{
 "schema": "ausmt-station",
 "version": "0.1",
 "ausmt_id": "au.bowen-basin-1976-80.KO",
 "station": "KO",
 "survey": "Bowen Basin magnetotelluric survey 1976-80",
 "survey_id": "bowen-basin-1976-80",
 "country": "Australia",
 "organisation": "The University of Queensland",
 "location": {
  "lat": -24.541667,
  "lon": 148.758333
 },
 "data": {
  "type": "LPMT",
  "n_periods": 13,
  "period_min_s": 1.995251,
  "period_max_s": 398.10502
 },
 "diagnostics": {
  "median_relative_error": 0.196,
  "remote_reference": false,
  "tipper_available": false,
  "completeness_smoothness_diagnostic": {
   "value": 2.4,
   "basis": "e",
   "note": "not a quality or geological-value judgement"
  },
  "classification": "indeterminate",
  "method": "phase-tensor (Caldwell 2004)",
  "note": "screening diagnostic, not an interpretation product"
 },
 "processing": {
  "software": null,
  "algorithm": null,
  "remote_reference": false,
  "remote_site": null,
  "file_written_by": {
   "name": null,
   "version": null
  },
  "note": "Magnetotelluric transfer functions minted from Dekker, D.L. (1983) 'A\nmagnetotelluric survey of the Bowen Basin', PhD thesis, University of\nQueensland Department of Physics, doi:10.14264/29fd91e.  Apparent\nresistivity and phase from Appendix I (printed 186 to 200), station\npositions from Appendix E (printed 151). Transcription:\nGDS/inventories/dekker_1983_responses.csv and\ndekker_1983_site_locations.csv, both read off page renders rather than off\nthe scan's text layer, which collapses on the dot-matrix appendix tables.\nCompanion paper: Dekker, D.L. and Hastie, L.M. (1981), Physics of the Earth\nand Planetary Interiors 25(3): 219 to 225, doi:10.1016/0031-9201(81)90064-9.\n\nWHAT WAS TABULATED, AND WHAT WAS NOT.  Appendix I prints seven columns and\nnothing else:\nLOG PERIOD | LOG rhoXY | SIGMA LOGrhoXY | LOG rhoYX | SIGMA LOGrhoYX | PHASE ZXY | PHASE ZYX\nNo impedance, no diagonal tensor element, no tipper, no phase error, no\ncoherence and no skew is tabulated anywhere in the thesis.  ZXX and ZYY are\nwritten here as the EMPTY sentinel because they were never measured, NOT\nbecause they are zero.  The vertical field was recorded but its transfer\nfunction was abandoned as too scattered to use (printed 107), so no tipper\nblock and no HZ channel is declared.\n\nCONVENTION, AND THE TRAP IT AVOIDS.  The thesis declares its own time\ndependence in Appendix D5 (printed 130): 'In the following discussion the\ntime dependence (exp(iwt)) is omitted from the field equations for clarity',\nwhere w is the Greek omega, and on the same page 'the intrinsic impedance\nZ_j of the medium for a j polarized wave travelling downwards is defined\nhere for convenience as being negative, as is the boundary impedance Z^i_ji\n(the phase is -3pi/4)'.  Its axes are the EDI axes (printed 11): 'Axes are\nright handed with x pointing north, y pointing east and z pointing\ndownwards'.  Its tensor is the EDI tensor (Appendix D10, printed 145):\nE_x = Z_xx H_x + Z_xy H_y      E_y = Z_yx H_x + Z_yy H_y\nTime dependence, axes and tensor definition are therefore all the EDI\nconvention, so the printed phase IS the EDI phase and the mapping is the\nidentity:\nZXYR = |Zxy| cos(phi_xy)       ZXYI = |Zxy| sin(phi_xy)\nZYXR = |Zyx| cos(phi_yx)       ZYXI = |Zyx| sin(phi_yx)\nwith phi EXACTLY as printed.  NO conjugation, no sign change, no wrap and no\nfold is applied by this generator.  The absence of a transform is the\nfinding, which is why it is stated rather than left silent.\n\nThe trap: the companion paper's Figure A1 caption prints an injected line\ncurrent as (I e^-iwt), and reading that source label as the field convention\nwould conjugate every value in this survey and publish Zxy near -45 degrees\nand Zyx near +135.  The same paper's own half-space impedance, printed 224,\nis Z_n = (2 mu0 rho w i)^(1/2), whose argument is +45 degrees, and that\nagrees with the thesis and not with the caption.  The data settle it\nindependently: of 213 printed xy phases 212 lie in the first quadrant (0 to\n90 degrees), and of 196 printed yx phases 195 lie in the third (-180 to\n-90).  Under the opposite convention every one of those 409 cells would be\nin the wrong quadrant.  