Upper limits on the total radiant energy of solar flares     

H. S. Hudson  R. C. Willson 《Solar physics》1983,86(1-2):123-130

We establish limits on the total radiant energy of solar flares during the period 1980 February – November, using the solar-constant monitor (ACRIM) on board the Solar Maximum Mission. Typical limits amount to 6 × 10²⁹ erg/s for a 32-second integration time, with 5σ statistical significance, for an impulsive emission; for a gradual component, about 4 × 10³² ergs total radiant energy. The limits lie about an order of magnitude higher than the total radiant energy estimated from the various known emission components, suggesting that no heretofore unknown dominant component of flare radiation exists.  相似文献   

Noise storms and the structure of microwave emission of solar active regions     

V. M. Bogod  V. Garimov  G. B. Gelfreikh  K. R. Lang  R. F. Willson  J. N. Kile 《Solar physics》1995,160(1):133-149

Solar radio and microwave sources were observed with the Very Large Array (VLA) and the RATAN-600, providing high spatial resolution at 91 cm (VLA) and detailed spectral and polarization data at microwave wavelengths (1.7 to 20 cm - RATAN). The radio observations have been compared with images from the Soft X-ray Telescope (SXT) aboard theYohkoh satellite and with full-disk phoptospheric magnetic field data from the Kislovodsk Station of the Pulkovo Observatory. The VLA observations at 91 cm show fluctuating nonthermal noise storm sources in the middle corona. The active regions that were responsible for the noise storms generally had weaker microwave emission, fainter thermal soft X-ray emission, as well as less intense coronal magnetic fields than those associated with other active regions on the solar disk. The noise storms did, however, originate in active regions whose magnetic fields and radiation properties were evolving on timescales of days or less. We interpret these noise storms in terms of accelerated particles trapped in radiation belts above or near active regions, forming a decimetric coronal halo. The particles trapped in the radiation belts may be the source of other forms of nonthermal radio emission, while also providing a reservoir from which energetic particles may drain down into lower-lying magnetic structures.Presented at the CESRA-Workshop on Coronal Magnetic Energy Release at Caputh near Potsdam in May 1994.  相似文献   

Surface waves in restricted Hadamard materials     

A. J. Willson 《Pure and Applied Geophysics》1973,110(1):1967-1976

Summary The propagation of waves of small amplitude in an elastic medium composed of Hadamard material, satisfying also the Ordered Forces condition and the Strong Ellipticity condition, and subjected to a large homogeneous biaxial stress, is investigated in detail. Consideration is given to the existence and general properties of Rayleigh waves on the surface of a semi-infinite medium, and to the propagation of plate waves in a medium of finite thickness.  相似文献   

Solar total irradiance observations by Active Cavity Radiometers     

Richard C. Willson 《Solar physics》1981,74(1):217-229

Pyrheliometry, definition of the radiation scale in the International System of Units and monitoring the variability of solar total irradiance have been a focus of research at the Jet Propulsion Laboratory since the mid 1960's. A series of automated, electrically self-calibrating, cavity pyrheliometers known as Active Cavity Radiometers (ACR's) was developed as part of this program. A series of ground based experiments in 1968–69 led to the discovery of a systematic error in the International Pyrheliometric Scale. ACR's were among the instruments used to define the World Radiometric Reference in 1975.ACR flight experiments have been conducted to determine the 1 AU total solar irradiance and monitor its variability in time. A 1969 balloon experiment yielded a 1366 W m^-2 result. The value from a 1976 sounding rocket experiment was 1368.1 W m^-2. The results for two additional rocket experiments in 1978 and 80, revised in accordance with recent calibrations of ACR response to elevated pressures during these flights are: 1367.6 and 1367.8 W m^-2, respectively. An ACR experiment (ACRIM) on the Solar Maximum Mission satellite has shown continuous variability of the total solar flux below the ±0.05% level and two large, temporary decreases of 0.1–0.2% lasting more than a week. The mean 1 AU total flux for ACRIM's first five months' observations was 1367.7 W m^-2. Inflight comparison of ACR rocket and satellite measurements in May, 1980 demonstrated agreement to within ±0.05%. The 1 AU total solar irradiance results from ACR rocket and satellite experiments between 1976 and 1980 differ from their mean of 1367.8 W m^-2 by no more than ±0.02%. The less precise 1969 balloon result is 0.1% lower. Although no observations were made from 1970–75, if solar behaviour in those five years was similar to that observed since 1976 then the upper limits of long term solar total irradiance variability are ±0.2% for the 1969–1980 period and ±0.1% between 1976 and 1980, based on the set of ACR observations.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands.  相似文献   

