Overview
The experimental data were obtained to enable analyses of the broadband fluorescence detection channel (central wavelength at 470 nm ± 50 nm) implemented in the European Space Agency Mobile Mie-Raman Lidar (EMORAL). The data were collected across several field campaigns carried out in the period between September 2022 and August 2025 in Europe.
Instrument
EMORAL lidar emits simultaneously, coaxially, and vertically the laser pulses at 355, 532, and 1064 nm into the atmosphere with a 10 Hz pulse repetition rate. The laser photons scattered in backward direction by atmospheric particles and molecules are detected with the Cassegrain telescope (300 mm aperture, adjustable 2-3.6 mrad field of view). The detection is done at 8 channels: 3 elastic (355, 532, 1064 nm), 2 depolarization (355, 532 nm), 2 nitrogen Raman (387, 607 nm), water vapor Raman (408 nm), and a broad-band fluorescence channel (420-520 nm). For all channels, analogue and photon-counting detection is performed, except 1064 nm (analog only). The signals are collected with 3.75 m spatial and 60 s temporal resolutions. The overlap between the laser beams and the full field of view of the telescope is at 250-350 m a.g.l.
Observations
The EMORAL lidar measurements were collected during field-campaigns in several locations in Europe, at different time periods and seasons. The locations are listed below:
- Observation in Magurele, Romania (23 September – 01 October 2022), site PI: Doina Nicolae, the National Institute of R&D for Optoelectronics (INOE)
- Observation in Orasac, Croatia (3-8 October 2022), site PI: Pol Ribes, the European Space Agency (ESA-ESTEC)
- Observation in Wroclaw, Poland (21 November – 1 December 2022), site PI: Anetta Drzeniecka-Osiadacz, the University of Wroclaw
- Observation in Magurele, Romania (21-21 May 2024), site PI: Livio Belegante, the National Institute of R&D for Optoelectronics (INOE)
- Observation in Cabauw, the Netherlands (06-26 June 2024), site PI: Arnoud Apituley, the Royal Netherlands Meteorological Institute (KNMI)
- Observation in Windorf, Germany (7 May 2025), site PI: Matthias Resch, InnoLas Laser GmbH
- Observation in Tor Vergata, Rome, Italy (9-15 June 2025), PI: Davide Dionisi, Italian National Research Council (CNR-ISMAR)
- Observation in Gdansk, Poland (11-12 August 2025), site PI: Lucja Janicka, University of Warsaw
- Observation in Wroclaw, Poland (21-28 August 2025), site PI: Tymoteusz Sawiński, the University of Wroclaw
- Observation in Uniejow, Poland (27-28 August 2025), site PI: Maciej Karasewicz, University of Warsaw
Data evaluation
The data evaluation was done using the Expandable Module for Rapid Analysis of Lidar Data (EMERALD) developed by the RS-Lab Team at the University of Warsaw (development lead by PI: Afwan Hafiz).
The collected and processed data comprise spatio-temporal profiles of raw and pre-processed lidar signals, quasi-optical properties at different wavelengths, lidar intensive properties, fluorescence backscatter, and fluorescence capacity.
The dataset contains observations at the different lidar detection channels, all stored in netCDF (.nc) format. The netCDF files can be accessed using freely available open-source software, including Python with packages such as xarray or netCDF4, as well as with applications such as Panoply for viewing file contents and variables.
File naming convention
Files are named using the following structure:
“L0Raw_all_channels_nrm_[observation_name]_[start_time]_to_[end_time].nc”
where:
L0Raw
Raw lidar measurement data refer to “Level-0”.
all_channels
The file includes all available lidar detection channels.
nrm
Refer to the normal lidar measurement
[observation_name]
Name identifying the measurement site or campaign name.
[start_time]
Start of the measurement period included in the file.
[end_time]
End of the measurement period is included in the file.
.nc
netCDF file format.
Example file name:
“L0Raw_all_channels_nrm_CABAUW_JUN_TNA_2024-06-25_220000_to_2024-06-26_020000.nc”
This informs that the file contains lidar measurements from the observation identified as “CABAUW_JUN_TNA”, covering the period from 25 June 2024 at 22:00:00 to 26 June 2024 at 02:00:00 UTC.
