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Charles L. Hyder 《Solar physics》1967,2(1):49-74
Here I present a simple gravitational model for the flarelike brightenings of the chromosphere that follow most disparitions brusques (disappearing filaments). I assume the ascending prominence material is lifted out of the initially stable magnetic dips that characterize quiescent prominences and falls along the arched field lines into the chromosphere where the kinetic energy of fall is dissipated in the bright areas. The examination of prominence and chromospheric characteristics leads naturally to many predictions and relations during and after prominence eruptions. In general the predictions are specific, but the observations of necessary detail and quality are nonexistent; however, the predictions appear to agree with the data that are available. The model appears to explain all non-active-region brightenings of the chromosphere that follow disparitions brusques and an unknown fraction of active-region flares. The conclusion is that two-ribbon flares are due to the disparitions brusques chromospheric flarelike brightening mechanism. In this paper it will become clear that many specific observations in and out of active regions will be necessary to test the predictions of the model given here. 相似文献
3.
Kelly-Gerreyn BA Hydes DJ Hartman MC Siddorn J Hyder P Holt MW 《Marine pollution bulletin》2007,54(7):850-862
This study evaluates the ship of opportunity (Ferrybox) concept for both sustained monitoring of UK shelf sea waters and numerical model validation. Release of phosphate from the wreck of a chemical tanker (MV Ece) in the western English Channel (49.73 degrees N, 3.25 degrees W) in March 2006 is used to demonstrate the importance of sustained observations in decision support systems and policy development. The Ferrybox system continuously collects sea surface (5m) data from a suite of autonomous electronic sensors installed on a passenger ferry operating year-round between Portsmouth (UK) and Bilbao (Spain). The detection of anomalously high concentrations of phosphate (1.54mmolm(-3), four times the usual level) and onset of phytoplankton growth close to the wreck site in March 2006 was placed in the context of multiple years of measurements (phosphate, nitrate, silicate and chlorophyll) collected from the Ferrybox system (2003-2006) and the long-term time series station E1 (50.03 degrees N, 4.65 degrees W, 1930-1987) in the English Channel. With regard to decision support, release of phosphate from the tanker is unlikely to pose a threat as phytoplankton growth at the end of winter is not unusual in this region and dissolved inorganic nitrogen rather than phosphate (DIN:DIP=10-18) is likely to ultimately limit algal growth in spring 2006. With regard to policy development, the Oslo and Paris (OSPAR) commissions recommendation of sampling every three years in "non-problem areas" is likely to provide statistically inadequate data, given the interannual and decadal variability identified in the Ferrybox and E1 data: the Ferrybox data show that oceanic winter nutrient concentrations varied by 35-50% between 2003/2004 and 2005/2006 due to deeper mixing of water off-shelf in early 2005/2006 and comparisons between the Ferrybox and E1 years show that the western English Channel is currently experiencing a low in phosphate concentrations similar to those in the 1960s. The importance of Ferrybox data in evaluating the reliability of predictive operational models needed in decision support is also demonstrated, by highlighting both strengths and weaknesses in a state-of-the-art ecosystem model designed for UK shelf waters. 相似文献
4.
One of the significant effects of considering soil-structure interaction in the analysis of structures is the increase in
the fundamental natural period compared to the fundamental natural period of a similar structure, fixed at the base. Applied
Technology Council (ATC) originally set forth some provisions to calculate the fundamental natural period of flexible based
structures using the period of a similar structure, fixed at the base, and lateral and rocking stiffness coefficients of the
foundation. These provisions became the basis of current soil-structure interaction recommendations in several building codes.
The fundamental natural periods of structures founded on different types of foundations computed using recommendations of
the ATC are compared with those computed using a simplified model to perform soil-structure interaction of shear-type structures.
Results show that the provisions given in ATC may be used for structures supported on shallow footings but may not be applicable
for structures supported on pile foundations or foundations having the ratio of lateral to rotational stiffness coefficients
different from those of shallow foundations. An equation, similar to the equation recommended by ATC, is presented to estimate
the fundamental natural period of structures supported on pile foundations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Charles L. Hyder 《Solar physics》1968,5(1):29-41
Analysis of the effects of polarization in lines used in longitudinal (Babcock) and transverse (Severny) magnetographs shows that previous straightforward analyses of observations may lead to spurious results. Measures of the longitudinal magnetic-field strengths in prominences and in the chromosphere have been underestimated by more than 10% whenever the measured field has been less than 10 gauss. Transverse magnetograph results are subject to resonance polarization effects that may dominate the magnetic signal. The panchromatic transverse magnetograph results discussed by Dollfus and Leroy are based solely on curve of growth polarization interpretations. Again, except within a few degrees of the center of the disk, resonance polarization effects can dominate, and radically change, the interpretations of the observations. 相似文献
7.
