scholarly journals Response of the Antarctic Ionosphere to Some Intense Geomagnetic Storms

2017 ◽  
Vol 11 (1) ◽  
pp. 16-28
Author(s):  
Gustavo A. Mansilla
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
Recovery Phase ◽  
High Solar Activity ◽  
Negative Effects ◽  
Storm Effects ◽  
Positive Effects ◽  
Physical Mechanisms ◽  
Last Stage ◽  
The Antarctic

Background:The effect of geomagnetic storms on the mid-high latitude F2 region is studied.Method:For this purpose, foF2 data from four Antarctic stations were analyzed during three intense magnetic storms occurred in high solar activity (years 2002 and 2003). In general, negative storm effects irrespective of the local time were observed during the first part of the storms (main phase). Negative effects were also observed more often than positive effects during the first part of the recovery phase, which seems to indicate almost no longitudinal dependence in this stage of the storm.Conclusion:The negative effects frequently changed to positive during the last stage of the recovery. Several physical mechanisms were operative during the different stages of the storms.

Observational evidence of solar activity interaction with chlorine chemistry curbing Antarctic ozone loss

2021 ◽  
Author(s):  
Annika Seppälä ◽  
Emily Gordon ◽  
Bernd Funke ◽  
Johanna Tamminen ◽  
Kaley Walker
Keyword(s):  
Solar Activity ◽  
Observational Evidence ◽  
High Solar Activity ◽  
Quasi Biennial Oscillation ◽  
Ozone Loss ◽  
Reservoir Species ◽  
Antarctic Ozone ◽  
Catalytic Ozone Destruction ◽  
The Antarctic ◽  
The Impact

<p>We present the impact of the so-called energetic particle precipitation (EPP), part of natural solar forcing on the atmosphere, on polar stratospheric NO<sub>x</sub>, ozone, and chlorine chemistry in the Antarctic springtime, using multi-satellite observations covering the overall period of 2005–2017. We find consistent ozone increases when high solar activity occurs during years with easterly phase of the quasi biennial oscillation. These ozone enhancements are also present in total O<sub>3</sub> column observations. We find consistent decreases in springtime active chlorine following winters of elevated solar activity. Further analysis shows that this is accompanied by increase of chemically inactive chlorine reservoir species, explaining the observed ozone increase. This provides the first observational evidence supporting the previously proposed mechanism relating to EPP modulating chlorine driven ozone loss. Our findings suggest that solar activity via EPP has played an important role in modulating Antarctic ozone depletion in the last 15 years. As chlorine loading in the polar stratosphere continues to decrease in the future, this buffering mechanism will become less effective and catalytic ozone destruction by EPP produced NO<sub>x</sub> will likely become a major contributor to Antarctic ozone loss.</p>

scholarly journals Accuracy of Global Ionosphere Maps in Relation to Their Time Interval

2021 ◽  
Vol 13 (18) ◽  
pp. 3552
Author(s):  
Beata Milanowska ◽  
Paweł Wielgosz ◽  
Anna Krypiak-Gregorczyk ◽  
Wojciech Jarmołowski
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
High Solar Activity ◽  
Time Interval ◽  
Electron Content ◽  
Dual Frequency ◽  
Total Electron ◽  
Low Latitudes ◽  
Globally Distributed ◽  
Gnss Observations

Global ionosphere maps (GIMs) representing ionospheric total electron content (TEC) are applicable in many scientific and engineering applications. However, the GIMs provided by seven Ionosphere Associated Analysis Centers (IAACs) are generated with different temporal resolutions and using different modeling techniques. In this study, we focused on the influence of map time interval on the empirical accuracy of these ionospheric products. We investigated performance of the high-resolution GIMs during high (2014) and low (2018) solar activity periods as well as under geomagnetic storms (19 February 2014 and 17 March 2015). In each of the analyzed periods, GIMs were also assessed over different geomagnetic latitudes. For the evaluation, we used direct comparison of GIM-derived slant TEC (STEC) with dual-frequency GNSS observations obtained from 18 globally distributed stations. In order to perform a comprehensive study, we also evaluated GIMs with respect to altimetry-derived vertical TEC (VTEC) obtained from the Jason-2 and Jason-3 satellites. The study confirmed the influence of GIMs time interval on the provided TEC accuracy, which was particularly evident during high solar activity, geomagnetic storms, and also at low latitudes. The results show that 120-min interval contributes significantly to the accuracy degradation, whereas 60-min one is sufficient to maintain TEC accuracy.