Use of Rhodamine water tracer in the marshland upwelling system   总被引：1，自引：0，他引：1  

Richardson SD  Willson CS  Rusch KA 《Ground water》2004,42(5):678-688

Rhodamine water tracer (RWT) was used to characterize the migration of waste water within the saline subsurface of a marshland upwelling system (MUS), which is an alternative on-site waste water treatment system for coastal areas. Field tracer studies were performed to investigate the fresh waste water plume movement within the saline ground water. Pore velocities were calculated using first detection times and ranged from 0.68 to 10.7 x 10(-4) cm/sec for the loamy sandy soil matrix present at the site. Use of RWT in the field also allowed determination of main and preferential flowpaths. One- and two-dimensional laboratory experiments were performed using silica sand to investigate the interactions of the organically rich waste water with RWT within the zone surrounding the point of injection (one-dimensional) and the impact of background salinity on plume movement (two-dimensional). The results from these studies were used to help explain the field data. One-dimensional breakthrough curves revealed retardation factors for the RWT in the waste water mixture of 1.73 to 1.90. These results were similar to other researchers, indicating little interaction between the waste water and RWT. Variations in pore water salinity (5, 15, 25, and 35 ppt) were found to have a significant effect on pore water velocities of the fresh water plume (two-dimensional), indicating the need to incorporate background salinities into the design process for MUS.  相似文献   

Observations of preburst heating and magnetic field changes in a coronal loop at 20 cm wavelength     

Robert F. Willson 《Solar physics》1984,92(1-2):189-198

The Very Large Array (VLA) has been used at 20 cm wavelength to study the evolution of a burst loop with 4 resolution on timescales as short as 10 s. The VLA observations show that the coronal loop began to heat up and change its structure about 15 min before the eruption of two impulsive bursts. The first of these bursts occurred near the top of the loop that underwent preburst heating, while the second burst probably occurred along the legs of an adjacent loop. These observations evoke flare models in which coronal loops twist, develop magnetic instabilities and then erupt. We also combine the VLA observations with GOES X-ray data to derive a peak electron temperature of T _e = 2.5 × 10⁷ K and an average electron density of N _e 1 × 10¹⁰ cm^–3 in the coronal loop during the preburst heating phase.  相似文献   

Active cavity radiometer type IV     

Richard C. Willson 《Solar physics》1980,65(1):109-109

A new cavity pyrheliometer, the active cavity radiometer type IV (ACR IV), has been developed for the measurement of total solar optical irradiance. Analysis predicts its ability to measure at the solar constant level with 0.1% uncertainty in SI units. In comparison tests ACR IVs have consistently demonstrated 0.5% higher results than the World Radiometrie Reference scale. A prototype has been tested, and a flight instrument has been developed and flown in a sounding rocket experiment to determine the solar constant. ACR IV instrumentation is being developed for flight experiments on the Spacelab 1 and Solar Maximum Missions to monitor the total solar output of optical radiation as part of a long-term program to detect variations of climatological significance.The full paper appeared in Appl. Opt. 18 (1979), 179.  相似文献   

SH waves in stressed elastic plates     

A. J. Willson 《Pure and Applied Geophysics》1973,110(1):1977-1981

Summary A theoretical study is made of the propagation ofSH waves of small amplitude in an infinite elastic plate subjected to a primary normal stress. It is shown that the effect of the stress may be represented by a re-scaling of the plate thickness, provided that one elastic constant is also redefined suitably.  相似文献   

Wave-propagation in biaxially-stressed elastic media     

A. J. Willson 《Pure and Applied Geophysics》1972,95(1):48-58

Summary The propagation of small-amplitude plane waves through a homogeneous, isotropic elastic medium, with a particular form of strain-energy function and subjected to a large primary deformation, produced by a homogeneous biaxial stress, is considered in detail. The properties of such waves in an unbounded medium, the conditions for their existence, their speeds and their polarisations are investigated and similar results are also obtained for Rayleigh surface waves.  相似文献   

The decay of gravity waves     

A. J. Willson 《Pure and Applied Geophysics》1970,83(1):9-20

Summary The decay of waves of small amplitude in a viscous liquid of finite depth is investigated. It is shown that the various modes may be conveniently classified and that in many limiting cases the modes of aperiodic decay are of particular importance. Detailed numerical results are given for these modes.  相似文献