Surface energy fluxes in complex terrain

The emphasis of the 1985 NASA project activity was on field measurements of wind data and heat balance data. Initiatives included a 19 station mountaintop monitoring program, testing and refining the surface flux monitoring systems and packing and shipping equipment to the People's Republic of China in preparation for the 1986 Tibet Experiment. Other work included more extensive analyses of the 1984 Gobi Desert and Rocky Mountain observations plus some preliminary analyses of the 1985 mountaintop network data. Details of our field efforts are summarized and results of our data analyses are presented

Cooperative vs. Non-Cooperative Truels: Little Agreement, But Does That Matter?

It is well-known that non-cooperative and cooperative game theory may yield different solutions to games. These differences are particularly dramatic in the case of truels, or three-person duels, in which the players may fire sequentially or simultaneously, and the games may be one-round or n-round. Thus, it is never a Nash equilibrium for all players to hold their fire in any of these games, whereas in simultaneous one-round and n-round truels such cooperation, wherein everybody survives, is in both the alpha-core and beta-core. On the other hand, both cores may be empty, indicating a lack of stability, when the unique Nash equilibrium is one survivor. Conditions under which each approach seems most applicable are discussed. Although it might be desirable to subsume the two approaches within a unified framework, such unification seems unlikely since the two approaches are grounded in fundamentally different notions of stability.COOPERATIVE GAME; NON-COOPERATIVE GAME; TRUEL; NASH EQUILIBRIUM; CORE

Measurements of SCRF cavity dynamic heat load in horizontal test system

The Horizontal Test System (HTS) at Fermilab is currently testing fully assembled, dressed superconducting radio frequency (SCRF) cavities. These cavities are cooled in a bath of superfluid helium at 1.8K. Dissipated RF power from the cavities is a dynamic heat load on the cryogenic system. The magnitude of heat flux from these cavities into the helium is also an important variable for understanding cavity performance. Methods and hardware used to measure this dynamic heat load are presented. Results are presented from several cavity tests and testing accuracy is discussed.Comment: 6 pp. Cryogenic Engineering Conference and International Cryogenic Materials Conference 28 Jun - 2 Jul 2009. Tucson, Arizon

Cooperative VS. Non-cooperative Truels: Little Agreement, but Does that Matter?

It is well-known that non-cooperative and cooperative game theory may yield different solutions to games. These differences are particularly dramatic in the case of truels, or three-person duels, in which the players may fire sequentially or simultaneously, and the games may be one-round or n-round. Thus, it is never a Nash equilibrium for all players to hold their fire in any of these games, whereas in simultaneous one-round and n-round truels such cooperation, wherein everybody survives, is in both the a -core and ß -core. On the other hand, both cores may be empty, indicating a lack of stability, when the unique Nash equilibrium is one survivor. Conditions under which each approach seems most applicable are discussed. Although it might be desirable to subsume the two approaches within a unified framework, such unification seems unlikely since the two approaches are grounded in fundamentally different notions of stability.Nous analysons des « truels » qui sont des jeux spécifiques avec trois joueurs. Il est démontré que, dans ces jeux, les résultats de la théorie des jeux non-coopératifs sont très différents des résultats qui sont obtenus en utilisant une théorie coopérative

Numerical modeling of a multiscale gravity wave event and its airglow signatures over Mount Cook, New Zealand, during the DEEPWAVE campaign

A 2-D nonlinear compressible model is used to simulate a large-amplitude, multiscale mountain wave event over Mount Cook, NZ, observed as part of the Deep Propagating Gravity Wave Experiment (DEEPWAVE) campaign and to investigate its observable signatures in the hydroxyl (OH) layer. The campaign observed the presence of a _x=200ækm mountain wave as part of the 22nd research flight with amplitudes of \u3e20æK in the upper stratosphere that decayed rapidly at airglow heights. Advanced Mesospheric Temperature Mapper (AMTM) showed the presence of small-scale (25_28ækm) waves within the warm phase of the large mountain wave. The simulation results show rapid breaking above 70ækm altitude, with the preferential formation of almost-stationary vortical instabilities within the warm phase front of the mountain wave. An OH airglow model is used to identify the presence of small-scale wave-like structures generated in situ by the breaking of the mountain wave that are consistent with those seen in the observations. While it is easy to interpret these feature as waves in OH airglow data, a considerable fraction of the features are in fact instabilities and vortex structures. Simulations suggest that a combination of a large westward perturbation velocity and shear, in combination with strong perturbation temperature gradients, causes both dynamic and convective instability conditions to be met particularly where the wave wind is maximized and the temperature gradient is simultaneously minimized. This leads to the inevitable breaking and subsequent generation of smaller-scale waves and instabilities which appear most prominent within the warm phase front of the mountain wave. ©2017. American Geophysical Union. All Rights Reserved

