1] 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 of 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 in the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 particles cm À2 s À1 sr À1 (pfu) at energy >10 MeV) 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 of $20) and to a much smaller extent to anomalies in geostationary orbits (the rate increases by a factor of $4). The efficiency in producing anomalies is found to be negligible for proton fluences <100 pfu at energies >10 MeV. Elevated fluxes of energetic (>2 MeV) electrons >10 8 cm À2 d À1 sr À1 are observed by GOES on days with satellite anomalies occurring at geostationary (GOES, SCATHA, METEOSAT, MARECS A, etc.) and low-altitude (<1500 km) near-polar (>55°) orbits (Kosmos, SAMPEX, etc.). These elevated fluxes are not observed on days of anomalies registered in high-altitude near-polar orbits. Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed. Citation: Iucci, N., et al. (2005), Space weather conditions and spacecraft anomalies in different orbits, Space Weather, 3, S01001,

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A slow forward shock-type discontinuity observed by Helios 1 on day 147, 1980, at 0.31 AU is analyzed in detail, employing high-resolution (40.5 s) plasma and magnetic field measurements. It is shown within the bounds of uncertainties in the various parameters (1) that this event is not an MHD discontinuity, as the total pressure balance is violated and as the entropy increases across this structure even after inclusion of the alpha particles, (2) that the Hada-Kennel relations, i.e., Ti/Te < 1 and/3 < 1, are satisfied upstream of this event even after inclusion of the alpha particles, indicating that steepening of MHD slow waves dominates Landau damping, (3) that the Rankine-Hugoniot relations are fulfilled to an absolute difference of <10 -5 by employing any possible combination of an upstream with a downstream time-averaged data set, (4) that the MHD evolutionary conditions are satisfied for any solution to the jump conditions, and (5) that the shock speed, the amplitudes, and the relative amplitudes associated with this event are absolutely comparable to those derived earlier for fast mode shock waves within 1 A U. It is shown that this event is an almost quasi-perpendicular slow forward MHD shock wave. INTRODUCTIONFirst observational evidence on the possibility that slow mode MHD shock waves might actually be present in the interplanetary medium was given by Chao and Olbert [ 1970], who presumably identified two slow forward shocks, and by Burlaga and Chao [1971], who "most probably" found one reverse and one forward slow shock. More recently, Feldman et al. [1984] and Smith et al. [1984] provided partial evidence that the lobe-plasma sheet boundary in the central part of the distant geomagnetic tail is often a slow mode shock. Up to now, these examples of interplanetary slow shocks could be regarded as the more serious candidates in the sense (1) that all the plasma and magnetic field parameters necessary for their identification have been taken into account, and (2) that it has been shown that the observations do, within their bounds of uncertainties, fulfill both the Rankine-Hugoniot relations and the "evolutionary conditions" [e.g., Chao, 1970] for MHD shock waves.Two further yet rather essential tests in association with slow shocks, which actually have to be carried out before the optimization of the space probe data to the shock model, have, however, not been realized by these authors. First is to explicitly show that their events are not MHD discontinuities. A more comprehensive study of several slow mode shock-type discontinuities observed by the Helios space probes within 1 AU has unfortunately revealed that by including the alpha particles many of these events are MHD discontinuities rather than shock waves [e.g., Hsieh and . Second is to prove that by following the relations derived by Hada and Kennel [1985] the plasmadynamical conditions of the upstream medium do actually allow for a steepening rather than for a damping of MHD slow waves.

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Abstract. We present the results of a ship survey conducted from Italy to Antarctica and back during the 1996-1997 solar minimum measuring the latitude variation in the neutron component of cosmic radiation at sea level. High-energy atmospheric neutrons were detected by a 3NM-64 and thermalized atmospheric neutrons were detected by two bare BF3 counters. Discussions of the internal consistency of the data and the stability of the detectors, investigations of meteorological effects, and data corrections are presented in two companion papers. In this paper we compute updated vertical cutoff rigidities corrected for the penumbra effect, and we estimate apparent cutoff rigidities, which take into account the contribution of nonvertically incident particles to the counting rate. When comparing cosmic ray intensities observed in the same place, a small forward-backward effect is found and explained as the effect of an asymmetric shielding structure around the monitor. Latitude dependencies (i.e., neutron intensities versus cutoff rigidity) and associated coupling functions are computed for both monitors and compared. The NM latitude dependence obtained for the 1996-1997 solar minimum is found to be almost identical to that obtained by other authors in the previous solar minimum. The absence of the so-called "crossover" effect when comparing coupling functions of subsequent solar minima is discussed also on the basis of cosmic ray intensity changes observed by neutron monitor stations.

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Abstract. During the 1996-1997 austral summer, a 3NM-64 neutron monitor was operated on board the ship Italica to record cosmic ray neutron intensities in ocean areas from Italy to Antarctica and back. Two bare B F3 counters also measured the flux of thermalized neutrons.The main purpose of this research was the determination of an accurate latitude curve of cosmic ray nucleonic intensity during solar minimum to be used for obtaining the coupling function appropriate for this phase of solar cycle. Accuracy was achieved through reliable instrumentation and proper control of the experiment and by determining and applying for the first time all corrections, for (1) changes in vertical atmospheric mass colunto, by taking into account wind effect; (2) oscillations of the ship produced by sea roughness; (3) atmospheric ternperamre changes; (4) primary cosmic ray temporal variations including north-south asymmetry; and (5) temporal variations in the cosmic ray east-west effect, caused by asymmetric shielding on the ship. In this paper we describe the experiment, present the complex procedure of data reduction which was required for the survey data, evaluate the intensity changes produced by primary cosmic ray temporal variations, correct the data for meteorological effects, and present the "fully corrected" daily values of neutron intensity as a function of threshold rigidity. Several independent tests are applied to evaluate the quality of the "fully corrected" data and to determine their residual statistical uncertainty. In two companion papers, all meteorological effects are investigated in detail, geomagnetic effects are evaluated, and coupling functions are computed.

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