摘要:

We modify the corotating convection model usually applied to the Jovian magnetosphere by including a term that simulates the effects of microdiffusion. By applying a technique of Fourier analysis followed by three‐mode truncation, we recover precisely the well known Lorenz equations of meteorology. The implications are that under certain restrictions plasma motion in the Jovian magnetosphere, which is modulated by ionospheric ohmic drag through the Pedersen ionospheric conductivity Σ, can be expected to be chaotic if Σ is less than a critical value Σc; if Σ is greater than Σcthe plasma motion is steady‐state convection. The value of Σcdepends on a parameterqwhich characterizes an assumed stationary radial profile (∝L−q) in plasma mass per unit

ISSN:0094-8276    

DOI:10.1029/92GL01808

年代:1992

数据来源: WILEY

摘要:

We describe plasma flow perturbations in the outer magnetosphere during the passage of magnetopause boundary waves and cylindrically shaped flux transfer events (FTEs). Spacecraft which remain within the magnetosphere observe bipolar flows normal to the nominal magnetopause accompanied by flows nearly opposite to the direction of boundary wave and/or FTE motion. Flows are generally discontinuous across FTE and magnetopause boundaries, with reversals in the component of flow tangential to the nominal magnetopause expected during all magnetopause crossings and some entries into FTEs. No bipolar flows normal to the nominal magnetopause occur within FTEs unless they rotate and none occur in the magnetosheath unless the boundary waves propagate relative to the magnetosheath flow. IRM satellite observations on October 28, 1984 may be interpreted either in terms of FTEs or boundary waves.

ISSN:0094-8276    

DOI:10.1029/92GL01614

年代:1992

数据来源: WILEY

摘要:

We present AMPTE UKS data from a well‐studied magnetospheric flux transfer event, showing detailed ion phase‐space distributions for each region of this layered event. We show that the perpendicular temperature anisotropy maximizes at the center of the event. This is inconsistent with recent suggestions that FTE signatures may result from the spacecraft moving into and then out of the magnetosheath via the plasma depletion layer. We present an explanation for the temperature anisotropy structure in terms of a reconnection mo

ISSN:0094-8276    

DOI:10.1029/92GL01618

年代:1992

数据来源: WILEY

摘要:

Substorm associated large amplitude bipolar magnetic events occurred when ISEE 3 was in the distant geotail's plasma sheet boundary layer (PSBL). The characteristics of these events, their substorm association and their possible source mechanisms are examined. We propose that these PSBL events are signatures of a passing plasmoid in the plasma sheet, analogous to the traveling compression region model in the geomagnetic lobes.

ISSN:0094-8276    

DOI:10.1029/92GL02102

年代:1992

数据来源: WILEY

摘要:

Approximate analytic solutions to the well‐known and commonly used time‐dependent electron energy balance equation for the upper ionosphere and plasmasphere have been obtained and are discussed. The various potential heating sources for the terrestrial plasmasphere are summarized and the corresponding electron temperatures and related characteristic heating and cooling times are calculated. A comparison between the analytic expressions for the temperature variations and relevant measurements shows excellent agreem

ISSN:0094-8276    

DOI:10.1029/92GL01940

年代:1992

数据来源: WILEY

摘要:

Observations by the ElSCAT and Millstone Hill radars of strongly enhanced, often asymetric, ion acoustic line spectra in the topside auroral ionosphere have been reported recently by a number of researchers. Such strongly enhanced ion acoustic line spectra are shown to arise naturally in a plasma unstable to the ion‐ion two‐stream instability. A linear theory of density fluctuations is used for the calculations, which should be applicable to weakly unstable non‐magnetized plasmas near the onset threshold of the instab

ISSN:0094-8276    

DOI:10.1029/92GL02101

年代:1992

数据来源: WILEY

摘要:

Following the massive eruption of Mt. Pinatubo during June of 1991, twilight slant column abundances of NO2were observed to decrease by 30–40% at Lauder, New Zealand (45°S). Johnston et al. [1992] proposed that at most, 10–15% of the observed decrease could be due to alterations of the effective optical path of light received by the detector associated with increased scattering, the balance likely being the result of heterogeneous conversion of odd‐nitrogen chemical species to nitric acid on the surfaces of the volcanic aerosols. In this study, it is shown that nearly all of the observed decrease in twilight NO2slant column abundance is likely to be due to heterogeneous chemistry. Airmass factors calculated with a spherical Monte Carlo radiative transfer model are shown to be relatively insensitive to the presence of the Pinatubo volcanic aerosols above about 20 km, although some significant differences are obtained below this altitude. Changes in photolysis rates due to increased scattering are also shown to have only a small effect on the total twilight NO2column abun

ISSN:0094-8276    

DOI:10.1029/92GL01938

年代:1992

数据来源: WILEY

摘要:

Stratospheric aerosol from Mount Pinatubo heated the tropical lower stratosphere by about 0.3 K/day mainly due to absorption of terrestrial infrared radiation. This heating was dissipated by (1) an observed increase in stratospheric temperatures, which enhanced the radiative cooling, (2) additional mean upward motion, observed for the aerosol cloud, which led to adiabatic cooling and (3) reductions in ozone concentrations resulting from enhanced upward motions. Each of these processes operated on a different time scale: maximum temperatures were observed after about 90 days; maximum ozone losses of about −1.5 ppm occurred after 140 days when the enhanced vertical velocities effectively lifted the ozone profile by about 2 km. We believe this shows that ozone plays an important role in buffering vertical motion in the tropical lower stratosphere, and hence the residual Brewer Dobson circulation of the whole stratospher

ISSN:0094-8276    

DOI:10.1029/92GL01937

年代:1992

数据来源: WILEY

摘要:

The vertical profiles of ClO, HCl, HO2and O3were determined from thermal emission measurements by a balloon‐borne spectrometer operating near 640 GHz. Results are in broad agreement with previous measurements and models, but differ significantly with model photochemistry for the ratio of ClO to HC

ISSN:0094-8276    

DOI:10.1029/92GL01884

年代:1992

数据来源: WILEY

摘要:

A discharge fast flow system with mass spectrometric detection was used to determine the rate constant of the title reaction to be k(1) = (1.3±0.2)×10−13cm3molecule−1s−1. This experimental value is roughly a factor of 20 higher than previously recommended. It is suggested that the title reaction should be considered as a removal process in modeling stratospher

ISSN:0094-8276    

DOI:10.1029/92GL02100

年代:1992

数据来源: WILEY