Seasonal Variation of High‐Latitude Geomagnetic Activity in Individual Years

Tanskanen, Eija; Hynönen, Reko; Мурсула, К.

doi:10.1002/2017ja024276

Cited by 8 publications

(6 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The peak months of all three studied quantities in the declining phase of SC23 occur exclusively in the northern hemisphere winter, while the classic pattern of equinoctial peaks seems more typical in the preceding years. The peak months in both IMF power and ground ULF power closely resemble the ones reported for solar wind in Tanskanen et al (2017).…”

Section: Discussionsupporting

confidence: 78%

Solar cycle evolution of ULF wave power in solar wind and on ground

Hynönen

Tanskanen

Francia

2020

J. Space Weather Space Clim.

Self Cite

View full text Add to dashboard Cite

The solar cycle evolution of the ultra-low frequency (ULF) power was studied in solar wind and on ground. We aim finding out how the ULF power in interplanetary and on ground magnetic field evolves over the solar cycle 23 (SC23) and how well do they follow each other in monthly time scales. The hourly power of the ULF waves was computed in the Pc5 frequency range 2–7 mHz for years 1998–2008. The highest wave power in SC23 is found to occur in late 2003 and the lowest at the solar minimum. Ground ULF power follows the IMF power and solar wind speed, particularly well during declining phase. The ULF power in winter exceeds the ULF power in other seasons during the declining phase of SC23, while equinoxes dominate in the ascending phase and the solar maximum. The ground ULF power was found to rise with magnetic latitude from 54° to 73°, after which Pc5 power decreases towards the polar cap. The Pc5 power in the auroral zone is larger in the nightside than the dayside due to substorm activity implying that magnetotail processes are an important contributor to the nightside ULF power.

show abstract

Section: Discussionsupporting

confidence: 78%

Solar cycle evolution of ULF wave power in solar wind and on ground

Hynönen

Tanskanen

Francia

2020

J. Space Weather Space Clim.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Tanskanen et al () studied the seasonal variation of high‐latitude geomagnetic activity in 1995–2014 using the IL index and in 1966–2014 using the AL index. They found that during the past 45 years, only less than one fourth of the individual years follow the classical two‐equinox maximum pattern.…”

Section: Discussionmentioning

confidence: 99%

“…They found enhanced activity in spring and fall when studying multiyear averaged data. Although the two‐equinox pattern in geomagnetic variation is seen in the multiyear averages, only one fourth of the year between 1966 and 2014 show this pattern (Tanskanen et al, ). In addition to large year‐to‐year variability, we found distinct latitudinal differences on seasonal variation.…”

Section: Discussionmentioning

confidence: 99%

High‐Frequency Geomagnetic Fluctuations at Auroral Oval and Polar Cap

et al. 2018

Self Cite

View full text Add to dashboard Cite

Rapid magnetic fluctuations are known to be closely linked to the high-latitude geomagnetic activity, in particular, to geomagnetic pulsations and subtorms. Increasing amount of commercial activity in the arctic regions requires better monitoring capability and improved understanding on the effects of geomagnetic hazards to infrastructure. In this study, we analyze rapid, 1-s fluctuations in Greenland. To measure high-frequency geomagnetic fluctuations in the auroral oval and polar cap, we use high time resolution data of 1 s from 12 stations covering a large latitudinal range of 64 to 84 quasi-dipole geomagnetic latitude (QDGMlat). We found out that the large magnetic field fluctuations exceeding 0.2 nT/s are observed 10-30% of the time in auroral oval latitudes, depending on the solar cycle phase and station location. The latitudinal differences are much larger in fluctuation coverage (fractional derivative rate, FDR) than in fluctuations amplitude (dH∕dt). The highest |dH∕dt| and FDRs at noon are observed at the northern stations from 72 to 84 QDGMlat, while in south Greenland from 72 to 65 QDGMlat, the highest |dH∕dt| and FDRs are recorded at midnight. The largest differences in seasonal variation between noon and midnight are observed in the polar cap, where a summer increase is seen at noon and almost flat seasonal profile at midnight. Plain Language SummaryWe analyze Earth's magnetic field measurements from Greenland in 2011-2013. We use high time resolution measurements obtained from 12 stations, covering a large geographic area. We use the rate of change of the magnetic field as the basis of our analysis, and we have developed a new method called the fractional derivative rate for this purpose. Differences between the years, time of day, and geographic location along the north-south axis are studied separately. We found out that there are significant differences between the stations, with the northernmost stations being more magnetically active during noon and the southernmost stations more active during midnight. The largest differences in these activity patterns are seen in the northernmost area, the polar cap. Understanding these variations in activity between the geographic locations will help us prepare more accurate and better targeted space weather forecasts in the future.

show abstract

“…The distributions of geomagnetic activity (Tanskanen et al, 2017) and geomagnetic indices (Campbell, 1979;Lockwood et al, 2017Lockwood et al, , 2018 vary both within and between solar cycles (Tindale & Chapman, 2016. The distributions of solar wind variables can be non-Gaussian (Veselovsky et al, 2010, and references therein).…”

Section: 1029/2018sw001884mentioning

confidence: 99%

Reproducible Aspects of the Climate of Space Weather Over the Last Five Solar Cycles

2018

View full text Add to dashboard Cite

Each solar maximum interval has a different duration and peak activity level, which is reflected in the behavior of key physical variables that characterize solar and solar wind driving and magnetospheric response. The variation in the statistical distributions of the F10.7 index of solar coronal radio emissions, the dynamic pressure P Dyn and effective convection electric field E y in the solar wind observed in situ upstream of Earth, the ring current index D ST , and the high-latitude auroral activity index AE are tracked across the last five solar maxima. For each physical variable we find that the distribution tail (the exceedences above a threshold) can be rescaled onto a single master distribution using the mean and variance specific to each solar maximum interval. We provide generalized Pareto distribution fits to the different master distributions for each of the variables. If the mean and variance of the large-to-extreme observations can be predicted for a given solar maximum, then their full distribution is known.Plain Language Summary Earth's near-space plasma environment is highly dynamic, with its own space weather. Space weather impacts include electrical power loss, aviation disruption, interrupted communications, and disturbance to satellite systems. The drivers of space weather, the sun and solar wind, and the response seen at Earth have now been almost continually monitored by ground-and space-based observations over the last five solar cycles (more than 50 years). Each of the last five solar maxima has a different duration and peak activity level and as a consequence the climate of Earth's space weather is also different at each solar maximum. We find that some aspects of the space weather climate are in fact reproducible; they can be inferred from that of previous solar maxima. This may help understand the behavior of future solar maxima.

show abstract

Seasonal Variation of High‐Latitude Geomagnetic Activity in Individual Years

Cited by 8 publications

References 44 publications

Solar cycle evolution of ULF wave power in solar wind and on ground

Solar cycle evolution of ULF wave power in solar wind and on ground

High‐Frequency Geomagnetic Fluctuations at Auroral Oval and Polar Cap

Reproducible Aspects of the Climate of Space Weather Over the Last Five Solar Cycles

Contact Info

Product

Resources

About