Magnetic Survey

These magnetic data channels were pulled from the Wisconsin Skytem example in this repository

Dataset Reference: Minsley, B.J, Bloss, B.R., Hart, D.J., Fitzpatrick, W., Muldoon, M.A., Stewart, E.K., Hunt, R.J., James, S.R., Foks, N.L., and Komiskey, M.J., 2022, Airborne electromagnetic and magnetic survey data, northeast Wisconsin (ver. 1.1, June 2022): U.S. Geological Survey data release, https://doi.org/10.5066/P93SY9LI.

import matplotlib.pyplot as plt
from os.path import join
import numpy as np
import gspy
from gspy import Survey
import xarray as xr
from pprint import pprint

Convert the magnetic csv data to NetCDF

Initialize the Survey

# Path to example files
data_path = '..//..//..//..//example_material//mag_example'

# Survey metadata file
metadata = join(data_path, "WI_Magnetics_survey_md.yml")

# Establish the Survey
survey = Survey.from_dict(metadata)

data_container = survey.gs.add_container('data', **dict(content = "raw and gridded data",
                                                        comment = "This is a test"))

1 - Raw Data - Import raw mag data from CSV-format. Define input data file and associated metadata file

d_data1 = join(data_path, 'WI_Magnetics.csv')
d_supp1 = join(data_path, 'WI_Magnetics_raw_data_md.yml')

# Add the raw AEM data as a tabular dataset
data_container.gs.add(key='raw_data', data_filename=d_data1, metadata_file=d_supp1)

<xarray.DataTree 'raw_data'>
Group: /survey/data/raw_data
│   Dimensions:      (index: 6785)
│   Coordinates:
│     * index        (index) int32 27kB 0 1 2 3 4 5 ... 6780 6781 6782 6783 6784
│       spatial_ref  float64 8B 0.0
│       x            (index) float64 54kB 7.243e+05 7.239e+05 ... 6.604e+05
│       y            (index) float64 54kB 4.916e+05 4.917e+05 ... 3.866e+05
│       z            (index) float64 54kB 176.8 217.3 231.6 ... 273.2 276.4 288.7
│   Data variables: (12/20)
│       fid          (index) float64 54kB 2.349e+05 2.349e+05 ... 1.868e+06
│       line         (index) int64 54kB 100101 100101 100101 ... 115201 115201
│       e_nad83      (index) float64 54kB 7.243e+05 7.239e+05 ... 6.604e+05
│       n_nad83      (index) float64 54kB 4.916e+05 4.917e+05 ... 3.866e+05
│       lon          (index) float64 54kB -87.41 -87.42 -87.42 ... -88.25 -88.25
│       lat          (index) float64 54kB 44.87 44.87 44.87 ... 43.94 43.94 43.94
│       ...           ...
│       mag_raw      (index) float64 54kB 5.481e+04 5.481e+04 ... 5.413e+04
│       tmi          (index) float64 54kB 5.482e+04 5.482e+04 ... 5.413e+04
│       rmf          (index) float64 54kB 210.6 210.6 197.3 ... -122.7 -124.5 -120.3
│       igrf         (index) float64 54kB 5.461e+04 5.461e+04 ... 5.425e+04
│       inc          (index) float64 54kB 71.13 71.13 71.13 ... 70.48 70.48 70.48
│       dec          (index) float64 54kB -4.796 -4.792 -4.787 ... -3.975 -3.972
│   Attributes:
│       content:     raw data
│       comment:     Contains mag data
│       type:        data
│       structure:   tabular
│       mode:        airborne
│       method:      magnetic
│       submethod:   total field
│       instrument:  cesium vapour
│       property:    magnetic susceptibility
└── Group: /survey/data/raw_data/magnetic_system
        Dimensions:      (dim_0: 1)
        Dimensions without coordinates: dim_0
        Data variables:
            sample_rate  (dim_0) float64 8B 0.1
            resolution   (dim_0) float64 8B 0.002
        Attributes:
            type:        system
            mode:        airborne
            method:      magnetic
            submethod:   total field
            instrument:  cesium vapour
            name:        magnetic_system

xarray.DataTree

'raw_data'

