Coincident extremely large sporadic sodium and sporadic E layers observed in the lower thermosphere over Colorado and Utah

International audienceOn the night of 2 June 2002, the sodium lidar in Fort Collins, CO (40.6 N, 105 W) measured an extremely strong sporadic sodium layer lasting from 03:30 to 05:00 UT with several weaker layers later in the night at 06:00 and 09:00 UT. There is a double layer structure with peaks at 101 and 104 km. The peak sodium density was 21 000 atoms/cm3 with a column abundance of up to twice that of the normal sodium layer. The peak density was 500 times greater than the typical density at that altitude. The sporadic layer abundance and strength factor were higher than any reported in the literature. The two lidar beams, separated by 70 km at this altitude, both measured 0.6 h periodicities in the abundance, but out of phase with each other by 0.3 h. There is also evidence for strong wave activity in the lidar temperatures and winds. The NOAA ionosonde in Boulder, CO (40.0 N, 105 W) measured a critical frequency (foEs) of 14.3 MHz at 03:00 UT on this night, the highest value anytime during 2002. The high values of total ion density inferred means that Na+ fraction must have been only a few percent to explain the neutral Na layer abundances. The Bear Lake, Utah (41.9 N, 111.4 W) dynasonde also measured intense Es between 02:00 and 05:00 UT and again from 06:00 to 08:00 UT about 700 km west of the lidar, with most of the ionograms during these intervals measuring Es up to 12 MHz, the limit of the ionosonde sweep. Other ionosondes around North America on the NGDC database measured normal foEs values that night, so it was a localized event within North America. The peak of Es activity observed in Europe during the summer of 2002 occurred on 4 June. The observations are consistent with the current theories where a combination of wind shears and long period waves form and push downward a concentrated layer of ions, which then chemically react and form a narrow layer of sodium atoms

Multi-year Observations of Mid-latitude Middle Atmospheric Winds, Waves, and Temperature associated with SSW Events over Northern Utah

We investigate the behavior of 14 years of wind, wave, and temperature observations in the middle atmosphere over northeastern Utah, USA during periods of sudden stratospheric warming events. This systematic review of the impacts of sudden stratospheric warming events on the middle atmosphere at a northern mid-latitude site is conducted using ground based measurements from imaging Doppler interferometry and meteor wind radar and Na and Raleigh lidar and space based measurements made by the Sounding of the Atmosphere Using Broadband Emission Radiometry sensor onboard the NASA sponsored Thermosphere Ionosphere mesosphere Energetics Dynamics Mission

ASTRA: ASTrometry and phase-Referencing Astronomy on the Keck interferometer

ASTRA (ASTrometric and phase-Referencing Astronomy) is an upgrade to the existing Keck Interferometer which aims at providing new self-phase referencing (high spectral resolution observation of YSOs), dual-field phase referencing (sensitive AGN observations), and astrometric (known exoplanetary systems characterization and galactic center general relativity in strong field regime) capabilities. With the first high spectral resolution mode now offered to the community, this contribution focuses on the progress of the dual field and astrometric modes.Comment: 10 pages, 6 figures, 2 tables, SPIE 201

Cretaceous and Tertiary in Mongolia

7 p. : map ; 24 cm

Keck Interferometer Nuller Data Reduction and On-Sky Performance

We describe the Keck Interferometer nuller theory of operation, data reduction, and on-sky performance, particularly as it applies to the nuller exozodiacal dust key science program that was carried out between 2008 February and 2009 January. We review the nuller implementation, including the detailed phasor processing involved in implementing the null-peak mode used for science data and the sequencing used for science observing. We then describe the Level 1 reduction to convert the instrument telemetry streams to raw null leakages, and the Level 2 reduction to provide calibrated null leakages. The Level 1 reduction uses conservative, primarily linear processing, implemented consistently for science and calibrator stars. The Level 2 processing is more flexible, and uses diameters for the calibrator stars measured contemporaneously with the interferometer’s K-band cophasing system in order to provide the requisite accuracy. Using the key science data set of 462 total scans, we assess the instrument performance for sensitivity and systematic error. At 2.0 Jy we achieve a photometrically-limited null leakage uncertainty of 0.25% rms per 10 minutes of integration time in our broadband channel. From analysis of the Level 2 reductions, we estimate a systematic noise floor for bright stars of ~0.2% rms null leakage uncertainty per observing cluster in the broadband channel. A similar analysis is performed for the narrowband channels. We also provide additional information needed for science reduction, including details on the instrument beam pattern and the basic astrophysical response of the system, and references to the data reduction and modeling tools

Preliminary seismological and geological studies of the San Fernando, California, earthquake of February 9 1971

The San Fernando earthquake was the largest earthquake to occur in the metropolitan Los Angeles area in more than 50 years. It has tentatively been assigned a magnitude, M_L of 6.6, a focal depth of 13.0 km, and an epicentral location about 12 km east of Newhall, California, at 34°24.0'N, 118°23.7'W (Figure 1), but these figures undoubtedly will be modified as further data become available. Although the focal depth is not as well defined as the epicenter, it is consistent with other observations suggesting thrusting on a fault plane dipping north about 45 ° and breaking the surface in the Sylmar-San Fernando area (Figure 1). It should be emphasized that the hypocenter of the main shock represents only the point of initial rupture. Breaking, presumably, then propagated southward and upward from this point, so that the main geological and engineering effects were observed farther south where the fault was shallower and the displacement greater. The location of the main shock is based on readings from permanent stations of the Caltech network, as well as the U. S. Geological Survey station at Point Mugu (SBLG) and the California Department of Water Resources stations at Pyramid (PYR) and Cedar Springs (CSP). Portable Caltech seismographs were installed in the epicentral area as early as 3 hr following the main shock, and, within a few days, there were at least 30 portable units in the region operated by various groups and agencies

