Profiling Lidars

Nadir-pointing single-beam atmospheric profiling lidar models. Each instrument records a vertical column directly beneath the platform; there is no cross-track swath. Horizontal resolution is set by post-processing averaging windows times ground speed.

For a worked tutorial covering all three pre-configured instruments, see notebooks/profiling_lidar_planning.ipynb.

The Doppler wind profiler family (AWP) is not part of this hierarchy because its dual-LOS vector-retrieval geometry needs a different abstraction. See AWP Profiling.

Base class

class ProfilingLidar[source]

Bases: Sensor

Base class for nadir-pointing single-beam airborne profiling lidars.

Captures the geometry and timing parameters that matter for flight planning: laser wavelengths, pulse rate, telescope/beam optics, vertical bin resolution, and FPGA-averaged sampling rate. Helpers compute footprint diameter from altitude (when beam divergence is known) and effective horizontal resolution from a post-processing averaging window.

__init__(name, *, wavelengths, pulse_rate, telescope_diameter, vertical_resolution, sampling_rate, beam_divergence=None, native_horizontal_resolution=None)[source]
Parameters:
footprint_diameter(altitude_agl)[source]

Laser footprint diameter on the ground at the given altitude AGL.

Requires beam_divergence to have been set at construction; raises HyPlanValueError otherwise.

Return type:

Quantity

Parameters:

altitude_agl (Quantity)

horizontal_resolution(ground_speed, averaging_time)[source]

Effective horizontal resolution for a post-processing averaging window.

Return type:

Quantity

Parameters:
pulses_per_profile(averaging_time)[source]

Number of laser pulses averaged into one profile at the given window.

Return type:

int

Parameters:

averaging_time (Quantity)

NASA Langley HSRL-2

3-wavelength (355/532/1064 nm) backscatter and extinction lidar with a Michelson interferometer for the 355 nm channel. Defaults reflect the TCAP 2012 deployment (Müller et al., 2014); pulse rate, telescope, and beam divergence are inherited from the HSRL-1 design (Hair et al., 2008).

class HSRL2[source]

Bases: ProfilingLidar

NASA Langley High Spectral Resolution Lidar, second generation.

3-wavelength (355/532/1064 nm) backscatter and extinction lidar with a Michelson interferometer for the 355 nm channel. Successor to HSRL-1 (Hair et al., 2008); inherits the same Fibertek-built Nd:YAG laser, 16-inch Newtonian telescope, and 200 Hz pulse rate, extended with a third wavelength channel and Michelson interferometer (Burton et al., 2018). Defaults reflect the airborne TCAP 2012 deployment documented in Müller et al. (2014).

__init__(name='HSRL-2', *, wavelengths=(<Quantity(355, 'nanometer')>, <Quantity(532, 'nanometer')>, <Quantity(1064, 'nanometer')>), pulse_rate=<Quantity(200, 'hertz')>, telescope_diameter=<Quantity(40.6, 'centimeter')>, beam_divergence=<Quantity(0.8, 'milliradian')>, vertical_resolution=<Quantity(15, 'meter')>, sampling_rate=<Quantity(2, 'hertz')>, native_horizontal_resolution=<Quantity(100, 'meter')>)[source]
Parameters:

NASA Langley HALO

Multi-function airborne nadir lidar combining HSRL aerosol/cloud profiling with water-vapor and methane DIAL/IPDA (Carroll et al., 2022). Reconfigurable across three transmitter modes (CH₄+HSRL, H₂O+HSRL, CH₄+H₂O) sharing a common multi-channel receiver. The default wavelengths lists all four channels — override at construction to model a specific transmitter mode.

class HALO[source]

Bases: ProfilingLidar

NASA Langley High Altitude Lidar Observatory.

Multi-function airborne nadir lidar combining HSRL aerosol/cloud profiling with water-vapor and methane DIAL/IPDA. Uses a higher 1 kHz-PRF laser than HSRL-2 and adds 935 nm (H2O) and 1645 nm (CH4) channels.

