rating is provided

standard deviation

data_quality.rating.value

data_quality.rating.value

Description

Example

Required: True

Units: None

Type: Integer

Style: Number

Rating from 1-5 where 1 is bad

4

data_quality.warning

data_quality.warning

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any warnings about the data that should be noted for users.

periodic pipeline noise

dc.end

dc.end

Description

Example

Required: False

Units: volts

Type: Float

Style: Number

Ending DC value; if more than one measurement input as a list [1

1.5

dc.start

dc.start

Description

Example

Required: False

Units: volts

Type: Float

Style: Number

Starting DC value; if more than one measurement input as a list [1

1.1

dipole_length

dipole_length

Description

Example

Required: True

Units: meters

Type: Float

Style: Number

Length of the dipole

55.25

fdsn.channel_code

fdsn.channel_code

Description

Example

Required: False

Units: None

Type: String

Style: Alpha-Numeric

FDSN channel code, this is a 3 character code in the form [band][type][direction]

LQN

See also

https://ds.iris.edu/ds/nodes/dmc/data/formats/seed-channel-naming/ for more information on channel codes.

filter.applied

filter.applied

Description

Example

Required: True

Units: None

Type: Boolean

Style: List

Boolean if filter has been applied or not. If more than one filter input as a list that matches filter.names

[True, False]

filter.comments

filter.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on filters that is important for users.

low pass is not calibrated

filter.name

filter.name

Description

Example

Required: True

Units: None

Type: String

Style: List

Name of filter applied or to be applied. If more than one filter input as a list in the order in which the should be applied.

[gain,

highpass_e]

measurement_azimuth

measurement_azimuth

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Azimuth angle of the channel in the specified survey.orient ation.reference_frame.

0

measurement_tilt

measurement_tilt

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Tilt angle of channel in surve y.orientation.reference_frame.

0

negative.elevation

negative.elevation

Description

Example

Required: True

Units: meters

Type: Float

Style: Number

Elevation of negative electrode in datum specified at survey level.

123.4

negative.id

negative.id

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Negative electrode ID Number

electrode01

negative.latitude

negative.latitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Latitude of negative electrode in datum specified at survey level.

23.134

negative.longitude

negative.longitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Longitude of negative electrode in datum specified at survey level.

14.23

negative.manufacturer

negative.manufacturer

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Person or organization that manufactured the electrode.

Electro-Dudes

negative.model

negative.model

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Model version of the electrode.

falcon5

negative.type

negative.type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Type of electrode

Ag-AgCl

positive.elevation

positive.elevation

Description

Example

Required: False

Units: meters

Type: Float

Style: Number

Elevation of the positive electrode in datum specified at survey level.

123.4

positive.id

positive.id

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Positive electrode ID Number

electrode02

positive.latitude

positive.latitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Latitude of positive electrode in datum specified at survey level.

23.134

positive.longitude

positive.longitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Longitude of positive electrode in datum specified at survey level.

14.23

positive.manufacturer

positive.manufacturer

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Name of group or person that manufactured the electrode.

Electro-Dudes

positive.model

positive.model

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Model version of the electrode.

falcon5

positive.type

positive.type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Type of electrode

Pb-PbCl

sample_rate

sample_rate

Description

Example

Required: True

Units: samples per second

Type: Float

Style: Number

Sample rate of the channel.

8

time_period.end

time_period.end

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

End date and time of collection in UTC

2020-02-04 T16: 23:45.453670 +00:00

time_period.start

time_period.start

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

Start date and time of collection in UTC.

2020-02-01T 09:23:45.453670 +00:00

transformed_azimuth

transformed_azimuth

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Azimuth angle of channel that has been transformed into a specified coordinate system. Note this value is only for derivative products from the archived data.

0

transformed_tilt

transformed_tilt

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Tilt angle of channel that has been transformed into a specified coordinate system. Note this value is only for derivative products from the archived data.

