A5010824424- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Laser Applications
- Atmospheric aerosols and clouds
- Advanced Optical Sensing Technologies
- Meteorological Phenomena and Simulations
- Atmospheric chemistry and aerosols
- Laser Design and Applications
- Atmospheric Ozone and Climate
- Solid State Laser Technologies
- Analytical Chemistry and Sensors
- Remote Sensing and LiDAR Applications
- Ocular and Laser Science Research
- Wind and Air Flow Studies
- Air Traffic Management and Optimization
- Aeolian processes and effects
- Aerospace and Aviation Technology
- Advanced Fiber Laser Technologies
- Photonic and Optical Devices
- Medical Imaging Techniques and Applications
- CCD and CMOS Imaging Sensors
- Precipitation Measurement and Analysis
- Remote Sensing in Agriculture
- Air Quality Monitoring and Forecasting
- Photoacoustic and Ultrasonic Imaging
- Particle Dynamics in Fluid Flows
Earth Observing Laboratory
2012-2024
NSF National Center for Atmospheric Research
2014-2024
U.S. National Science Foundation
2024
NOAA National Severe Storms Laboratory
2016
National Oceanic and Atmospheric Administration
2016
NOAA Earth System Research Laboratory
2016
National Centre for Earth Observation
2011
Zolo Technologies (United States)
2007
Colorado School of Mines
2000-2002
Abstract A grand challenge from the wind energy industry is to provide reliable forecasts on mountain winds several hours in advance at microscale (∼100 m) resolution. This requires better wind-energy physics included forecasting tools, for which field observations are imperative. While mesoscale (∼1 km) measurements abound, processes not monitored practice nor do plentiful exist this scale. After a decade of preparation, group European and U.S. collaborators conducted campaign during 1...
Optical properties and precipitation efficiency of atmospheric clouds are largely determined by turbulent mixing with their environment. When cloud liquid water is reduced upon mixing, droplets may evaporate uniformly across the population or, in other extreme, a subset completely, leaving remaining drops unaffected. Here, we use airborne holographic imaging to visualize spatial structure droplet size distribution at smallest scales, thereby observing response entrainment clear air. The...
Abstract. A field-deployable water vapor profiling instrument that builds on the foundation of preceding generations diode-laser-based differential absorption lidar (DIAL) laboratory prototypes was constructed and tested. Significant advances are discussed, including a unique shared telescope design allows expansion outgoing beam for eye-safe operation with optomechanical thermal stability; multistage optical filtering enabling measurement during daytime bright-cloud conditions; rapid...
The Canopy Horizontal Array Turbulence Study (CHATS) took place in spring 2007 and is the third series of (HATS) experiments. HATS experiments have been instrumental testing developing subfilterscale (SFS) models for large-eddy simulation (LES) planetary boundary layer (PBL) turbulence. CHATS campaign a deciduous walnut orchard near Dixon, California, was designed to examine impacts vegetation on SFS Measurements were collected both prior following leafout capture impact leaves turbulence,...
Abstract A water vapor micropulse differential absorption lidar (DIAL) instrument was developed collaboratively by the National Center for Atmospheric Research (NCAR) and Montana State University (MSU). This innovative, eye-safe, low-power, diode-laser-based system has demonstrated ability to obtain unattended continuous observations in both day night. Data comparisons with well-established observing systems, including radiosondes, Emitted Radiance Interferometers (AERIs), microwave...
Abstract. Continuous water vapor and temperature profiles are critically needed for improved understanding of the lower atmosphere potential advances in weather forecasting skill. Ground-based, national-scale profiling networks part a suite instruments to provide such observations; however, technological method must be cost-effective quantitative. We have been developing an active remote sensing technology based on diode-laser-based lidar address this observational need. Narrowband,...
The design features of, and first observations from, a new elastic backscatter lidar system at wavelength of 1543 nm are presented. transmitter utilizes stimulated Raman scattering in high-pressure methane to convert fundamental Nd:YAG radiation by means the 1st Stokes shift. wavelength-converting gas cell multipass operation internal fans. Unlike previous developments that used methane, pump beam is not focused present configuration. This feature prevents optical breakdown inside cell....
We describe implementation and demonstration of a polarization technique adapted for lidar to measure all unique elements the volume backscatter phase matrix. This capability allows detection preferential orientation within scattering volume, may improve inversions on oriented ice crystals. The is enabled using Mueller formalism commonly employed in polarimetry, which does not require instrument be preserving. Instead, accuracy measurements are limited by characterization. A high spectral...
We present a demonstration of diode-laser-based high spectral resolution lidar. It is capable performing calibrated retrievals aerosol and cloud optical properties at 150 m range with less than 1 minute integration time over an approximate 12 km during day night. This instrument operates 780 nm, wavelength that well established for reliable semiconductor lasers detectors, was chosen because it corresponds to the D2 rubidium absorption line. A heated vapor reference cell isotopic 87 used as...
Abstract. A method for expanding the observational capabilities of diode-laser-based atmospheric lidar is discussed. straightforward test, consisting interleaved "long'' and "short'' laser pulses, was developed to demonstrate how shot-to-shot modification pulse characteristics can enhance performance low-power, could benefit observations. Two examples are given technique. In first, water vapor profiling extended closer surface while simultaneously maintaining consistent far-range...
