Doppler Wind Lidars

There are two Doppler wind lidars at the Barbados Cloud Observatory (BCO) – both HALO Photonics (formerly; now Lumi Bird) Stream Line Pro Scanning Doppler Lidars.

Both instruments use a laser beam with a wavelength of 1550 nm to measure line-of-sight component of wind velocity in the atmospheric boundary layer. Two modes of operation are possible - staring at the zenith and scanning in several vertically inclined directions. These two modes may be distinguished by the zenith angle of the measurement.

Nomenclature of instruments

Both Doppler wind lidars at BCO are the same instruments in terms of their specifications (both are commercially produced models of the same kind). Therefore we will simply distinguish them by their order of arrival at BCO.

• WindLidar1 -> Chronologically first at BCO

• WindLidar2 -> Chronologically second at BCO

Configurations

Wind lidars have been operated in different configurations over time. These configurations can be distinguished by the number of averaging gates along the laser beam and their length. The different available configurations are listed here:

Dataset	Gates number	Gate length	Start date	End date
BCO.windlidar1_c1_v1	100	30.0 m	2015-07-26 2015-09-18 2019-09-01 2021-07-21 2025-09-23	2015-09-17 2019-08-27 2019-10-31 2024-09-20 today
BCO.windlidar1_c2_v1	1000	30.0 m	2019-08-27	2019-09-01
BCO.windlidar1_c3_v1	100	60.0 m	2015-09-17	2015-09-18
BCO.windlidar2_c1_v1	100	30.0 m	2019-02-18 2021-05-21 2024-09-20	2021-04-11 2021-07-21 2025-09-10
BCO.windlidar2_c2_v1	160	60.0 m	2021-04-11	2021-05-21

Deployments

During the operation at BCO wind lidars were deployed on two containers. The locations of instruments at different periods of time are listed here:

Instrument	Location (container)	Mode	Start date	End date
WindLidar1	Testbed	Scan	2015-07-26	2016-02-29
WindLidar1	Testbed	Stare	2016-03-02	2019-10-31
WindLidar1	WBand	Stare	2021-07-21	2024-09-20
WindLidar1	WBand	Stare	2025-09-23	today
WindLidar2	WBand	Stare	2019-02-18	2019-03-05
WindLidar2	WBand	Scan	2019-03-06	2021-07-21
WindLidar2	WBand	Stare	2024-09-20	2025-09-10

Notes on the Deployments table

• Modes:

  • Stare mode: provides only vertical winds

  • Scan mode: provides both horizontal and vertical winds

• Testbed and WBand containers are roughly 5 m apart and have the same height.

• The temporal resolution of the vertical wind speed is 1.3 s (information obtained from Wiki as on 30.07.2025).

• We decided that the change of location (between two containers 5 m apart) does not warrant the dataset to be provided as being measurements from two deployments, therefore WindLidar1’s Stare mode data from both Testbed and WBand containers are provided in the same dataset.

Example

Get wind lidar dataset from tcodata:

import intake


cat = intake.open_catalog("https://tcodata.mpimet.mpg.de/catalog.yaml")
wl1 = cat.BCO.windlidar1_c1_v1(chunks=None).to_dask()
wl1

/builds/tco/bco/docs/.venv/lib/python3.12/site-packages/intake_xarray/base.py:21: FutureWarning: The return type of `Dataset.dims` will be changed to return a set of dimension names in future, in order to be more consistent with `DataArray.dims`. To access a mapping from dimension names to lengths, please use `Dataset.sizes`.
  'dims': dict(self._ds.dims),

