{"thg_l2_mag_y49a_00000000_v01.cdf":{"CDFFileInfo":[{"FileVersion":"3.9.1"},{"Format":"SINGLE"},{"Majority":"ROW"},{"Encoding":"NETWORK"}],"CDFglobalAttributes":[{"Project":[{"0":"THEMIS"}]},{"Source_name":[{"0":"THG_L2>THEMIS Ground Based Observatory"}]},{"Data_type":[{"0":"MAG"}]},{"Data_version":[{"0":"1"}]},{"Logical_source":[{"0":"thg_l2_mag_y49a"}]},{"Logical_file_id":[{"0":"thg_l2_mag_y49a_20260101_v01"}]},{"Time_resolution":[{"0":"1.0 s"}]},{"Generated_by":[{"0":"THEMIS SOC"}]},{"Generation_date":[{"0":"Wed Apr  1 02:12:35 2026"}]},{"ADID_ref":[{"0":"NSSD0110"}]},{"File_naming_convention":[{"0":"source_datatype_descriptor"}]},{"Software_version":[{"0":"xxxx"}]},{"TEXT":[{"0":"Part of a collaboration between the USGS Geomagnetism Program and the Earthquake Hazards Program and Global Seismographic Network Program to use variometers installed at seismic stations to densify magnetic field observations and to enable cross-corrections. Further details can be found in the journal article U.S. Geological Survey Geomagnetic Variometer Data: Capitalizing on Seismic Infrastructure by A. Ringler et. al. (2025) at https://doi.org/10.1785/0220250185  This dataset contains variometer magnetic field variation data, here transformed from calibrated geographic vector coordinates into local magnetic HEZ vector components.   The USGS provides both \"observatory\" grade magnetic field data and \"variometer\" grade magnetometer data. The former are generally considered to be more accurate, precise, and complete. Calibrated observatory archives can be obtained from the USGS Geomagnetism Program and INTERMAGNET, while uncalibrated USGS variometer data archives are maintained by IRIS/Earthscope.   Relative variations are considered reliable; however, static offsets can be substantial, will vary site-by-site, and may even change following events such as routine maintenance.  USGS variometer data is mirrored at THEMIS in both the 1 second and 0.1 second time cadence (1 Hz and 10 Hz sampling rate). The Time Resolution global attribute indicates the time cadence of this file."}]},{"Spase_datasetresourceid":[{"0":" "}]},{"Doi":[{"0":" "}]},{"LINK_TEXT":[{"0":"USGS source data can be found at the "},{"1":"USGS variometer data can be retrieved using the "},{"2":"The THEMIS data archive for this station can be found at the "}]},{"Mission_group":[{"0":"THEMIS"}]},{"Instrument_type":[{"0":"Ground-Based Magnetometers, Riometers, Sounders"}]},{"Acknowledgement":[{"0":"Original data provided by the USGS Geomagnetism Program."}]},{"Discipline":[{"0":"Space Physics>Magnetospheric Science"},{"1":"Space Physics>Ionospheric Science"}]},{"LINK_TITLE":[{"0":"USGS GeomagPlots page"},{"1":"Geomagnetism Data Web Service (under /algorithms/filter/)"},{"2":"THEMIS ftp site"}]},{"PI_affiliation":[{"0":"United States Geological Survey, 1711 Illinois St, Golden, CO 80401-1865, USA"}]},{"PI_name":[{"0":"The USGS Geomagnetism Program"}]},{"Rules_of_use":[{"0":"Access to preliminary data is provided as-is. We request that you acknowledge the USGS Geomagnetism Program in all published documents which make use of USGS data."}]},{"Descriptor":[{"0":"Y49A>Blount Mountain, AL, USA"}]},{"Logical_source_description":[{"0":"THEMIS GMAG Level 2 Ground-based Vector Magnetic Field at Blount Mountain, AL, USA"}]},{"HTTP_LINK":[{"0":"https://geomag.usgs.gov/plots/variometer?stations=Y49A"},{"1":"https://themis.ssl.berkeley.edu/data/themis/thg/l2/variometers/y49a/"},{"2":"https://geomag.usgs.gov/ws/docs#/default/Filtered_Algorithm_algorithms_filter__get"}]},{"MODS":[{"0":"Rev-2026-02-12 (dcar): CDF template created."}]}],"CDFVariables":[{"thg_mag_y49a":[{"VarDescription":[{"DataType":"CDF_REAL4"},{"NumElements":1},{"NumDims":1},{"DimSizes":[3]},{"RecVariance":"VARY"},{"DimVariances":["VARY"]},{"PadValue":-1.0E+30}]},{"VarAttributes":[{"CATDESC":"Magnetic field vector, HEZ vector components; depends on epoch, compno."