We consider the effect that coherent motion has on the observed brightness of moving clouds above the photosphere. We find that steady state clouds (constant N
e
and T
e
) that are moving perpendicular to the line of sight will appear brighter in H for speeds between 8 and 100 km/sec and dimmer for speeds greater than 135 km/sec. The brightening and dimming are due to apparent Doppler shifts of the respective H absorption and the Lyman- emission profiles seen by the absorption profile of the moving cloud.We apply this analysis, along with optical depth and geometrical considerations, to the observed brightness variations of the 1 March 1969 limb eruptive prominence. We find that all of the observed brightening and dimming can be explained by the motions, and that no significant change in the prominence N
e
or T
e
was necessary during the observed H event. This conclusion is significant in interpreting an X-ray burst that began as the prominence velocity increased abruptly at the time of maximum H intensity. The thermal X-ray peak occurred 150 sec later when the prominence had become faint again. There was no associated flare that was visible in H. We discuss the relative brightness of H and D
3 in a specific moving prominence knot.We note that the observed range of limb speeds (30–150 km/sec) may be due to the combined H Doppler brightening and Lyman- dimming effects. We also discuss generally the H brightness of disk surges (bright and dark) and flares, and sprays and puffs that occur at or near the limb.Now at the Dept. of Physics and Astrophysics, University of Colorado, and High Altitude Observatory (NCAR) Boulder, Colo., U.S.A. 相似文献
8.
An ultraviolet spectral probe for a hydrogen-rich planetary atmosphere, such as that of Jupiter, is suggested, utilizing discrete lines in the H2staggered+ 2pπu?1sσg electronic transition. For the Jovian atmosphere, the dominant mechanism for exciting H2+ to its 2pπu state appears to be photoexcitation, principally through absorption of the solar Lyman-α line. We estimate that the Jovian column emission rate of the H2+ 2pπu(ν′ = 2, J′ = 1) →1sσg(ν″ = 18,J″ = 0) fluorescent line at 1236.6 Å is if1 photon cmsu-2 secsu-1; i.e., that if1 photon secsu-1 of this radiation would strike a 15-cm diameter mirror in a Jupiter fly-by at an impact parameter of 3 × 105km. The critical role of corrections to the Born-Oppenheimer approximation in the use of an H2+ probe is discussed. 相似文献
9.
Sea breezes are characteristic features of coastal regions that can extend large distances from the coastline. Oscillations close to the inertial period are thought to account for around half the kinetic energy in the global surface ocean and play an important role in mixing. In the vicinity of 30°N/S, through a resonance between the diurnal and inertial frequencies, diurnal winds could force enhanced anti-cyclonic rotary motions that contribute to near-inertial energy.Observations of strong diurnal anti-cyclonic currents in water of depth 175 m off the Namibian coastline at 28.6°S are analysed over the annual cycle. Maxima in the diurnal anti-cyclonic current and wind stress amplitudes appear to be observed during the austral summer. Both the diurnal anti-cyclonic current and wind stress components have approximately constant phase throughout the year. These observations provide further evidence that these diurnal currents may be wind forced. Realistic General Ocean Turbulence Model (GOTM) 1-D simulations of diurnal wind forcing, including the first order coast-normal surface slope response to diurnal wind forcing, represent the principal features of the observed diurnal anti-cyclonic current but do not replicate the observed vertical diurnal current structure accurately. Cross-shelf 2-D slice simulations suggest that the first order surface slope response approximation applies away from the coast (>140 km). However, nearer to the coast, additional surface slope variations associated with spatial variations in the simulated velocity field (estimated from Bernoulli theory) appear to be significant and also result in transfer of energy to higher harmonics. Evidence from 3-D simulations at similar latitude in the northern hemisphere suggests that 3-D variations, including propagating near-inertial waves, may also need to be considered. 相似文献
10.
Ulf Gräwe Eric Deleersnijder Syed Hyder Ali Muttaqi Shah Arnold Willem Heemink 《Ocean Dynamics》2012,62(4):501-514
During the last decades, the Euler scheme was the common “workhorse” in particle tracking, although it is the lowest-order approximation of the underlying stochastic
differential equation. To convince the modelling community of the need for better methods, we have constructed a new test
case that will show the shortcomings of the Euler scheme. We use an idealised shallow-water diffusivity profile that mimics the presence of a sharp pycnocline and thus a quasi-impermeable
barrier to vertical diffusion. In this context, we study the transport of passive particles with or without negative buoyancy.
A semi-analytic solutions is used to assess the performance of various numerical particle-tracking schemes (first- and second-order
accuracy), to treat the variations in the diffusivity profile properly. We show that the commonly used Euler scheme exhibits a poor performance and that widely used particle-tracking codes shall be updated to either the Milstein scheme or second-order schemes. It is further seen that the order of convergence is not the only relevant factor, the absolute
value of the error also is. 相似文献