0

type

type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Data type for the channel.

electric

units

units

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Units of the data

counts

Example Electric Channel JSON

{
 "electric": {
    "ac.end": 10.2,
    "ac.start": 12.1,
    "channel_number": 2,
    "comments": null,
    "component": "EX",
    "contact_resistance.end": 1.2,
    "contact_resistance.start": 1.1,
    "data_quality.rating.author": "mt",
    "data_quality.rating.method": "ml",
    "data_quality.rating.value": 4,
    "data_quality.warning": null,
    "dc.end": 1.0,
    "dc.start": 2.0,
    "dipole_length": 100.0,
        "fdsn.channel_code": "LQN",
    "filter.applied": [false],
    "filter.comments": null,
    "filter.name": [ "counts2mv", "lowpass"],
    "measurement_azimuth": 90.0,
    "measurement_tilt": 20.0,
    "negative.elevation": 100.0,
    "negative.id": "a",
    "negative.latitude": 12.12,
    "negative.longitude": -111.12,
    "negative.manufacturer": "test",
    "negative.model": "fats",
    "negative.type": "pb-pbcl",
    "positive.elevation": 101.0,
    "positive.id": "b",
    "positive.latitude": 12.123,
    "positive.longitude": -111.14,
    "positive.manufacturer": "test",
    "positive.model": "fats",
    "positive.type": "ag-agcl",
    "sample_rate": 256.0,
    "time_period.end": "1980-01-01T00:00:00+00:00",
    "time_period.start": "2020-01-01T00:00:00+00:00",
    "type": "electric",
    "units": "counts"
  }
}

Magnetic Channel

A magnetic channel is a recording of one component of the magnetic field at a single station for a single run.

Magnetic Channel Attributes

channel_number

channel_number

Description

Example

Required: True

Units: None

Type: Integer

Style: Number

Channel Number on the data logger.

1

comments

comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about the channel that would be useful to a user.

Pc1 at 6pm local time.

component

component

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Name of the component measured. Options -> [Hx; Hy; Hz]

Hx

data_quality.rating.author

data_quality.rating.author

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Name of person or organization who rated the data.

graduate student ace

data_quality.rating.method

data_quality.rating.method

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

The method used to rate the data. Should be a descriptive name and not just the name of a software package. If a rating is provided

standard deviation

data_quality.rating.value

data_quality.rating.value

Description

Example

Required: True

Units: None

Type: Integer

Style: Number

Rating from 1-5 where 1 is bad

4

data_quality.warning

data_quality.warning

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any warnings about the data that should be noted for users.

periodic pipeline noise

fdsn.channel_code

fdsn.channel_code

Description

Example

Required: False

Units: None

Type: String

Style: Alpha-Numeric

FDSN channel code, this is a 3 character code in the form [band][type][direction]

LQN

See also

https://ds.iris.edu/ds/nodes/dmc/data/formats/seed-channel-naming/ for more information on channel codes.

filter.applied

filter.applied

Description

Example

Required: True

Units: None

Type: Boolean

Style: List

Boolean if filter has been applied or not. If more than one filter input as a list that matches filter.names

[True, False]

filter.comments

filter.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on filters that is important for users.

low pass is not calibrated

filter.name

filter.name

Description

Example

Required: True

Units: None

Type: String

Style: List

Name of filter applied or to be applied. If more than one filter input as a list in the order in which the should be applied.

[gain, lowpass_h]

h_field_max.end

h_field_max.end

Description

Example

Required: False

Units: nanotesla

Type: Float

Style: Number

Maximum magnetic field strength at end of measurement.

34526.1

h_field_max.start

h_field_max.start

Description

Example

Required: False

Units: nanotesla

Type: Float

Style: Number

Maximum magnetic field strength at beginning of measurement.

34565.2

h_field_min.end

h_field_min.end

Description

Example

Required: False

Units: nanotesla

Type: Float

Style: Number

Minimum magnetic field strength at end of measurement.