<xarray.Dataset> Size: 325GB
Dimensions:              (time: 132128643, range: 100)
Coordinates:
    alt                  int64 8B ...
    lat                  float64 8B ...
    lon                  float64 8B ...
  * range                (range) float64 800B 15.0 45.0 ... 2.955e+03 2.985e+03
    sensor_alt           int64 8B ...
  * time                 (time) datetime64[ns] 1GB 2015-07-26T21:11:44.379600...
Data variables: (12/13)
    azi                  (time) float64 1GB ...
    beta                 (time, range) float64 106GB ...
    doppler              (time, range) float64 106GB ...
    focus                (time) int64 1GB ...
    gate_length          float64 8B ...
    gates_number         int64 8B ...
    ...                   ...
    pitch                (time) float64 1GB ...
    pulses               (time) int64 1GB ...
    resolution           float64 8B ...
    roll                 (time) float64 1GB ...
    timejump_correction  (time) bool 132MB ...
    zenith               (time) float64 1GB ...
Attributes: (12/13)
    Conventions:           CF-1.12
    _logical_cutoff_date:  2023-06-26T00:00:00Z
    bcoproc_version:       0.0.0.post1185.dev0+c830e01
    featureType:           timeSeriesProfile
    history:               processed with bcoproc l1
    institution:           Max Planck Institute for Meteorology, Hamburg
    ...                    ...
    location:              The Barbados Cloud Observatory (BCO), Deebles Poin...
    platform:              BCO
    source:                Halo Photonics Stream Line Pro Scanning Doppler Lidar
    summary:               The Halo Photonics Stream Line Pro Scanning Dopple...
    title:                 WindLidar data from BCO (Level 1)
    tool_versions:         {"Python": "3.11.2 (main, Apr 28 2025, 14:11:48) [...

xarray.Dataset

• Dimensions:
  • time: 132128643
  • range: 100
• Coordinates: (6)
  • alt
    ()
    int64
    ...

    long_name :

    height above mean sea level

    standard_name :

    altitude

    units :

    m

    [1 values with dtype=int64]

  • lat
    ()
    float64
    ...

    long_name :

    north latitude

    units :

    degree_north

    valid_max :

    90.0

    valid_min :

    -90.0

    [1 values with dtype=float64]

  • lon
    ()
    float64
    ...

    long_name :

    east longitude

    units :

    degree_east

    valid_max :

    180.0

    valid_min :

    -180.0

    [1 values with dtype=float64]

  • range
    (range)
    float64
    15.0 45.0 ... 2.955e+03 2.985e+03

    array([  15.,   45.,   75.,  105.,  135.,  165.,  195.,  225.,  255.,  285.,
            315.,  345.,  375.,  405.,  435.,  465.,  495.,  525.,  555.,  585.,
            615.,  645.,  675.,  705.,  735.,  765.,  795.,  825.,  855.,  885.,
            915.,  945.,  975., 1005., 1035., 1065., 1095., 1125., 1155., 1185.,
           1215., 1245., 1275., 1305., 1335., 1365., 1395., 1425., 1455., 1485.,
           1515., 1545., 1575., 1605., 1635., 1665., 1695., 1725., 1755., 1785.,
           1815., 1845., 1875., 1905., 1935., 1965., 1995., 2025., 2055., 2085.,
           2115., 2145., 2175., 2205., 2235., 2265., 2295., 2325., 2355., 2385.,
           2415., 2445., 2475., 2505., 2535., 2565., 2595., 2625., 2655., 2685.,
           2715., 2745., 2775., 2805., 2835., 2865., 2895., 2925., 2955., 2985.])

  • sensor_alt
    ()
    int64
    ...

    [1 values with dtype=int64]

  • time
    (time)
    datetime64[ns]
    2015-07-26T21:11:44.379600 ... 2...

    axis :

    T

    standard_name :

    time

    units_metadata :

    leap_seconds: utc

    array(['2015-07-26T21:11:44.379600000', '2015-07-26T21:11:48.458400000',
           '2015-07-26T21:11:51.010800000', ..., '2023-06-25T23:59:56.810400000',
           '2023-06-25T23:59:58.030800000', '2023-06-25T23:59:59.251200000'],
          shape=(132128643,), dtype='datetime64[ns]')

• Data variables: (13)
  • azi
    (time)
    float64
    ...

    long_name :

    horizontal angle offset to North (0 degrees)

    standard_name :

    sensor_azimuth_angle

    units :

    degree

    [132128643 values with dtype=float64]

  • beta
    (time, range)
    float64
    ...