Description: Raw files of measurements, converted from the native acquisition resolution to the netCDF. The files contain time-resolved range profiles for multiple channels and both detection modes, if applicable:
Elastic channels:
- 355 nm: co-polar (parallel) and cross-polar (perpendicular), analog (mV) and photon counting (counts)
- 532 nm: co- and cross-polar, analog (mV) and photon counting (counts)
- 1064 nm: analog only (mV)
Inelastic channels:
- 387 nm (Raman N₂, excited at 355 nm): analog + photon counting
- 408 nm (Raman H₂O, excited at 355 nm): analog + photon counting
- 607 nm (Raman N₂, excited at 532 nm): analog + photon counting
Fluorescence channel:
- 470 nm (broadband fluorescence): analog + photon counting
Raw files preserve the measurement structure (time, range/altitude bins) and include instrument metadata required for further processing.
Data structure and variables
Dimensions:
1. channel: identifies the lidar detection channels. The file contains 17 channels.
2. altitude: identifies the vertical measurement bins. The file contains 16,000 vertical bins.
3. time: identifies measurement profiles recorded during the observation period. The number of time steps may differ between files.
4. wavelength: identifies wavelengths used for calculated wavelength-dependent profiles, i.e., variable “molecular_transmission”
Coordinates:
The following coordinate variables identify the channel, vertical position, wavelength, and observation time associated with the measurement data.
1. Channel
1.1. Dimensions: (channel)
1.2. Data type: int32
1.3. Description: Numeric index used to identify each of the 17 lidar channels.
2. channel_str
2.1. Dimensions: (channel)
2.2. Data type: string
2.3. Description: Text identifier for each lidar channel, including information such as wavelength, polarization, and detection mode.
3. Altitude
3.1. Dimensions: (altitude)
3.2. Data type: float64
3.3. Units: meters
3.4. Resolution: 3.75 meters
3.5. Description: Vertical coordinate associated with the lidar profile bins.
4. Time
4.1. Dimensions: (time)
4.2. Data type: datetime64[ns]
4.3. Units: UTC
4.4. Description: Timestamp associated with each recorded lidar profile.
5. acquisition_time
5.1. Dimensions: (time)
5.2. Data type: string
5.3. Units: UTC
5.4. Description: Acquisition time provided in text format.
6. Wavelength
6.1. Dimensions: (wavelength)
6.2. Data type: int32
6.3. Units: nm
6.4. Description: Wavelength coordinate used for wavelength-dependent calculated profiles.
Data variables:
Main Variables:
1. Variable: lidar_signal
1.1. Dimensions: (channel, altitude, time)
1.2. Data type: int32
1.3. Description: Raw lidar signal profiles recorded for each channel, height bin, and measurement time.
1.4. Units: mV for analog channels and photon counts for photon-counting channels.
Recommendation Note:
The “lidar_signal” variable contains a vertical signal profile for each lidar channel and each observation time. For example, a user can select a particular channel, such as the 532 nm cross-polarized photon-counting channel, and examine how its vertical atmospheric profile changes over time.
Because analog and photon-counting channels use different measurement units, users should consult the channel identifiers before comparing values between channels.
Channel-specific supporting variables:
1. first_bin
1.1. Dimensions: (channel)
1.2. Data type: int32
1.3. Description: Index of the first valid or usable vertical bin for each lidar channel, refers to the 0 meters of lidar measurement.
2. background_level
2.1. Dimensions: (channel)
2.2. Data type: float64
2.3. Description: Estimated background signal level for each lidar channel, calculated using measurements between 40 km and 60 km altitude.
2.4. Units: mV for analog channels and photon counts for photon-counting channels.
Definition: The background level describes signal contributions not associated with atmospheric laser backscatter, such as detector noise and ambient background light.
3. background_std
3.1. Dimensions: (channel)
3.2. Data type: float64
3.3. Description: Standard deviation of the estimated background signal for each lidar channel.
3.4. Units: Same units as the corresponding background_level.
Auxiliary Data: Radiosonde-derived atmospheric profiles
Where available, the files contain atmospheric molecular profiles derived from the radiosonde observations (temperature, pressure). The obtained molecular profiles are provided at the same vertical resolution as the lidar profiles. They are used to support further lidar processing and analysis. When the radiosonde data is not available, the temperature and pressure from the Standard Atmospheric Model are used to obtain the atmospheric molecular profiles.