• Groups: (1)
  /survey/data/raw_data/magnetic_system

  • Dimensions:
    • index: 6785
    • dim_0: 1
  • Data variables: (2)
    • sample_rate
      (dim_0)
      float64
      0.1

      grid_mapping :

      spatial_ref

      array([0.1])

    • resolution
      (dim_0)
      float64
      0.002

      grid_mapping :

      spatial_ref

      array([0.002])

  • Attributes: (6)

    type :

    system

    mode :

    airborne

    method :

    magnetic

    submethod :

    total field

    instrument :

    cesium vapour

    name :

    magnetic_system

• Dimensions:
  • index: 6785
• Coordinates: (5)
  • index
    (index)
    int32
    0 1 2 3 4 ... 6781 6782 6783 6784

    standard_name :

    index

    long_name :

    Index of individual data points

    units :

    not_defined

    null_value :

    not_defined

    valid_range :

    [ 0. 6784.]

    grid_mapping :

    spatial_ref

    array([   0,    1,    2, ..., 6782, 6783, 6784], shape=(6785,), dtype=int32)

  • spatial_ref
    ()
    float64
    0.0

    crs_wkt :

    PROJCRS["NAD83(HARN) / Wisconsin Transverse Mercator",BASEGEOGCRS["NAD83(HARN)",DATUM["NAD83 (High Accuracy Reference Network)",ELLIPSOID["GRS 1980",6378137,298.257222101,LENGTHUNIT["metre",1]]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],ID["EPSG",4152]],CONVERSION["Wisconsin Transverse Mercator 83",METHOD["Transverse Mercator",ID["EPSG",9807]],PARAMETER["Latitude of natural origin",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8801]],PARAMETER["Longitude of natural origin",-90,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["Scale factor at natural origin",0.9996,SCALEUNIT["unity",1],ID["EPSG",8805]],PARAMETER["False easting",520000,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False northing",-4480000,LENGTHUNIT["metre",1],ID["EPSG",8807]]],CS[Cartesian,2],AXIS["easting (X)",east,ORDER[1],LENGTHUNIT["metre",1]],AXIS["northing (Y)",north,ORDER[2],LENGTHUNIT["metre",1]],USAGE[SCOPE["State-wide spatial data management."],AREA["United States (USA) - Wisconsin."],BBOX[42.48,-92.89,47.31,-86.25]],ID["EPSG",3071]]

    semi_major_axis :

    6378137.0

    semi_minor_axis :

    6356752.314140356

    inverse_flattening :

    298.257222101

    reference_ellipsoid_name :

    GRS 1980

    longitude_of_prime_meridian :

    0.0

    prime_meridian_name :

    Greenwich

    geographic_crs_name :

    NAD83(HARN)

    horizontal_datum_name :

    NAD83 (High Accuracy Reference Network)

    projected_crs_name :

    NAD83(HARN) / Wisconsin Transverse Mercator

    grid_mapping_name :

    transverse_mercator

    latitude_of_projection_origin :

    0.0

    longitude_of_central_meridian :

    -90.0

    false_easting :

    520000.0

    false_northing :

    -4480000.0

    scale_factor_at_central_meridian :

    0.9996

    authority :

    EPSG

    wkid :

    3071

    array(0.)

  • x
    (index)
    float64
    7.243e+05 7.239e+05 ... 6.604e+05

    standard_name :

    projection_x_coordinate

    long_name :

    Easting, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83)

    units :

    meter

    null_value :

    not_defined

    axis :

    X

    valid_range :

    [655123.04631746 732074.68735257]

    grid_mapping :

    spatial_ref

    array([724307.20605749, 723880.91270463, 723449.81378067, ...,
           661200.42566018, 660784.61064617, 660377.67411788], shape=(6785,))

  • y
    (index)
    float64
    4.916e+05 4.917e+05 ... 3.866e+05

    standard_name :

    projection_y_coordinate

    long_name :

