Wayman Baker (NOAA/NWS) brought the meeting to order. Wayman stated the meeting purpose: to advance lidar technology toward achieving a space wind measurement capability. He discussed the meeting schedule.
He reviewed the Action Items from the June 2003 meeting in Bar Harbor, ME. The status of these items is summarized as follows:
Zoltan Toth presented ?Recent Results from the Winter Storm Reconnaissance (WSR) Program.? Dropwindsondes were used to measure humidity, temperature, and wind, supported by the NOAA Aircraft Operations Center and the US Air Force. Universities and government participated in the activity. WSR made measurements over the northeast Pacific, observing only significant weather events with potential for high societal impact. Before the event, they determined the best tracks for flights and conducted the flights. Data were processed in the operational data stream. Runs with and without the dropsonde data were compared. Results show mostly positive impact, although a smaller number of areas of negative impact or no improvement were observed. The largest impact is over the Pacific approaching the verification region and in the verification region. A large positive impact was observed for the President?s Day storm on February 16, 2003. WSR 2004 begins January 21. Future work will address why less impact was observed than in prior years, impact of AIRS satellite over WSR areas, and increase in resolution. A mission includes two flights with 20 dropsondes per flight. Bob Brown offered to provide scatterometer data.
Zoltan Toth presented an ?Overview of the THORPEX Long Term Research Program.? THORPEX is a long-term global atmospheric research program started in 1988-1989. It investigates new techniques with a goal of improving the utility of 1- to 14- day forecasts for high impact weather. The results suggest that enhanced collaboration is the most promising approach to achieving the goal. Milestones include a draft Science and Implementation Plan in November 2002 and an Announcement of Opportunity in June 2003. The new NWP approach recommends:
THORPEX is addressing science questions on observing systems, data assimilation, forecast procedures, socio-economic applications, integrating NWP procedures, and OSEs.
Upendra Singh summarized ?NASA?s Laser Risk Reduction Program (LRRP) - Accomplishments and Update? coauthored with William Heaps. LRRP is a NASA-wide program. Laser technology is central to many applications, including wind measurement. The program was originated in year 2000 by the Earth Science Independent Laser Review Board that has industry, university and government participation. The Board reviewed NASA Earth Sciences laser remote sensing activities and capabilities. Board recommendations included improving fundamental technology, forming a Laser Research Super Center, and forming interagency technical alliances. NASA started an Agency level lidar technology program in FY02, funded by Codes Y and R. The program brings together a strong team with government, industry, and academia participation to address end-to-end lidar technology. A chart was presented showing advanced optical remote sensing technical elements. A National Consortium for Excellence in Active Optical Remote Sensing is being considered. The program aims to validate technology before initiating the proposal process and to transfer technology to industry, and is expected to have far reaching impact. Dave Emmitt asked where optimization is being addressed in the program. Upendra said optimization is addressed in the demonstration activities where components are brought together. Bob Brown inquired about the extent of the role of academia, and Upendra identified participating colleges and the budget for university support. Ingrid Guch asked if the Mars exploration goal is being addressed, and Upendra said the program is addressing how to use technology in exploration and how to adapt sensing techniques to exploration.
Rex Fleming delivered a presentation on ?Department of Homeland Security (DHS) Interaction.? Rex discussed activities proposed by UCAR in June and August 2003 responding to DHS Broad Area Announcements (BAAs). These proposals addressed approaches to minimize damage from nuclear, biological or chemical attacks. Proposals were submitted to the Combating Terrorism Technology Support Office and the Science and Technology Division Office University Programs. Rex?s presentation addressed plume measurement and forecasting. He described response times and resolution requirements in space and time, including data needed for plume models up to 20,000 ft. High resolution data and models that contain wind, temperature, water vapor, and plume composition measurements are needed. Rex also described approaches to acquire data with manned and unmanned aircraft and ground vehicles, including description of an airborne UCAR air sampler. He introduced a proposed tactical observing system that could be staged throughout the country, and described strategic and tactical observing systems with ground-based DWLs at major coastal cities, devices for measuring plume composition, and environmental sensors. Improved data assimilation procedures and relocatable finer scale versions of the NCAR MM5 model are needed. Finally, he pointed the emphasis by the Homeland Security Advanced Research Projects Agency (HSARPA) in research for quick payoff, including personnel protection for VIPs and infrastructure protection. The proposed programs are not yet moving forward.
