Tuesday, January 17
Wayman Baker brought to order the 25th meeting of the Working Group on Space-Based Lidar Winds with introductory remarks. The purpose of the meeting was to review the latest advances in lidar technology toward achieving a capability to measure global wind fields from space. Since 1994, the Working Group has met twice a year to bring together potential users of Doppler Wind Lidar (DWL) data, including international representatives, and lidar technologists to enhance the exchange of information, review the latest technology developments, and build a consensus for space missions.
In the past year, a key focus has been to assess the feasibility of a DWL demonstration on an NPOESS spacecraft as part of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Pre-Planned Product Improvement (P3I) program. Open sessions on this topic were included in the previous meeting and this meeting for government, industry, and academia, including invited speakers. Minutes and scientific presentations are posted on the Lidar Working Group website: http://space.hsv.usra.edu/LWG/Index.html .
Wayman reviewed action items from the previous meetings. Action Items from this and previous meetings follow.
New Action Items from January 2006
1. Brief NOAA senior management (R. Spinrad, D. Johnson, G. Withee) on the concept for a DWL demonstration mission and potential impact on NOAA’s mission. - M. Hardesty, K. Miller
2. Consider giving an informational briefing to NASA HQ (M. Cleave et al.), taking into account the advice from the NOAA briefings. - M. Hardesty
3. Pursue possible cost sharing of an Integrated Program Office (IPO)-funded ISAL effort by ESTO for an 833 km DWL multi-spectral demonstration mission and request information for scaling to a 400 km orbit. - B. Gentry
4. Pursue possible scenarios for deploying a DWL on a research aircraft and use the data in a Winter Storm Reconnaissance (WSR) campaign. - M. Hardesty, D. Emmitt
5. Update the Integrated Operational Requirements Document (IORD) requirements with the threshold/objective requirements vetted through the NASA Earth-Sun System Technology Office (ESTO) Laser/Lidar Working Group. - J. Yoe
6. Invite Department of Defense (DOD) representatives to future LWG meetings. - W. Baker
7. Make the Langley Research Center (LaRC) NPOESS DWL accommodation study results available to the Goddard Space Flight Center (GSFC) Instrument Synthesis and Analysis Lab (ISAL) Team. - M. Kavaya
8. Seek support for a DWL mission from the Tropical Meteorology community. - R. Atlas
9. Continue to invite scientists to present DWL data requirements for their research areas at future LWG meetings. - W. Baker
10. Prepare a DWL mission white paper for either an 833 km or 400 km deployment. - K. Miller
11. Collaborate on a WSR campaign for ~ 2008 in the Pacific. - M. Hardesty, O. Reitebuch
12. LWG members should attend the ADM Workshop at the European Space Research and Technology Center (ESTEC) in the Netherlands, September 26 – 28, 2006. (The focus is on the use of ADM data and the technology status.) - M. Hardesty
13. Inventory the various wind lidars for wind measurement. - D. Emmitt
Open Action Items from June 2005
1. Monitor the Japanese effort to deploy a DWL on the International Space Station (ISS). - D. Emmitt
2. Estimate direct detection peak and average power, assuming a 10% duty cycle. - J. Wang
3. Develop a long-term DWL mission concept and schedule with key milestones. - M. Hardesty et al.
4. In preparing for the next Earth System Science Pathfinder (ESSP) program opportunity, brief the NASA Associate Administrator and high level officials in other agencies. - TBD
5. Continue studies to project on-orbit performance based on demonstrated performance of ground-based and airborne systems. Concentrate on the domain of weak signals. Justify the areas where improved performance can be invoked in space-based systems. - M. Hardesty, D. Emmitt, B. Gentry, M. Kavaya, M. Dehring
6. Use the Geoscience Laser Altimeter System (GLAS) data to improve existing models of aerosol backscatter at both ultraviolet (UV) and near infrared (NIR) wavelengths. - D. Emmitt, J. Spinhirne, D. Bowdle
7. Investigate the potential impact of improved detector efficiency at 1 micron. - B. Gentry, J. Spinhirne
8. Identify key technology risks and the means for retiring them. - M. Hardesty et al.
9. Maintain a current response package addressing questions about ADM; maintain a liaison with ADM; improve the information exchange with ADM; encourage an ADM person to attend future LWG meetings. - M. Hardesty
10. Fly the hybrid DWL in an aircraft. - D. Emmitt, M. Kavaya, B. Gentry, M. Hardesty
11. Continue data impact studies at the National Centers for Environmental Prediction (NCEP) and GSFC to refine adaptive targeting strategies and technology requirements. - D. Emmitt, R. Atlas, Z. Toth, E. Kalnay
12. Interact with the community involved with transport studies. - W. Bach
Open Action Items from February 2005
1. Obtain coincident intercomparisons - Either lidar vs. lidar, or lidar vs. sondes. - B. Gentry
2. Explore advances in batteries that could result in kJ of power. - J. Reagan
Open Action Items from June 2004
1. A benchmark statistical description of the sub-grid scale velocity field is needed. - R. Brown, R. Frehlich, D. Emmitt, R. Foster
2. Develop a proposal for deployment of a wind lidar on commercial aircraft. - R. Fleming, R. Atlas, D. Emmitt, M. Hardesty
3. The LWG should use the Lidar Technology Roadmap to track progress and provide updates to Ken Miller.
4. Pursue the use of GLAS data to improve the height assignment of Geostationary Operational Environmental Satellite (GOES) winds. - J. Reagan
5. Coordinate and scale to space, using observations from existing lidar systems, to verify space-based instrument specifications - M. Hardesty, D. Emmitt, B. Gentry, M. Kavaya, P. Gatt, I. Dors
6. Determine how to approach NASA HQ on the importance of tropospheric winds, including how the measurements could be valuable in gaining a better understanding of the atmosphere of Mars. - D. Tratt, R. Atlas, B. Gentry, D. Emmitt, W. Baker
7. Prepare articles for the refereed literature updating the many advances in lidar technology, Observing System Simulation Experiments (OSSEs), ground-based and airborne measurements, etc. since the Bulletin of the American Meteorological Society (BAMS) 1995 article was published. - R. Atlas, D. Emmitt, J. Ryan, J. Yoe (J. Yoe to chair discussion of possible BAMS II article)
8. Identify technology readiness levels (TRLs) of the various subsystems in the context of the technology roadmap. - U. Singh
Presentations
Mike Hardesty presented “Update on the 2005 National Academy of Sciences Presentation.” Mike addressed recommendations made to the National Academy of Science (NAS) Decadal Study on Earth Science and Applications from Space in the area of lidar winds. NAS will recommend a prioritized list of measurements and identify new space-based capabilities and supporting activities within NASA, NOAA, and USGS to support national needs for research and monitoring of the dynamic Earth system during the decade 2005-2015 and identify directions for planning beyond 2015 (http://qp.nas.edu/decadalsurvey). There are seven Decadal Study panels, one of which is the Weather Panel. The Weather Panel focus areas are weather, chemical weather, and space weather. Weather panel focus includes observations that improve weather and air quality prediction and assimilation of satellite products. NAS issued an RFI in January 2005, and received more than 100 responses, including at least three focused on winds. Mike gave an invited presentation to a NAS Panel meeting on DWL from space to the Weather Panel in August 2005. The Decadal Study report is scheduled for release in late 2006.