The ability to detect relative changes in backscatter polarization from a scanning high-pulse-energy lidar system at 1.54-µm wavelength is demonstrated. new capability was tested during the dissemination of various biological aerosol simulants and other particulate emissions U.S. Army's Dugway Proving Ground. Results demonstrate that sensitive different types aerosols, departures atmospheric background depolarization ratio are consistent with limited amount information available on degree...
Oriented particles can exhibit different polarization properties than randomly oriented particles. These cannot be resolved by conventional lidar systems and are capable of corrupting the interpretation depolarization ratio measurements. Additionally, typical characteristics backscatter phase matrices from atmospheric not well established. The National Center for Atmospheric Research High Spectral Resolution Lidar was outfitted in spring 2012 to measure matrix, allowing it fully characterize...
We discuss the design and performance of an airborne (underwing) in-line digital holographic imaging system developed for characterizing atmospheric cloud water droplets ice particles in situ. The environment constrained space to simple optical layout that non-beam-splitting holography affords. desired measurement required largest possible sample volume which smallest particle size (∼5 μm) could still be resolved, consequently magnification requirement was driven by pixel camera this size....
This work presents the first demonstration of atmospheric temperature measurement using differential absorption lidar (DIAL) technique. While DIAL is routinely used to measure gases such as ozone and water vapor, almost no success has been found in temperature. Attempts a well-mixed gas like oxygen (O2) have largely failed based on need for quantitative ancillary measurements vapor aerosols. Here, described demonstrated that simultaneously measures O2 absorption, number density, aerosol...
Abstract A field-deployable scanning direct-detection elastic backscatter lidar system that is eye safe at all ranges presented. The first two-dimensional spatial images created by this new 1.54-μm wavelength system, and time-lapse animations (viewable in the online version of article) those images, are shown. has a useful range from approximately 500 m to several kilometers or more (depending on weather conditions) with 3-m resolution. reveal advection macroscopic structure aerosol...
A Raman shifter is optimized for generating high-energy laser pulses at a 1.54 microm wavelength. forward-scattering design described, including details of the multiple pass and nonfocused optical design, Stokes injection seeding, internal gas recirculation. First-Stokes conversion efficiencies up to 43%--equivalent 62% photon efficiency--were measured. Experimental results show output average power in excess 17.5 W, pulse energies 350 mJ 50 Hz, with good beam quality (M2<6). Narrow...
A laser transmitter has been developed and incorporated into a micro-pulse differential absorption lidar (DIAL) for water vapor profiling in the lower troposphere as an important step towards long-term autonomous field operation. The utilizes two distributed Bragg reflector (DBR) diode lasers to injection seed pulsed tapered semiconductor optical amplifier (TSOA), is capable of producing up 10 mJ pulse energy with 1 ms duration kHz repetition frequency. on-line wavelength can operate...
A potential new laser-based air pollution measurement technique, capable of measuring ultralow concentrations urban toxins in the field and real time, is examined. Cavity ringdown laser absorption spectroscopy (CRLAS) holds promise as an monitor because it a highly sensitive species detection technique that uses either pulsed or continuous tunable sources. The sensitivity results from extremely long path length fact quantity measured, cavity decay unaffected by fluctuations source. In...
We discuss an optical fiber-based continuous-wave coherent laser system for measuring the wind speed in undisturbed air ahead of aircraft. The operational principles instrument are described, and estimates performance presented. is demonstrated as a single line sight, data from inaugural test flight August 2010 was successfully operated under various atmospheric conditions, including cloud clear up to 12 km (40,300 ft).
Photon counting lidar signals generally require smoothing to suppress random noise. While the process of reducing resolution profile reduces errors, it can also create systematic errors due smearing high gradient signals. The balance between and is scene dependent difficult find, because caused by blurring are not analytically quantified. In this work, we introduce use Poisson thinning, which allows optimal selection filter parameters for a particular based on quantitative evaluation...
Abstract In this study, we explore the utilization of penalized likelihood estimation for analysis sparse photon counting data obtained from distributed target lidar systems. Specifically, adapt Poisson Total Variation processing technique to cater application. By assuming a noise model count observations, our approach yields denoised estimates backscatter flux and related parameters. This facilitates raw signals with exceptionally high temporal range resolutions (demonstrated here 50 Hz 75...
The Pentagon, and its 25,000+ occupants, represents a likely target for future terrorist attack using chemical, biological, or radiological material released into the atmosphere. Motivated by this, building-protection system, called Pentagon Shield, is being developed deployed number of government, academic, private organizations. system consists variety data-assimilation forecast models that resolve processes from mesoscale to city scale building scale, assimilate meteorological contaminant...
High-sensitive multi-species detection around 1550 nm using a modulated grating Y-branch, MG-Y, diode laser tunable between 1529 and 1565 is presented. The MG-Y based on the Vernier effect of two gratings, exhibits quasi-continuous tuning over 36 nm. Multi-species achieved by fast sequential scanning single absorption lines CH4, CO, C2H2, CO2 distributed range laser. wavelength scanned about 10 GHz each line for 5 ms this followed discrete large jump in operating to next line. has good...