The reduction is why the census is so clean: section\n2.8 step 5 (printed 40) kept 'Variances and median values are calculated\nover tenth decade bands from impedances whose phase lies in the correct\nquadrant'.\n\nUNITS AND THE IMPEDANCE ARITHMETIC.  Per printed row, with |Z| in mV/km per\nnT:\nT      = 10 ** (printed LOG PERIOD)          seconds\nrho_a  = 10 ** (printed LOG rho)             ohm metres\n|Z|    = sqrt(rho_a / (0.2 T))               mV/km per nT\nZ      = |Z| (cos phi + i sin phi)           phi as printed, degrees\nThe thesis's own symbol list (printed 12) gives the same relation in SI form\nas P = Z^2_alphabeta / mu0 w.  FREQ is 1/T, written to five significant\nfigures, which recovers the printed log10 period grid to well inside its\nfour printed decimals.\n\nUNCERTAINTIES, AND THE RULING BEHIND THEM.  The tabulated sigma is treated\nas ONE standard deviation of log10 apparent resistivity.  That is a ruling,\nand the ambiguity it settles is real and is not hidden here: the Appendix I\nfootnote (printed 186) says only 'Sigma (standard deviations)', while\nAppendix D10 (printed 147) says results 'are presented as a median and a\nconfidence interval equal to two standard deviations of the median', and the\nthesis never resolves whether the printed number is one standard deviation\nor half of that interval.  The choice changes every uncertainty in this file\nby a factor of two.  Section 2.8 step 6 makes it a site-level quantity\naveraged over all recordings at the site, not a single-recording error bar.\nPropagation:\nsigma_ln|Z| = ln(10) * sigma_log10rho / 2\nsigma_|Z|   = |Z| * sigma_ln|Z|\nZXY.VAR     = sigma_|Z| squared              likewise ZYX.VAR\nThe source prints NO phase error, so nothing from the phase enters these\nvariances. What is written is a magnitude variance mapped onto a complex\nelement.  It is not a full covariance and it does not constrain the phase: a\nconsumer weighting phase by it will over-weight that phase.\n\nCOORDINATES, AND THE RULING BEHIND THEM.  AGD66 is ASSUMED, and is carried\nas an assumption rather than as a fact.  No datum, map sheet, grid or\nconversion statement is printed anywhere in the thesis: not in Appendix E,\nnot in chapter 6, not in the captions of Figures 6.2, 6.3 and 6.7, and not\nin the symbols and notation section. AGD66 is a reasonable working\nassumption for Queensland work of this period, and no transformation of any\nkind is applied.  Positions are printed to degrees and whole or half\nminutes, so the quantisation is 30 arc seconds, about 0.93 km north to\nsouth, and THAT is the positional precision.  The AGD66 to WGS84 shift in\nthis part of Queensland is of order 200 m, about a fifth of that quantum, so\nthe printed coordinate sits inside its own uncertainty under either datum.\n\nFRAME: MAGNETIC north, declared and not rotated.  Section 5.1.2 (printed\n83): 'The four E lines were laid north, south, east and west (magnetic) from\nthe datalogger with the four extreme ends electrically connected to the\nsoil.  Magnetic and electric field sensors were aligned parallel and\nperpendicular to magnetic north to within plus or minus 1 degree.'  Section\n5.2.2 (printed 85) fixes the polarity: 'The north and south lines are\nconnected to the Ex datalogger inputs, and the electric field is taken as\npositive if north is positive.  The Ey field is positive if east is\npositive.'  The Appendix I headings print rhoXY and ZXY unprimed where the\nsymbol list reserves Z'_ij for 'Rotated impedance tensor elements', and the\nsix-step reduction contains no rotation step, so these are unrotated\nmeasurement-frame values.  ZROT is written as zero throughout: the values\nare served in the frame the thesis recorded them in.  The thesis prints no\ndeclination anywhere, so none is quoted and none is applied.\n\nCAMPAIGN AND INSTRUMENT.  Field work ran from 1976 to 1980, mainly 1979 to\n1980 (abstract; section 1.2).  The southern survey 'was carried out between\n1979 and 1980' (section 6.4); NO date at all is printed for the northern\ntraverse, and no per-site date exists anywhere in the thesis, which is why\nACQDATE is absent rather than filled with a boilerplate value.  