Bill Heaps presented “NASA Laser Risk Reduction Program (LRRP) and Its Application to Wind Lidar from Space.” LRRP is advancing the TRL of laser and lidar for space-based measurements in support of the Office of Earth Science (OES). LRRP has made great progress in developing enabling technology and improving lasers for space instrumentation. LRRP began in 2002 with effort at GSFC and LaRC and is scheduled to conclude in FY06. It addresses the need for lidar in altimetry, differential absorption, backscatter, and Doppler measurements. Bill discussed the history of 16 pulsed Lidar space missions dating back to the 1971 Apollo ranging instruments for moon missions: nine were rated as successful, one is en route to Mercury, and one is under development (CALIPSO). Laser issues were noted in seven missions. They included contamination, energy decline, laser diode dropouts, and overruns. Space is hostile to lasers in the areas of long term reliability, launch conditions, thermal management, contamination, radiation, frequency conversion components, and spacecraft limits on mass, volume, and power. Bill reported LRRP progress in high-power laser diode arrays, laser development, laser diode reliability, oscillator efficiency, amplifiers, thermal management, environmental effects, frequency stabilization, and laser subsystem breadboards. He discussed future expectations in fiber optic components and frequency conversion. Support is needed if LRRP is to continue beyond FY06.
Oliver Reitebuch presented “The Wind Lidar Mission ADM-Aeolus: Status” co-authored with M. Endemann. Much progress was made last year, particularly in hardware development. There are about 50 companies on the team. The mission will use a 1.5 m telescope. Both Mie and Rayleigh scattering will be used to achieve 0.5 km vertical resolution from 0 to 2 km altitude, 1 km resolution to 16 km, and 2 km resolution to 30 km. Measurements will be averaged over 7 s, or 50 km horizontal along path. Mission duration is three years. Horizontal Line-of-Sight (HLOS) accuracy is 1 m/s to 2 km altitude, and 2 m/s to 16 km. Power laser head mass is 31 kg (without laser electronics and reference laser head). Two lasers will be used for redundancy, for a total laser mass of 62 kg. Critical Design Review was held in August and September 2005. The laser was first operated in September. Laser-induced damage has proven challenging. Ground processing algorithms have been refined. Mission mass is 1100 kg dry plus 116 to 266 kg of fuel. The instrument mass is 470 kg. Telescope primary and structural mass is 50 kg. Average mission power is 1400 watts with instrument average power of 840 watts (laser average power is 510 watts). Charge coupled device (CCD) detector quantum efficiency is 80%. The laser produces 125 to 150 mJ/pulse at 100 Hz. Master oscillators are on all the time for stability, but the power amplifier is switched on five seconds before operation. Attitude control and pointing results are good. The ground system will use one receiver at Svalbard. Launch date is scheduled for late 2008. The launch has been delayed about one year, primarily because of laser diode development. A constellation of two to three satellites was investigated for ADM-Aeolus operational follow-on missions.
Steve Mango presented “Update on the Status of NPOESS.” Steve reviewed NPOESS status and addressed a number of points of current interest to the DWL community. He reported that NPOESS is experiencing cost overruns. There is a possible data gap between the Defense Meteorological Satellite Program (DMSP) and the successor NPOESS. P3I projects for NPOESS C1 and C2 orbits and openings are being re-planned, which could impact a DWL demonstration. Planning for the Global Earth Observation System of Systems (GEOSS) is moving forward with Low Earth Orbit (LEO) and Geosynchronous Earth Orbit (GEO) plans. Landsat will not be on NPOESS C1 or C4, which frees up some space on NPOESS. P3I instrument and integration costs must be borne by a non-NPOESS sponsor.
G.-J. Marseille presented “SOSE (Sensitivity Observing System Experiment) for DWL Scenarios in the Post-ADM Era” coauthored with A. Stoffelen and J. Barkmeijer. The Prediction Improvement of Extreme Weather (PIEW) project was funded by the European Space Agency (ESA). A PIEW objective is to assess the added value of a space-borne DWL in numerical weather prediction (NWP) systems to predict high-impact weather systems. PIEW is also developing requirements for the ADM follow-on system. SOSE was developed to assess the impact of future observing systems for extreme weather events in the presence of all existing observation types including TIROS Operational Vertical Sounder (TOVS). It includes a database of extreme events, observation simulations, assimilation in the ECMWF operational model, and impact assessment. He described the sensitivity principle to reduce forecast error by correcting the forecast initial state. Sensitivity structures improved forecast examples over the Mediterranean by 40%. He pointed out that ADM samples sensitive structures in otherwise data-sparse regions. He discussed ADM follow-on candidates including dual perspective DWL, tandem-Aeolus, triple-Aeolus, and dual-inclination Aeolus used in the study. He showed case study illustrations. Findings suggest substantial improvement in two-day weather prediction. Improvements (under study assumptions) listed from most to least were in the following order: triple-Aeolus, tandem-Aeolus, dual-perspective, dual-inclination-Aeolus, Aeolus. One conclusion was to use multiple Aeolus satellites rather than more complex dual-perspective satellites. A cycling method to improve the SOSE results was described. In the discussion that followed, it was pointed out that the Global Tropospheric Wind Sounder (GTWS) specifications call for multiple lines of biperspective observations, not a single line, which would affect the study conclusions.
Y. Song presented “Recent Progress on the National Center for Environmental Prediction (NCEP) OSSE Project: Lidar Adaptive Targeting Experiments with OSSEs.” The space demonstration mission for hybrid DWL proposes to use 100% duty cycle for coherent detection and 10% duty cycle for direct detection. Yucheng discussed experiments addressing where to turn on the direct detection DWL. 100% direct detection and 100% coherent detection duty cycles provided the best improvement over control. 10% direct detection adaptively selected was very good, whereas 10% direct detection without adaptive selection did not have much impact. 50% direct detection without adaptive selection had some impact.