Jan Paegle reported on ?Initial State Sensitivity in Higher Resolution Predictability Experiments.? Jan addressed sensitivity of forecast error to model errors and initial state errors. He discussed predictability experiments with the Utah global model that show the importance of smaller scales (wavelength less than about 4000 km) in initial state uncertainty for short forecasts of two to three days. After this the remaining portion of the initial state uncertainty spectrum also limits forecast accuracy. Regional, continental-scale targeting of the initial state has value for one to two-day prediction in winter mid-latitude conditions. Local targeting produces longer-term benefits in summer. Using higher resolution in the Utah model made short waves more effective. However, long waves are more effective than short waves in the model. In ten days, the effects of disturbances can spread all the way around the globe. Accuracy of these conclusions is limited by model approximations and by estimates of initial state uncertainty.
Rod Frehlich spoke on ?Climatology of Wind Field Statistics from Operational NWP Models and Implications for Space-Based Wind Measurements - Optimal Data Assimilation and Model Parameterizations,? coauthored with Robert Sharman. Rod discussed the Aviation Safety Program at NCAR. The program addresses turbulence forecasts for commercial aviation using NWP output. The study focuses on smaller scale phenomena, uses spatial filtering and climatology of turbulence. Findings include a statistical description of wind field spatial variability, addressing sampling error and estimation error for coherent lidar. He showed statistical findings regarding small scale turbulence climatology, model corrections, and sampling error predictions based on analysis of empirical data. The FAA sponsors in situ turbulence measurement on 101 commercial aircraft, downloaded as part of the ACARS data stream and providing 4 million samples per year. Other observations included:
Rod described implications of his results for optimal data assimilation, OSSEs, and NWP models. Optimal data assimilation requires total observation error covariance, which in turn requires local sampling error, instrument error, climatology of turbulence, and analysis error. Future work includes determining global climatology and universal scaling of small scale turbulence, calculating total observation error for critical data, determining optimal data assimilation, OSSEs, model parameterization, and ensemble forecasts.
C. Shuman was unable to attend to present the scheduled paper ?ICESat Mission Overview ? First Year Results.?
Ken Miller presented ?Summary and Update of DWL Technology Roadmap,? coauthored with F. Amzajerdian, D. Emmitt, B. Gentry, I. Guch, M. Kavaya, and J. Yoe. The briefing addressed how to achieve mature DWL technology and reduce risk for achieving operational wind profiles from space. Ken discussed three alternative lidar instrument approaches: coherent, direct detection, and hybrid. Roadmaps for key technology elements were presented, assuming a hybrid instrument. Although the hybrid instrument concept substantially reduces the instrument technology gap relative to the other two approaches, significant advances are needed in lasers, detectors, low-mass telescopes, scanners, and momentum compensation. Near term issues identified were technology development, trade studies between data requirements vs. benefits, and architectural concepts. Architectural concept areas included hybrid instrument reference designs, calibration and validation, mission and spacecraft alternatives, and impacts on data products from atmospheric properties, DWL alternatives, and spacecraft mechanics. Component roadmaps were discussed, showing current status of key activities. The longest lead time estimates were for flight qualified lasers and electro-optic scanners. Time to an operational mission depends on future funding levels and technology advances. Sources were ?GTWS Strategy for Obtaining Operational Wind Profiles from Space? (June 2003) and ?Technology Roadmap for Deploying Operational Wind Lidar? (January 2004) prepared jointly by NOAA and NASA. The latter paper is available on the LWG website in the January 2004 meeting folder.
Michael Dehring presented ?BalloonWinds Update,? coauthored with Carl Nardell and Jinxue Wang. Michael described the BalloonWinds mission, including flights, program status, and instrument subsystem models. The objective is to measure photometric return and wind profiles from a high-altitude, down-looking platform, validate system models, and scale findings to a space mission. The schedule includes four balloon flights to 100,000 ft from Holloman Air Force Base in New Mexico. The instrument is a direct detection fringe imaging DWL oriented at 45o below horizontal. The gondola rotates at less than three rotations per hour. The flights will demonstrate DWL wind measurement under four different atmospheric conditions: night with clear air, day partly cloudy, day and night partly cloudy in spring season, and day and night partly cloudy in autumn. Flight durations are 12 hours, with 8 hours of data collection. Michael described status of design, build, test, and integration of the main subsystems, and the optical path for BalloonWinds measurements. He provided information and graphical descriptions on thermal management and mechanical design of the gondola and subsystems. At the next LWG meeting, many subsystems will be in the build/test phase, the interferometer throughput will be characterized, and prototype CCD camera will be tested. The mission is expected to demonstrate an instrument that is optically equivalent and scalable to a space instrument, measurements from above the atmosphere, and several components that are proto-flight or flight qualified.