Large-amplitude mesospheric response to an orographic wave generated over the Southern Ocean Auckland Islands (50.7°S) during the DEEPWAVE project

The Deep Propagating Gravity Wave Experiment (DEEPWAVE) project was conducted over New Zealand and the surrounding regions during June and July 2014, to more fully understand the generation, propagation, and effects of atmospheric gravity waves. A large suite of instruments collected data from the ground to the upper atmosphere (~100 km), with several new remote-sensing instruments operating on board the NSF Gulfstream V (GV) research aircraft, which was the central measurement platform of the project. On 14 July, during one of the research flights (research flight 23), a spectacular event was observed as the GV flew in the lee of the sub-Antarctic Auckland Islands (50.7°S). An apparent ship wave pattern was imaged in the OH layer (at ~83.5 km) by the Utah State University Advanced Mesospheric Temperature Mapper and evolved significantly over four successive passes spanning more than 4 h. The waves were associated with orographic forcing generated by relatively strong (15-20 m/s) near-surface wind flowing over the rugged island topography. The mountain wave had an amplitude T_ ~ 10 K, a dominant horizontal wavelength ~40 km, achieved a momentum flux exceeding 300 m2 s-2, and eventually exhibited instability and breaking at the OH altitude. This case of deep mountain wave propagation demonstrates the potential for strong responses in the mesosphere arising from a small source under suitable propagation conditions and suggests that such cases may be more common than previously believed. © 2016. American Geophysical Union. All Rights Reserved

Midtropospheric influences on boundary layer evolution in the Mexico City basin

Mexico City lies in a horseshoe-shaped basin at 2250 m AGL. These authors have simulated the effects of thermally-forced local to regional-scale circulation patterns on the ozone distribution within the basin. On most of the case days studied a relationship could be found between the spatial and temporal evolution of wind patterns and ozone concentration, particularly in the southwestern part of the basin. In this paper, the authors focus upon defining the relationship between the vertical structure of the atmosphere, by examining stability and wind shear, and the near surface pollution. This work was prompted by the need to better understand the role of midtropospheric flow in contributing to, or alleviating, the pollution problem in the basin. The role of vertical exchange processes in this locale has so far been only peripherally explored. From this investigation the authors hope to assess the importance of upper level winds in contributing to ventilation of pollutants out of the basin above the mountaintop level, in flushing the polluted airmass out of the basin, and in the development of basin-wide recirculation patterns. The results of preliminary data analyses are described

Spectral and picosecond temporal properties of flared guide Y‐coupled phase‐locked laser arrays

Spatio‐spectral and spatio‐temporal properties of flared waveguide ‘‘Y’’‐coupled laser arrays are investigated in both cw and pulsed operation. In each case, regular sustained self‐pulsations are exhibited. Destabilization of phase locking, caused by amplitude phase coupling, is thought to be the origin of the pulsations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70525/2/APPLAB-53-24-2380-1.pd

Cavity length dependence of mode beating in passively Q-switched Nd-solid state lasers.

Abstract Not Provide

Momentum flux estimates accompanying multiscale gravity waves over Mount Cook, New Zealand, on 13 July 2014 during the DEEPWAVE campaign

Observations performed with a Rayleigh lidar and an Advanced Mesosphere Temperature Mapper aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V research aircraft on 13 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) measurement program revealed a large-amplitude, multiscale gravity wave (GW) environment extending from ~20 to 90 km on flight tracks over Mount Cook, New Zealand. Data from four successive flight tracks are employed here to assess the characteristics and variability of the larger- and smaller-scale GWs, including their spatial scales, amplitudes, phase speeds, and momentum fluxes. On each flight, a large-scale mountain wave (MW) having a horizontal wavelength ~200-300 km was observed. Smaller-scale GWs over the island appeared to correlate within the warmer phase of this large-scale MW. This analysis reveals that momentum fluxes accompanying small-scale MWs and propagating GWs significantly exceed those of the large-scale MW and the mean values typical for these altitudes, with maxima for the various small-scale events in the range ~20-105 m2 s-2. Key Points Mountain waves penetrate the mesosphere under suitable propagation conditions Small-scale gravity waves can attain very large momentum fluxes Occurrence of peak momentum fluxes is often dictated by multiscale environments. © 2015. American Geophysical Union. All Rights Reserved