HALO is reconfigurable across three transmitter modes sharing a common multi-channel receiver:

  • CH4 DIAL + HSRL (active: 532, 1064, 1645 nm)

  • H2O DIAL + HSRL (active: 532, 935, 1064 nm)

  • CH4 DIAL + H2O DIAL (active: 935, 1064, 1645 nm)

The default wavelengths lists all four channels; override to model a specific mode. Planning geometry is identical across modes — this class does not enforce which combinations are physically simultaneous.

Defaults reflect the ACT-America 2019 NASA C-130 deployment documented in Carroll et al. (2022). Beam divergence is not published for HALO and is left unset by default.

__init__(name='HALO', *, wavelengths=(<Quantity(532, 'nanometer')>, <Quantity(935, 'nanometer')>, <Quantity(1064, 'nanometer')>, <Quantity(1645, 'nanometer')>), pulse_rate=<Quantity(1, 'kilohertz')>, telescope_diameter=<Quantity(40, 'centimeter')>, beam_divergence=None, vertical_resolution=<Quantity(15, 'meter')>, sampling_rate=<Quantity(2, 'hertz')>, native_horizontal_resolution=None)[source]
Parameters:

NASA Goddard CPL

Compact 3-wavelength (355/532/1064 nm) backscatter lidar for high-altitude platforms (ER-2, Global Hawk, WB-57). Uses a 5 kHz-PRF, low-pulse-energy, photon-counting design — a different operating regime from the NASA Langley HSRL family. Defaults reflect the standard 1 Hz / 30 m × 200 m product documented in McGill et al. (2002).

class CPL[source]

Bases: ProfilingLidar

NASA Goddard Cloud Physics Lidar.

Compact 3-wavelength (355/532/1064 nm) backscatter lidar designed for high-altitude platforms (ER-2, Global Hawk, WB-57). Uses a 5 kHz-PRF low-pulse-energy laser with photon-counting detection — a different operating regime from NASA Langley’s HSRL family. Primary science is cirrus and aerosol profiling.

Defaults reflect the standard product (1 Hz, 30 m vertical x 200 m horizontal); the raw 10 Hz / 20 m horizontal product is also available operationally but not modeled as the default.

The 100 microradian value is McGill 2002’s receiver field of view. CPL’s transmit divergence is matched to the receive FOV by design, so the same value is used here for beam_divergence.

References

McGill, M., et al. (2002). Cloud Physics Lidar: instrument description and initial measurement results. Applied Optics, 41(18), 3725-3734. https://doi.org/10.1364/AO.41.003725

__init__(name='CPL', *, wavelengths=(<Quantity(355, 'nanometer')>, <Quantity(532, 'nanometer')>, <Quantity(1064, 'nanometer')>), pulse_rate=<Quantity(5, 'kilohertz')>, telescope_diameter=<Quantity(20, 'centimeter')>, beam_divergence=<Quantity(100, 'microradian')>, vertical_resolution=<Quantity(30, 'meter')>, sampling_rate=<Quantity(1, 'hertz')>, native_horizontal_resolution=<Quantity(200, 'meter')>)[source]
Parameters:

References

  1. Müller, D., Hostetler, C. A., Ferrare, R. A., Burton, S. P., et al. (2014). Airborne Multiwavelength High Spectral Resolution Lidar (HSRL-2) Observations during TCAP 2012. Atmospheric Measurement Techniques, 7, 3487-3496. https://doi.org/10.5194/amt-7-3487-2014

  2. Hair, J. W., et al. (2008). Airborne High Spectral Resolution Lidar for profiling aerosol optical properties. Applied Optics, 47(36), 6734-6752. https://doi.org/10.1364/AO.47.006734

  3. Burton, S. P., et al. (2018). Calibration of a high spectral resolution lidar using a Michelson interferometer, with data examples from ORACLES. Applied Optics, 57(21), 6061-6075. https://doi.org/10.1364/AO.57.006061

  4. Carroll, B. J., Nehrir, A. R., Kooi, S. A., et al. (2022). Evaluation of the High Altitude Lidar Observatory (HALO) methane retrievals during the summer 2019 ACT-America campaign. Atmospheric Measurement Techniques, 15, 4623-4650. https://doi.org/10.5194/amt-15-4623-2022

  5. McGill, M., et al. (2002). Cloud Physics Lidar: instrument description and initial measurement results. Applied Optics, 41(18), 3725-3734. https://doi.org/10.1364/AO.41.003725