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Long-term analysis of geomagnetic disturbances

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Long-term analysis of geomagnetic disturbances

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Earth’s magnetic field, also known as the geomagnetic field, interacts with the solar wind, a stream of charged particles originating from the Sun. The interaction causes the geomagnetic field to undergo variations, called geomagnetic disturbances or geomagnetic activity. This bachelor thesis features a long-term trend in the geomagnetic activity, using data from individual geomagnetic stations since 1845.
The first objective is to reduce the raw recorded data of a selection of stations to the Kp-index, which provides information of geomagnetic disturbances on a planetary scale. The official Kp-index is only available from 1932, due to a lack of older data from the original Kp-index stations. The by now 83 years of Kp-index data is insufficient when examining centurial variation, which is why this thesis uses data from individual stations operating as far back as 1845 to extend the existing data.
The second objective is to use this new extended data set to look for long-term trends in geomagnetic disturbances. Geomagnetic disturbances are related to solar activity, which undergoes both periodic and irregular changes. The periodic changes are called solar cycles or sunspot cycles,
with an average cycle duration of 11 years. The solar (sunspot) cycle is defined by the average number of sunspots on the solar surface, where sunspots have been observed for hundreds of years.
The geomagnetic activity per solar cycle is compared to the number of sunspots to examine whether the geomagnetic activity is a↵ected by the sunspot activities. The results show that, thus far, the current solar cycle #24, being one of low solar activity, also features the lowest geomagnetic activity recorded since at least 1915. Furthermore, the declining phase of the examined solar cycles includes more geomagnetic activity for the same number of sunspots than the other phases of the cycle. When comparing individual solar cycles, some cycles also show di↵erent geomagnetic activity for the same number of sunspots, suggesting that some cycles are more geo-e↵ective than others. The number of sunspots at the maximum of the solar cycle appears to be an indicator of this geo-e↵ectiveness.
One of the consequences of geomagnetic activity is aurora, for which all-sky cameras are now commonly used all over the world. Since the relation between the aurora and geomagnetic activity is not clear, auroral activity must also be quantified. Such a quantification requires automatic
detection of aurora from all-sky camera images. This thesis introduces an algorithm for detection of auroras using all-sky camera images.

Toon meer
OrganisatieDe Haagse Hogeschool
OpleidingTIS Technische Natuurkunde
AfdelingFaculteit Technologie, Innovatie & Samenleving
PartnersSwedish Institute of Space Physics
Jaar2015
TypeBachelor
TaalEngels

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