Lars-Peter Riishojgaard presented “Relative Merit of One vs. Two Lidar Wind Perspectives,” coauthored with R. Atlas, D. Emmitt. The first study tested the impact of single versus dual component wind observations in a 2000 by 3000 km region. Dual perspective outperformed single for a given number of observations. Single perspective observations led to analysis errors more than twice as large as dual perspective. The second study addressed global assimilation and forecast. The assimilation of wind-observations-only provided good depiction of instantaneous flow field and reasonable initial conditions for forecast. Using wind-data-only caused the loss of 1 day of forecast skill after five days. Dropping one of the wind components cost more than that. Assimilation of U- or V- component observations-only provided some resemblance of instantaneous flow field and poor initial conditions for forecast. Lars-Peter observed that perspectives don’t have to be collocated, but should be sampled within one half hour.
Michael Dehring presented “BalloonWinds Integration Status.” The BalloonWinds system is a direct detection gondola-mounted DWL designed for balloon flights to 30 km. Flights are scheduled to begin in 2006 in New Mexico. BalloonWinds goals are to validate instrument models for a downward looking platform in a near space environment, demonstrate photon-recycled fringe imaging from high altitude, and demonstrate technology under a variety of atmospheric conditions. BalloonWinds is undergoing system integration at the University of New Hampshire (UNH). The gondola and instrument, built at Michigan Aerospace Corporation, was recently shipped to UNH. The DWL has a 50 cm telescope. The laser has 4.2 watts output, 50 Hz pulse repetition frequency, and requires 250 watts input power. Michael described the fringe imaging detector technique with photon recycling, the BalloonWinds team, an overview of balloon flight plans, and gondola design and physical properties. He discussed the completion status of subsystems. Three of eight subsystems have been delivered. The BalloonWinds trailer is complete, containing an office and all ground support equipment. Michael provided a comparison of GroundWinds and BalloonWinds, showing significant advances in several areas. The BalloonWinds improvement areas include the (Fibertek) laser is diode pumped and more efficient, the CCD package is improved, the Circle to Line Optic (CLIO) package is external rather than internal to enhance packaging with the CCD. An improved telescope is used, active beam steering accommodates environmental stresses, and fringe resolution is increased. Michael showed detailed photographs and drawings of the subsystems and packaging. By next meeting, the full system integration will be complete as well as side-by-side intercomparison with GroundWinds NH, thermal vacuum testing of the gondola system, and first flight.
Oliver Reitebuch presented “First Flights of the ALADIN Airborne Demonstrator (A2D).” coauthored with C. Lemmerz, E. Nagel, U. Paffrath, T. Schroder, Y. Durand, M. Endemann, R. Meynart, M. Chaloupy, E. Chinal, R. Treichel, C. Wuhrer. In October 2005, A2D was integrated into a Falcon research aircraft from the German Aerospace Centre (DLR) and successful test flights performed. The design of the ALADIN down-looking direct detection lidar and signal processing are being tested by flying the A2D airborne prototype before launch of Aeolus in 2008. Thermal stability and vibration were issues in adapting the instrument to the aircraft. Vibration caused problems in laser seeding and alignment.
Dave Emmitt presented “Status of TODWL and GWOLF,” coauthored with C. O’Handley. Dave showed photographs of the Twin Otter DWL (TODWL) aircraft and its mounted instrumentation. The TODWL lidar is 2 micron, 2 mJ, 330 nanosecond pulse, 500 Hz pulse repetition frequency. The telescope diameter is 10 cm. End-to-end optical/detector efficiency is 7 to 10%. The scanner is mounted on a side door and scans on two axes +/- 30 and +/- 120 degrees. The new TODWL system was installed in December 2005 and is ready for missions. Checkout flight objectives were to check hardware, evaluate a new “complex terrain” scan pattern, underfly Quikscat and/or WindSat, and collect profiles near Monterey CA. Dave showed wind data from checkout flights, Quikscat, buoys, and MM5 analysis around Monterey CA. NASA installed a hemispherical scanner on the Ground-based Wind Observing Lidar Facility (GWOLF) trailer at NASA Langley Research Center (LaRC) in December. Internal hardware installation is scheduled for completion March 15. Dave showed photographs of GWOLF and its equipment. GWOLF operates in conjunction with LaRC’s validation lidar (VALIDAR) facility. It will be used to generate wind distributions and lidar performance characteristics throughout an annual cycle in Virginia. It will be used in the National Science Foundation (NSF) funded measurement of desert dust redistribution within sparsely vegetated regions and in proposed plume studies at Redstone Arsenal. It is planned to operate in conjunction with the Center for Inter-Disciplinary Remotely Piloted Aircraft Studies (CIRPAS) radar in a tornado study in 2007.
Lars Peter Riishojgaard presented “The Molniya Orbit Imager and the Assimilation of MODerate-resolution Imaging Spectroradiometer (MODIS) Winds.” Lars Peter discussed effects of high-latitude winds on numerical weather prediction, MODIS winds, and the Molniya Orbit Imager. Molniya Orbit Imager is a mission concept for high-latitude imaging and winds. A new weather mission is being studied as a way to reduce the severity and frequency of forecast “busts”, which over North America frequently originate in high latitudes. There is a lack of high latitude wind observations. MODIS generates high-latitude wind fields by tracking cloud and water vapor features. Coverage is above 65 degrees toward the pole. These observations have a positive impact on forecast skill. There are no operational satellite winds beyond 55-60 degrees latitude. Experimental polar winds from MODIS are available until 2008. Data latency is 4 to 6 h and image refresh rate is about 100 min. There is a latitudinal coverage gap between MODIS and GEO winds. Molniya Orbit Imager is a good candidate to provide imagery over high latitude regions. Molniya is a highly elliptical orbit, with 39,750 km apogee (vs. 36000 km for GEO orbit), 600 km perigee, 63.4 degree inclination, and an orbital period of about 11 h 58 min. The location of the apogee with respect to Earth is fixed and stable. The platform is in imaging position near the apogee for about two thirds of the orbit duration. Molniya orbit is used by the USSR and US for communications. It is ideal for feature tracking. GEO technology can be reused to save cost and reduce risk. It provides the best high latitude satellite coverage, complements GEO data, with no LEO-like latitudinal coverage gap. It allows a simple ground segment with real time dissemination from a single ground station. OSSEs showed forecast improvement over North America. Additional science applications include sea ice, vegetation/forest fire monitoring, volcanic eruptions, clouds and fog, polar weather, snow-cover and albedo monitoring, regional weather quality, surface radiation balance and Soil Vegetation Atmosphere Transfer models. Lars Peter discussed mission level requirements and mission implementation studies. The GSFC Integrated Design Capability determined that the mission is low risk and estimated cost of a three year mission is $275M with 30% margin. Molniya Orbit Imager has a mature baseline concept, a mission proposal is anticipated for NASA Earth System Science Pathfinder (ESSP), and GSFC is working to develop partnerships.