Michael Dehring continued with a presentation on ?Laser Frequency Instability and Wind Error? coauthored with Jinxue Wang, and Carl Nardell. The goal was to determine the dependence of wind error on laser frequency instability and drift for a photon recycled fringe imaging DWL. Michael described the technical requirements for frequency stability in the GroundWinds and BalloonWinds lidar design. Because multiple laser shots are averaged on a chip, frequency jitter is a critical factor. Michael described the Monte Carlo simulation, parameters, and assumptions used to conduct the study, and wind error dependence on laser jitter and drift. The simulation selected random frequencies in a Gaussian distribution and used shot accumulation for a laser reference spectrum and a Doppler shifted sky spectrum. Inversion used a non-linear least squares fitting routine. The instrument functions corresponded to those of the BalloonWinds instrument. Michael also described the experiments and results, including trades between number of shots averaged vs. stability for the aerosol and molecular channels and drift vs. laser jitter. Conclusions were that the maximum Gaussian laser jitter should be less than 100 MHz, resulting in degradation of wind accuracy by less than 0.25 m/s. Michael stated that most lasers have 100 to 200 MHz jitter, corresponding to less than 0.5 m/s error in direct detection. The frequency drift should be less than +/-0.1 MHz/shot. Results apply to etalon stability and etalon thermal drift as well as to the laser. Aerosol detection experiences aliasing with this much jitter, which increases error.
Carl Nardell presented ?Fringe Imaging/Improved Double Edge Direct Detection Doppler Lidar,? coauthored with Paul Hays and Michael Dehring. Fringe Imaging and Double Edge are detection techniques that are strong candidates for use in direct detection DWLs for space deployment. A comparison of optimized versions of the two is needed to compare their intrinsic sensitivities. This study developed a Double Edge detector design that employs photon recycling and optimized configurations for Double Edge and Fringe Imaging detection. Carl described an optimizing design procedure that searched thousands of instrument configurations for each technique and compared results with respect to wind error for various aerosol concentrations and instrument sizes. The trade space included etalon spacing, etalon reflectivity, number of recycles, and number of orders. Parameters were treated separately for the molecular and aerosol channels. Carl discussed Double Edge detectors with and without photon recycling. Conclusions were:
In the discussion, Bruce Gentry said he would like to compare double edge optimizations with this analysis.
M. Newchurch, K. Fuller, and D. Bowdle ?The Regional Atmospheric Profiling Center for Discovery (RAPCD) at the National Space Science and Technology Center (NSSTC) in Huntsville, Alabama: Infrastructure, Instrumentation, and Science.? This talk was deferred to the summer LWG meeting.
Dave Emmitt presented ?Comparison of Measured and Modeled Aerosol Backscatter during Twin Otter Doppler Wind Lidar (TODWL)/2003,? coauthored with D. Bowdle and C. O?Handley. He described Office of Naval Research (ONR) and Integrated Program Office (IPO) funded DWL activities, including TODWL and development of a trailer version called GWOLF. ONR and IPO co-funded upgrades and NASA/LaRC provided a hemispherical scanner allowing for independent airborne and trailer DWLs. IPO is interested in calibration and validation of scatterometers, cloud and water vapor motion winds, ground based sounders, GPS derived winds, and future space-based DWLs and validation of DWL simulation models. The Twin Otter aircraft is operated by CIRPAS out of Marina CA. It is unpressurized, normally operating up to 10,000 t and cruising at 100 to 140 kts, and instrumented with GPS/INS, dropsondes, aerosol probes, temperature, water vapor, and turbulence sensors. The DWL is a 2-micron coherent lidar, with 4 to 6 mJ, 330 nanosecond pulse, 80 pulses per second. The 10-cm two-axis scanner is mounted on a side door, GUI with real time control and display. It scans up, down, and straight ahead and performs VAD scanning and processing. TODWL 2003 flights took place near Monterey CA in February 2003. The experiments examined issues unique to space, including downward look and measurement over water. They included underflight of the NPOESS Airborne Sounder Testbed (NAST) aircraft. Other activities were investigation of aerosol/wind correlated structures, validation of the NPS MM5 model winds over complex terrain and coastline, and development of sampling strategies for deployment in THORPEX adaptive targeting experiments and C-BLAST investigations. Dave described observations of organized marine boundary layer structures. Advanced signal processing techniques are needed for shear measurements because of non-gaussian smearing of spectra. TODWL provided coincident aerosol and wind observations for evaluating β/U correlations for their potential impacts on spacebased DWL data products. Within MBL, biases of 0.25 to 0.50 m/s can be expected for aerosol direct detection systems. Larger biases may be realized in the presence of wave-like structures in the mid and upper troposphere. A Lidar Altitude and Height Determination and Signal Search Algorithm (LAHDSSA) that uses surface return to correct for aircraft ground speeds was discussed. Data showed atmospheric structure. Removal of aircraft attitude and motion effects was discussed. The soundings were processed to obtain accuracies of <0.1 m/s in each component (u,v,w). Comparison with other sounders must be interpreted with caution since integration times and sample volumes vary. A significant effort is needed to understand the differences between TODWL vs. MM5 predictions.