    Northing, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83)

    units :

    meter

    null_value :

    not_defined

    axis :

    Y

    valid_range :

    [380085.03524677 492697.25185284]

    grid_mapping :

    spatial_ref

    array([491569.63134953, 491709.20454699, 491852.56571001, ...,
           386191.43371437, 386361.43421179, 386555.06172562], shape=(6785,))

  • z
    (index)
    float64
    176.8 217.3 231.6 ... 276.4 288.7

    standard_name :

    z

    long_name :

    Digital elevation model

    units :

    meter

    null_value :

    not_defined

    axis :

    Z

    positive :

    up

    datum :

    North American Vertical Datum of 1988 (NAVD88)

    valid_range :

    [172.52357302 354.1462611 ]

    grid_mapping :

    spatial_ref

    array([176.81996173, 217.30522261, 231.55221132, ..., 273.20891296,
           276.40131368, 288.74400026], shape=(6785,))

• Data variables: (20)
  • fid
    (index)
    float64
    2.349e+05 2.349e+05 ... 1.868e+06

    standard_name :

    fiducial

    long_name :

    Unique fiducial number

    units :

    not_defined

    null_value :

    not_defined

    valid_range :

    [ 234882.1 1869320.7]

    grid_mapping :

    spatial_ref

    array([ 234882.1,  234902.1,  234922.1, ..., 1868434.2, 1868454.2,
           1868474.2], shape=(6785,))

  • line
    (index)
    int64
    100101 100101 ... 115201 115201

    standard_name :

    line

    long_name :

    Line number

    units :

    not_defined

    null_value :

    not_defined

    valid_range :

    [100101. 115201.]

    grid_mapping :

    spatial_ref

    array([100101, 100101, 100101, ..., 115201, 115201, 115201], shape=(6785,))

  • e_nad83
    (index)
    float64
    7.243e+05 7.239e+05 ... 6.604e+05

    standard_name :

    easting_nad83

    long_name :

    Easting, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83)

    units :

    meter

    null_value :

    not_defined

    axis :

    x

    valid_range :

    [655123.04631746 732074.68735257]

    grid_mapping :

    spatial_ref

    array([724307.20605749, 723880.91270463, 723449.81378067, ...,
           661200.42566018, 660784.61064617, 660377.67411788], shape=(6785,))

  • n_nad83
    (index)
    float64
    4.916e+05 4.917e+05 ... 3.866e+05

    standard_name :

    northing_nad83

    long_name :

    Northing, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83)

    units :

    meter

    null_value :

    not_defined

    axis :

    y

    valid_range :

    [380085.03524677 492697.25185284]

    grid_mapping :

    spatial_ref

    array([491569.63134953, 491709.20454699, 491852.56571001, ...,
           386191.43371437, 386361.43421179, 386555.06172562], shape=(6785,))

  • lon
    (index)
    float64
    -87.41 -87.42 ... -88.25 -88.25

    standard_name :

    longitude

    long_name :

    Longitude, World Geodetic System of 1984 (WGS84)

    units :

    degree

    null_value :

    not_defined

    valid_range :

    [-88.31068224 -87.31895983]

    grid_mapping :

    spatial_ref

    array([-87.41369744, -87.41903223, -87.42442654, ..., -88.24074896,
           -88.24588231, -88.25089915], shape=(6785,))

  • lat
    (index)
    float64
    44.87 44.87 44.87 ... 43.94 43.94

    standard_name :

    latitude

    long_name :

    Latitude, World Geodetic System of 1984 (WGS84)

    units :

    degree

    null_value :

    not_defined

    valid_range :

    [43.87692377 44.87925387]

    grid_mapping :

    spatial_ref

    array([44.86825562, 44.86963284, 44.87104525, ..., 43.93530275,
           43.93691228, 43.93873252], shape=(6785,))

  • alt
    (index)
    float64
    276.3 270.1 274.2 ... 320.0 331.7

    standard_name :

    altitude

    long_name :