Michael Kavaya presented a “Summary of NASA Laser/Lidar Working Group Recommendations,” coauthored with B. Gentry. The objective of this NASA activity is to update mission requirements in several areas. This Working Group is part of an Atmospheric Dynamics Science Subgroup. Michael presented an overview of the requirements definition process. Laser/Lidar science focus is in three areas: Atmospheric Composition, Atmospheric Dynamics, and Topography and Oceans. Michael reviewed space winds measurement requirements and showed graphics of current wind profile observations and desired global tropospheric wind profiles (demo, threshold, and objective). He discussed the biperspective measurement requirement. An atmospheric winds roadmap chart showed past activities in 1 micron altimetry, 2 micron winds from ground and airborne observations, and 0.355 micron winds ground observations. Future steps were combined 0.355 and 2 micron (hybrid DWL) airborne measurements with a space-like measurement geometry and scanning capability, NPOESS hybrid DWL demo mission, and DWL operational mission.
Dave Emmitt presented “Latest Simulations for a Tropospheric Wind Sounder on NPOESS and Beyond,” coauthored with S. Wood, B. Gentry, and M. Kavaya. Dave presented hybrid DWL parameters to meet space demonstration mission and threshold mission requirements. The hybrid DWL includes two DWL subsystems, coherent and direct detection. The demonstration mission parameters were determined for an 832 km orbit and the threshold mission parameters for 400 km. The briefing included global wind observation performance profiles from the Simpson Weather Associates (SWA) Doppler Lidar Simulation Model (DLSM). Performance profiles plot percentage of target volumes viewed vs. altitude, showing rms wind velocity error bar graphs. A Reference Performance Profile chart showed performance for a coherent DWL with 20 J/pulse, 10 Hz pulse repetition frequency, 1 m aperture, 400 km orbit in background atmosphere with log-normal variability, with four biperspective tracks and meeting threshold requirements for altitude and horizontal resolution. The results characterized the best possible global coverage with a coherent DWL. Performance profiles were then shown for a space demonstration mission at 833 km orbit with a hybrid lidar. Four profile charts showed direct and coherent biperspective performance in background and enhanced aerosol atmospheres. The direct detection subsystem was a double-edge detection molecular DWL. Parameters are shown in the table below. Simulated performance profiles were also shown for 400 km missions meeting threshold requirements (see table) with 30 degree nadir angle and with 45 degree nadir angle. Recent advances in adaptive targeting and improved laser wallplug efficiency are reflected in the results. Plans for next year include developing a conceptual design for the hybrid demonstration instrument. Some key questions include what subsystems can be shared between direct and coherent lidars, what is the power required for direct detection in an adaptive targeting mode, and scanner design.
833 km Demo |
400 km |
||
Direct Detection |
J/pulse |
0.337 |
0.337 |
Coherent Detection |
J/pulse |
0.25 |
0.25 |
Wednesday, January 18 Science Session
Yucheng Song presented “Review of WSR 2005.” The WSR program has been operational since 2001. WSR 2005 took place 20 January through 17 March 2005 in the northeast Pacific region. Dropwindsonde observations were taken by NOAA aircraft and US Air Force Reserve aircraft. Adaptive observations were collected only prior to significant weather events in areas that might most influence forecasts. 31 flights and around 500 dropsondes were used. The Ensemble Transform Kalman Filter (ETKF) method identified observation regions to minimize forecast error. Yucheng discussed deployment and forecast impact for the blizzard of January 22-23, 2005. ETKF spotted the target area on January 18. Overall results showed improvement for 73% and degradation for 23% of cases in forecasting surface pressure, temperature, vector wind, and humidity. The study suggests the need for new high latitude measurements. Future improvements are planned for ensemble products, targeting, and verification of products. Increased program duration is being considered for WSR07-08. Expansion of adaptive observations in the Gulf of Mexico and western Atlantic is being considered for 12-24 h short storm forecasting.
Chris Barnet presented “Trace Gas Products from High-Resolution Instruments.” Chris discussed the carbon cycle, space-borne measurement concepts, and status of infrared trace gas products (ozone, carbon monoxide, methane, and carbon dioxide). He discussed the current measurement network for surface level carbon dioxide and the global distribution of fossil fuel emissions. Carbon dioxide has a strong seasonal fluctuation and is increasing from year to year. Chris discussed the many processes involved and the uncertainties in the carbon dioxide budget. Since source and sink strengths are uncertain, prediction of future climate forcing is also uncertain. Chris discussed measurements of atmospheric CO2, surface-atmosphere carbon flux, carbon pool size and size changes, compilations of statistical information, and auxiliary data to understand underlying processes. Strategies to measure trace gases from space include passive thermal, passive solar, and active. AIRS, AMSU, and MODIS have an opportunity to explore techniques for future operational sounder missions. The NOAA/NESDIS strategy is to use existing operational sounders to develop algorithms (Aqua AIRS/AMSU/MODIS instruments). In 2006, these algorithms migrate to METOP/IASI/AVHRR. In 2008, they migrate to NPOESS Preparatory Project (NPP) and NPOESS CrIS/ATMS/VIIRS. In 2012, they migrate to GOES-R/HES/ABI. Chris discussed techniques and strategies for ozone, carbon monoxide, and methane measurement and analysis and inter-hemispheric transport. The CO2 lifetime is 100 y with conversion to limestone the main sink. Main sources include fossil fuel emissions and biomass burning. Atmospheric concentration increases at 1.5 ppm/year. Terrestrial exchange is largely from photosynthesis and respiration, and ocean exchange from phytoplanckton. The AIRS product is the first climatology of CO2 in the mid-troposphere and is still in development. High spectral resolution operational thermal sounders are capable of measuring global atmospheric carbon. The CO product is robust and being validated, CH4 is difficult and under development. Many algorithms are being inter-compared for CO2. AIRS, IASI, and CrIS may contribute to source/sink determination by simultaneous measurements globally. Use of AIRS CO2 requires accurate transport models.
Robert Atlas presented “Application of Remote Sensing and Innovative Modeling to Hurricane Prediction.” Higher resolution models showed gains in hurricane forecasting. Transition from one half degree to one quarter degree was a significant improvement. All OSSEs show potential for space-based winds. OSSEs need full profile wind observations. Quick OSSEs are a new tool. Current resolution is about 1/8 degree (14 km), with 1 km – 4 km resolution possible within five years.
