On a refinement of the theory of the Moon's physical librations     

Professor of Aerospace Engineering Irving Michelson 《Pure and Applied Geophysics》1966,63(1):109-120

Summary The standard formulation of the dynamics of physical librations of the Moon is re-examined in the light of currently accepted reduced estimates of the mechanical ellipticity of the lunar equator. It is seen that a more complete mathematical model is required which accounts for centrifugal couples and in which the sum of inclinations of lunar orbit (5°9) and equator (1°30) is not regarded as an infinitesimal quantity. Although it remains doubtful whether linearized differential equations can be expected to yield a quantitatively useful theory, a preliminary to more accurate calculation consists in analyzing the motion with fewer restrictions than has been customary. The main features of such a treatment are given which unify the classical analysis by showing how the afore-mentioned inclinations can be used to estimate the two principal mass parameters that affect physical librations. When accurate short-period libration data become available, the constants in question can be evaluated without recourse to orbital data used in the past.  相似文献   

On the Behavior of the Stable Boundary Layer and the Role of Initial Conditions     

Xingzhong Shi  Richard T. McNider  M. P. Singh  David E. England  Mark J. Friedman  William M. Lapenta  William B. Norris 《Pure and Applied Geophysics》2005,162(10):1811-1829

Previous studies of the stable atmospheric boundary layer using techniques of nonlinear dynamical systems (MCNIDER et al., 1995) have shown that the equations support multiple solutions in certain parameter spaces. When geostrophic speed is used as a bifurcation parameter, two stable equilibria are found—a warm solution corresponding to the high-wind regime where the surface layer of the atmosphere stays coupled to the outer layer, and a cold solution corresponding to the low-wind, decoupled case. Between the stable equilibria is an unstable region where multiple solutions exist. The bifurcation diagram is a classic S shape with the foldback region showing the multiple solutions. These studies were carried out using a simple two-layer model of the atmosphere with a fairly complete surface energy budget. This allowed the dynamical analysis to be carried out on a coupled set of four ordinary differential equations. The present paper extends this work by examining additional bifurcation parameters and, more importantly, analyzing a set of partial differential equations with full vertical dependence. Simple mathematical representations of classical problems in dynamical analysis often exhibit interesting behavior, such as multiple solutions, that is not retained in the behavior of more complete representations. In the present case the S-shaped bifurcation diagram remains with only slight variations from the two-layer model. For the parameter space in the foldback region, the evolution of the boundary layer may be dramatically affected by the initial conditions at sunset. An eigenvalue analysis carried out to determine whether the system might support pure limit-cycle behavior showed that purely complex eigenvalues are not found. Thus, any cyclic behavior is likely to be transient.  相似文献   

Paleomagnetism of gabbros of the Early Proterozoic Blachford Lake Intrusive Suite and the Easter Island dyke,Great Slave Lake,NWT: Possible evidence for the earliest continental drift     

E. Irving  A. Davidson  J. C. McGlynn 《Surveys in Geophysics》1984,7(1):1-25

The Caribou Lake gabbro, part of the Blachford Lake Intrusive Suite accurately dated at –2186±10 mA, has a predominantNW–/SE+ magnetization with a mean, irrespective of sign, ofD=119°,I=50°, ₉₅=5° and a palaeopole 14°N, 064°W,A ₉₅=5°; it has not proved possible to determine if the magnetization is primary. The Easter Island dyke, less well-dated in the range –2200 to –2500 Ma, has a predominantWNW+ magnetization, whose mean, when corrected for an 8° tilt, isD=288°,I=46°, ₉₅=5 and palaeopole is 32°S, 2°W,A ₉₅=5°; the magnetization is probably primary. A vertical magnetization (D), not significantly different from the present field, occurs sporadically in both units and is considered to be Late Phanerozoic in age. Palaeopoles from the Caribou Lake gabbro and the Easter Island dyke, together with those already known from Early Proterozoic intrusives of the Archaean Slave Structural Province, roughly define a swath (the Slave Track) which maps the motion of the Slave Province relative to the geomagnetic axis during this interval. The corresponding array of palaeopoles (the Superior Track) from the Superior Structural Province does not fall in the same place. Hence it would appear that Slave and Superior were not in their present relative positions in the Early Proterozoic in disagreement with arguments that have been made for a fixed supercontinent during much of the Proterozoic. Mid-Proterozoic paleomagnetic signatures indicate that Slave and Superior had assumed their present relative position by about –1750 mA. These Early Proterozoic relative motions are the earliest for which there is palaeomagnetic evidence.Earth Physics Branch Contribution No. 1111.  相似文献   