Equipment\nwas built in the department: four 300 m telluric lines on ceramic porous\npots filled with copper sulphate solution and containing a copper electrode,\nthree orthogonal coils, and a 12-bit CMOS datalogger after Iliceto (1977)\nrecording to cassette tape.  Processing was the cross-frequency method\n(section 2.4.2, Appendix D10 Method 3) on a PDP-11/34, band averaged over\nsixteen-point sub-bands and then over tenth-decade bands, using medians\nrather than means; the tabulated values are the smoothed, band-averaged\nproduct.  Northern sites were recorded as single stations, southern sites as\ntwin synchronous stations.\n\nEMPTY, AND HOW IT READS.  The EMPTY sentinel is 1.0E+32.  mt_metadata\nconverts it to an exact complex zero on read rather than to a NaN, so an\nexact complex zero in an impedance element here is the sentinel and NOT a\nmeasurement; AusMT's own reader classifies an exact complex zero as absent\nfor that reason.  No printed phase in this survey lies on 0, plus or minus\n90 or plus or minus 180 degrees, and every printed apparent resistivity is\nfinite and positive, so no real value in this survey can collide with that\nsentinel.  A blank in the printed table is ABSENT and is never zero: across\nthe survey 60 rows carry the xy mode alone and 43 carry the yx mode alone.\n\nSTATION: Kooyong, thesis site code KO, Southern traverse. Appendix E prints\nits position as 24 deg 32'30\" S, 148 deg 45'30\" E, which is -24.541667,\n148.758333. This file carries the 13 printed rows that hold a value in at\nleast one mode, from 2.0 s to 398.1 s. Of those rows 9 carry the xy mode and\n11 the yx mode, so 2 carry xy alone and 4 carry yx alone; the absent mode is\nwritten as the EMPTY sentinel and is absent, never zero.\n\nThis file is published as station au.bowen-basin-1976-80.KO. Dates in this\nfile are ISO 8601."
 },
 "distribution": {
  "edi_available": true,
  "license": "CC-BY-4.0",
  "edi_path": "edi/bowen-basin-1976-80/KO.edi"
 },
 "provenance": {
  "pipeline": "ausmt/extract.build_portal",
  "pipeline_version": "0.2.1",
  "extractor": "mt_metadata (community canonical)",
  "software": {
   "python": "3.12.14",
   "mt_metadata": "1.0.10",
   "mth5": "0.6.8"
  },
  "git_commit": "25c90921c42c72bbc5455b4bbdab9137cf8b8e48",
  "parameters": {
   "dimensionality": {
    "beta_per_period_deg": 3.0,
    "skew_3d_deg": 5.0,
    "pct_periods_3d_threshold": 40,
    "ellip_2d_deg": 0.1,
    "min_rez_row_sine": 0.01,
    "beta_physical_cap_deg": 15.0,
    "min_usable_period_frac": 0.5,
    "skew_aggregation": "median"
   },
   "diagnostic": "completeness/smoothness (median rel error + coverage + smoothness)"
  },
  "generated": "2026-09-09T06:22:47.791693+00:00",
  "input_file": "KO.edi",
  "input_sha256": "382c3f3875814723e8c3595c1a83213f75b5deb9745774a008fafba348e2c180"
 },
 "coordinate_qc": null,
 "canonical_conditioning": [
  "survey.id->bowen-basin-1976-80",
  "survey.project->Bowen_Basin_magnetotelluric_survey",
  "survey.geographic_name sanitized",
  "station.geographic_name sanitized",
  "sign_convention: '+' is a library default — EDI carries no machine-readable sign convention; NOT asserted by source",
  "declination.epoch/model: library defaults (epoch=None, model=IGRF) — an EDI states only the declination value; epoch/model NOT asserted by source",
  "citation.authors<-survey_meta:D.L. Dekker",
  "citation.title<-survey_meta",
  "copyright.release_status=Data Citation Required; conditions_of_use set from licence CC-BY-4.0 (replaced mt_metadata default boilerplate)"
 ],
 "frame": {
  "evidence": {
   "branch": "mt",
   "zrot": "0",
   "trot": null,
   "rotspec": null,
   "hmeas_azimuths": {
    "hx": 0.0,
    "hy": 90.0
   },
   "emeas_azimuths": {
    "ex": null,
    "ey": null
   }
  },
  "impedance_rotation_deg_source": null,
  "tipper_rotation_deg_source": null,
  "derotated": false,
  "frame_served": "declared-zero",
  "declared_azimuth_deg": 0.0,
  "convention_check": {
   "verdict": "ok",
   "phs_xy_median_deg": 38.2,
   "phs_yx_median_deg": -135.4,
   "n_periods_used": 7,
   "detail": null
  }
 },
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