Zhaoxia Pu presented “The Impact of Satellite Wind Data on High-Impact Weather Forecasts and Possible Strategies of Targeting Observations.” This presentation demonstrated the importance of wind data in the forecasts of high impact weather systems such as hurricanes and tropical cyclone forecasts and discussed the possible strategies of targeting observations for observing system design and data assimilation. Forecasts for hurricanes require accurate representation of the vortex in initial conditions. Vortices in large scale analyses from operational centers are often too weak, sometimes misplaced, and observations too sparse in the vicinity of the hurricane.
Dr. Pu discussed a Bogus Vortex scheme based on data assimilation. The results showed that 3-D wind data and assimilation of satellite data are very important for hurricane initialization. She presented work on the impact of satellite wind data on landfall forecasts, using QuikSCAT surface vector winds and GOES-11 cloud track winds. Most targeting strategies improve track forecast, but may not be adequate to improve intensity and structural forecasts. Future work will evaluate targeting methods and develop targeting strategies.
Oliver Reitebuch presented “Impact of Airborne Doppler Lidar Observations on the Forecast of the Global Model at ECMWF during Atlantic THORPEX Regional Campaign (ATReC),” coauthored with A. Dornbrack, S. Rahm, M. Weissmann, C. Cardinali. A Falcon aircraft based in Keflavik, Iceland was equipped with dropsondes and a 2 micron Doppler lidar. The period of activity was 14 to 28 November 2003 for the Falcon, and 13 October to 12 December 2003 for the A-TReC. There were six local flights and two transfer flights, accumulating 28.5 hours of lidar measurements. The lidar had a conical scanner with a 20 degree nadir angle and 24 line of sight positions per scan. It captures a vertical profile of the u,v,w wind vector. Vertical resolution is 100 m. Flight tracks and Lidar vertical coverage as a function of relative humidity and altitude were discussed, as was a statistical comparison of lidar and dropsonde readings for wind speed and direction. Total error for airborne lidar of 1 to 1.5 m/s included 0.75 to 1 m/s for the instrument and < 0.5 m/s for representativeness error. This compares to 2 to 3 m/s for ADM HLOS and dropsonde/radiosonde, and 2 to 6 m/s for cloud motion vectors. Six experiments adding DWL aircraft observations to other observations in the ECMWF model showed significant forecast impact. Both lidar and dropsonde data reduced the forecast error, with the lidar data having more impact than the dropsonde data. This was the first time lidar observations were assimilated into a global model. Airborne lidar had the lowest observation error of all operational wind observations, due to higher representativity and low instrument error. Data impact on the analysis was about 40% higher for lidar than dropsondes, total information content was about three times higher. Lidar observations over the North Atlantic reduced forecast error by 2% - 6%, with a mean of 3%, while dropsondes had a mean reduction of 1%. DWL data exhibited clear positive impact on forecast skill for two to four days.
Eric Smith presented “Role of Direct Wind Observations on Understanding and Modeling the Hydrologic Cycle.” Eric described the hydrologic cycle and how it is being modeled and analyzed. Accurate, high resolution three dimensional wind measurements are needed for water cycle research. Winds are the biggest unknown in water cycle modeling and validation.
Ivan Dors presented “GroundWinds Performance and Predictions,” coauthored with M. Dehring. He discussed technology, performance, and scaling to space. The GroundWinds DWL uses photon recycling to increase optical efficiency, a CLIO transformation to transform spectral rings into lines, and measures a recorded image of spectral line intensity. Ivan discussed the system variables and statistical limits that affect performance. Substantial improvements in optical alignment, spectral models and implementation, and detector noise were made in building the BalloonWinds DWL. Camera noise is the largest source of error in GroundWinds; the new Andor camera in BalloonWinds has two to three orders of magnitude less noise. Five issues were identified in assessing accuracy: analysis routines, CCD patterns, spatial undersampling, scalar optical offsets, and offsets from thick aerosol layers (molecular channel). Radiosondes do not provide enough information to solve these issues. Data from the 2003 GroundWinds/MiniMOPA Campaign are being used to address the issues. Space simulation parameters were discussed: 400 km orbit, vertical resolution 1 km above 3 km, vertical resolution 0.25 km below 3 km, telescope diameter 1 m, pulse energy 400 mJ, repetition rate 50 Hz, and integration time ten seconds. A table of component efficiencies was presented, with total system efficiency of 0.275. GroundWinds HI performance was scaled to space indicating that 3 m/s accuracy is possible with these instrument specifications.
Sara Tucker presented “Preliminary Intercomparison Results of the October 2003 Experiment with GroundWinds NH and NOAA's mini-MOPA lidar,” coauthored with I. Dors, M. Hardesty, and W. Brewer. In October 2003, a field experiment was conducted with NOAA’s mini-MOPA (Master Oscillator Power Amplifier) coherent DWL, the GroundWinds New Hampshire (GWNH) DWL, and occasional balloon-sonde launches. Objectives of this comparison and validation are to verify GWNH performance, check for improvements over GWNH 2000 data, verify photon count for scaling to space, and quantify sensitivity improvements due to photon recycling. Other factors analyzed were sensitivity vs. theoretical limit, effect of pulse duration and averaging time on sensitivity, extraction of mini-MOPA data at low SNR, pulse modeling, and turbulence profiling. The mini-MOPA DWL operates at 9 to 11 microns, with 1 to 2 mJ per pulse, 300 Hz pulse repetition frequency, and full hemispheric scanning. Maximum range is 18 km, precision is 10 cm/s, and range resolution is 45 to 300 m. NOAA’s GWNH validation activities sought to independently estimate GWNH velocity variance and effects of photon-recycling and to compare the mini-MOPA and GWNH performance. Mini-MOPA performance agrees with models, and MOPA data provided useful comparisons for low level GroundWinds data. GWNH profiles generally compare well to MOPA and balloon-sonde data when clouds are not present. GWNH velocity variations approach the measurement limit modeled by UNH, but are higher than the theoretical detected-photon limit because of receiver limitations. GWNH measurements showed variable offsets relative to mini-MOPA data.