    DGPS instrument altitude

    units :

    meter

    null_value :

    not_defined

    valid_range :

    [216.91549347 414.04403623]

    grid_mapping :

    spatial_ref

    array([276.32180917, 270.07647878, 274.22084766, ..., 311.8       ,
           320.        , 331.7       ], shape=(6785,))

  • height
    (index)
    float64
    99.5 52.77 42.67 ... 38.6 43.6 42.9

    standard_name :

    instrument_height

    long_name :

    Instrument height above ground

    units :

    meter

    null_value :

    not_defined

    valid_range :

    [ 19.32837783 142.95900842]

    grid_mapping :

    spatial_ref

    array([99.50184743, 52.77125617, 42.66863635, ..., 38.6       ,
           43.6       , 42.9       ], shape=(6785,))

  • dem
    (index)
    float64
    176.8 217.3 231.6 ... 276.4 288.7

    standard_name :

    dem

    long_name :

    Digital elevation model

    units :

    meter

    null_value :

    not_defined

    axis :

    Z

    positive :

    up

    datum :

    North American Vertical Datum of 1988 (NAVD88)

    valid_range :

    [172.52357302 354.1462611 ]

    grid_mapping :

    spatial_ref

    array([176.81996173, 217.30522261, 231.55221132, ..., 273.20891296,
           276.40131368, 288.74400026], shape=(6785,))

  • date
    (index)
    object
    '2021/01/20' ... '2021/02/08'

    standard_name :

    date

    long_name :

    Date, yyyy/mm/dd

    units :

    not_defined

    null_value :

    not_defined

    grid_mapping :

    spatial_ref

    array(['2021/01/20', '2021/01/20', '2021/01/20', ..., '2021/02/08',
           '2021/02/08', '2021/02/08'], shape=(6785,), dtype=object)

  • time
    (index)
    object
    '17:14:42' ... '15:01:14'

    standard_name :

    time_utc

    long_name :

    Universal coordinated time (UTC), hh:mm:ss

    units :

    not_defined

    null_value :

    not_defined

    grid_mapping :

    spatial_ref

    array(['17:14:42', '17:15:02', '17:15:22', ..., '15:00:34', '15:00:54',
           '15:01:14'], shape=(6785,), dtype=object)

  • base_mag
    (index)
    float64
    -1e+04 -1e+04 ... -1e+04 -1e+04

    standard_name :

    base_magnetometer

    long_name :

    Raw magnetic base station data

    units :

    nanoTesla

    null_value :

    -9999.99

    valid_range :

    [54184.75555939 54540.91684654]

    grid_mapping :

    spatial_ref

    array([-9999.99, -9999.99, -9999.99, ..., -9999.99, -9999.99, -9999.99],
          shape=(6785,))

  • diurnal
    (index)
    float64
    -10.18 -10.22 ... 1.363 1.312

    standard_name :

    magnetic_diurnal

    long_name :

    Magnetic base station diurnal variation

    units :

    nanoTesla

    null_value :

    not_defined

    valid_range :

    [-15.8048103 10.85530477]

    grid_mapping :

    spatial_ref

    array([-10.17806224, -10.22429797, -10.22322891, ...,   1.31899733,
             1.36302559,   1.3124682 ], shape=(6785,))

  • mag_filt
    (index)
    float64
    5.481e+04 5.481e+04 ... 5.413e+04

    standard_name :

    total_magnetic_intensity_filtered

    long_name :

    Filtered total magnetic intensity data

    units :

    nanoTesla

    null_value :

    not_defined

    valid_range :

    [53748.78052716 55382.3731643 ]

    grid_mapping :

    spatial_ref

    array([54810.74082178, 54811.7314644 , 54799.12595733, ...,
           54126.9316965 , 54125.81827479, 54130.6798889 ], shape=(6785,))

  • mag_raw
    (index)
    float64
    5.481e+04 5.481e+04 ... 5.413e+04

    standard_name :

    total_magnetic_intensity_raw

    long_name :