Dave Emmitt presented ?Using Surface Returns to Correct for Aircraft Motion Induced Errors,? coauthored with C. O?Handley. Dave described the IPO funded Twin Otter DWL (TODWL), issues related to removal of aircraft attitude and motion effects on wind retrievals, adapting Lidar Altitude and Height Determination and Signal Search Algorithm (LAHDSSA) to TODWL, and some results. The Navy Twin Otter aircraft and instrument are described in the preceding section. TODWL measures profiles of horizontal wind above and below flight level, as well as information on vertical motion, aerosol structures, and turbulence. The goal was to obtain line of sight velocity accuracies with bias <10 cm/s and rms error <10 cm/s. Beam alignment relative to aircraft axes was an issue. Primary sensitivities were to pitch and yaw. Ground returns over land were used to determine altitude offsets to calibrate wind retrievals for open water investigations. LAHDSSA computed pitch and yaw corrections from the variables of flight and instrument dynamics, for a 12 point conical scan with 2-s dwell time, identifying ground return for each dwell. Ground speed error before LAHDSSA averaged 1.298 m/s with standard deviation of 0.156. After LAHDSSA, the error averaged 0.001 m/s with 0.094 standard deviation. Pitch and yaw offsets were determined using ~100 downward viewing Velocity Azimuth Displays (VADs) with ground returns.
S. Wood presented ?The Doppler Lidar Simulation Model (DSLM) On-Line,? coauthored with Dave Emmitt. The DSLM, available on-line or on CD, is an integrated simulation model that produces realistic lidar winds results using either global or mesoscale atmospheric model wind fields. DLSM includes wind and atmospheric data and algorithms for direct detection double edge and coherent detection algorithms. It can be used to address feasibility, trades, algorithm development, and optimization for space or aircraft based DWLs. For access to DLSM, register on the Simpson Weather Associates web page http://www.swa.com/.
Bruce Gentry presented ?Update on Wind Lidar Activities at Goddard,? coauthored with H. Chen, S. Mathur, and J. Comer. Bruce described the Goddard Lidar Observatory for Wind (GLOW) participation in the International H2O Project (IHOP) in 2002, new technology developments and demonstrations, and future directions. GLOW operated in IHOP at the Homestead site in the Oklahoma panhandle in May and June 2002. The Goddard Scanning Raman Lidar (SRL) and the Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) also participated, along with the NOAA High Resolution Doppler Lidar (HRDL), and three other lidars and numerous other ground, mobile, and airborne instruments. In addition to low level winds from GLOW, SLR collected water vapor profiles and HARLIE provided backscatter profiles. This was the first simultaneous deployment of GLOW, SRL, and HARLIE. GLOW wind profile measurements were optimized for the bottom 5 km of atmosphere. Bruce showed the geometric sampling method, temperature and Brillouin scattering effects on molecular scattering and the resulting double edge sensitivity curves. Operations included over 210 hours of wind profiles in 34 days of operations. Oscillations, roll clouds, gravity waves, and undular bores all were observed. Bruce showed time sequences of wind profiles from bore waves and pointed out that these waves are best studied by lidars. NASA has taken delivery of a Fibretek high brightness solid state, conductively cooled laser with 50 mJ at 50 pps. The prototype developed with SBIR and ESTO funding is working, vibration tested, and installed in GLOW in parallel with the flash lamp pumped Continuum laser. The laser meets airborne requirements and demonstrates a path to a space-qualified laser. Wind measurements taken in September and October showed improvements because of the higher PRF and average power. A combination of the HARLIE Holographic Optical Element (HOE) scanner and the GLOW molecular Doppler receiver is expected to be ready for demonstration in the spring of 2004. In future directions, an airborne direct detection DWL with an HOE scanner has been proposed to fly beside a coherent DWL to compare data taken under simultaneous conditions. Bruce indicated the Proteus aircraft, capable of operating for 18 hours at a 20 km altitude, may be a possible future platform for wind lidar experiments.
