scholarly journals Differential absorption lidar for water vapor isotopologues in the 1.98 μm spectral region: sensitivity analysis with respect to regional atmospheric variability

2021 ◽  
Author(s):  
Jonas Hamperl ◽  
Clément Capitaine ◽  
Jean-Baptiste Dherbecourt ◽  
Myriam Raybaut ◽  
Patrick Chazette ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Water Vapor ◽  
Spectral Region ◽  
Hydrological Cycle ◽  
Numerical Study ◽  
Lower Troposphere ◽  
Atmospheric Conditions ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Relative Precision

Abstract. Laser active remote sensing of tropospheric water vapor is a promising technology to complement passive observational means in order to enhance our understanding of processes governing the global hydrological cycle. In such context, we investigate the potential of monitoring both water vapor H216O and its isotopologue HD16O using a differential absorption lidar (DIAL) allowing for ground-based remote measurements at high spatio-temporal resolution (150 m and 10 min) in the lower troposphere. This paper presents a sensitivity analysis and an error budget for a DIAL system under development which will operate in the two-micron spectral region. This numerical study uses different atmospheric conditions ranging from tropical to polar latitudes with realistic aerosol loads. Our simulations show that the measurement of the main isotopologue H216O is possible over the first 1.5 km of atmosphere with a relative precision in the water vapor mixing ratio of < 1 % in a mid-latitude or tropical environment. For the measurement of HD16O mixing ratios under the same conditions, relative precision is shown to be of similar order, thus allowing for the retrieval of range-resolved isotopic ratios. We also show that expected precisions vary by an order of magnitude between tropical and polar conditions, the latter giving rise to reduced precision due to low water vapor content and low aerosol load. Such values have been obtained for a commercial InGaAs PIN photodiode, as well as temporal and line-of-sight resolutions of 10 min and 150 m, respectively. Additionally, using vertical isotopologue profiles derived from a previous field campaign, precision estimates for the HD16O isotopic abundance are provided.

scholarly journals Differential absorption lidar for water vapor isotopologues in the 1.98 µm spectral region: sensitivity analysis with respect to regional atmospheric variability

2021 ◽  
Vol 14 (10) ◽  
pp. 6675-6693
Author(s):  
Jonas Hamperl ◽  
Clément Capitaine ◽  
Jean-Baptiste Dherbecourt ◽  
Myriam Raybaut ◽  
Patrick Chazette ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Water Vapor ◽  
Spectral Region ◽  
Hydrological Cycle ◽  
Numerical Study ◽  
Lower Troposphere ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Relative Precision ◽  
Mixing Ratios

Abstract. Laser active remote sensing of tropospheric water vapor is a promising technology to complement passive observational means in order to enhance our understanding of processes governing the global hydrological cycle. In such a context, we investigate the potential of monitoring both water vapor H216O and its isotopologue HD16O using a differential absorption lidar (DIAL) allowing for ground-based remote measurements at high spatio-temporal resolution (150 m and 10 min) in the lower troposphere. This paper presents a sensitivity analysis and an error budget for a DIAL system under development which will operate in the 2 µm spectral region. Using a performance simulator, the sensitivity of the DIAL-retrieved mixing ratios to instrument-specific and environmental parameters is investigated. This numerical study uses different atmospheric conditions ranging from tropical to polar latitudes with realistic aerosol loads. Our simulations show that the measurement of the main isotopologue H216O is possible over the first 1.5 km of atmosphere with a relative precision in the water vapor mixing ratio of <1 % in a mid-latitude or tropical environment. For the measurement of HD16O mixing ratios under the same conditions, relative precision is found to be slightly lower but still sufficient for the retrieval of range-resolved isotopic ratios with precisions in δD of a few per mil. We also show that expected precisions vary by an order of magnitude between tropical and polar conditions, the latter giving rise to poorer sensitivity due to low water vapor content and low aerosol load. Such values have been obtained for a commercial InGaAs PIN photodiode, as well as for temporal and line-of-sight resolutions of 10 min and 150 m, respectively. Additionally, using vertical isotopologue profiles derived from a previous field campaign, precision estimates for the HD16O isotopic abundance are provided for that specific case.