    long_name :

    backscatter intensity beta

    units :

    m-1 sr-1

    [13212864300 values with dtype=float64]

  • doppler
    (time, range)
    float64
    ...

    long_name :

    uncorrected doppler velocity

    standard_name :

    radial_velocity_of_scatterers_away_from_instrument

    units :

    m s-1

    [13212864300 values with dtype=float64]

  • focus
    (time)
    int64
    ...

    long_name :

    focus position with respect to the device

    units :

    m

    [132128643 values with dtype=int64]

  • gate_length
    ()
    float64
    ...

    long_name :

    length of the averaging gate

    units :

    m

    [1 values with dtype=float64]

  • gates_number
    ()
    int64
    ...

    long_name :

    number of gates for the measurement

    units :

    1

    [1 values with dtype=int64]

  • intensity
    (time, range)
    float64
    ...

    long_name :

    backscatter intensity (SNR + 1)

    units :

    1

    [13212864300 values with dtype=float64]

  • pitch
    (time)
    float64
    ...

    description :

    positive pitch indicates that the side with the optical unit is higher than the other part

    long_name :

    pitch angle of the instrument

    resolution :

    0.1 degrees

    standard_name :

    platform_pitch

    units :

    degree

    [132128643 values with dtype=float64]

  • pulses
    (time)
    int64
    ...

    long_name :

    number of pulses constituting one ray

    units :

    1

    [132128643 values with dtype=int64]

  • resolution
    ()
    float64
    ...

    long_name :

    resolution of the velocity measured by the Doppler shift

    units :

    m s-1

    [1 values with dtype=float64]

  • roll
    (time)
    float64
    ...

    description :

    positive roll indicates that the northward side is higher

    long_name :

    roll angle of the instrument

    resolution :

    0.1 degrees

    standard_name :

    platform_roll

    units :

    degree

    [132128643 values with dtype=float64]

  • timejump_correction
    (time)
    bool
    ...

    [132128643 values with dtype=bool]

  • zenith
    (time)
    float64
    ...

    long_name :

    vertical angle offset to the zenith (0 degrees)

    standard_name :

    sensor_zenith_angle

    units :

    degree

    [132128643 values with dtype=float64]

• Indexes: (2)
  • range
    PandasIndex

    PandasIndex(Index([  15.0,   45.0,   75.0,  105.0,  135.0,  165.0,  195.0,  225.0,  255.0,
            285.0,  315.0,  345.0,  375.0,  405.0,  435.0,  465.0,  495.0,  525.0,
            555.0,  585.0,  615.0,  645.0,  675.0,  705.0,  735.0,  765.0,  795.0,
            825.0,  855.0,  885.0,  915.0,  945.0,  975.0, 1005.0, 1035.0, 1065.0,
           1095.0, 1125.0, 1155.0, 1185.0, 1215.0, 1245.0, 1275.0, 1305.0, 1335.0,
           1365.0, 1395.0, 1425.0, 1455.0, 1485.0, 1515.0, 1545.0, 1575.0, 1605.0,
           1635.0, 1665.0, 1695.0, 1725.0, 1755.0, 1785.0, 1815.0, 1845.0, 1875.0,
           1905.0, 1935.0, 1965.0, 1995.0, 2025.0, 2055.0, 2085.0, 2115.0, 2145.0,
           2175.0, 2205.0, 2235.0, 2265.0, 2295.0, 2325.0, 2355.0, 2385.0, 2415.0,
           2445.0, 2475.0, 2505.0, 2535.0, 2565.0, 2595.0, 2625.0, 2655.0, 2685.0,
           2715.0, 2745.0, 2775.0, 2805.0, 2835.0, 2865.0, 2895.0, 2925.0, 2955.0,
           2985.0],
          dtype='float64', name='range'))