Asteroseismology of the Beta Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identification

We report a multisite photometric campaign for the Beta Cephei star 12 Lacertae. 750 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with 9 telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Eleven of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that seemingly present in several Beta Cephei stars. We perform mode identification from our colour photometry, derive the spherical degree l for the five strongest modes unambiguously and provide constraints on l for the weaker modes. We find a mixture of modes of 0 <= l <= 4. In particular, we prove that the previously suspected rotationally split triplet within the modes of 12 Lac consists of modes of different l; their equal frequency splitting must thus be accidental. One of the periodic signals we detected in the light curves is argued to be a linearly stable mode excited to visible amplitude by nonlinear mode coupling via a 2:1 resonance. We also find a low-frequency signal in the light variations whose physical nature is unclear; it could be a parent or daughter mode resonantly coupled. The remaining combination frequencies are consistent with simple light-curve distortions. The range of excited pulsation frequencies of 12 Lac may be sufficiently large that it cannot be reproduced by standard models. We suspect that the star has a larger metal abundance in the pulsational driving zone, a hypothesis also capable of explaining the presence of Beta Cephei stars in the LMC.Comment: 12 pages, 7 figures, MNRAS, in pres

Later sediments of central Mongolia

16 p. : map ; 24 cm."It appears from this listing of the formational units distinguished by locality and structural features that there are at least four formations of locality significance of late Mesozoic age, presumably Upper and Lower Cretaceous, and four formations belonging to the Upper Tertiary, including beds of Miocene and Pliocene age. The early Tertiary is much less fully represented, or else is represented by formations not yet furnishing adequate fossil criteria. Only the Irdin Manha formation, in the Iren Dabasu region, and the beds of Shara Murun, one of the basins on the Uliasutai Trail, may have been placed earlier than the Miocene on fossil evidence. It may be, of course, that the lower barren beds of the Hsanda Gol are pre-Miocene also; but for this there is no direct evidence. This is an additional reason for grouping these scattered formational units into definite series. There are no used or published terms that have suitable limitations for this purpose. Obruchev's 'Gobi Series' was used by him to include all sorts of later sedimentary beds, without age distinction. Von Richthofen's term 'Khan-Khai Beds' has been used in the same way for all of the later sediments, without more intimate discrimination... the following terms are proposed for the smaller groups: 1. The Tsagan Nor Series (Upper Tertiary). 2. An unnamed series (Lower Tertiary). 3. The Shamo Series (Upper Mesozoic). The Tsagan Nor Series is intended to include formations of Pliocene and Miocene age, or the Upper Tertiary. To it belong the units already described as the Hung Kureh, Hsanda Gol, Ardyn Obo and Houldjin formations. Another series ought to include the Lower Tertiary, or the pre-Miocene Tertiary. Thus far, the only formations classified in this series are the Irdin Manha and the beds of another basin, the Shara Murun, farther west... The Shamo Series is pre-Tertiary. It is intended to include the Cretaceous beds overlying the great unconformity above the folded and eroded Jurassic. The units distinguished in the field are the Iren Dabasu, Ondai Sair, Ashile, and Dja-doch-ta formations... it appears that no less than 6000 to 8000 feet of later sedimentary strata are accounted for in the complex series of later sediments lying above the great post-Jurassic unconformity in the Gobi region of Mongolia. All of the formations named are distinguished by characteristic fossil content... All are of strictly continental type. No evidence of marine invasion was found anywhere..."--P. 13-16

Consumption patterns of sweet drinks in a population of Australian children and adolescents (2003–2008)

<p>Abstract</p> <p>Background</p> <p>Intake of sweet drinks has previously been associated with the development of overweight and obesity among children and adolescents. The present study aimed to assess the consumption pattern of sweet drinks in a population of children and adolescents in Victoria, Australia.</p> <p>Methods</p> <p>Data on 1,604 children and adolescents (4–18 years) from the comparison groups of two quasi-experimental intervention studies from Victoria, Australia were analysed<it>.</it> Sweet drink consumption (soft drink and fruit juice/cordial) was assessed as one day’s intake and typical intake over the last week or month at two time points between 2003 and 2008 (mean time between measurement: 2.2 years).</p> <p>Results</p> <p>Assessed using dietary recalls, more than 70% of the children and adolescents consumed sweet drinks, with no difference between age groups (p = 0.28). The median intake among consumers was 500 ml and almost a third consumed more than 750 ml per day. More children and adolescents consumed fruit juice/cordial (69%) than soft drink (33%) (p < 0.0001) and in larger volumes (median intake fruit juice/cordial: 500 ml and soft drink: 375 ml). Secular changes in sweet drink consumption were observed with a lower proportion of children and adolescents consuming sweet drinks at time 2 compared to time 1 (significant for age group 8 to <10 years, p = 0.001).</p> <p>Conclusion</p> <p>The proportion of Australian children and adolescents from the state of Victoria consuming sweet drinks has been stable or decreasing, although a high proportion of this sample consumed sweet drinks, especially fruit juice/cordial at both time points.</p