Synoptic controls on ozone over the northeastern US and continental export

This dissertation focused on the impact of circulation, a key climate variable, on air quality from regional to global scale. The relationships between circulation and tropospheric ozone (O3) levels were investigated for the surface over the northeastern U.S. as well as for the spring-, winter- and summertime North American export and trans-Atlantic Transport. The latter studies utilized the Tropospheric Emission Spectrometer (TES) retrievals of O3 and carbon monoxide (CO) to explore the three-dimensional structure of continental outflow and to identify anthropogenic influence on the free troposphere over the remote oceanic region. The key findings are summarized as follows. First, the most common among the top five circulation patterns across the northeastern U.S. for summers 2000-2004, identified with a correlation-based synoptic categorization technique, was associated with stagnant warm conditions that were intimately associated with occurrence of high O3. O 3 varied on an interannual timescale from a mean daily maximum value of 64 ppbv in 2002 to 52 ppbv in 2004. The sea level pressure (SLP) system intensity and frequency of each map type accounted for 46% of the interannual variability. The remainder was possibly due to non-linear relationships between climate and biogenic emissions and decreasing power plant emissions over the analysis period. Second, during spring continental export was evident from enhanced O3 (\u3e55 ppbv) and CO (\u3e115 ppbv) at the 681 hPa retrieval level suggesting anthropogenic influence. The export was found to be facilitated by both the primary and secondary branches of the warm conveyor belt (WCB) of cyclones which lofted pollutants from the continental boundary layer to the free troposphere enabling fast long distance transport with subsequent global impact. Ample evidence suggested stratospheric intrusions associated with cyclonic circulations particularly to the north of 45°N. Third, during winter the O3 levels at 681 hPa were uniformly low (∼45 ppbv) and the continental export was only evident in enhanced CO. Export to the free troposphere was mainly via the WCB and shallow convection behind cold fronts resulting from cold air flowing over warmer ocean waters. In summer O3 levels were highly variable and the main export band was shifted northward around the Bermuda High, except during the passage of weak cyclones and cold fronts when export was shifted further south

A Functional Description of a Digital Flight Test System for Navigation and Guidance Research in the Terminal Area

A guidance, navigation, and control system, the Simulated Shuttle Flight Test System (SS-FTS), when interfaced with existing aircraft systems, provides a research facility for studying concepts for landing the space shuttle orbiter and conventional jet aircraft. The SS-FTS, which includes a general-purpose computer, performs all computations for precisely following a prescribed approach trajectory while properly managing the vehicle energy to allow safe arrival at the runway and landing within prescribed dispersions. The system contains hardware and software provisions for navigation with several combinations of possible navigation aids that have been suggested for the shuttle. The SS-FTS can be reconfigured to study different guidance and navigation concepts by changing only the computer software, and adapted to receive different radio navigation information through minimum hardware changes. All control laws, logic, and mode interlocks reside solely in the computer software

Flight test pilot evaluation of a delayed flap approach procedure

Using NASA's CV-990 aircraft, a delayed flap approach procedure was demonstrated to nine guest pilots from the air transport industry. Four demonstration flights and 37 approaches were conducted under VFR weather conditions. A limited pilot evaluation of the delayed flap procedure was obtained from pilot comments and from questionaires they completed. Pilot acceptability, pilot workload, and ATC compatibility were quantitatively rated. The delayed flap procedure was shown to be feasible, and suggestions for further development work were obtained

Delayed flap approach procedures for noise abatement and fuel conservation

The NASA/Ames Research Center is currently investigating the delayed flap approach during which pilot actions are determined and prescribed by an onboard digital computer. The onboard digital computer determines the proper timing for the deployment of the landing gear and flaps based on the existing winds and airplane gross weight. Advisory commands are displayed to the pilot. The approach is flown along the conventional ILS glide slope but is initiated at a higher airspeed and in a clean aircraft configuration that allows for low thrust and results in reduced noise and fuel consumption. Topics discussed include operational procedures, pilot acceptability of these procedures, and fuel/noise benefits resulting from flight tests and simulation

Flight performance of a navigation, guidance, and control system concept for automatic approach and landing of space shuttle orbiter

Unpowered automatic approaches and landings were conducted to study navigation, guidance, and control problems associated with terminal area approach and landing for the space shuttle vehicle. The flight tests were performed in a Convair 990 aircraft equipped with a digital flight control computer connected to the aircraft control system and displays. The tests were designed to evaluate the performance of a navigation and guidance concept that utilized blended radio/inertial navigation with VOR, DME, and ILS as the ground navigation aids. Results from 36 automatic approaches and landings from 11,300 m (37,000 ft) to touchdown are presented. Preliminary results indicate that this concept may provide sufficient accuracy to accomplish automatic landing of the shuttle orbiter without air-breathing engines

Flight tests of IFR landing approach systems for helicopters

Joint NASA/FAA helicopter flight tests were conducted to investigate airborne radar approaches (ARA) and microwave landing system (MLS) approaches. Flight-test results were utilized to prove NASA with a data base to be used as a performance measure for advanced guidance and navigation concepts, and to provide FAA with data for establishment of TERPS criteria. The first flight-test investigation consisted of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico, using weather/mapping radar, operational pilots, and a Bell 212 helicopter. The second flight-test investigation consisted of IFR MLS approaches at Crows Landing (near Ames Research Center), with a Bell UH-1H helicopter, using NASA, FAA, and operational industry pilots. Tests are described and results discussed

Wider-frequency combs generation, noise reduction, and repetition rate tuning in quantum-dot mode-locked lasers

We describe the technique allowing for generation of low-noise wider frequency combs and pulses of shorter duration in quantum-dot mode-locked lasers. We compare experimentally noise stabilization techniques in semiconductor modelocked lasers. We discuss the benefits of electrical modulation of the laser absorber voltage (hybrid mode-locking), combination of hybrid mode-locking with optical injection seeding from the narrow linewidth continues wave master source and optical injection seeding of two coherent sidebands separated by the laser repetition rate