50453.2

h_field_min.start

h_field_min.start

Description

Example

Required: False

Units: nt

Type: Float

Style: Number

Minimum magnetic field strength at beginning of measurement.

40345.1

location.elevation

location.elevation

Description

Example

Required: False

Units: meters

Type: Float

Style: Number

elevation of magnetometer in datum specified at survey level.

123.4

location.latitude

location.latitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Latitude of magnetometer in datum specified at survey level.

23.134

location.longitude

location.longitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Longitude of magnetometer in datum specified at survey level.

14.23

measurement_azimuth

measurement_azimuth

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Azimuth of channel in the specified survey.orientation.r eference_frame.

0

measurement_tilt

measurement_tilt

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Tilt of channel in survey.orie ntation.reference_frame.

0

sample_rate

sample_rate

Description

Example

Required: True

Units: samples per second

Type: Float

Style: Number

Sample rate of the channel.

8

sensor.id

sensor.id

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Sensor ID Number or serial Number.

mag01

sensor.manufacturer

sensor.manufacturer

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Person or organization that manufactured the magnetic sensor.

Magnets

sensor.model

sensor.model

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Model version of the magnetic sensor.

falcon5

sensor.type

sensor.type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Type of magnetic sensor

induction coil

time_period.end

time_period.end

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

End date and time of collection in UTC.

2020-02-04 T16: 23:45.453670 +00:00

time_period.start

time_period.start

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

Start date and time of collection in UTC.

2020-02-01 T09: 23:45.453670 +00:00

transformed_azimuth

transformed_azimuth

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Azimuth angle of channel that has been transformed into a specified coordinate system. Note this value is only for derivative products from the archived data.

0

transformed_tilt

transformed_tilt

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Tilt angle of channel that has been transformed into a specified coordinate system. Note this value is only for derivative products from the archived data.

0

type

type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Data type for the channel

magnetic

units

units

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Units of the data. if archiving should always be counts. Options: [ counts ; nanotesla ]

counts

Example Magnetic Channel JSON

{    "magnetic": {
        "comments": null,
        "component": "Bz",
        "data_logger": {
            "channel_number": 2},
        "data_quality": {
            "warning": "periodic pipeline",
            "rating": {
                "author": "M. Tee",
                "method": "Machine Learning",
                "value": 3}},
                "fdsn": {
             "channel_code": "LQN",
        "filter": {
            "name": ["counts2nT", "lowpass_mag"],
            "applied": [true, false],
            "comments": null},
        "h_field_max": {
            "start": 40000.,
            "end": 420000.},
        "h_field_min": {
            "start": 38000.,
            "end": 39500.},
        "location": {
            "latitude": 25.89,
            "longitude": -110.98,
            "elevation": 1234.5},
        "measurement_azimuth": 0.0,
        "measurement_tilt": 180.0,
        "sample_rate": 64.0,
        "sensor": {
            "id": 'spud',
            "manufacturer": "F. McAraday",
            "type": "tri-axial fluxgate",
            "model": "top hat"},
        "time_period": {
            "end": "2010-01-01T00:00:00+00:00",
            "start": "2020-01-01T00:00:00+00:00"},
        "type": "magnetic",
        "units": "nT"
    }
}

Filters

Filters is a table that holds information on any filters that need to be applied to get physical units, and/or filters that were applied to the data to analyze the signal. This includes calibrations, notch filters, conversion of counts to units, etc. The actual filter will be an array of numbers contained within an array named name and formatted according to type. The preferred format for a filter is a look-up table which programatically can be converted to other formats.

