Reliability measurement during software development

During the development of data base software for a multi-sensor tracking system, reliability was measured. The failure ratio and failure rate were found to be consistent measures. Trend lines were established from these measurements that provided good visualization of the progress on the job as a whole as well as on individual modules. Over one-half of the observed failures were due to factors associated with the individual run submission rather than with the code proper. Possible application of these findings for line management, project managers, functional management, and regulatory agencies is discussed. Steps for simplifying the measurement process and for use of these data in predicting operational software reliability are outlined

Comment on "Energetic particle sounding of the magnetospheric cusp with ISEE-1" by K. E. Whitaker et al., Ann. Geophys., 25, 1175–1182, 2007

No abstract available

Cluster Observations of Bow Shock Energetic Ion Transport Through the Magnetosheath into the Cusp

The observation of energetic particles by polar orbiting satellites in the magnetospheric cusp resulted in a controversy about their source region. It has been suggested that these cusp energetic particles (CEP) with significant fluxes from magnetosheath energies up to several hundred keV/e are accelerated locally in the cusp by the turbulence found in cusp diamagnetic cavities (CDC). As an alternative to the local acceleration region, the quasi‐parallel shock is successful as a source region for CEP events. Energetic ions accelerated at the bow shock can be transported downstream and enter the cusp along newly reconnected field lines. Composition and energy spectra of these CEP events resemble those of bow shock energetic diffuse ions. This study investigates a northern cusp pass by the Cluster satellites that encountered two CDCs with CEP ions. We use recently developed techniques to determine the location of the reconnection site at the magnetopause, draping interplanetary magnetic field lines over the magnetopause and mapping those field lines back into the solar wind to show magnetic connection of the cusp regions, Earth’s bow shock, and upstream region. Energetic ions are also observed outside the magnetopause in the boundary layer streaming from the quasi‐parallel shock toward the cusp which supports an outside source region for CEP ions

Cusp energetic ions: A bow shock source

Recent interpretations of cusp energetic ions observed by the POLAR spacecraft have suggested a new energization process in the cusp [Chen et al., 1997; 1998]. Simultaneous enhancement of H+, He+2, and O\u3e+2 fluxes indicates that they are of solar wind origin. In the present study, we examine H+ and He+2 energy spectra from 20 eV to several 100 keV measured by the Hydra, Toroidal Imaging Mass-Angle Spectrograph (TIMAS), and Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) on POLAR. The combined spectrum for each species is shown to be continuous with a thermal distribution below 10 keV/e and an energetic component above 20 keV/e. Energetic ions with comparable fluxes and a similar spectral shape are commonly observed downstream from the Earth\u27s quasi-parallel (Q∥) bow shock. In addition to the similarity in the ion spectra, electric and magnetic field noise and turbulence detected in the cusp by the Plasma Wave Instrument (PWI) and Magnetic Field Experiment (MFE) onboard POLAR are similar to the previously reported observations at the bow shock. The waves appear to be coincidental to the cusp energetic ions rather than causal. We suggest that these ions are not accelerated locally in the cusp. Rather, they are accelerated at the Q∥ bow shock and enter the cusp along open magnetic field lines connecting both regions

Evidence of Multiple Reconnection Lines at the Magnetopause from Cusp Observations

Recent global hybrid simulations investigated the formation of flux transfer events (FTEs) and their convection and interaction with the cusp. Based on these simulations, we have analyzed several Polar cusp crossings in the Northern Hemisphere to search for the signature of such FTEs in the energy distribution of downward precipitating ions: precipitating ion beams at different energies parallel to the ambient magnetic field and overlapping in time. Overlapping ion distributions in the cusp are usually attributed to a combination of variable ion acceleration during the magnetopause crossing together with the time-of-flight effect from the entry point to the observing satellite. Most "step up" ion cusp structures (steps in the ion energy dispersions) only overlap for the populations with large pitch angles and not for the parallel streaming populations. Such cusp structures are the signatures predicted by the pulsed reconnection model, where the reconnection rate at the magnetopause decreased to zero, physically separating convecting flux tubes and their parallel streaming ions. However, several Polar cusp events discussed in this study also show an energy overlap for parallel-streaming precipitating ions. This condition might be caused by reopening an already reconnected field line, forming a magnetic island (flux rope) at the magnetopause similar to that reported in global MHD and Hybrid simulation

IMF Dependence of Energetic Oxygen and Hydrogen Ion Distributions in the Near-Earth Magnetosphere

Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (\u3e ~274 keV) from Cluster/Research with Adaptive Particle Imaging Detectors were used to statistically study the energetic ion distributions in the near-Earth region. The dawn-dusk asymmetries of the distributions in three different regions (dayside magnetosphere, near-Earth nightside plasma sheet, and tail plasma sheet) are examined in Northern and Southern Hemispheres. The results show that the energetic ion distributions are influenced by the dawn-dusk interplanetary magnetic field (IMF) direction. The enhancement of ion intensity largely correlates with the location of the magnetic reconnection at the magnetopause. The results imply that substorm-related acceleration processes in the magnetotail are not the only source of energetic ions in the dayside and the near-Earth magnetosphere. Energetic ions delivered through reconnection at the magnetopause significantly affect the energetic ion population in the magnetosphere. We also believe that the influence of the dawn-dusk IMF direction should not be neglected in models of the particle population in the magnetosphere

Observations of whistler mode waves with nonlinear parallel electric fields near the dayside magnetic reconnection separatrix by the Magnetospheric Multiscale mission

We show observations from the Magnetospheric Multiscale (MMS) mission of whistler mode waves in the Earth's low-latitude boundary layer (LLBL) during a magnetic reconnection event. The waves propagated obliquely to the magnetic field toward the X line and were confined to the edge of a southward jet in the LLBL. Bipolar parallel electric fields interpreted as electrostatic solitary waves (ESW) are observed intermittently and appear to be in phase with the parallel component of the whistler oscillations. The polarity of the ESWs suggests that if they propagate with the waves, they are electron enhancements as opposed to electron holes. The reduced electron distribution shows a shoulder in the distribution for parallel velocities between 17,000 and 22,000 km/s, which persisted during the interval when ESWs were observed, and is near the phase velocity of the whistlers. This shoulder can drive Langmuir waves, which were observed in the high-frequency parallel electric field data

High‐density magnetospheric He+ at the dayside magnetopause and its effect on magnetic reconnection

Observations from the Magnetospheric Multiscale (MMS) mission are used to quantify the maximum effect of magnetospheric H+ and He+ on dayside magnetopause reconnection. A data base of current-sheet crossings from the first 2 years of the MMS mission is used to identify magnetopause crossings with the highest He+ concentrations. While all of these magnetopause crossings exhibit evidence of plasmaspheric plume material, only half of the crossings are directly associated with plasmaspheric plumes. The He+ density varies dramatically within the magnetosphere adjacent to the magnetopause, with density variations of an order of magnitude on timescales as short as 10 s, the time resolution of the composition instrument on MMS. Plasma wave observations are used to determine the total electron density, and composition measurements are used to determine the mass density in the magnetosheath and magnetosphere. These mass densities are then used with the magnetic field observations to determine the theoretical reduction in the reconnection rate at the magnetopause. The presence of high-density plasmaspheric plume material at the magnetopause causes transient reductions in the reconnection rate of up to ∼40%.publishedVersio