scholarly journals Seasonal and diurnal variation of geomagnetic activity: RevisedDstversus external drivers

2003 ◽  
Vol 108 (A2) ◽  
Author(s):  
Lasse V. T. Häkkinen ◽  
Tuija I. Pulkkinen ◽  
Risto J. Pirjola ◽  
Heikki Nevanlinna ◽  
Eija I. Tanskanen ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Geomagnetic Activity ◽  
Seasonal And Diurnal Variation

scholarly journals Variability of Weddell Sea ionospheric anomaly as deduced from observations at the Akademik Vernadsky station

2021 ◽  
pp. 47-55
Author(s):  
A. Zalizovski ◽  
◽  
I. Stanislawska ◽  
V. Lisachenko ◽  
O. Charkina ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Electron Density ◽  
Geomagnetic Activity ◽  
Dynamic Equilibrium ◽  
Doppler Frequency ◽  
Weddell Sea ◽  
K Index ◽  
Weddell Sea Anomaly ◽  
Index Level ◽  
Solar Ultraviolet

Ionospheric Weddell Sea anomaly is an inversion of diurnal variation of the electron density in the ionosphere over Antarctic Peninsula, Weddell Sea, and neighbor territories observed during Antarctic summer. This paper aims at analyzing the reaction of the ionosphere during the Weddell Sea anomaly to changes in solar and geomagnetic activity as deduced from the data of vertical sounding of the ionosphere conducted at the Akademik Vernadsky station. The aim is achieved by comparing the monthly median values of the critical frequencies of the ionosphere (foF2) during Weddell Sea anomaly for the years of high and low solar activity; as well as by comparison of median December height-time diagrams (HT-diagrams) of foF2 calculated separately for the time intervals characterized by low or high levels of F10.7 and K indices for the period from 2007 till 2016. It was experimentally demonstrated that the Weddell Sea anomaly depends on the levels of solar ultraviolet flux and local K indices. The biggest nighttime maximum of ionization corresponds to low K indices and high values of F10.7. The most accurate inversion of diurnal variation of electron density in the F region is observed under the low values of K index and low F10.7 flux. The growth of geomagnetic activity decreases the nighttime ionization under both low and high levels of F10.7 fluxes and leads to a blur of the night maximum. Visible virtual heights of maximums increase together with F10.7 independently of the K index level. Blurring of the night maximum can be explained by destruction of the field of thermospheric winds supporting the nighttime anomaly, and/or by increasing role of plasma drifts in comparison with wind impact. The growth of visible virtual height of the nighttime maximum with increasing solar F10.7 flux could be explained by the gain of equatorward thermospheric wind with increasing solar ultraviolet flux that leads to growth of plasma upwelling effect. The Doppler frequency shift of the signals reflected from the ionosphere during nighttime in presence of the Weddell Sea anomaly is close to zero which could be explained by a stable F2 layer formed as a result of dynamic equilibrium between photochemical processes and upward plasma transport.

scholarly journals Heart rate sensor validation and seasonal and diurnal variation of body temperature and heart rate in domestic sheep

2019 ◽  
Vol 8 ◽  
pp. 100075 ◽  
Author(s):  
Boris Fuchs ◽  
Kristin Marie Sørheim ◽  
Matteo Chincarini ◽  
Emma Brunberg ◽  
Solveig Marie Stubsjøen ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Diurnal Variation ◽  
Domestic Sheep ◽  
Sensor Validation ◽  
Seasonal And Diurnal Variation ◽  
Rate Sensor

Geomagnetic activity and diurnal variation of cosmic ray neutron intensity

1965 ◽  
Vol 62 (3) ◽  
pp. 139-144
Author(s):  
D. S. R. Murty ◽  
Y. Nagabhushanam ◽  
K. Ramanuja Rao
Keyword(s):  
Diurnal Variation ◽  
Geomagnetic Activity ◽  
Cosmic Ray ◽  
Neutron Intensity

Seasonal and diurnal variation of downstream fish movement at four small‐scale hydropower plants

2019 ◽  
Vol 29 (1) ◽  
pp. 74-88 ◽  
Author(s):  
Josef Knott ◽  
Melanie Mueller ◽  
Joachim Pander ◽  
Juergen Geist
Keyword(s):  
Diurnal Variation ◽  
Small Scale ◽  
Fish Movement ◽  
Hydropower Plants ◽  
Seasonal And Diurnal Variation

Seasonal and diurnal variations of geomagnetic activity and their role in Space Weather forecast

2001 ◽  
Vol 79 (6) ◽  
pp. 907-920 ◽  
Author(s):  
W Lyatsky ◽  
A M Hamza
Keyword(s):  
Solar Wind ◽  
Seasonal Variation ◽  
Diurnal Variation ◽  
Geomagnetic Activity ◽  
Space Weather ◽  
Weather Forecast ◽  
Diurnal Variations ◽  
Ionospheric Conductivity ◽  
Solar Wind Parameters ◽  
Possible Cause

A possible test for different models explaining the seasonal variation in geomagnetic activity is the diurnal variation. We computed diurnal variations both in the occurrence of large AE (auroral electrojet) indices and in the AO index. (AO is the auroral electrojet index that provides a measure of the equivalent zonal current.) Both methods show a similar diurnal variation in geomagnetic activity with a deep minimum around (3–7) UT (universal time) in winter and a shallower minimum near 5–9 UT in equinoctial months. The observed UT variation is consistent with the results of other scientists, but it is different from that expected from the Russell–McPherron mechanism proposed to explain the seasonal variation. It is suggested that the possible cause for the diurnal and seasonal variations may be variations in nightside ionospheric conductivity. Recent experimental results show an important role for ionospheric conductivity in particle acceleration and geomagnetic disturbance generation. They also show that low ionospheric conductivity is favorable to the generation of auroral and geomagnetic activity. The conductivity in conjugate nightside auroral zones (where substorm generation takes place) is minimum at equinoxes, when both auroral zones are in darkness. The low ionospheric conductivity at equinoxes may be a possible cause for the seasonal variation in the geomagnetic activity with maxima in equinoctial months. The diurnal variation in geomagnetic activity can be produced by the UT variation in the nightside ionospheric conductivity, which in winter and at equinoxes has a maximum around 4–5 UT that may lead to a minimum in geomagnetic activity at this time. We calculated the correlation patterns for the AE index versus solar-wind parameters inside and outside the (2–7) UT sector related to the minimum in geomagnetic activity. The correlation patterns appear different in these two sectors indeed, which is well consistent with the UT variation in geomagnetic activity. It also shows that it is possible to improve significantly the reliability of the Space Weather forecast by taking into account the dependence of geomagnetic activity not only on solar-wind parameters but also on UT and season. Our test shows that a simple account for the dependence of geomagnetic activity on UT can improve the reliability of the Space Weather forecast by at least 50% in the 2–7 UT sector in winter and equinoctial months. PACS No.: 91.25Le

Seasonal and diurnal variation in concentrations of gaseous and particulate phase endosulfan

2012 ◽  
Vol 61 ◽  
pp. 620-626 ◽  
Author(s):  
Qingbo Li ◽  
Xianyu Wang ◽  
Jing Song ◽  
Hongqi Sui ◽  
Lei Huang ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Particulate Phase ◽  
Seasonal And Diurnal Variation
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