Editorial     

Mel Friedman 《Tectonophysics》1984,101(3-4)

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A new type of isotopic anomaly in shergottite sulfides     

Heather B. Franz  Nanping Wu  James Farquhar  Anthony J. Irving 《Meteoritics & planetary science》2019,54(12):3036-3051

The isotopic composition and abundance of sulfur in extraterrestrial materials are of interest for constraining models of both planetary and solar system evolution. A previous study that included phase‐specific extraction of sulfur from 27 shergottites found the sulfur isotopic composition of the Martian mantle to be similar to that of terrestrial mid‐ocean ridge basalts, the Moon, and nonmagmatic iron meteorites. However, the presence of positive Δ³³S anomalies in igneous sulfides from several shergottites, indicating incorporation of atmospherically processed sulfur into the subsurface, complicated this interpretation. The current study expands upon the previous work through analyses of 20 additional shergottites, enabling tighter constraints on the isotopic composition of juvenile Martian sulfur. The updated composition (δ³⁴S = ?0.24 ± 0.05‰, Δ³³S = 0.0015 ± 0.0016‰, and Δ³⁶S = 0.039 ± 0.054‰, 2 s.e.m.), representing the weighted mean for all shergottites within the combined population of 47 without significant Δ³³S anomalies, strengthens our earlier result. The presence of sulfur isotopic anomalies in igneous sulfides of some meteorites suggests that their parent magmas may have assimilated crustal material. We observed small negative Δ³³S anomalies in sulfides from two meteorites, NWA 7635 and NWA 11300. Although negative Δ³³S anomalies have been observed in nakhlites and ALH 84001, previous anomalies in shergottites have all shown positive values of Δ³³S. Because NWA 7635 has formation age of 2.4 Ga and is much more ancient than shergottites analyzed previously, this finding expands our perspective on the continuity of Martian atmospheric sulfur photochemistry over geologic time.  相似文献   

Excursion to Bishop's Stortford and Stansted: July 15th, 1905     

A. Irving  Percy A. Irving  T.W. Reader 《Proceedings of the Geologists' Association. Geologists' Association》1905,19(5):222-225

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Organic Matter as a Geological agent     

A. Irving 《Proceedings of the Geologists' Association. Geologists' Association》1892,12(6):227-238

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Palaeomagnetism of Precambrian Sedimentary Rocks from NW Scotland and the Apparent Polar Wandering Path of Laurentia     

A. D. Stewart  E. Irving 《Geophysical Journal International》1974,37(1):51-72

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Solar soft X-ray flare spectra from OSO-4     

J. F. Meekins  G. A. Doschek  H. Friedman  T. A. Chubb  R. W. Kreplin 《Solar physics》1970,13(1):198-212

Solar flare spectral data, covering the wavelength range 0.7–8.5 Å, are derived from the NRL Bragg crystal spectrometers aboard OSO-4. A detailed analysis of the soft X-ray spectra for the 3b flare of 16 November 1967 (2140 UT) is presented, and it is found that electron temperatures derived from continua and emission lines are compatible with a two or more component plasma, differing in temperature by 6–10 × 10⁶K.  相似文献   

An analysis of the positions of the Earth''s magnetic pole in the geological past     

E. Irving 《Geophysical Journal International》1962,7(2):279-283

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