It is important to note that filters will be identified by name and must be consistent throughout the file. Names should be descriptive and self evident. Examples:

  • coil_2284 \longrightarrow induction coil Number 2284

  • counts2mv \longrightarrow conversion from counts to mV

  • e_gain \longrightarrow electric field gain

  • datalogger_response_024 \longrightarrow data logger Number 24 response

  • notch_60hz \longrightarrow notch filter for 60 Hz and harmonics

  • lowpass_10hz \longrightarrow low pass filter below 10 Hz

In each channel there are keys to identify filters that can or have been applied to the data to get an appropriate signal. This can be a list of filter names or a single filter name. An applied key also exists for the user to input whether that filter has been applied. A single Boolean can be provided True if all filters have been applied, or False if none of the filters have been applied. Or applied can be a list the same length as names identifying if the filter has been applied. For example name: "[counts2mv, notch_60hz, e_gain]" and applied: "[True, False, True] would indicate that counts2mv and e_gain have been applied but noth_60hz has not.

Filter Attributes

type

type

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Filter type. Options: [look up

; poles zeros ; converter ; FIR ; …]

lookup

name

name

Description

Example

Required: True

Units: None

Type: String

Style: Alpha Numeric

Unique name for the filter such that it is easy to query. See above for some examples.

counts2mv

units_in

units_in

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

The input units for the filter. Should be SI units or counts.

counts

units_out

units_out

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

The output units for the filter. Should be SI units or counts.

millivolts

calibration_date

calibration_date

Description

Example

Required: True

Units: None

Type: String

Style: Date Time

If the filter is a calibration

2010-01-01 T00:00:00 +00:00

Example Filter JSON

{
    "filter":{
        "type": "look up",
         "name": "counts2mv",
         "units_in": "counts",
         "units_out": "mV",
         "calibration_date": "2015-07-01",
        "comments": "Accurate to 0.001 mV"
    }
}

Auxiliary Channels

Auxiliary channels include state of health channels, temperature, etc.

Auxiliary Channel Attributes

channel_number

channel_number

Description

Example

Required: True

Units: None

Type: Integer

Style: Number

Channel Number on the data logger.

1

comments

comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments about the channel that would be useful to a user.

Pc1 at 6pm local time.

component

component

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Name of the component measured. Options: [ temperature ; battery ; … ]

temperature

data_quality.rating.author

data_quality.rating.author

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Name of person or organization who rated the data.

graduate student ace

data_quality.rating.method

data_quality.rating.method

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

The method used to rate the data. Should be a descriptive name and not just the name of a software package. If a rating is provided

standard deviation

data_quality.rating.value

data_quality.rating.value

Description

Example

Required: True

Units: None

Type: Integer

Style: Number

Rating from 1-5 where 1 is bad

4

data_quality.warning

data_quality.warning

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any warnings about the data that should be noted for users.

periodic pipeline noise

fdsn.channel_code

fdsn.channel_code

Description

Example

Required: False

Units: None

Type: String

Style: Alpha-Numeric

FDSN channel code, this is a 3 character code in the form [band][type][direction]

LQN

See also

https://ds.iris.edu/ds/nodes/dmc/data/formats/seed-channel-naming/ for more information on channel codes.

filter.applied

filter.applied

Description

Example

Required: True

Units: None

Type: Boolean

Style: List

Boolean if filter has been applied or not. If more than one filter input as a list that matches filter.names

[True, False]

filter.comments

filter.comments

Description

Example

Required: False

Units: None

Type: String

Style: Free Form

Any comments on filters that is important for users.

low pass is not calibrated

filter.name

filter.name

Description

Example

Required: True

Units: None

Type: String

Style: List

Name of filter applied or to be applied. If more than one filter input as a list in the order in which the should be applied.

[gain, lp_aux]

location.elevation

location.elevation

Description

Example

Required: False

Units: meters

Type: Float

Style: Number

Elevation of channel location in datum specified at survey level.

123.4

location.latitude

location.latitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Latitude of channel location in datum specified at survey level.

23.134

location.longitude

location.longitude

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Longitude of channel location in datum specified at survey level.

14.23

measurement_azimuth

measurement_azimuth

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Azimuth of channel in the specified survey.orientation.r eference_frame.