    Raw total magnetic intensity data

    units :

    nanoTesla

    null_value :

    not_defined

    valid_range :

    [53748.69003127 55382.36268256]

    grid_mapping :

    spatial_ref

    array([54810.79920632, 54811.68274571, 54799.1318    , ...,
           54126.88075488, 54125.79409894, 54130.7198    ], shape=(6785,))

  • tmi
    (index)
    float64
    5.482e+04 5.482e+04 ... 5.413e+04

    standard_name :

    total_magnetic_intensity

    long_name :

    Diurnally corrected filtered total magnetic intensity

    units :

    nanoTesla

    null_value :

    not_defined

    valid_range :

    [53747.01299979 55391.25656274]

    grid_mapping :

    spatial_ref

    array([54820.91888403, 54821.95576237, 54809.34918625, ...,
           54125.61269917, 54124.4552492 , 54129.36742069], shape=(6785,))

  • rmf
    (index)
    float64
    210.6 210.6 197.3 ... -124.5 -120.3

    standard_name :

    residual_magnetic_field

    long_name :

    Residual magnetic field, IGRF corrected based on 2015 model

    units :

    nanoTesla

    null_value :

    not_defined

    valid_range :

    [-477.06537569 810.79350952]

    grid_mapping :

    spatial_ref

    array([ 210.59657846,  210.6424326 ,  197.31952694, ..., -122.69013946,
           -124.51264653, -120.25329335], shape=(6785,))

  • igrf
    (index)
    float64
    5.461e+04 5.461e+04 ... 5.425e+04

    standard_name :

    magnetic_igrf_model

    long_name :

    Magnetic IGRF value from 2015 model

    units :

    nanoTesla

    null_value :

    not_defined

    valid_range :

    [54214.68388696 54617.76946961]

    grid_mapping :

    spatial_ref

    array([54610.32230557, 54611.31332977, 54612.02965931, ...,
           54248.30283863, 54248.96789573, 54249.62071404], shape=(6785,))

  • inc
    (index)
    float64
    71.13 71.13 71.13 ... 70.48 70.48

    standard_name :

    inclination

    long_name :

    IGRF inclination

    units :

    degree

    null_value :

    not_defined

    valid_range :

    [70.428085 71.13609905]

    grid_mapping :

    spatial_ref

    array([71.12617307, 71.12744956, 71.1287454 , ..., 70.47968109,
           70.48106373, 70.48259329], shape=(6785,))

  • dec
    (index)
    float64
    -4.796 -4.792 ... -3.975 -3.972

    standard_name :

    decliniation

    long_name :

    IGRF declination

    units :

    degree

    null_value :

    not_defined

    valid_range :

    [-4.8578344 -3.9487948]

    grid_mapping :

    spatial_ref

    array([-4.79558025, -4.79154367, -4.78745496, ..., -3.97909162,
           -3.97524359, -3.97151876], shape=(6785,))

• Attributes: (9)

  content :

  raw data

  comment :

  Contains mag data

  type :

  data

  structure :

  tabular

  mode :

  airborne

  method :

  magnetic

  submethod :

  total field

  instrument :

  cesium vapour

  property :

  magnetic susceptibility

1 - Gridded Data - Import a tif of gridded mag data.

d_supp1 = join(data_path, 'WI_Magnetics_grids_md.yml')

