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[en] The paper discusses basic properties of linear motion detectors focussing on two particular systems which highlight the difficulties involved in approaching the Standard Quantum Limit. The current observational situation is briefly reported
[en] We have maintained a solar oscillations observing program for more than 13 years at Stanford. The observations are most sensitive to low degree solar modes and have been used for the study of long period p-mode and g-mode oscillations. At the start of the 1987 observing season (summer) some long-standing problems with the instrument were corrected which (along with good weather) allowed the cleanest set of data to date. This paper reports the current state of the search for evidence of g-modes in this data. Analysis of this data shows good evidence for g-modes. Various methods were used for mode identification with a statistical search for a simple-pattern of even spacing in period selected as the most robust. Using this method, a possible g-mode identification was made with an asymptotic period separation T0 = 37.1 minutes. This identification was consistent with a rotation splitting of 1.6 microHz. Tests with randomly generated spectral peaks find as significant a possible set of modes in only 2 out of 100 cases
[en] Further evidence has been found that a significant fraction of the gravity mode power density in the total irradiance observations appears in sidebands of classified eigenfrequencies. These sidebands whose amplitudes vary from year to year are interpreted as harmonics of the rotational frequencies of the nonuniform solar surface. These findings are for non axisymmetric modes and corroborate the findings of Kroll, Hill and Chen for axisymmetric modes. It is demonstrated that the generation of the sidebands lifts the usual restriction on the parity of the eigenfunctions for modes detectable in total irradiance observations
[en] The impacts of different wave spectrum formulations with high frequency tail on the Stokes drift are studied in this paper. Two wave spectrum formulations are described. One is from the Donelan and Pierson spectrum extended to the high frequency range (denoted by EDP spectrum) by Paskyabi and Jenkins, and the other is a combined spectrum (termed the Combi spectrum) provided by Tsagareli. Using the EDP spectrum and Combi spectrum, the Stokes drift velocities and Stokes transports are calculated for the different wind speeds. The results show that the high frequency spectral tail of the surface gravity waves obviously changes the Stokes drift velocity on the sea surface, but has little impact on the Stokes transport. (paper)
[en] Complete text of publication follows. Planetary waves (PW) change the global background wind fields and thus modify global gravity wave (GW) distributions by critical level filtering and modulation of the GW spectrum by refraction. On the other hand, forcing by breaking GWs has a longitudinal structure which can amplify or suppress PWs. We will analyze global GW distributions inferred from the SABER instrument for signatures of PWs and compare the results to PW fields inferred from the SABER temperature measurements. These experimental results will be compared to global ray tracing modeling with the GROGRAT ray tracer. The influence of assumptions generally made in GW parameterization schemes, such as vertical propagation, on the longitudinal asymmetries in the GW induced acceleration will be quantified and the GW forcing of PWs will be discussed.
[en] Complete text of publication follows. Gravity (buoyancy) waves play an important role in transferring momentum from source regions in the lower atmosphere to the middle and upper atmosphere. Body forces produced by breaking waves lead to residual circulations that profoundly affect the state of the atmosphere. This talk will summarize results from a campaign held near Darwin in northern Australia in January-February 2006 to measure wave generation and propagation and the associated momentum fluxes. The project used a variety of radars to study the spatial and temporal variability of rainfall and the associated latent heat release during large convective storms. A high-resolution numerical model utilized the latent heat release to compute the spatial and geographic variation of gravity wave generation and propagation into the lower stratosphere. Gravity wave ray-tracing techniques were then used to estimate the wave flux penetrating to heights near 90 km, where the results were compared with direct measurements made using a meteor radar. It is shown that there is excellent agreement between the direct and indirect estimates of wave activity. Wave fluxes show a high degree of temporal variability, with consequent variability in momentum flux deposition and wave drag.
[en] Attempts to detect atmospheric gravity waves generated by solar eclipse by measuring eclipse-oriented fluctuations of the total electron content of the ionosphere during the period of a solar eclipse are briefly reviewed. Due to disturbed magnetic conditions during solar eclipse, it has not been possible so far to establish a definite link between eclipse and gravity waves. (M.G.B.)
[en] The effect of the upper layer of water-immiscible oil on the process of regularization of breaking standing gravity waves on the free surface of a two-layer system in a rectangular vessel has been experimentally investigated for the first time. A comparison is made with the case of standing gravity waves on the free surface of homogeneous liquids (water and seed oil). (paper)