  • time
    PandasIndex

    PandasIndex(DatetimeIndex(['2015-07-26 21:11:44.379600', '2015-07-26 21:11:48.458400',
                   '2015-07-26 21:11:51.010800', '2015-07-26 21:11:53.541600',
                   '2015-07-26 21:11:56.068800', '2015-07-26 21:11:58.599600',
                   '2015-07-26 21:12:01.130400', '2015-07-26 21:12:03.661200',
                   '2015-07-26 21:12:06.188400', '2015-07-26 21:12:10.198800',
                   ...
                   '2023-06-25 23:59:48.210000', '2023-06-25 23:59:49.419600',
                   '2023-06-25 23:59:50.640000', '2023-06-25 23:59:51.849600',
                   '2023-06-25 23:59:53.070000', '2023-06-25 23:59:54.290400',
                   '2023-06-25 23:59:55.600800', '2023-06-25 23:59:56.810400',
                   '2023-06-25 23:59:58.030800', '2023-06-25 23:59:59.251200'],
                  dtype='datetime64[ns]', name='time', length=132128643, freq=None))

• Attributes: (13)

  Conventions :

  CF-1.12

  _logical_cutoff_date :

  2023-06-26T00:00:00Z

  bcoproc_version :

  0.0.0.post1185.dev0+c830e01

  featureType :

  timeSeriesProfile

  history :

  processed with bcoproc l1

  institution :

  Max Planck Institute for Meteorology, Hamburg

  license :

  CC0-1.0

  location :

  The Barbados Cloud Observatory (BCO), Deebles Point, Barbados, West Indies

  platform :

  BCO

  source :

  Halo Photonics Stream Line Pro Scanning Doppler Lidar

  summary :

  The Halo Photonics Stream Line Pro Scanning Doppler Lidar is used for wind velocity measurements in the atmospheric boundary layer. The WindLidar detects the Doppler shift from moving aerosols and cloud particles along the laser beam and derives the corresponding line-of-sight component of wind velocity. The laser wavelength is 1550 nm. Two modes of operation are possible - staring at the zenith and scanning in several vertically inclined directions. These two modes may be distinguished by the zenith angle of the measurement.

  title :

  WindLidar data from BCO (Level 1)

  tool_versions :

  {"Python": "3.11.2 (main, Apr 28 2025, 14:11:48) [GCC 12.2.0]", "pandas": "2.2.3", "cloudpickle": "3.1.1", "bcoproc": "0.0.0.post1185.dev0+c830e01", "importlib_metadata": "8.7.0", "attrs": "25.3.0", "locket": "1.0.0", "cftime": "1.6.4.post1", "partd": "1.4.2", "datarecords": "0.0.0.post1185.dev0+c830e01", "dask": "2025.4.1", "numpy": "2.2.5", "yarl": "1.20.0", "multidict": "6.4.3", "pendulum": "3.1.0", "iniconfig": "2.1.0", "xarray": "2025.4.0", "pytest": "8.3.5", "idna": "3.10", "pluggy": "1.5.0", "frozenlist": "1.6.0", "bcologs": "0.0.0.post1185.dev0+c830e01", "fsspec": "2025.3.2", "zipp": "3.21.0", "click": "8.1.8", "pyyaml": "6.0.2", "toolz": "1.0.0", "six": "1.17.0", "aiohttp": "3.11.18", "tzdata": "2025.2", "propcache": "0.3.1", "ruff": "0.13.0", "certifi": "2025.4.26", "aiohappyeyeballs": "2.6.1", "packaging": "25.0", "pytz": "2025.2", "netcdf4": "1.7.2", "aiosignal": "1.3.2", "python-dateutil": "2.9.0.post0"}

def is_vertical(ds):
    return ds["zenith"] < 2

def is_reliable(ds):
    # mask signals from the point where it became too much attenuated
    return (ds["intensity"] <= 1.015).cumsum("range") < 1

# cut, filter, resample and plot the data
wl1_day = wl1.sel(time="2019-01-01", range=slice(70, 1000))
wl1_1min_avg = wl1_day["doppler"].where(is_vertical(wl1_day) & is_reliable(wl1_day)).resample(time="1min").mean()
wl1_1min_avg.plot(x="time", y="range", vmin=-1, vmax=1, figsize=(12, 4), cmap="bwr")

<matplotlib.collections.QuadMesh at 0x7f07a94145f0>

Note

The intensity threshold follows Päschke et al. [2015].