1. sonde_MR
1.1. Dimensions: (altitude)
1.2. Data type: float64
1.3. Description: Water-vapour mixing-ratio profile derived from radiosonde data.
1.4. Units: g kg⁻¹
2. sonde_RELH
2.1. Dimensions: (altitude)
2.2. Data type: float64
2.3. Description: Relative-humidity profile derived from radiosonde data.
2.4. Units: %
3. Temperature
3.1. Dimensions: (altitude)
3.2. Data type: float64
3.3. Description: Atmospheric temperature profile derived from radiosonde data.
3.4. Units: K
3.5. Source: Sonde calculation. Note: only when radiosonde is available, if not, source: Model calculation
4. Pressure
4.1. Dimensions: (altitude)
4.2. Data type: float64
4.3. Description: Atmospheric pressure profile derived from radiosonde data.
4.4. Units: Pa
4.5. Source: Sonde calculation. Note: only when radiosonde is available, if not, source: Model calculation
5. molecular_number_density
5.1. Dimensions: (altitude)
5.2. Data type: float64
5.3. Description: Molecular nitrogen number-density profile calculated from radiosonde data.
5.4. Units: molecules m⁻³
Molecular reference variables
The files include wavelength-dependent molecular atmospheric properties profiles. These variables provide a molecular-atmosphere reference for further lidar data evaluation.
1. molecular_scattering_coefficients
1.1. Dimensions: (wavelength, altitude)
1.2. Data type: float64
1.3. Description: Molecular scattering coefficient profile calculated for each wavelength and altitude bin.
1.4. Units: m⁻¹ sr⁻¹
2. molecular_extinction_coefficients
2.1. Dimensions: (wavelength, altitude)
2.2. Data type: float64
2.3. Description: Molecular extinction coefficient profile calculated for each wavelength and altitude bin.
2.4. Units: m⁻¹
3. molecular_transmission
3.1. Dimensions: (wavelength, altitude)
3.2. Data type: float64
3.3. Description: Molecular atmospheric transmission profile calculated for each wavelength and altitude bin.
3.4. Units: Dimensionless.
4. molecular_lidar_ratio
4.1. Dimensions: Scalar value.
4.2. Data type: float64
4.3. Description: Molecular lidar ratio used in the molecular reference calculation.
4.4. Units: sr
5. attenuated_molecular_backscatter_coefficient
5.1. Dimensions: (wavelength, altitude)
5.2. Data type: float64
5.3. Description: Molecular backscatter coefficient after accounting for atmospheric attenuation.
5.4. Units: m⁻¹ sr⁻¹
Global file attributes
The netCDF files include global attributes that describe the observation setting and processing status of the complete file.
1. date: Date or observation period represented in the file.
2. capaign_name: Name of the measurement campaign or observation activity.
3. station_height: Height of the lidar station in meters above sea level (m a.s.l.).
4. longitude: Longitude of the measurement station.
5. latitude: Latitude of the measurement station.
6. zenith_angle: Zenith pointing angle of the lidar beam.
7. azimuth_angle: Horizontal pointing direction of the lidar beam.
8. range_corrected: Indicates whether range correction has been applied to the lidar signal.
9. normalized: Indicates whether signal normalization has been applied.
10. smoothing: Indicates whether smoothing has been applied and, where relevant, the smoothing method or window size.
11. Range Corrected Signal Flags: Processing-status information related to range-corrected lidar signals.
12. gluing status: Indicates whether analog and photon-counting measurements have been combined into a continuous signal profile.
13. Acq. Shots: Number of emitted laser shots accumulated in each recorded profile.
14. Mol. Calc. Source: Source of the atmospheric information used for molecular calculations, for example, radiosonde observations.
ATTENTION:
We offer free access to this dataset. The user is however, encouraged to share the information on the data use with the Remote Sensing Laboratory by sending an e-mail to rslab@fuw.edu.pl.
In the case this dataset is used for a scientific communication (publication, conference contribution, thesis), we would like to kindly ask for considering to acknowledge data provision by adding the following statement in Acknowledgments: "We acknowledge the data originators for quality-assurance, evaluation, and provision of data sets of the Remote Sensing Laboratory at the Institute of Geophysics, Faculty of Physics, University of Warsaw, Poland."
Acknowledgements
We thank Opto-Electronics section (TEC-MME) at the European Space Research and Technology (ESTEC) of the European Space Agency (ESA) for providing the ESA Mobile Raman Lidar (EMORAL) that was upgraded in a non-commercial scientific collaboration of the University of Warsaw (UW, Poland, PI: Iwona Stachlewska), the Ludwig-Maximilians-Universität München (LMU, Germany, PI: Volker Freudenthaler), and Raymetrics S.A. (Athens, Greece, PI: George Georgoussis) within the “Technical assistance for Polish Radar and Lidar Mobile Observation System (POLIMOS)” funded by ESA-ESTEC Contract no. 4000119961/16/NL/FF/mg.
The ACTRIS station in Wroclaw run by the University of Wroclaw obtained financial support for operational activities from the Ministry of Science and Higher Education (Poland) under the programme 'Support for the participation of Polish scientific teams in international research infrastructure projects' as a part of ACTRIS-PL project under agreement no. 2024/WK/04.
