6 research outputs found
Effective non-vertical and apparent cutoff rigidities for a cosmic ray latitude survey from Antarctica to Italy in minimum of solar activity
In this paper we will report the results of the computation of cutoff rigidities of vertical and non-vertical incident cosmic ray particles.
Non-vertical effective cutoff rigidities have been computed by tracing particle trajectories through the ‘‘real’’ geomagnetic magnetic field
comprising the International Geomagnetic Reference Field model (IGRF95, IAGA Division 5 Working Group 8, 1996: Sabaka, T.J.,
Langel, R.A., Baldwin, R.T., Conrad, J.A. The geomagnetic field, 1900–1995, including the large scale fields from magnetospheric
sources and NASA candidate models for the 1995 IGRF revision. J. Geomag. Geoelect. 49, 157–206, 1997.) and the Tsyganenko [Tsyganenko,
N.A. A magnetospheric magnetic field model with a warped tail current sheet. Planet. Space Sci. 37, 5–20, 1989.] magnetosphere
model. The computation have been done for the backward route (from Antarctica to Italy) of the Italian Antarctic ship
survey 1996–1997, for geographic points corresponding to the daily average coordinates of the ship; for zenith angles 15°, 30°, 45°
and 60°, and azimuth angles from 0° to 360° in steps of 45°. By means of the obtained non-vertical cutoffs the apparent cutoff rigidities
have been calculated. The information on integral multiplicities of secondary neutrons detected by the neutron monitor in dependence of
the zenith angle of incoming primary cosmic ray particles have also been used. This information is based on the theoretical calculations
of meson-nuclear cascades of primary protons with different rigidities arriving to the Earth’s atmosphere at the zenith angles of 0°, 15°,
30°, 45°, 60° and 75°. The difference between the computed apparent and vertical cutoff rigidities reaches ~1 GV at rigidities >7–8 GV.
At rigidities of 10–16 GV, the difference between the apparent and vertical cutoff rigidities is larger than that obtained earlier by Clem
et al. [Clem, J.M., Bieber, J.W., Duldig, M., Evenson, P., Hall, D., Humble, J.E. Contribution of obliquely incident particles to neutron
monitor counting rate. J. Geophys. Res. 102, 26919–26926, 1997.] and Dorman et al. [Dorman, L.I., Villoresi, G., Iucci, N., Parisi, M.,
Tyasto, M.I., Danilova, O.A., Ptitsyna, N.G. Cosmic ray survey to Antarctica and coupling functions for neutron component near solar
minimum (1996–1997), 3. Geomagnetic effects and coupling functions. J. Geophys. Res. 105, 21047–21056, 2000.].
© 2007 COSPAR. Published by Elsevier Ltd. All rights reserved
Space weather and space anomalies
A large database of anomalies, registered by
220 satellites in different orbits over the period 1971–1994
has been compiled. For the first time, data from 49 Russian
Kosmos satellites have been included in a statistical
analysis. The database also contains a large set of daily
and hourly space weather parameters. A series of statistical
analyses made it possible to quantify, for different satellite
orbits, space weather conditions on the days characterized
by anomaly occurrences. In particular, very intense
fluxes (>1000 pfu at energy >10MeV) of solar protons are
linked to anomalies registered by satellites in high-altitude
(>15 000 km), near-polar (inclination >55_) orbits typical
for navigation satellites, such as those used in the GPS network,
NAVSTAR, etc. (the rate of anomalies increases by
a factor ~20), and to a much smaller extent to anomalies in
geostationary orbits, (they increase by a factor ~4). Direct
and indirect connections between anomaly occurrence and
geomagnetic perturbations are also discussed
Different space weather effects in anomalies of the high and low orbital satellites
Preliminary results of the EU INTAS Project 00810, which aims to improve the methods of safeguarding satellites in the Earth's
magnetosphere from the negative effects of the space environment, are presented. Anomaly data from the ‘‘Kosmos’’ series satellites
in the period 1971–1999 are combined in one database, together with similar information on other spacecraft. This database contains,
beyond the anomaly information, various characteristics of the space weather: geomagnetic activity indices (Ap, AE and Dst),
fluxes and fluences of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary
and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried
out for the total number of anomalies (about 6000 events), and separately for high (~5000 events) and low (about 800 events) altitude
orbit satellites. No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies,
averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and
low (<1500 km) altitude orbits revealed a big difference in a behavior. Satellites were divided on several groups according to the
orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found
to be different for various orbits that should be taken into account under developing of the anomaly frequency models.
© 2004 COSPAR. Published by Elsevier Ltd. All rights reserved