scholarly journals Multi-station investigation of spread F over Europe during low to high solar activity

2018 ◽  
Vol 8 ◽  
pp. A27 ◽  
Author(s):  
Krishnendu Sekhar Paul ◽  
Haris Haralambous ◽  
Christina Oikonomou ◽  
Ashik Paul ◽  
Anna Belehaki ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Occurrence Rate ◽  
High Solar Activity ◽  
Solar Cycle Variation ◽  
F Region ◽  
Perkins Instability ◽  
Spread F ◽  
Triggering Mechanisms

Spread F is an ionospheric phenomenon which has been reported and analyzed extensively over equatorial regions on the basis of the Rayleigh-Taylor (R-T) instability. It has also been investigated over midlatitude regions, mostly over the Southern Hemisphere with its generation attributed to the Perkins instability mechanism. Over midlatitudes it has also been correlated with geomagnetic storms through the excitation of travelling ionospheric disturbances (TIDs) and subsequent F region uplifts. The present study deals with the occurrence rate of nighttime spread F events and their diurnal, seasonal and solar cycle variation observed over three stations in the European longitude sector namely Nicosia (geographic Lat: 35.29 °N, Long: 33.38 °E geographic: geomagnetic Lat: 29.38 °N), Athens (geographic Lat: 37.98 °N, Long: 23.73 °E geographic: geomagnetic Lat: 34.61 °N) and Pruhonice (geographic Lat: 50.05 °N, Long: 14.41 °E geographic: geomagnetic Lat: 47.7 °N) during 2009, 2015 and 2016 encompassing periods of low, medium and high solar activity, respectively. The latitudinal and longitudinal variation of spread F occurrence was examined by considering different instability triggering mechanisms and precursors which past literature identified as critical to the generation of spread F events. The main findings of this investigation is an inverse solar cycle and annual temporal dependence of the spread F occurrence rate and a different dominant spread F type between low and high European midlatitudes.

scholarly journals Spatial and Temporal Variations of Polar Ionospheric Total Electron Content over Nearly Thirteen Years

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 540 ◽  
Author(s):  
Hui Xi ◽  
Hu Jiang ◽  
Jiachun An ◽  
Zemin Wang ◽  
Xueyong Xu ◽  
...  
Keyword(s):  
Solar Activity ◽  
Total Electron Content ◽  
Geomagnetic Storms ◽  
Weddell Sea ◽  
The Arctic ◽  
Electron Content ◽  
Spherical Cap ◽  
Total Electron ◽  
Ionospheric Total Electron Content ◽  
The Antarctic

It is of great significance for the global navigation satellite system (GNSS) service to detect the polar ionospheric total electron content (TEC) and its variations, particularly under disturbed ionosphere conditions, including different phases of solar activity, the polar day and night alternation, the Weddell Sea anomaly (WSA) as well as geomagnetic storms. In this paper, four different models are utilized to map the ionospheric TEC over the Arctic and Antarctic for about one solar cycle: the polynomial (POLY) model, the generalized trigonometric series function (GTSF) model, the spherical harmonic (SH) model, and the spherical cap harmonic (SCH) model. Compared to other models, the SCH model has the best performance with ±0.8 TECU of residual mean value and 1.5–3.5 TECU of root mean square error. The spatiotemporal distributions and variations of the polar ionospheric TEC are investigated and compared under different ionosphere conditions in the Arctic and Antarctic. The results show that the solar activity significantly affects the TEC variations. During polar days, the ionospheric TEC is more active than it is during polar nights. In polar days over the Antarctic, the maximum value of TEC always appears at night in the Antarctic Peninsula and Weddell Sea area affected by the WSA. In the same year, the ionospheric TEC of the Antarctic has a larger amplitude of annual variation than that of the TEC in the Arctic. In addition, the evolution of the ionization patch during a geomagnetic storm over the Antarctic can be clearly tracked employing the SCH model, which appears to be adequate for mapping the polar TEC, and provides a sound basis for further automatic identification of ionization patches.

scholarly journals Effect of solar and magnetic activity on VHF scintillations near the equatorial anomaly crest

2004 ◽  
Vol 22 (8) ◽  
pp. 2849-2860 ◽  
Author(s):  
R. P. Singh ◽  
R. P. Patel ◽  
A. K. Singh
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Electric Fields ◽  
Recovery Phase ◽  
Magnetic Activity ◽  
Magnetic Storms ◽  
High Solar Activity ◽  
Equatorial Anomaly ◽  
Probability Of Occurrence

