The Solar Quiet Chromosphere—Corona Transition Region

The chromosphere-corona transition region of the Sun enjoys both simplicities of character and complexities of character which result from its very thin geometrical extent. The simplicities derive from the reasonably clear view of the energy balance (both observationally and theoretically), while the complexities derive from both the proximity of the not-so-clearly viewed regions below and above, and the almost certain convolutions and perhaps discontinuities in the three dimensional geometry of the transition sheet. While observational resolution and spectral information has improved greatly in recent years, the problems associated with a single vantage point, the Earth and its environs, have not gone away. To understand the transition region we must resolve structures radially and temporally as well as in the plane of the sky. This revised version was published online in June 2006 with corrections to the Cover Date.     

Meteor Phenomena and Bodies

Meteoroids can be observed at collision with the Earth's atmosphere as meteors. Different methods of observing meteors are presented: besides the traditional counts of individual events, exact methods yield also data on the geometry of the atmospheric trajectory; on the dynamics and ablation of the body in the atmosphere; on radiation; on the spectral distribution of radiation; on ionization; on accompanying sounds; and also data on orbits. Theoretical models of meteoroid interaction with the atmosphere are given and applied to observational data. Attention is paid to radar observations; to spectroscopic observations; to experiments with artificial meteors and to different types of meteor sounds. The proposed composition and structure of meteoroids as well as their orbits link them to meteorites, asteroids and comets. Meteor streams can be observed as meteor showers and storms. The rate of influx of meteoroids of different sizes onto Earth is presented and potential hazards discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

The ACE Science Center

The Advanced Composition Explorer (ACE) mission is supported by the ACE Science Center for the purposes of processing and distributing ACE data, and facilitating collaborative work on the data by instrument investigators and by the space physics community at large. The Science Center will strive to ensure that the data are properly archived and easily available. In particular, it is intended that use of a centralized science facility will guarantee appropriate use of data formatting standards, thus easing access to the data, will improve communications within and to the ACE science working team, and will reduce redundant effort in data processing. Secondary functions performed by the Science Center include acting as an interface between the scientists and the mission operations team. This revised version was published online in June 2006 with corrections to the Cover Date.     

Direct comparison of transient radiation belt topology and dynamics in 1991 based on measurements onboard Mir space station and NOAA satellite.

In March 1991 the CRRES spacecraft measured a new transient radiation belt resulting from a solar proton event and subsequent geomagnetic disturbance. The presence of this belt was also noted by dosimeter-radiometers aboard the Mir space station (approx. 400 km, 51 degrees orbit) and by particle telescopes on the NOAA-10 spacecraft (850 km, 98 degrees). This event provides a unique opportunity to compare particle flux and dose measurements made by different instruments in different orbits under changing conditions. We present here a comparison of the measurements made by the different detectors. We discuss the topology and dynamics of the transient radiation belt over a period of more than one year.     

An Integer Precise Point Positioning technique for sea surface observations using a GPS buoy

GPS data dedicated to sea surface observation are usually processed using differential techniques. Unfortunately, the precision of resulting kinematic positions is baseline-length dependent. So, high precision sea surface observations using differential GPS techniques are limited to coasts, lakes, and rivers. Recent improvements in GPS satellite products (orbits, clocks, and phase biases) make phase ambiguity fixing at the zero difference level achievable and opens up the observation of the sea surface without geographical constraints. This paper recalls the concept of the Integer Precise Point Positioning technique and discusses the precision of GPS buoy positioning. A sequential version of the GINS software has been implemented to achieve single epoch GPS positioning. We used 1 Hz data from a two week GPS campaign conducted in the Kerguelen Islands. A GPS buoy has been moored close to a radar gauge and 90 m away from a permanent GPS station. This infrastructure offers the opportunity to compare both kinematic Integer Precise Point Positioning and classical differential GPS positioning techniques to in situ radar gauge data. We found that Precise Point Positioning results are not significantly biased with respect to radar gauge data and that horizontal time series are consistent with differential processing at the sub-centimetre precision level. Nevertheless, standard deviations of height time series with respect to radar gauge data are typically [4–5] cm. The dominant driver for noise at this level is attributed to errors in tropospheric estimates which propagate into position solutions.     