},{"DEPEND_0":"thg_mag_y49a_epoch"},{"DEPEND_1":"thg_mag_y49a_compno"},{"DISPLAY_TYPE":"time_series"},{"FIELDNAM":"B in HEZ Components"},{"FILLVAL":"NaN"},{"FORMAT":"f9.2"},{"LABL_PTR_1":"thg_mag_y49a_labl"},{"UNIT_PTR":"thg_mag_y49a_unit"},{"VALIDMIN":[-60000.0,-60000.0,-60000.0]},{"VALIDMAX":[60000.0,60000.0,60000.0]},{"VAR_TYPE":"data"},{"SCALETYP":"linear"},{"DEPEND_TIME":"thg_mag_y49a_time"},{"DEPEND_EPOCH0":"thg_mag_y49a_epoch0"},{"COORDINATE_SYSTEM":"HEZ"},{"STATION_LATITUDE":"33.8577"},{"STATION_LONGITUDE":"273.5881"},{"STATION_ELEVATION":"362"},{"STATION_DECLINATION":"0.0"}]}]},{"thg_mag_y49a_unit":[{"VarDescription":[{"DataType":"CDF_CHAR"},{"NumElements":2},{"NumDims":1},{"DimSizes":[3]},{"RecVariance":"NOVARY"},{"DimVariances":["VARY"]},{"NumWrittenRecords":1},{"PadValue":" "},{"BlockingFactor":1}]},{"VarAttributes":[{"CATDESC":"Units for each of the B field vector components."},{"FIELDNAM":"Y49A Units"},{"FORMAT":"a2"},{"VAR_TYPE":"metadata"},{"DICT_KEY":"label"}]},{"VarData":["nT","nT","nT"]}]},{"thg_mag_y49a_compno":[{"VarDescription":[{"DataType":"CDF_INT4"},{"NumElements":1},{"NumDims":1},{"DimSizes":[3]},{"RecVariance":"NOVARY"},{"DimVariances":["VARY"]},{"NumWrittenRecords":1},{"PadValue":-2147483647},{"BlockingFactor":1}]},{"VarAttributes":[{"CATDESC":"Index for the HEZ component number."},{"FIELDNAM":"Y49A Component Number"},{"FILLVAL":-2147483648},{"FORMAT":"i2"},{"LABL_PTR_1":"thg_mag_y49a_labl"},{"VALIDMIN":[1,1,1]},{"VALIDMAX":[3,3,3]},{"VAR_TYPE":"support_data"},{"SCALETYP":"linear"},{"DICT_KEY":"number"},{"UNITS":" "}]},{"VarData":[1,2,3]}]},{"thg_mag_y49a_time":[{"VarDescription":[{"DataType":"CDF_REAL8"},{"NumElements":1},{"NumDims":0},{"RecVariance":"VARY"},{"PadValue":-1.0E+30}]},{"VarAttributes":[{"CATDESC":"UTC Time, in seconds since 01-Jan-1970 00:00:00. Depends on thg_mag_y49a_epoch"},{"DEPEND_0":"thg_mag_y49a_epoch"},{"FIELDNAM":"Y49A Time"},{"FILLVAL":"NaN"},{"FORMAT":"E13.6"},{"VALIDMIN":0.0},{"VALIDMAX":5.0E+9},{"VAR_TYPE":"support_data"},{"UNITS":"sec"},{"LABLAXIS":"UT"},{"VAR_NOTES":"Unleaped seconds"}]}]},{"thg_mag_y49a_epoch":[{"VarDescription":[{"DataType":"CDF_EPOCH"},{"NumElements":1},{"NumDims":0},{"RecVariance":"VARY"},{"PadValue":"0000-01-01T00:00:00.000"}]},{"VarAttributes":[{"CATDESC":"Sample epoch, as human-readable date."},{"FIELDNAM":"Y49A Epoch"},{"FILLVAL":"9999-12-31T23:59:59.999"},{"VALIDMIN":"2001-01-01T00:00:00.000"},{"VALIDMAX":"2100-12-31T23:59:59.999"},{"VAR_TYPE":"support_data"},{"LABLAXIS":"UT"},{"VIRTUAL":"TRUE"},{"FUNCT":"comp_themis_epoch"},{"COMPONENT_0":"thg_mag_y49a_epoch0"},{"COMPONENT_1":"thg_mag_y49a_time"}]}]},{"thg_mag_y49a_epoch0":[{"VarDescription":[{"DataType":"CDF_EPOCH"},{"NumElements":1},{"NumDims":0},{"RecVariance":"NOVARY"},{"PadValue":"0000-01-01T00:00:00.000"},{"BlockingFactor":1}]},{"VarAttributes":[{"CATDESC":"EPOCH0 of THEMIS TIME BASE"},{"FIELDNAM":"Y49A Epoch0"},{"FILLVAL":"9999-12-31T23:59:59.999"},{"VALIDMIN":"1900-01-01T00:00:00.000"},{"VALIDMAX":"2029-12-31T23:59:59.999"},{"VAR_TYPE":"support_data"},{"UNITS":"msec"},{"LABLAXIS":"timebase"},{"VAR_NOTES":"EPOCH of 01-Jan-1970 00:00:00"}]}]},{"range_epoch":[{"VarDescription":[{"DataType":"CDF_EPOCH"},{"NumElements":1},{"NumDims":0},{"RecVariance":"VARY"},{"PadValue":"0000-01-01T00:00:00.000"}]},{"VarAttributes":[{"CATDESC":"range_epoch"},{"FIELDNAM":"range_epoch"},{"FILLVAL":"9999-12-31T23:59:59.999"},{"VALIDMIN":"2001-01-01T00:00:00.000"},{"VALIDMAX":"2100-12-31T23:59:59.999"},{"VAR_TYPE":"support_data"},{"UNITS":"msec"},{"LABLAXIS":"UT"}]}]},{"thg_mag_y49a_labl":[{"VarDescription":[{"DataType":"CDF_CHAR"},{"NumElements":21},{"NumDims":1},{"DimSizes":[3]},{"RecVariance":"NOVARY"},{"DimVariances":["VARY"]},{"NumWrittenRecords":1},{"PadValue":" "},{"BlockingFactor":1}]},{"VarAttributes":[{"CATDESC":"Descriptive labels for each of the B field vector components."},{"FIELDNAM":"Y49A Label"},{"FORMAT":"a21"},{"VAR_TYPE":"metadata"},{"DICT_KEY":"label"}]},{"VarData":["Magnetic North, local","Magnetic East, local ","Vertical Down        "]}]}]}}