# Add the raw AEM data as a tabular dataset
data_container.gs.add(key='grids', metadata_file=d_supp1)

<xarray.DataTree 'grids'>
Group: /survey/data/grids
    Dimensions:       (x: 799, nv: 2, y: 1155)
    Coordinates:
      * x             (x) float64 6kB 6.551e+05 6.552e+05 ... 7.348e+05 7.349e+05
      * nv            (nv) int64 16B 0 1
      * y             (y) float64 9kB 4.953e+05 4.952e+05 ... 3.8e+05 3.799e+05
        spatial_ref   float64 8B 0.0
    Data variables:
        x_bnds        (x, nv) float64 13kB 6.55e+05 6.551e+05 ... 7.349e+05
        y_bnds        (y, nv) float64 18kB 4.954e+05 4.953e+05 ... 3.8e+05 3.799e+05
        magnetic_tmi  (y, x) float64 7MB nan nan nan nan nan ... nan nan nan nan nan
        magnetic_rmf  (y, x) float64 7MB nan nan nan nan nan ... nan nan nan nan nan
    Attributes:
        content:     gridded magnetic maps
        comment:     This dataset includes AEM-derived estimates of the elevation...
        type:        data
        structure:   raster
        mode:        airborne
        method:      magnetic
        submethod:   total field
        instrument:  cesium vapour
        property:    magnetic

xarray.DataTree

'grids'

• Dimensions:
  • x: 799
  • nv: 2
  • y: 1155
• Coordinates: (4)
  • x
    (x)
    float64
    6.551e+05 6.552e+05 ... 7.349e+05

    standard_name :

    projection_x_coordinate

    long_name :

    Easting, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83)

    units :

    meter

    null_value :

    not_defined

    axis :

    X

    valid_range :

    [655072.0482 734872.0482]

    grid_mapping :

    spatial_ref

    bounds :

    x_bnds

    array([655072.0482, 655172.0482, 655272.0482, ..., 734672.0482, 734772.0482,
           734872.0482], shape=(799,))

  • nv
    (nv)
    int64
    0 1

    standard_name :

    nv

    long_name :

    Number of vertices for bounding variables

    units :

    not_defined

    null_value :

    not_defined

    valid_range :

    [0. 1.]

    grid_mapping :

    spatial_ref

    array([0, 1])

  • y
    (y)
    float64
    4.953e+05 4.952e+05 ... 3.799e+05

    standard_name :

    projection_y_coordinate

    long_name :

    Northing, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83)

    units :

    meter

    null_value :

    not_defined

    axis :

    Y

    valid_range :

    [379902.3947 495302.3947]

    grid_mapping :

    spatial_ref

    bounds :

    y_bnds

    array([495302.3947, 495202.3947, 495102.3947, ..., 380102.3947, 380002.3947,
           379902.3947], shape=(1155,))

  • spatial_ref
    ()
    float64
    0.0

    crs_wkt :

    PROJCRS["NAD83(HARN) / Wisconsin Transverse Mercator",BASEGEOGCRS["NAD83(HARN)",DATUM["NAD83 (High Accuracy Reference Network)",ELLIPSOID["GRS 1980",6378137,298.257222101,LENGTHUNIT["metre",1]]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],ID["EPSG",4152]],CONVERSION["Wisconsin Transverse Mercator 83",METHOD["Transverse Mercator",ID["EPSG",9807]],PARAMETER["Latitude of natural origin",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8801]],PARAMETER["Longitude of natural origin",-90,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["Scale factor at natural origin",0.9996,SCALEUNIT["unity",1],ID["EPSG",8805]],PARAMETER["False easting",520000,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False northing",-4480000,LENGTHUNIT["metre",1],ID["EPSG",8807]]],CS[Cartesian,2],AXIS["easting (X)",east,ORDER[1],LENGTHUNIT["metre",1]],AXIS["northing (Y)",north,ORDER[2],LENGTHUNIT["metre",1]],USAGE[SCOPE["State-wide spatial data management."],AREA["United States (USA) - Wisconsin."],BBOX[42.48,-92.89,47.31,-86.25]],ID["EPSG",3071]]

    semi_major_axis :

    6378137.0

    semi_minor_axis :

    6356752.314140356

    inverse_flattening :

    298.257222101

    reference_ellipsoid_name :

    GRS 1980

    longitude_of_prime_meridian :

    0.0

    prime_meridian_name :

    Greenwich

    geographic_crs_name :

    NAD83(HARN)

    horizontal_datum_name :

    NAD83 (High Accuracy Reference Network)

    projected_crs_name :

    NAD83(HARN) / Wisconsin Transverse Mercator

    grid_mapping_name :

    transverse_mercator

    latitude_of_projection_origin :

    0.0

    longitude_of_central_meridian :

    -90.0

    false_easting :

    520000.0

    false_northing :

    -4480000.0

    scale_factor_at_central_meridian :

    0.9996

    authority :

    EPSG

    wkid :

    3071

    GeoTransform :

    (655022.0482, 100.0, 0.0, 495352.3947, 0.0, -100.0)

    array(0.)

