摘要:

A simple probabilistic model was constructed for the average value of a cosmogenic nuclide as a function of depth in a regolith. An arbitrary function was chosen for the size distribution of craters. The resulting integro‐differential equation was found to reduce in limiting cases to: 1) the marching equation with a characteristic residence time, and 2) to the diffusion equation. The regolith diffusion constant is shown to be a simple integral of the cratering rate weighted by geometrical terms. This formal treatment provides a direct and general connection between cosmogenic nuclides and cratering rates and crater population in a simple analytical form. The validity of this model remains to be teste

ISSN:0094-8276    

DOI:10.1029/GL002i011p00477

年代:1975

数据来源: WILEY

摘要:

Helium −3 has been found in the aluminum antenna housing from the recovered second stage of a pre‐Apollo Saturn test flight launched January 28, 1964 and returned to earth on April 28, 1966. The amount of ³He found is about 6 × 10−10cc (STP)/cm² with a4He/³He ratio of 145 or less. The ³He is shown to come from the lower radiation belt as all other sources of ³He are orders of magnitude lower than the observed value. We suggest that there is a significant component of low energy flare particles in the radiation belts, although it is impossible to rule out ot

ISSN:0094-8276    

DOI:10.1029/GL002i011p00480

年代:1975

数据来源: WILEY

摘要:

It is shown that phase differences in geomagnetic micropulsation signals seen at different locations should bear a direct relationship to energy flux in the magnetospheric wave structure.

ISSN:0094-8276    

DOI:10.1029/GL002i011p00483

年代:1975

数据来源: WILEY

摘要:

A new model for the near‐wake studies is presented. It pertains to a tenuous plasma medium with negligible magnetic field effects. The wake‐generating body moves at a mesothermal speed (Vb) i.e. intermediate between the thermal speeds of ions and electrons of the ambient plasma which is bi‐thermal (Ti

ISSN:0094-8276    

DOI:10.1029/GL002i011p00485

年代:1975

数据来源: WILEY

摘要:

Theoretical analysis of magnetoacoustic waves driven unstable by a neutral charged‐particle beam suggests that such waves can be generated in the plasma sheet at the onset of a substorm. It is further suggested that the magnetohydro‐dynamic waves observed to occur at the onset of substorms (often called Pi2 pulsations) may be attributed to the coupling of the magnetoacoustic waves to shear Alfvén waves on locally‐resonant field lines on the nightside of the earth. Experimental determinations of the distribution of resonant field lines for various frequency components of the waves, together with the theoretical concepts, can ultimately yield information on the inward velocity of hot plasma particles at substorm

ISSN:0094-8276    

DOI:10.1029/GL002i011p00489

年代:1975

数据来源: WILEY

摘要:

In an experiment simulating certain characteristics of the equatorial electrojet plasmalow frequencywaves travelling indirection are observed. These waves are identified to the modes generated by the cross‐field instability. The spectrum of the potential fluctuations has an index β ≃ −5.8. The observed spectrum also indicates generation of a mode by wave‐wave interaction of two modes, as well as a m = o mode stationary in thed

ISSN:0094-8276    

DOI:10.1029/GL002i011p00492

年代:1975

数据来源: WILEY

摘要:

It has been shown that the sporadic E configuration observed in the ionograms from equatorial stations can suddenly appear or disappear in a time period of one minute or less. Such short decoy (or growth) times are found to agree with theoretical estimates of cross‐field instability calculations. These findings further support the identification of Es‐q to cross‐field instabilities. Attempts should be made to study the real time evolution of these irregularities by backscatter radars or finer time resolved ionos

ISSN:0094-8276    

DOI:10.1029/GL002i011p00496

年代:1975

数据来源: WILEY

ISSN:0094-8276    

DOI:10.1029/GL002i011p00499

年代:1975

数据来源: WILEY

摘要:

Concentrations of ice nuclei of up to 106per gram active at −10°C have been obtained from cultures of laboratory stocks of phytoplankton. Some of the nuclei obtained were active at temperatures as warm as −3°C. These observations support earlier work indicating that zones of profuse marine phytoplankton growth may release large numbers of ice nuclei into the atmos

ISSN:0094-8276    

DOI:10.1029/GL002i011p00500

年代:1975

数据来源: WILEY

摘要:

Classically, field and laboratory investigations have relied on averaged results from Lagrangian measurements to establish longshore current velocities. Likewise, conservation equations have been time averaged in the formulation of longshore current theories. Recent experimental measurements by the authors indicate that at a fixed point in the surf zone variations in excess of 150 percent of the mean current velocity occur over time periods from three to eighty seconds. These unsteady motions in longshore currents persist horizontally across the surf zone and vertically from the surface to the bottom. This persistence and magnitude of the observed velocity fluctuations from this investigation imply that time dependent analytic treatments of conservation equations are necessary in order to properly determine longshore current velocity.

ISSN:0094-8276    

DOI:10.1029/GL002i011p00503

年代:1975

数据来源: WILEY