Floyd Hovis presented “Progress in Laser Transmitters for Direct Detection Wind Lidars,” coauthored with J. Wang, M. Dehring. Floyd described development of a robust, single frequency 355 nm laser for airborne and space-based direct detection DWLs. The laser will be all solid state, diode pumped, conductively cooled, robustly packaged, vibration tolerant, and of a space-qualifiable design. The transmitters will be incorporated into the ground-based Goddard Lidar Observatory for Winds (GLOW) and airborne (UNH and Michigan Aerospace BalloonWinds) field systems to demonstrate and evaluate designs. The program will scale findings to higher powers and pulse energies using a Raytheon funded Risk Reduction Laser and an Air Force SBIR. The program will work toward lighter, smaller lasers with radiation hardenened electronics. The BalloonWinds laser transmitter has been delivered for integration at Michigan Aerospace. The Raytheon system is in final assembly and test. The laser designs and modeling approach have been validated. Recent test results include pulse energy >700 mJ in a conductively cooled design, M2 about two for final amplifier output, near field spatial distribution is rectangular super Gaussian. Beam asymmetry in the final system will be reduced by fine tuning. Performance for 100% duty cycle, 50 Hz operation:
Reduced duty cycle on and off demonstrations, life testing, and a field demonstration of the risk-reduction laser transmitter are planned in 2006.
Dave Emmitt presented “Examination of Adaptive Targeting Schemes and Their Technology Implications.” Adaptive targeting has gained importance in the design of a hybrid DWL for space. The direct detection subsystem of a hybrid DWL requires much more power than the coherent detection subsystem. The mission concept is to operate the coherent lidar with 100% duty cycle and the direct detection lidar with a lower duty cycle. Dave discussed targeting objectives and techniques and their technology implications. The objectives are to gain maximum utility from limited platform resources, avoid nighttime operations, increase on-orbit life, avoid interference with other instruments, and optimize the sampling of targets of opportunity. Primary targets for an adaptive targeting lidar are significant shear regions, divergent regions, partly cloudy regions, and tropics. Adaptive targeting would capture direct detection wind profiles for high impact weather situations. Adaptive targeting of DWL observations has been evaluated with OSSEs by IPO and THORPEX, and with field demonstrations by NASA Convection and Moisture Experiment (CAMEX), and NOAA Winter Storm Reconnaissance (WSR) and other experiments. Most DWL profile benefits can be obtained with less than 100% duty cycle. Dave discussed examples of adaptive targeting coverage for NPOESS, optional targeting methods, and target selection schemes. An adaptive targeting study for DWL operations is being conducted by D. Emmitt, Z. Toth, E. Kalnay, and R. Atlas. The Local Ensemble Transform Kalman Filter (LETKF) method, designed at the University of Maryland, and the Initial Condition Adaptive Targeting method promise to be effective in target selection. Technology enablers include ability to turn the laser on and off, versatile beam pointing, variable pulse repetition frequency lasers, look-ahead imager or other sensor, and on-board reconfiguration. Technology issues include power management, thermal management, laser lifetime, and beam pointing mechanics.
Mike Hardesty presented “Ship-Based Measurements of Low Level Wind Fields Over the Ocean: Results and Implications for Satellite Wind Measurements,” coauthored with A. Brewer, S. Tucker, J. Intrieri.
Bruce Gentry presented “TWiLiTE Instrument Incubator Project Update,” coauthored with G. Schwemmer, M. McGill, M. Hardesty, T. Wilkerson, M. Sirota, S. Lindemann, A. Brewer, R. Atlas. The NASA Earth-Sun System Technology Office (ESTO) Instrument Incubator Program (IIP) timeline allows three years for IIP technology development. A science solicitation takes place in the third year. After the third year, mission development begins. IIP should bring the TRL up to level 6. Tropospheric Wind Lidar Technology Experiment (TWiLiTE) is an IIP effort to advance direct detection DWL technologies toward mission development. Key technologies are high spectral resolution solid state laser transmitter, optical filters, efficient 355 nm photon counting molecular Doppler receivers, and Holographic Optical Element telescope and scanner. Bruce presented the project organization, requirements and error budget, instrument development status and a description of the NASA Johnson WB57 aircraft and mounting. The receiver design reduces volume by 90% compared to the current GLOW receiver, minimizes optical path lengths, increases end-to-end throughput by 60%, and increases signal dynamic range by two orders of magnitude. Michigan Aerospace is designing the TWiLiTE etalon. Vibration tests are scheduled for February to prepare for aircraft environment. The holographic telescope has a rotating 40 cm primary optic, 45 degree nadir angle, compact folded optical path, coaxial laser transmission, and active laser bore-sight. TWiLiTE will be integrated on a 3 ft pallet with an enclosure to accommodate environmental extremes. At the end of the three year project, NASA will have a fully autonomous, integrated DWL capable of measuring full profiles from a high altitude aircraft. NASA is seeking input on the instrument design requirements, including potential applications and field experiments.
Michael Kavaya presented “LaRC Instrument Incubator Proposal Update,” coauthored with G. Koch, J. Yu, U. Singh, B. Trieu, and F. Amzajerdian. The program started in December 2005 for three years duration. LaRC’s 2 micron laser technology will be used. Work will begin with partially conductively cooled laser design, in which the laser diode arrays are conductively cooled and the laser is liquid cooled, possibly advancing to a fully conductively cooled laser. Packaging will advance toward aircraft and space environments. Beyond the IIP, telescope, scanner, and software are needed for aircraft operation. Michael discussed a technology roadmap and tables showing laser development status and milestones. He discussed status and trends in pulsed laser efficiency.
Michael Newchurch presented “Development of a Remote-Sensing Testbed for Multi-Scale, Regional, Tropospheric Air Quality and Winds Near Huntsville, Alabama,” coauthored by D. Bowdle, D. Emmitt, M. Hardesty, S. Johnson, W. Petersen, K. Knupp, R. McNider. Michael described a broad array of facilities and capabilities that have been assembled for atmospheric research in the Huntsville area.