• Data variables: (4)
  • x_bnds
    (x, nv)
    float64
    6.55e+05 6.551e+05 ... 7.349e+05

    standard_name :

    projection_x_coordinate_bounds

    long_name :

    Easting, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83) cell boundaries

    units :

    meter

    null_value :

    not_defined

    axis :

    X

    valid_range :

    [655022.0482 734922.0482]

    grid_mapping :

    spatial_ref

    array([[655022.0482, 655122.0482],
           [655122.0482, 655222.0482],
           [655222.0482, 655322.0482],
           ...,
           [734622.0482, 734722.0482],
           [734722.0482, 734822.0482],
           [734822.0482, 734922.0482]], shape=(799, 2))

  • y_bnds
    (y, nv)
    float64
    4.954e+05 4.953e+05 ... 3.799e+05

    standard_name :

    projection_y_coordinate_bounds

    long_name :

    Northing, Wisconsin Transverse Mercator (WTM), North American Datum of 1983 (NAD83) cell boundaries

    units :

    meter

    null_value :

    not_defined

    axis :

    Y

    valid_range :

    [379852.3947 495352.3947]

    grid_mapping :

    spatial_ref

    array([[495352.3947, 495252.3947],
           [495252.3947, 495152.3947],
           [495152.3947, 495052.3947],
           ...,
           [380152.3947, 380052.3947],
           [380052.3947, 379952.3947],
           [379952.3947, 379852.3947]], shape=(1155, 2))

  • magnetic_tmi
    (y, x)
    float64
    nan nan nan nan ... nan nan nan nan

    standard_name :

    total_magnetic_intensity

    long_name :

    Total magnetic intensity, diurnally corrected and filtered

    units :

    nanoTesla

    null_value :

    -9999.99

    valid_range :

    [53745.6015625 55396.48828125]

    grid_mapping :

    spatial_ref

    array([[nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan],
           ...,
           [nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan]], shape=(1155, 799))

  • magnetic_rmf
    (y, x)
    float64
    nan nan nan nan ... nan nan nan nan

    standard_name :

    residual_magnetic_field

    long_name :

    Residual magnetic field, IGRF corrected from 2015 model

    units :

    nanoTesla

    null_value :

    -9999.99

    valid_range :

    [-478.36932373 815.26867676]

    grid_mapping :

    spatial_ref

    array([[nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan],
           ...,
           [nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan],
           [nan, nan, nan, ..., nan, nan, nan]], shape=(1155, 799))

• Attributes: (9)

  content :

  gridded magnetic maps

  comment :

  This dataset includes AEM-derived estimates of the elevation of the top of bedrock produced by USGS

  type :

  data

  structure :

  raster

  mode :

  airborne

  method :

  magnetic

  submethod :

  total field

  instrument :

  cesium vapour

  property :

  magnetic

Save to NetCDF file

d_out = join(data_path, 'WI_Magnetics.nc')
survey.gs.to_netcdf(d_out)

Reading back in

new_survey = gspy.open_datatree(d_out)['survey']

print(new_survey)