Abstract. The VHF amplitude scintillation recorded during the period January 1991 to December 1993 in the declining phase of a solar cycle and April 1998 to December 1999 in the ascending phase of the next solar cycle at Varanasi (geogr. lat.=25.3°, long.=83.0°, dip=37°N) have been analyzed to study the behavior of ionospheric irregularities during active solar periods and magnetic storms. It is shown that irregularities occur at arbitrary times and may last for <30min. A rise in solar activity increases scintillations during winter (November-February) and near equinoxes (March-April; September-October), whereas it depresses the scintillations during the summer (May-July). In general, the role of magnetic activity is to suppress scintillations in the pre-midnight period and to increase it in the post-midnight period during equinox and winter seasons, whilst during summer months the effect is reversed. The pre-midnight scintillation is sometimes observed when the main phase of Dst corresponds to the pre-midnight period. The annual variation shows suppression of scintillations on disturbed days, both during pre-midnight and post-midnight period, which becomes more effective during years of high solar activity. It is observed that for magnetic storms for which the recovery phase starts post-midnight, the probability of occurrence of irregularities is enhanced during this time. If the magnetic storm occurred during daytime, then the probability of occurrence of scintillations during the night hours is decreased. The penetration of magnetospheric electric fields to the magnetic equator affects the evolution of low-latitude irregularities. A delayed disturbance dynamo electric field also affects the development of irregularities.

scholarly journals After-effects of geomagnetic storms: statistical analysis and theoretical explanation

2018 ◽  
Vol 4 (4) ◽  
pp. 32-42
Author(s):  
Константин Ратовский ◽  
Konstantin Ratovsky ◽  
Максим Клименко ◽  
Maksim Klimenko ◽  
Владимир Клименко ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Geomagnetic Storms ◽  
Geomagnetic Latitude ◽  
Recovery Phase ◽  
Theoretical Explanation ◽  
After Effects ◽  
Storm Effects ◽  
Ionospheric Effects ◽  
First Time ◽  
Good Agreement

Our previous studies have shown the presence of daytime positive electron density disturb-ances during several days after the start of the recovery phase. The aim of this paper is to study after-effects of geomagnetic storms (after-storm effects), i.e. ionospher-ic effects observed on the 3–5th day after the beginning of the storm recovery phase. From numerical calcula-tions with the GSM TIP model, we have found the main mechanisms for the formation of the after-storm effects. Using Irkutsk (52° N, 104° E) and Kaliningrad (54° N, 20° E) ionosonde data, we have carried out a statistical analysis of daytime ionospheric responses to geomagnetic storms. As a result of the analysis, we obtained averaged ionospheric responses at the beginning of the storm recovery phase and for five consecutive days. The statistical analysis results received near the beginning of the recovery phase are in good agreement with the well-known ionospheric effects of geomagnetic storms obtained in previous studies. For the first time, the obtained statistics of iono-spheric responses observed on the 3–5th day after the beginning of the recovery phase allowed us to reveal the dependence of after-storm ionospheric effects on season, storm intensity, and ionosonde geomagnetic latitude. In addition, we for the first time present the interpretation of after-storm ionospheric effects from numerical simulation results.

scholarly journals Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC

Radiocarbon ◽  
2017 ◽  
Vol 59 (4) ◽  
pp. 1147-1156 ◽  
Author(s):  
Junghun Park ◽  
John Southon ◽  
Simon Fahrni ◽  
Pearce Paul Creasman ◽  
Richard Mewaldt
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
Solar Energetic Particle ◽  
Peak Height ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
High Solar Activity ◽  
Published Data ◽  
Enhanced Production ◽  
Mass Ejection

ABSTRACTSince the AD 775 and AD 994 Δ14C peak (henceforth M12) was first measured by Miyake et al. (2012, 2013), several possible production mechanisms for these spike have been suggested, but the work of Mekhaldi et al. (2015) shows that a very soft energy spectrum was involved, implying that a strong solar energetic particle (SEP) event (or series of events) was responsible. Here we present Δ14C values from AD 721–820 Sequoiadendron giganteum annual tree-ring samples from Sequoia National Park in California, USA, together with Δ14C in German oak from 650–670 BC. The AD 721–820 measurements confirm that a sharp Δ14C peak exists at AD 775, with a peak height of approximately 15‰ and show that this spike was preceded by several decades of rapidly decreasing Δ14C. A sharp peak is also present at 660 BC, with a peak height of about 10‰, and published data (Reimer et al. 2013) indicate that it too was preceded by a multi-decadal Δ14C decrease, suggesting that solar activity was very strong just prior to both Δ14C peaks and may be causally related. During periods of strong solar activity there is increased probability for coronal mass ejection (CME) events that can subject the Earth’s atmosphere to high fluencies of solar energetic particles (SEPs). Periods of high solar activity (such as one in October–November 2003) can also often include many large, fast CMEs increasing the probability of geomagnetic storms. In this paper we suggest that the combination of large SEP events and elevated geomagnetic activity can lead to enhanced production of 14C and other cosmogenic isotopes by increasing the area of the atmosphere that is irradiated by high solar energetic particles.