scholarly journals Differential absorption lidar measurements of water vapor by the High Altitude Lidar Observatory (HALO): Retrieval framework and validation

2021 ◽  
Author(s):  
Brian J. Carroll ◽  
Amin R. Nehrir ◽  
Susan Kooi ◽  
James Collins ◽  
Rory A. Barton-Grimley ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Altitude ◽  
Dynamic Range ◽  
Precipitable Water ◽  
Spatiotemporal Variability ◽  
High Spectral Resolution ◽  
Atmospheric Conditions ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Wide Range

Abstract. Airborne differential absorption lidar (DIAL) offers a uniquely capable solution to the problem of measuring water vapor (WV) with high precision, accuracy, and resolution throughout the troposphere and lower stratosphere. The High Altitude Lidar Observatory (HALO) airborne WV DIAL was recently developed at NASA Langley Research Center and was first deployed in 2019. It uses four wavelengths at 935 nm to achieve sensitivity over a wide dynamic range, and simultaneously employs 1064 nm backscatter and 532 nm high spectral resolution lidar (HSRL) measurements for aerosol and cloud profiling. A key component of the WV retrieval framework is flexibly trading resolution for precision to achieve optimal data sets for scientific objectives across scales. A technique for retrieving WV in the lowest few hundred meters of the atmosphere using the strong surface return signal is also presented. The five maiden flights of the HALO WV DIAL spanned the tropics through midlatitudes with a wide range of atmospheric conditions, but opportunities for validation were sparse. Comparisons to dropsonde WV profiles were qualitatively in good agreement, though statistical analysis was impossible due to systematic error in the dropsonde measurements. Comparison of HALO to in situ WV measurements onboard the aircraft showed no substantial bias across three orders of magnitude, despite variance (R2 = 0.66) that may be largely attributed to spatiotemporal variability. Precipitable water vapor measurements from the spaceborne sounders AIRS and IASI compared very well to HALO with R2 > 0.96 over ocean and R2 = 0.86 over land.

scholarly journals Field-deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor

2015 ◽  
Vol 8 (3) ◽  
pp. 1073-1087 ◽  
Author(s):  
S. M. Spuler ◽  
K. S. Repasky ◽  
B. Morley ◽  
D. Moen ◽  
M. Hayman ◽  
...  
Keyword(s):  
Water Vapor ◽  
Diode Laser ◽  
Temporal Resolution ◽  
Filter Design ◽  
Wide Field ◽  
Atmospheric Conditions ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Atmospheric Sciences ◽  
Range Resolution

Abstract. A field-deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes was constructed and tested. Significant advances are discussed, including a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with optomechanical and thermal stability; multistage optical filtering enabling measurement during daytime bright-cloud conditions; rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions; and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing, and intercomparisons are performed and discussed. In general, the instrument has a 150 m range resolution with a 10 min temporal resolution; 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument is shown capable of autonomous long-term field operation – 50 days with a > 95% uptime – under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.

scholarly journals Field deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor

2014 ◽  
Vol 7 (11) ◽  
pp. 11265-11302 ◽  
Author(s):  
S. M. Spuler ◽  
K. S. Repasky ◽  
B. Morley ◽  
D. Moen ◽  
M. Hayman ◽  
...  
Keyword(s):  
Water Vapor ◽  
Diode Laser ◽  
Temporal Resolution ◽  
Filter Design ◽  
Wide Field ◽  
Atmospheric Conditions ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Atmospheric Sciences ◽  
Range Resolution

Abstract. A field deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes has been constructed and tested. Significant advances are discussed, including: a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with opto-mechanical and thermal stability, multi-stage optical filtering enabling measurement during daytime bright-cloud conditions, rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions, and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing and intercomparisons have been performed and are discussed. In general, the instrument has 150 m range resolution with 10 min temporal resolution – 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument was shown capable of autonomous long term field operation – 50 days with a >95% uptime – under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.