In-Situ CHAMP Observation of Ionosphere-Thermosphere Coupling

The coupling between the ionised plasma and the neutral thermospheric particles plays an important role for the dynamics of the upper atmosphere. Significant progress in understanding the related processes has been achieved thanks to the availability of continuous accurate measurements of thermospheric parameters like mass density and wind by high resolution accelerometers on board the satellites CHAMP and GRACE. Here we present some examples of ionosphere-thermosphere coupling where CHAMP observations contributed considerably to their interpretation. We start with the derived properties of the thermosphere at altitudes around 400 km. A new aspect is the significant control of the geomagnetic field geometry on thermospheric features. Phenomena discussed in some depths are the equatorial mass density anomaly, the cusp-related mass density enhancement and the thermospheric response to magnetospheric substorms. Here we consider both the effect on the density and on the wind. A?long predicted process is the wind-driven ionospheric F region dynamo. The high-resolution magnetic field measurements of CHAMP enabled for the first time a systematic study of that phenomenon considering longitudinal, local time, seasonal and solar flux dependences. Some open issues that require further investigations are mentioned at the end.     

Battery condition management: an important way to protect acritical asset

The efficacy of employing battery condition management equipment and procedures is demonstrated on the solid basis of field experience in which the host batteries were found either to be flawed or operated in ways that would compromise reliability. Examples found using such equipment and reported in this paper include a cell whose voltage vacillated daily while on float, post/strap joints whose accept/reject connection integrity was erratic with time, chargers whose voltages were improperly set (both high and low), and a battery room environment whose conditions were life-shortening to electrolytic cells     

E region electric fields at the dip equator and anomalous conductivity effects

Zonal and vertical electric fields were estimated at E region heights in the Brazilian sector. Zonal electric fields are obtained from the vertical electric fields based on their relation through the Hall-to-Pedersen ionospheric conductivities ratio. The technique for obtaining the vertical electric field is based on its proportionality to the Doppler velocities of type 2 irregularities as detected by coherent radars. The 50 MHz backscatter coherent (RESCO) radar was used to estimate the Doppler velocities of the type 2 irregularities embedded in the equatorial electrojet. A magnetic field-line integrated conductivity model was developed to provide the conductivities. It considers a multi-species ionosphere and a multi-species neutral atmosphere, and uses the IRI 2007, the MISIS 2000 and the IGRF 10 models as input parameters for ionosphere, neutral atmosphere and Earth’s magnetic field, respectively. The ion-neutral collision frequencies of all the species are combined through the momentum transfer collision frequency equation, and different percentages of electron-neutral collisions were artificially included for studying the implication of such increase in the zonal electric field, which resulted ranging from 0.13 to 0.49 mV/m between the 8 and 18 h (LT), under quiet magnetic conditions.     

Verification of a mathematical model of dynamic loading in the quasistatic statement for a helicopter tubular skid landing gear by the results of drop tests

We present the results of verifying a mathematical model of dynamic loading of the helicopter skid landing gear with regard for two successive landing impacts. Also presented are the results of analyzing the interaction of springs in the course of drop tests.     

Coastal salinity measurement using a Doppler Radiometer

Coastal salinity is characterised by large and variable salinity contrasts on relatively small scales. Measurements of salinity at a resolution compatible with these coastal regions on a regular basis would provide a rich source of information that could be used for a number of applications that have a fundamental bearing on the world’s lifestyle. Doppler radiometry offers an approach to capture such measurements, as it reduces the number of required antennas needed to form an image, compared with an Interferometer type instrument.