scholarly journals After-effects of geomagnetic storms: statistical analysis and theoretical explanation

2018 ◽  
Vol 4 (4) ◽  
pp. 26-32 ◽  
Author(s):  
Константин Ратовский ◽  
Konstantin Ratovsky ◽  
Максим Клименко ◽  
Maksim Klimenko ◽  
Владимир Клименко ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Geomagnetic Storms ◽  
Geomagnetic Latitude ◽  
Recovery Phase ◽  
Theoretical Explanation ◽  
After Effects ◽  
Storm Effects ◽  
Ionospheric Effects ◽  
First Time ◽  
Good Agreement

Our previous studies have shown the presence of daytime positive electron density disturb-ances during several days after the start of the recovery phase. The aim of this paper is to study after-effects of geomagnetic storms (after-storm effects), i.e. ionospher-ic effects observed on the 3–5th day after the beginning of the storm recovery phase. From numerical calcula-tions with the GSM TIP model, we have found the main mechanisms for the formation of the after-storm effects. Using Irkutsk (52° N, 104° E) and Kaliningrad (54° N, 20° E) ionosonde data, we have carried out a statistical analysis of daytime ionospheric responses to geomagnetic storms. As a result of the analysis, we obtained averaged ionospheric responses at the beginning of the storm recovery phase and for five consecutive days. The statistical analysis results received near the beginning of the recovery phase are in good agreement with the well-known ionospheric effects of geomagnetic storms obtained in previous studies. For the first time, the obtained statistics of iono-spheric responses observed on the 3–5th day after the beginning of the recovery phase allowed us to reveal the dependence of after-storm ionospheric effects on season, storm intensity, and ionosonde geomagnetic latitude. In addition, we for the first time present the interpretation of after-storm ionospheric effects from numerical simulation results.

scholarly journals Ionospheric <i>fo</i>F2 anomalies during some intense geomagnetic storms

2005 ◽  
Vol 23 (7) ◽  
pp. 2487-2499 ◽  
Author(s):  
R. P. Kane
Keyword(s):  
Geomagnetic Storms ◽  
Early Morning ◽  
Equatorial Ionosphere ◽  
Storm Event ◽  
Ionospheric Disturbances ◽  
High Latitudes ◽  
Negative Effects ◽  
Local Effects ◽  
Positive Effects ◽  
Low Latitudes

Abstract. The global evolutions of foF2 anomalies were examined for three very intense geomagnetic storms, namely the Halloween events of October-November 2003 (Event X, 29–30 October 2003, Dst –401 nT; Event Y, 20–21 November 2003, Dst –472 nT), and the largest Dst storm (Event Z, 13–14 March 1989, Dst –589 nT). For Event X, troughs (negative storms) were clearly seen for high northern and southern latitudes. For northern midlatitudes as well as for low latitudes, there were very strong positive effects on 29 October 2003, followed by negative effects the next day. For Event Y, there were no troughs in NH high latitudes for morning and evening hours but there were troughs for night. For midlatitudes and low latitudes, some longitudes showed strong negative effects in the early morning as expected, but some longitudes showed strong positive effects at noon and in the evening hours. Thus, there were many deviations from the model patterns. The deviations were erratic, indicating considerable local effects superposed on general patterns. A disconcerting feature was the presence of strong positive effects during the 24 h before the storm commencement. Such a feature appears only in the 24 h before the geomagnetic storm commencement but not earlier. If genuine, these could imply a prediction potential with a 24-h antecedence. For Event Z (13–14 March 1989, equinox), all stations (all latitudes and longitudes) showed a very strong "negative storm" in the main phase, and no positive storms anywhere. Keywords. Ionosphere (Equatorial ionosphere – Ionospheric disturbances – Mid-latitude Ionosphere – Polar ionosphere)

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