Stephan Rahm presented ?Airborne Wind Measurements in THORPEX,? coauthored with R. Busen, O. Reitebuch, R. Simmet, and M. Weissman. THORPEX is THe Observing-system Research and Predictability EXperiment. THORPEX is a ten-year international research program under the World Meteorological Organization/World Weather Research Program to accelerate improvements in weather predictions. Stephan described airborne experiments conducted over Iceland November 14-26, 2003 in the DLR Falcon aircraft. Wind, temperature, pressure and humidity measurements were made with dropsondes and a CTI 2-micron coherent lidar. The lidar parameters were 1.5 mJ, 500 Hz, scanning at 24 steps per revolution with 2-s stare time. There were eight flights with 20 hours of lidar data collected, with accuracy of 10 to 30 cm/s. Good agreement was observed in comparison with 49 dropwindsondes. Detailed comparisons and assimilation studies are underway now. Of particular interest was the observation of a 100 mph jet stream. ENVISAT SAR validation is planned for near-surface observations over the Atlantic.
Bill Heaps presented ?The Goddard Portion of the Laser Risk Reduction Program.? Bill summarized the Goddard activities under the NASA LRRP. Tasks included Knowledge Capture, Detector Technology, Wavelength Conversion, Pump Diode Evaluation, Component Development, and 1-micron Architecture. He described activities under each task and the balancing of priorities for limited resources. Pump diodes will require a lot of rework to qualify new sources, since the company that supplied them is no longer making them. The target for the laser component is a 1-J/pulse laser.
Geary Schwemmer presented ?Scanning Holographic Receivers for Air and Space.? Geary discussed techniques for the scanning optics for DWLs. Topics included the Airborne Molecular DWL, UV Holographic Optical Element (HOE) test results, diffraction limited HOEs, and hybrid Shared Aperture Diffractive Optical Element (SHADOE) concepts. HOE diffracts light at an angle, with the optics made from exposure of holographic film to diffraction patterns. It can focus light as well as bend it. SHADOE techniques use no moving parts to produce multiple laser spots with good optical efficiency. A 16-inch HOE SHADOE element is being tested in the lab, getting 62% diffraction efficiency. Problems have been encountered in using HOE for coherent DWLs because of aberration from the hologram and from gluing the film to glass. Contributing factors include uneven film thickness and epoxy glue thickness. Wavefront error correction techniques are being considered, using corrective prescription lenses to fix the aberration (Lawrence Livermore has developed this technique). This has been done up to 16-inch diameters, can go to 1 meter. Hybrid methods will combine IR and UV lasers by putting two HOEs on one plate. Since IR and UV are independent, holograms can separate them. He discussed developing multiple holograms in one film and other techniques.
Steve Mango reported on the status of NPOESS. He covered schedule and instruments. He reported that WindSat, which provides ocean surface wind vector measurements from space is working well. This demonstrates the capability to exploit passive microwave polarimetry to measure ocean surface wind field and other variables. He described the status of several other instruments. He discussed a wind lidar opportunity in a 2013 NPOESS launch, either as an operational instrument or as a demonstration. Tropospheric winds remain the number one need. NPOESS is studying the distribution and characterization of lidar scatterers in the atmosphere and studying adaptive targeting. There was a discussion of Department of Defense needs and interests in wind profiles. To develop interest, clarification (through OSSEs and simulations) is needed of potential DoD benefits from wind profiles. Benefits relate to the end products of weather forecasting and mission planning.