0

measurement_tilt

measurement_tilt

Description

Example

Required: True

Units: decimal degrees

Type: Float

Style: Number

Tilt of channel in survey.orie ntation.reference_frame.

0

sample_rate

sample_rate

Description

Example

Required: True

Units: samples per second

Type: Float

Style: Number

Sample rate of the channel.

8

time_period.end

time_period.end

Description

Example

Required: True

Units: None

Type: String

Style: time

End date and time of collection in UTC.

2020-02-04 T16: 23:45.453670 +00:00

time_period.start

time_period.start

Description

Example

Required: True

Units: None

Type: String

Style: time

Start date and time of collection in UTC.

2020-02-01 T09: 23:45.453670 +00:00

transformed_azimuth

transformed_azimuth

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Azimuth angle of channel that has been transformed into a specified coordinate system. Note this value is only for derivative products from the archived data.

0

transformed_tilt

transformed_tilt

Description

Example

Required: False

Units: decimal degrees

Type: Float

Style: Number

Tilt angle of channel that has been transformed into a specified coordinate system. Note this value is only for derivative products from the archived data.

0

type

type

Description

Example

Required: True

Units: None

Type: String

Style: Free Form

Data type for the channel.

temperature

units

units

Description

Example

Required: True

Units: None

Type: String

Style: Controlled Vocabulary

Units of the data. Options: SI units or counts.

celsius

Example Auxiliary XML

<auxiliary>
    <comments>great</comments>
    <component>Temperature</component>
    <data_logger>
        <channel_number type="Integer">1</channel_number>
    </data_logger>
    <data_quality>
        <warning>None</warning>
        <rating>
            <author>mt</author>
            <method>ml</method>
            <value type="Integer">4</value>
        </rating>
    </data_quality>
    <fdsn>
        <channel_code>LQN</channel_code>
    <fdsn>
    <filter>
        <name>
            <i>lowpass</i>
            <i>counts2mv</i>
        </name>
        <applied type="boolean">
            <i type="boolean">True</i>
        </applied>
        <comments>test</comments>
    </filter>
    <location>
        <latitude type="Float" units="degrees">12.324</latitude>
        <longitude type="Float" units="degrees">-112.03</longitude>
        <elevation type="Float" units="degrees">1234.0</elevation>
    </location>
    <measurement_azimuth type="Float" units="degrees">0.0</measurement_azimuth>
    <measurement_tilt type="Float" units="degrees">90.0</measurement_tilt>
    <sample_rate type="Float" units="samples per second">8.0</sample_rate>
    <time_period>
        <end>2020-01-01T00:00:00+00:00</end>
        <start>2020-01-04T00:00:00+00:00</start>
    </time_period>
    <type>auxiliary</type>
    <units>celsius</units>
</auxiliary>

Option Definitions

Electromagnetic Frequency Bands

Generalized electromagnetic period bands. Some overlap, use the closest definition.

Data Type

Definition

Frequency Range

AMT

radio magnetotellurics

>10^{3}

BBMT

broadband magnetotellurics

10^{3}10^{0}

LPMT

long-period magnetotellurics

<10^{0}

Channel Components

These are the common channel components. More can be added.

Channel Type

Definition

E

electric field measurement

B

magnetic field measurement

T

temperature

Battery

battery

SOH

state-of-health

Directions

The convention for many MT setups follows the right-hand-rule (Figure 2) with X in the northern direction, Y in the eastern direction, and Z positive down. If the setup has multiple channels in the same direction, they can be labeled with a Number. For instance, if you measure multiple electric fields Ex01, Ey01, Ex02, Ey02.

Direction

Definition

x

north direction

y

east direction

z

vertical direction

# {0–9}

variable directions

1

Corresponding Authors:

Jared Peacock (jpeacock@usgs.gov)

Andy Frassetto (andy.frassetto@iris.edu)