scholarly journals Water Vapor Profiling Using a Widely Tunable, Amplified Diode-Laser-Based Differential Absorption Lidar (DIAL)

2009 ◽  
Vol 26 (4) ◽  
pp. 733-745 ◽  
Author(s):  
Amin R. Nehrir ◽  
Kevin S. Repasky ◽  
John L. Carlsten ◽  
Michael D. Obland ◽  
Joseph A. Shaw
Keyword(s):  
Water Vapor ◽  
Diode Laser ◽  
Incident Angle ◽  
Scattered Light ◽  
Optical Filter ◽  
External Cavity ◽  
Lower Troposphere ◽  
Differential Absorption ◽  
Differential Absorption Lidar ◽  
Laser Transmitter

Abstract A differential absorption lidar (DIAL) instrument for automated profiling of water vapor in the lower troposphere has been designed, tested, and is in routine operation at Montana State University. The laser transmitter for the DIAL instrument uses a widely tunable external cavity diode laser (ECDL) to injection seed two cascaded semiconductor optical amplifiers (SOAs) to produce a laser transmitter that accesses the 824–841-nm spectral range. The DIAL receiver utilizes a 28-cm-diameter Schmidt–Cassegrain telescope; an avalanche photodiode (APD) detector; and a narrowband optical filter to collect, discriminate, and measure the scattered light. A technique of correcting for the wavelength-dependent incident angle upon the narrowband optical filter as a function of range has been developed to allow accurate water vapor profiles to be measured down to 225 m above the surface. Data comparisons using the DIAL instrument and collocated radiosonde measurements are presented demonstrating the capabilities of the DIAL instrument.

A Raman Differential Absorption Lidar for Ozone and Water Vapor Measurement in the Lower Troposphere

1999 ◽  
Vol 74 (1-4) ◽  
pp. 255-261 ◽  
Author(s):  
Beno[icaron]t Lazzarotto ◽  
Philippe Quaglia ◽  
Valentin Simeonov ◽  
Gilles Larchevěque ◽  
Hubert van den Bergh ◽  
...  
Keyword(s):  
Water Vapor ◽  
Lower Troposphere ◽  
Differential Absorption ◽  
Differential Absorption Lidar

scholarly journals Eye-Safe Diode-Laser-Based Micropulse Differential Absorption Lidar (DIAL) for Water Vapor Profiling in the Lower Troposphere

2011 ◽  
Vol 28 (2) ◽  
pp. 131-147 ◽  
Author(s):  
Amin R. Nehrir ◽  
Kevin S. Repasky ◽  
John L. Carlsten
Keyword(s):  
Water Vapor ◽  
Diode Laser ◽  
Second Generation ◽  
Continuous Wave ◽  
Single Photon ◽  
Average Power ◽  
Lower Troposphere ◽  
Master Oscillator ◽  
Differential Absorption ◽  
Differential Absorption Lidar

Abstract A second-generation diode-laser-based master oscillator power amplifier (MOPA) configured micropulse differential absorption lidar (DIAL) instrument for profiling of lower-tropospheric water vapor is presented. The DIAL transmitter is based on a continuous wave (cw) external cavity diode laser (ECDL) master oscillator that is used to injection seed two cascaded tapered semiconductor optical power amplifiers, which deliver up to 2-μJ pulse energies over a 1-μs pulse duration at 830 nm with an average power of ∼40 mW at a pulse repetition frequency of 20 kHz. The DIAL receiver utilizes a commercial 28-cm-diameter Schmidt–Cassegrain telescope, a 250-pm narrowband optical filter, and a fiber-coupled single-photon-counting Avalanche photodiode (APD) detector, yielding a far-field full-angle field of view of 170 μrad. A detailed description of the second-generation Montana State University (MSU) DIAL instrument is presented. Water vapor number density profiles and time–height cross sections collected with the water vapor DIAL instrument are also presented and compared with collocated radiosonde measurements, demonstrating the instruments ability to measure night- and daytime water vapor profiles in the lower troposphere.

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