[1] The daily variation of the geomagnetic field during quiet time at equinox features a longitudinal dependence, which is observed in the dip-latitude/longitude frame. Two explanations are considered: (1) the longitudinal changes of the geomagnetic latitude at constant dip-latitude and (2) the longitudinal variations of the main field, which modulates the ionospheric dynamo e.m.f. and determin...

The results of three series of rocket measurements of mesospheric electric ®elds carried out under di€erent geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric ®elds on geomagnetic activity at polar and high middle latitudes. The vertical electric ®elds in the lower mesosphere increase with the increase of geo...

A self-consistent method for day-time F2region modelling was applied to the analysis of Millstone Hill incoherent scatter observations during the storm period of March 16-22, 1990. The method allows us to calculate in a self-consistent way neutral composition, temperature and meridional wind as well as the ionized species height distribution. Theoretically calculated Ne(h) pro®les ®t the observ...

We have produced the first series of spherical harmonic, numerical maps of the time-dependent surface perturbations in the Earth's magnetic field following the onset of substorms. Data from 124 ground magnetometer stations in the Northern Hemisphere at geomagnetic latitudes above 33° were used. Ground station data averaged over 5 min intervals covering 8 years (1998-2005) were used to construct...

geomagnetic field is a one of the candidates for creation of anisotropy in azimuth distribution of extensive air showers over the entered cosmic rays to the atmosphere. here we present the question: is there any azimuth anisotropy flux in the upper level of the atmosphere due to the geomagnetic field over the entered cosmic-rays? the obtained answer is: yes. this investigation showed an agreeme...

The island Tristan da Cunha is located in the South Atlantic Anomaly, and until recently the area has been one of the largest gaps in the global geomagnetic observatory network. As part of the Danish project SAADAN we set up a geomagnetic observatory on the island. Here we report on how we established the observatory in 2009 and on its operation in 2010.

Magnetotactic bacteria are present in fresh water and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetota...

Geomagnetic field is a one of the candidates for creation of anisotropy in azimuth distribution of extensive air showers over the entered cosmic rays to the atmosphere. Here we present the question: Is there any azimuth anisotropy flux in the upper level of the atmosphere due to the geomagnetic field over the entered cosmic-rays? The obtained answer is: yes. This investigation showed an agreeme...

[1] The short-term relationship between equatorial ionosphere and geomagnetic activity is examined. Hourly averages of the total electron content (TEC) and critical frequency of the F2 layer (foF2) are compared with the Dst index, a proxy for equatorial geomagnetic activity, at three local times (0700–0800, 1200–1300, and 1600–1700 LT) from March 1998 to August 1999. Owing to the geomagnetic la...

We present the geomagnetic field model COV-OBS.x1, covering 1840 to 2020, from which have been derived candidate models for the IGRF-12. Towards the most recent epochs, it is primarily constrained by first differences of observatory annual means and measurements from the Oersted, Champ, and Swarm satellite missions. Stochastic information derived from the temporal spectra of geomagnetic series ...