Jim Wertz presented ?Low-Cost Responsive Approach to Global Tropospheric Wind Measurements from Space,? coauthored with Carl Nardell. Jim discussed mission architectures with multiple small spacecraft for wind measurements. He described the potential for lower overall cost than would be incurred in traditional missions and the advantages in coverage, lifetime, power, and redundancy. He compared relative risk factors between the single large satellite approach vs. the multiple smaller satellite approach in terms of failure modes (laser life, launch reliability, bus failures, etc.) The alternative architecture could have eight small lower cost spacecraft, launching two initially and maintaining six in reserve. Jim suggested that the smaller spacecraft could operate from orbits as low as 100 to 200 km depending on ballistic coefficients, reducing power requirements (and corresponding solar array size) and aperture requirements (and corresponding scanning and momentum compensation challenges). NRO has flown at low altitudes for limited periods. Lower cost launch alternatives included Pegasus, Taurus, and DARPA Falcon. Lifetime of the smaller spacecraft was estimated at six months to one year, power at 600-700 watts, and instrument costs at $8M per instrument. Jim recommended further study of this architecture.
J. Yu presented ?Two Micron Laser Development for Space-Based Wind Measurement,? coauthored with U. Singh and M. Kavaya. The laser development roadmap to space includes partially conductively cooled lasers then fully conductively cooled lasers. Fully conductively cooled lasers require advanced laser head technology. Demonstrations have included a fully conductively cooled 1050 mJ Q-switched laser and a fully conductively cooled laser at 220 mJ/pulse at 10 Hz. Work on liquid cooled lasers has reduced the number of water channels from 22 to six with substantial size reduction. Future work on fully conductively cooled components will evaluate oscillator performance, develop amplifiers, and demonstrate a 1.5-J 2-micron laser. If funding continues, a space qualified 2-J laser may be achieved in 2007. Additional time will be needed to address lifetime, packaging, and other engineering considerations. Two to 5 J are estimated as the requirement for a coherent lidar instrument, 500 mJ for a hybrid coherent instrument. Five percent wall plug efficiency is estimated for a fully conductively cooled instrument. Systems are now demonstrating 1% wall plug efficiency. The ISAL design assumed 2%. Beam quality has not been as good in conductively cooled lasers as in liquid cooled.
D. Emmitt presented ?GWOLF and VALIDAR Comparisons,? coauthored with M. Kavaya, G. Koch, and S. Wood. Dave described the lidar intercomparison facility at NASA LaRC, which includes the co-located Ground-based Lidar Wind Observations at Langley Facility (GWOLF) and the Validation Lidar (VALIDAR) Facility. GWOLF is the TODWL lidar with a CTI coherent instrument (discussed in an earlier presentation) housed in a trailer. VALIDAR objectives include demonstration of advanced 2-micron components in a complete system and making field validation measurements. GWOLF has been used for intercomparisons with VALIDAR, hard target experiments, cloud return studies, and vertical motion studies. The facility has a paved lot to support up to four lidar systems, utilities, and surveyed targets. Possible future enhancements were presented. Lidar capabilities for FY 02, 03, and 04 were presented, with a conductively cooled 100-mJ 5-Hz lidar planned in FY 04. GWOLF is funded by IPO as part of the NPOESS development of a calibration and validation program for space based wind observing systems such as QuikScat, WindSat, CMV, WVMV, and future DWLs. Data were presented for GWOLF and VALIDAR comparisons, GWOLF hard target measurements, cloud returns, and vertical wind velocities. The facility supports long term evaluation of lidar performance. It is planned to bring direct detection systems to LaRC for investigation.
D. Emmitt presented ?Comparisons of TOWDL Soundings with MM5, Microwave Sounders, Towers, and Other Wind Sensors,? coauthored with S. Wood, S. Greco, and C. O?Handley. Comparisons were made with microwave sounders, CTI ground lidars, NOAA BAO towers, NOAA Buoys, rawinsondes, NAST winds, and the MM5 model. NPOESS Aircraft Sounder Testbed (NAST) is an aircraft capable of fast flight at altitudes up to 64,000 ft. NAST wind data didn?t compare well to the lidar wind data; although wind direction compared well, velocity didn?t. MM5 wind data with 4-km resolution was hard to compare with the high-resolution lidar data. MM5 comparisons were OK at 1500 m over water, but not good over land. Comparisons were not very good at lower altitudes. Conclusions about comparisons require caution because of differences in integration times, resolution, and sampling conditions among different instruments and models.