<xarray.DataTree 'survey'>
Group: /survey
│   Dimensions:                 ()
│   Coordinates:
│       spatial_ref             float64 8B ...
│   Data variables:
│       survey_information      float64 8B ...
│       flightline_information  float64 8B ...
│       survey_equipment        float64 8B ...
│   Attributes:
│       title:        Magnetic data from SkyTEM Airborne Electromagnetic (AEM) Su...
│       institution:  USGS Geology, Geophysics, and Geochemistry Science Center
│       source:       SkyTEM raw data, USGS processed data
│       history:      (1) Data acquisition 01/2021 - 02/2021 by SkyTEM Canada Inc...
│       references:   Minsley, Burke J., B.R. Bloss, D.J. Hart, W. Fitzpatrick, M...
│       comment:      This dataset includes minimally processed (raw) AEM and raw...
│       summary:      Magnetic survey data were collected during January and Febr...
│       content:      Data
│       created_by:   gspy==2.0.0
│       conventions:  CF-1.8, GS-2.0
│       type:         survey
└── Group: /survey/data
    │   Dimensions:      ()
    │   Data variables:
    │       spatial_ref  float64 8B ...
    │   Attributes:
    │       content:  raw and gridded data
    │       comment:  This is a test
    │       type:     container
    ├── Group: /survey/data/raw_data
    │   │   Dimensions:      (index: 6785)
    │   │   Coordinates:
    │   │     * index        (index) int32 27kB 0 1 2 3 4 5 ... 6780 6781 6782 6783 6784
    │   │       spatial_ref  float64 8B ...
    │   │       x            (index) float64 54kB ...
    │   │       y            (index) float64 54kB ...
    │   │       z            (index) float64 54kB ...
    │   │   Data variables: (12/20)
    │   │       fid          (index) float64 54kB ...
    │   │       line         (index) int64 54kB ...
    │   │       e_nad83      (index) float64 54kB ...
    │   │       n_nad83      (index) float64 54kB ...
    │   │       lon          (index) float64 54kB ...
    │   │       lat          (index) float64 54kB ...
    │   │       ...           ...
    │   │       mag_raw      (index) float64 54kB ...
    │   │       tmi          (index) float64 54kB ...
    │   │       rmf          (index) float64 54kB ...
    │   │       igrf         (index) float64 54kB ...
    │   │       inc          (index) float64 54kB ...
    │   │       dec          (index) float64 54kB ...
    │   │   Attributes:
    │   │       content:     raw data
    │   │       comment:     Contains mag data
    │   │       type:        data
    │   │       structure:   tabular
    │   │       mode:        airborne
    │   │       method:      magnetic
    │   │       submethod:   total field
    │   │       instrument:  cesium vapour
    │   │       property:    magnetic susceptibility
    │   └── Group: /survey/data/raw_data/magnetic_system
    │           Dimensions:      (dim_0: 1)
    │           Dimensions without coordinates: dim_0
    │           Data variables:
    │               sample_rate  (dim_0) float64 8B ...
    │               resolution   (dim_0) float64 8B ...
    │           Attributes:
    │               type:        system
    │               mode:        airborne
    │               method:      magnetic
    │               submethod:   total field
    │               instrument:  cesium vapour
    │               name:        magnetic_system
    └── Group: /survey/data/grids
            Dimensions:       (x: 799, nv: 2, y: 1155)
            Coordinates:
              * x             (x) float64 6kB 6.551e+05 6.552e+05 ... 7.348e+05 7.349e+05
              * nv            (nv) int64 16B 0 1
              * y             (y) float64 9kB 4.953e+05 4.952e+05 ... 3.8e+05 3.799e+05
                spatial_ref   float64 8B ...
            Data variables:
                x_bnds        (x, nv) float64 13kB ...
                y_bnds        (y, nv) float64 18kB ...
                magnetic_tmi  (y, x) float64 7MB ...
                magnetic_rmf  (y, x) float64 7MB ...
            Attributes:
                content:     gridded magnetic maps
                comment:     This dataset includes AEM-derived estimates of the elevation...
                type:        data
                structure:   raster
                mode:        airborne
                method:      magnetic
                submethod:   total field
                instrument:  cesium vapour
                property:    magnetic

Plotting

plt.figure()
new_survey['data/raw_data']['height'].plot()
plt.tight_layout()

pd = new_survey['data/raw_data']['tmi']
plt.figure()
pd.plot()
plt.tight_layout()

m = new_survey['data/grids/magnetic_tmi']
plt.figure()
m.plot(cmap='jet')
plt.tight_layout()

plt.show()

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