Thursday, January 19
DWL Mission Definition Team Plenary Session
Marcos Sirota presented “Pointing Determination for a Coherent Wind Lidar Mission,” coauthored with C. Field, M. Kavaya. Marcos discussed the wind lidar mission concept, pointing determination in GLAS/ICESat, and a proposed system for coherent DWL pointing. Marcos described the geometry and dynamics of the instrument in orbit, lidar pulse round trip, spacecraft tilt rate, and pointing pattern for acquiring four biperspective lines of wind profiles. The telescope, scanner, and pointing determination system includes a nadir angle compensator and scan controller. Before a laser shot, the scanner is aimed (pre-shot pointing control +/- 2 degrees) and the local oscillator and electronic mixer are tuned to remove predicted earth motion (pre-shot pointing knowledge +/- 0.2 degrees). After the laser pulse is fired, the receiver axis must be aligned for 3 ms (stability 6.6 microradians/3 ms). Shots aimed in the same direction are accumulated over 12 s (stability +/-0.2 degrees/12 s). To remove residual spacecraft and earth rotation, final pointing knowledge is +/-60 microradians. Requirements for pre-shot control, pre-shot knowledge, stability, and final post-mission knowledge were discussed. The Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud, and land Elevation Satellite (ICESat) carried the first laser pointing determination in a lidar space mission. It has pointing knowledge accuracy of 7.5 microradians per axis, using star and laser imagers, gyroscope, and cross-reference optical sources. A block diagram, drawings, and performance curves for the ICESat pointing control system were discussed. The ICESat bus was selected based on its pointing accuracy and stability. A pointing determination system concept was described. Spacecraft slew rates for the ICESat bus demonstrated the required level of pointing control. Fine pointing can be achieved with an aft-optics beam steering mechanism. A fixed angle wedge or a tilt mirror may be introduced into the optical path between the fired pulse and the return pulse to compensate for the 3.1 microradian tilt from orbital motion. A nadir compensation mechanism will provide compensation from shot to shot during accumulation. Pointing requirements for a space based coherent DWL can be met with space proven technology and some current miniaturization efforts.
Geary Schwemmer presented “Space Radiation Environment Tests on Holographic Optical Elements (HOEs).” HOEs were tested in electron (gamma), proton, and ultraviolet radiation environments. Samples included glass, hologram, and epoxy layers. Optical tests were performed before and after exposure for diffraction efficiency at 355 nm, 0 degree incidence transmission at 355 nm and 2 micron, and 355 nm absorption. Preliminary results showed some degradation in diffraction efficiency and transmission at 355 nm due to gamma radiation over NPOESS mission life. Absorption was about 25% through 11.4 mm of glass. There was little or no hologram fading due to 254 nm or gamma radiation exposure. There was no degradation at 2 microns. Thinner glass will decrease absorption losses in a space design and alternative materials will be considered. Proton radiation and high intensity 355 nm UV tests are not yet scheduled.
Ken Miller presented “NPOESS DWL Mass and Power Estimation,” coauthored with D. Emmitt, B. Gentry, R. Khanna. Ken discussed mass and power estimates for DWL missions, beginning with the 2001 Global Tropospheric Wind Sounder (GTWS) designs from the GSFC Instrument Synthesis and Analysis Laboratory (ISAL) and Integrated Mission Design Center (IMDC) and more recent Atmospheric Dynamics Mission (ADM) designs. These DWL designs used only direct detection or only coherent detection and had high mass, volume, and power. Recent point designs for a hybrid DWL (with both coherent and direct detection subsystems) using adaptive targeting for the direct detection subsystem can be implemented with smaller mass, volume and power. This presentation described the results of scaling mass and power from the GTWS direct detection DWL designs to a direct detection subsystem for a conceptual NPOESS demonstration mission. The NPOESS demonstration mission would use an 833 km orbit and meet demonstration requirements that are somewhat relaxed from the GTWS threshold requirements. The major requirements variations were reduction from four tracks to two, vertical resolution of 2 km instead of 1 km, and a reduced duty cycle for the direct detection subsystem. The instrument is required to meet NPOESS spacecraft mass, volume, and power limitations. Performance profiles for the mission point designs were shown. An improved projection for future laser wallplug energy efficiency (4.2%) is a major factor in reducing mass in the NPOESS design. The budgets for the direct detection subsystem are 225 kg and 250 watts average power, as compared to 656 kg and 3438 watts average power for the GTWS direct detection design. Mass and power for the NPOESS direct detection subsystem were estimated to be 219 kg and 253 watts, close to the NPOESS budgets. The next steps are an instrument accommodation study at LaRC and an ISAL design for the NPOESS hybrid demonstration instrument at GSFC.
Discussion of NPOESS Demonstration Mission
Mike Hardesty led a discussion of the NPOESS Demonstration Mission and future directions toward spaceborne wind missions. He suggested the following list of topics.
Mike also listed three issues for consideration in the discussion.
The following discussion addressed many of the suggested topics.
There was general agreement to pursue the NPOESS demonstration, based on preliminary study results. Technology readiness has advanced rapidly and benefits studies consistently favored a lidar winds mission. It is important to reduce direct detection aperture size and possibly to have a shared telescope and scanner in a viable NPOESS demonstration instrument. A risk chart was suggested to identify failure modes. It was pointed out that the hybrid approach enhances redundancy.
Champions are needed in the government to achieve the big step up in resource allocation for a mission. There was discussion of which government managers will set priorities that affect lidar winds. It is necessary for NASA to be ready for the mission before the users give it top priority. End user support is not yet solid enough. The need for increased science emphasis was pointed out. Numerous science opportunities exist for a winds mission, as pointed out by Chris Barnet and Eric Smith in their talks on trace gases and hydrologic budget. Winds observations add value to observations from other environmental satellite instruments. An NPOESS mission focused on weather and hurricane forecasting should be of interest to NOAA, NASA, DOD, DHS, FAA, and FEMA. Science applications are of interest to a wide range of government and academic groups. It was recommended to prepare a briefing for high level managers and make it available on the web. It was recommended to have more science sessions at Lidar Working Group meetings, with speakers like Chris and Eric.
The National Research Council (NRC) is conducting a decadal survey that will make priority recommendations for space missions. At least three white papers were submitted to NRC recommending a lidar winds mission, and Mike Hardesty gave an invited presentation to NRC on the topic. Their report is expected in late 2006.
Industry support is needed to improve and advance the designs, capabilities, components, and mission concepts. Recently, the low level of support for a wind mission has restrained the level of industry participation.
General support can be enhanced with articles in more popular periodicals to acquaint the public with the opportunities and benefits. The need for more young people in the field was discussed.
Assimilation of DWL observations from commercial aircraft was suggested for consideration. Instruments are getting smaller and are flying successfully, and commercial aircraft could provide significant coverage. Oliver Reitebuch’s paper in an earlier session showed significant improvement in forecasts from assimilation of a small number of aircraft DWL observations.
There was a brief discussion of one vs. two line of sight perspectives and a review of the advantages of biperspective sampling to numerical weather prediction and science.
Thursday January 20, DWL Mission Definition Team Executive Session
Briefings to senior NASA and NOAA management were discussed.
The IPO proposal was discussed. A key part of the proposal is a rapid design team at GSFC ISAL for the hybrid NPOESS P3I instrument. It was suggested that we seek ESTO help in funding the ISAL. Bruce Gentry agreed to follow up with ESTO.
A mission concept white paper was discussed to define a single instrument capable of use at either 400 or 833 km orbit.