Ivan Dors presented ?GroundWinds New Hampshire and Hawaii Updates.? GroundWinds New Hampshire (GWNH) operations have been reduced to a weekly schedule. It is also being used as a test bed for BalloonWinds. BalloonWinds is a program of four future balloon-borne ascents with a direct detection DWL, managed by the University of New Hampshire (UNH). Data from the October 2003 campaign comparing GWNH with mini-MOPA is being analyzed for precision, accuracy, and sensitivity. Precision components include instrument, atmospheric, and statistical elements. Accuracy is being determined by comparison with data from the NOAA/ETL mini-MOPA. GroundWinds Hawaii (GWHI) operates daily and is part of the local weather forecast system. It ran with stable operations for eight months prior to its last service. A validation activity is being planned. Data is capable of providing temperature as well as wind velocity. Scientific studies include molecular scattering model, aerosol optical properties, and turbulence.
Q. Zheng presented ?GroundWinds Brillouin Scattering Investigation,? coauthored with Ivan Dors and James Ryan. Wind velocity is determined by the Doppler shift between an unshifted Rayleigh Brillouin Scattering (RBS) model and the measured shifted spectrum. RBS spectra in air are directly measured by the GroundWinds lidar. The RBS spectrum fluctuation in air has two components, pressure and entropy. Better models support better temperature and wind profile measurements. Several models were shown. Tenti?s S6 model provided a good match to empirical data, but there is still room for improvement. Additional corrections at low altitudes can be made using a priori Landau Placzek ratio. Data showed an RBS spectrum from the GWNH lidar and comparison with Gaussian thermal broadening. A comparison was shown between the Tenti S6 model and a fitted Gaussian distribution. Temperature profiles were compared between GWNH data and radiosonde data.
Dave Emmitt presented ?Status of IPO-Funded Hybrid Feasibility and Airborne Testbed,?coauthored with B. Gentry, M. Hardesty, and M. Kavaya. The presentation addressed hybrid DWL feasibility and an airborne testbed. IPO has funded planning for a project. Project objectives for hybrid feasibility were to provide input to the technology roadmap and to prepare for hybrid OSSEs and cost benefit studies. Dave discussed science advantages of a hybrid DWL approach. Parameters for two cases of combined IPO Hybrid DWL were presented, along with DWL data quality profiles. The IPO DWL airborne testbed and Cal/Val instruments were discussed. This would put DWLs on high altitude platforms along with NAST and enable studies of passive temperature and moisture sounders and active optical wind sounders. The Proteus has been considered as a target platform. The objective of the Multiagency Airborne Lidar Testbed (MALT) is to develop a sounder instrument suitable for autonomous operations on manned and unmanned platforms for a variety of applications of interest to several agencies. MALT would fly in tandem with NAST on the Proteus. The Doppler Lidar Technology Accelerator (DLTA) is a proposed multi-Center partnership to advance technology readiness for key component technologies for coherent and direct detection lidars. These technologies will be tested together at the system level to demonstrate the potential synergies of the hybrid approach. A DLTA lidar system roadmap was shown. In 2004, plans include realistic OSSEs for reference and hybrid systems, and presentation of a plan for a Proteus borne DWL/NAST instrument package.
Mike Hardesty presented ?Airborne Measurement of Horizontal Wind and Moisture Transport Using Co-deployed Doppler and DIAL Lidars,? coauthored with Alan Brewer, Brandi McCarty, Christoph Senff, Ed Tollerud, Gerhard Ehret, Andreas Fix, Goraszd Poberaj, Martin Wirth, and Christoph Kiemle. Mike described experiments to study transport of water by low level jets in the Kansas, Oklahoma, and Colorado region in IHOP. The NOAA HRDL DWL and DLR-DIAL instruments were flown on the DLR Falcon aircraft. Winds, water vapor, and aerosol were measured with 150-m vertical and horizontal resolution, processed to 1.5-km resolution. Aircraft velocity with respect to the ground was subtracted from each measured atmospheric velocity. Favorable comparisons with dropsonde profiles were shown. Sample profiles and lidar and dropsonde flux comparisons were shown. Vertical wind measurements were made and compared with King-Air and surface flux measurements. The raw data were corrected for aircraft pitch by using a turning mirror. Combined wind and water vapor measurements were made. Future HRDL upgrades were discussed including repackaging for improved aircraft performance, modular design, fiber coating, and new processor for 1-kHz PRF. HRDL will be deployed on a NOAA ship this summer for the New England air quality experiment. Co-deployment with an ozone lidar is planned during the 2005/2006 air quality studies. The experiments demonstrated high precision measurements of boundary layer wind velocities with co-deployed DIAL and Doppler lidars. Vertical fluxes were computed using eddy correlation. Backscatter weighting of vertical velocity measurements is being examined for its effect on a spacebased wind system.
Tom Wilkerson presented ?UVC Airborne Holographic Lidar Transceiver,? coauthored with M. Hammond, D. Huish, and S. Cornelsen. The objective of this activity is technology fusion of HARLIE and GLOW technology into the Doppler Lidar Technology Accelerator (DLTA) on a high altitude aircraft such as the ER-2 or Proteus. The instrument is a UV-Cornerstone (UVC) transceiver being designed at Space Dynamics Laboratory at Utah State University. The DLTA will include a holographic scanner at 355 nm and multi-channel transceiver. It will perform wind, aerosol, and cloud measurements and support calibration and validation for space-borne wind lidar. Instrument layouts, scan configurations, transceiver design, and expected performance were illustrated. Design is underway. The next steps include vibration analysis, design and fabrication. Composite construction is being investigated for strength and weight considerations.
Tom Wilkerson presented ?HARLIE Wind Observations at IHOP-2002, ? coauthored with C. Earl, S. Cornelsen, H. Hunter, J. Cutts, and D. Huish. The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE), Goddard Lidar Observatory for Winds (GLOW), sondes, and other instruments made atmospheric measurements in IHOP from May 13 to June 25, 2002. Tom discussed measurements and analysis of HARLIE data. HARLIE objectives were to operate continuously, compare results between HARLIE and GLOW wind lidars, and continue development of a calibration and validation capability for spaceborne lidar. HARLIE measurement timelines were presented, as well as profile comparisons with sondes, SkyCam, and GLOW. Differences among various systems seemed related to differences in observation location and time. Data analysis was restricted to places where balloon position coincided with HARLIE observation. Observed wind profile variability in direction, wind speed, and altitude was presented. Comparison scatterplots between manual and automatic HARLIE observation methods and between HARLIE and sonde data indicated some differences between the manual and automatic methods data reduction methods. The Hough Transform method for identifying wind speed and direction in the automatic method was illustrated. HARLIE curve fit analysis showed good agreement with sonde profiles, and operations approached 24/7. HARLIE and GLOW were shown to analyze complementary portions of the air column (clear vs. cloud). The Hough transform method used in the HARLIE automatic method is efficient but not yet as precise as the manual method. It is being developed further. Expanded holographic lidar applications are expected for the future.
Subcommittee discussions were held following the last presentation.
Subcommittee Reports and Recommendations were presented.
Bruce Gentry discussed some results from the Geoscience Laser Altimeter System (GLAS) instrument flying on ICESAT showing data from the 1 micron Cloud Digitzer (Courtesy of Jim Spinhirne and the GLAS science team). The data were taken in the first 40 days of the GLAS mission. Primary science for GLAS long term observation of change in the polar ice sheet height. In addition, there are two atmospheric channels, a one micron cloud channel similar to LITE and a 532-nm photon counting channel which is optimized for aerosol observations. Data from the green channel is also available but was not shown. The data showed cloud layering and smoke layers in the Amazon from fires. In March, data showed atmospheric effects from the Iraqi conflict and elevated dust clouds from dust storms. Saharan dust layers were seen above the ocean off Africa. Cloud layering showed a significant amount of cloud penetration by the instrument to lower layers. Validation of the Cloud Digitizer channel during THORPEX used data from the Cloud Physics Lidar on the NASA ER-2 aircraft under flying GLAS to refine calibration. Corrections were made for multiple scattering. The data showed significant aerosol sensitivity and ability to capture aerosol profiles as well as data on cloud height, thickness, and optical properties. ECMWF model comparison showed good agreement, but the model missed some points. There are 60 to 90 days of data with both wavelength channels operating. ICESAT and CALIPSO both have green channels and are eye safe for astronomers. The ICESAT and CALIPSO missions will provide a wealth of useful information on both composition and technology.
Michael Kavaya presented a synopsis of work toward a hybrid mission.
Action items for the next meeting were discussed and identified.
The next meeting will be held June 29 to July 1, 2004 in Frisco, Colorado. The Winter 2005 meeting will be held in Sedona, Arizona.
The minutes were prepared by Ken Miller.