Getting a DWL on a research aircraft for targeted observations was discussed. Several aircraft options were identified. Although the Twin Otter is not a candidate, the Twin Otter DWL can be swapped out for use in other aircraft. A direct detection DWL for this application can be available in 2009. Mike Hardesty agreed to look at alternatives and recommend an approach.
The Army has a Phase 2 SBIR for a ground system DWL.
Bruce Gentry’s WB57 direct detection DWL design and the possibility of flying direct and coherent detection together were discussed.
Mike Hardesty agreed to work with Oliver Reitebuch to define a Winter Storm Reconnaissance experiment covering both sides of the Atlantic in 2008.
Subcommittee Discussions
Friday, January 20
Subcommittee Reports and Recommendations
There was a general discussion of status and action items.
Presentation of Short Subjects
Bob Brown presented “Serendipity Revisited.” Bob pointed out the role of serendipity, or “the faculty or phenomenon of finding valuable or agreeable things not sought for,” in space instruments and data. He pointed out the many products and results found when scatterometer data became available to researchers, even though the intent was just to measure ocean surface winds. In 1978 the scatterometer product expectation was surface wind vectors. By 2005, it included global marine surface pressure fields, ocean fronts, atmospheric fronts, storm location and strength, mean Planetary Boundary Layer (PBL) temperature, surface stress vectors, pack ice location and thickness, Antarctic ice flow movement, and mean PBL stratification. If you have the data, people will come up with unexpected advances. In lidar, we have an instrument that can measure winds in the troposphere, the most important independent variable in the equations of motion - essential to accurate weather forecasting. He showed a list of lidar possibilities in the PBL, including wind vectors, global climate model updates, air-surface fluxes, rolls, PBL turbulence spectrum, inversion height, aerosol statistics, and surface characteristics. He described the hazards of taking wind measurements in rolls. In the PBL, because of rolls, single point profiles have a high variance. Increasingly complex models are being used with poor data as input. He discussed ways in which the scatterometer proved to be much more valuable than just measuring surface winds. Remote sensing data showed that the theory in many PBL models is physically incorrect and models will have to be revised as resolution increases. Satellite data suggest that rolls or coherent structures are present more often than not. There is no satellite determined wind data in the PBL and radiometer and in situ data sources are limited. Buoy and sonde point measurements have large errors due to turbulence and organized large eddies (OLE). Flux estimates require good boundary layer winds. Climate analysis is made on very poor data, yet it is increasingly an important political factor. No US wind satellites are yet planned.
Dave Emmitt presented “LOS Statistics from GLAS Data,” coauthored with S. Greco. Dave discussed GLAS and LITE data. GLAS provided a good look at cloud penetration statistics to answer the question of how often clouds are penetrated. On 28% of GLAS shots, no clouds were detected. He has statistics on numbers of layers encountered. Results suggest that coherent detection performance should be better than that shown by today’s models. He found that 43% of GLAS shots get a ground return, 70% hit clouds, 56% get 75 cloud free integrations down to 5 km. GLAS data are available on the web.
Wayman Baker led a Review of Action Items. The next meeting will be held in Welches, Oregon, June 27 -30, 2006. The meeting was adjourned.
These minutes were prepared by Kenneth Miller.
Glossary
A2D - ALADIN Airborne Demonstrator
ADM - ESA’s Atmospheric Dynamics Mission
ALADIN - Atmospheric Laser Doppler Instrument
ATReC - Atlantic THORPEX Regional Campaign
BAMS - Bulletin of the American Meteorological Society
CALIPSO - Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite
CAMEX - Convection and Moisture Experiment
CCD - Charge Coupled Device
CIRPAS - Center for Inter-Disciplinary Remotely Piloted Aircraft Studies
CLIO - Circle to Line Optic
DOD Department of Defense
DLR - German Aerospace Centre
DMSP - Defense Meteorological Satellite Program
DWL - Doppler Wind Lidar
ECMWF - European Centre for Medium-range Weather Forecasts
ESSP - Earth System Science Pathfinder (ESSP) program
ESTEC - European Space Research and Technology Center
ESTO - Earth-Sun System Technology Office
ETKF - Ensemble Transform Kalman Filter
GEO - Geosynchronous Earth Orbit
GEOSS - Global Earth Observation System of Systems
GLAS - Geoscience Laser Altimeter System
GLOW - Goddard Lidar Observatory for Winds
GOES - Geostationary Operational Environmental Satellite
GSFC - Goddard Space Flight Center
GTWS - Global Tropospheric Wind Sounder
GWHI - GroundWinds Hawaii
GWNH - GroundWinds New Hampshire
GWOLF - Ground-based Wind Observing Lidar Facility
HLOS - Horizontal Line of Sight
HOE - Holographic Optical Element
IIP - Instrument Incubator Program
ICESat - Ice, Cloud, and land Elevation Satellite
IMDC - GSFC Integrated Mission Design Center
IORD - Integrated Operational Requirements Document
IPO - Integrated Program Office that manages NPOESS
ISAL - GSFC Instrument Synthesis and Analysis Lab
ISS - International Space Station
LaRC - Langley Research Center
LEO - Low Earth Orbit
LETKF - Local Ensemble Transform Kalman Filter
LRRP - Laser Risk Reduction Program
LWG - Working Group on Space-Based Lidar Winds or Lidar Working Group
MDT - Mission Definition Team
MODIS - Moderate-resolution Imaging Spectroradiometer
MOPA - Master Oscillator Power Amplifier Lidar
NAS - National Academy of Sciences
NCEP - National Centers for Environmental Prediction
NIR - Near infrared region of the electromagnetic spectrum
NPOESS - National Polar-orbiting Operatonal Environmental Satellite System
NPP - NPOESS Preparatory Project
NSF - National Science Foundation
NWP - Numerical Weather Prediction
OES - Office of Earth Sciences
OLE - Organized Large Eddy
OSSE - Observing System Simulation Experiment
P3I - Pre-Planned Product Improvement program (NPOESS)
PBL - Planetary Boundary Layer
PIEW - Prediction Improvement for Extreme Weather
SBIR - Small Business Innovation Research
SNR - Signal to Noise Ratio
SOSE - Sensitivity Observing System Experiment
THORPEX - The Hemispheric Observing system Research and Predictability Experiment
TODWL - Twin Otter DWL
TOVS - TIROS Operational Vertical Sounder
TRL - Technology Readiness Level
TWiLiTE - Tropospheric Wind Lidar Technology Experiment
UNH - University of New Hampshire
UV - Ultraviolet
VALIDAR - Validation Lidar Facility
WSR - Winter Storm Reconnaissance Program