Geomagnetic Activity Index Kp Research Articles

A Nonlinear Dependence on the Geomagnetic Activity of the Ratio of the Maximum Stream Flux of Charged Particles in a Geostationary Orbit to the Minimum Stream Flux

A new mathematical model was proposed using an ordinary differential equation that analytically(when the index of geomagnetic activity Kp = const or Kp ≈ const) or numerically (if Kp(t) ≠ const) describesperpendicular (for a pitch angle of 90°) differential or integral fluxes of relativistic electrons in a geostationary(geosynchronous) orbit, as well as in any circular orbit in the Earth’s magnetosphere. The model assumes thatthe fluxes depend on the local time LT in orbit, the Kp, MacIlvwaine parameter and L, and the perpendiculardifferential flux or integral flux of relativistic electrons taken at 0000:00 LT. We use observations of relativistic(2 MeV) electron fluxes averaged over the local time hour along the orbit of the GOES spacecraft from 1995to 2009. The model is compared with these data. Almost perfect agreement was obtained for observationswith the model, where the prediction efficiency of predicting the accuracy of the model at PE = 0.9989. Usingsimilar data from the GOES 10 allows one to obtain PE = 0.9924. The proposed formulas make it possible tofind, for example, the average value of the perpendicular integral flux of relativistic electrons per day and topredict the maximum perpendicular integral flux of relativistic electrons in the geostationary orbit approximately1 day ahead. The nonlinear effect is theoretically predicted in the form of a nonlinear dependence ofthe ratio of the maximum perpendicular integral flux to the minimum flux of charged particles in the geostationaryorbit from the Kp-index of geomagnetic activity. Thus far, comparison of the model has been madewith the averaged integral relativistic electron flows fluxes produced for the 0 ≤ Kp 6 range with a predictedmaximum flow flux ratio of 24.4139 times at Kp = 8 and with the prediction efficiency of predicting the accuracyof the nonlinear effect PE = 0.8678.

Models for magnetospheric mass density and average ion mass including radial dependence

Analytical models for magnetospheric mass density, ρm, and average ion mass, M, were created from a database of ρm and electron density, ne, values from six spacecraft missions by making use of the Eureqa nonlinear genetic regression algorithm. All values of ρm were determined from Alfvén frequencies, and the values of ne were determined from plasma wave or spacecraft potential data. Models of varying complexity are listed. The most complex models appearing in this paper are capable of modeling ρm within a factor of 1.81, and M within a factor of 1.34 if ne is used as an input parameter, or within a factor of 1.45 if ne is not used. The most important parameters for modeling ρm are L, the solar EUV index F10.7, magnetic local time, MLT, the geomagnetic activity index Kp, and the solar wind dynamic pressure, Pdyn. The very simplest model for M depends on Kp. In more complex models for M including ne, the most important parameters are ne with L, F10.7, and Pdyn or Kp. In more complex models for M not including ne, the most important parameters are Kp, MLT, F10.7, L, and the auroral electrojet index, AE. Explanations for most of the dependencies are given. We also demonstrate the danger of calculating spatial dependence without taking account of different conditions sampled in different regions. Here we avoid that problem by using multivariant models.

Geomagnetic Activity Index Hpo

AbstractThe geomagnetic activity index Kp is widely used but is restricted by low time resolution (3‐hourly) and an upper limit. To address this, new geomagnetic activity indices, Hpo, are introduced. Similar to Kp, Hpo expresses the level of planetary geomagnetic activity in units of thirds (0o, 0+, 1−, 1o, 1+, 2−, …) based on the magnitude of geomagnetic disturbances observed at subauroral observatories. Hpo has a higher time resolution than Kp. 30‐min (Hp30) and 60‐min (Hp60) indices are produced. The frequency distribution of Hpo is designed to be similar to that of Kp so that Hpo may be used as a higher time‐resolution alternative to Kp. Unlike Kp, which is capped at 9o, Hpo is an open‐ended index and thus can characterize severe geomagnetic storms more accurately. Hp30, Hp60 and corresponding linearly scaled ap30 and ap60 are available, in near real time, at the GFZ website (https://www.gfz-potsdam.de/en/hpo-index).

Probabilistic hazard assessment: Application to geomagnetic activity

Probabilistic Hazard Assessment (PHA) provides an appropriate methodology for assessing space weather hazards and their impact on technology. PHA is widely used in geosciences to determine the probability of exceedance of critical thresholds, caused by one or more hazard sources. PHA has proved useful with limited historical data to estimate the likelihood of specific impacts. PHA has also driven the development of empirical and physical models, or ensembles of models, to replace measured data. Here we aim to highlight the PHA method to the space weather community and provide an example of how it could be used. In terms of space weather impact, the critical hazard thresholds might include the Geomagnetically Induced Current in a specific high voltage power transformer neutral, or the local pipe-to-soil potential in a particular metal pipe. We illustrate PHA in the space weather context by applying it to a twelve-year dataset of Earth-directed solar Coronal Mass Ejections (CME), which we relate to the probability that the global three-hourly geomagnetic activity index Kp exceeds specific thresholds. We call this a “Probabilistic Geomagnetic Hazard Assessment”, or PGHA. This provides a simple but concrete example of the method. We find that the cumulative probability of Kp > 6−, > 7−, > 8− and Kp = 9o is 0.359, 0.227, 0.090, 0.011, respectively, following observation of an Earth-directed CME, summed over all CME launch speeds and solar source locations. According to the historical Kp distribution, this represents an order of magnitude increase in the a priori probability of exceeding these thresholds. For the lower Kp thresholds, the results are somewhat distorted by our exclusion of coronal hole high-speed stream effects. The PHGA also reveals useful probabilistic associations between solar source location and subsequent maximum Kp for operational forecasters.

Modeling of Anisotropy Dynamics of the Proton Pitch Angle Distribution in the Earth’s Magnetosphere

Last years the attention to research of anisotropy of the charged particle pitch angle distribution has considerably increased. Therefore for research of anisotropy dynamics of the proton pitch angle distribution is used the two-dimensional Phenomenological Model of the Ring Current (PheMRC 2-D), which includes the radial and pitch angle diffusions with consideration of losses due to wave-particle interactions. Experimental data are collected on the Polar/MICS satellite during the magnetic storm on October 21–22, 1999. Solving the non-stationary two-dimensional equation of pitch angle and radial diffusions, numerically was determined the proton pitch angle distribution anisotropy index (or parameter of the proton pitch angle distribution) for the pitch angle of 90 degrees during the magnetic storm, when the geomagnetic activity Kp-index changed from 2 in the beginning of a storm up to 7+ in the end of a storm. Dependence of the perpendicular proton pitch angle distribution anisotropy index with energy E = 90 keV during the different moments of time from the McIlwain parameter L (2.26 < L < 6.6) is received. It is certain at a quantitative level for the magnetic storm on October 21–22, 1999, when and where on the nightside of the Earth’s magnetosphere (MLT = 2300) to increase in the geomagnetic activity Kp-index there is a transition from normal (pancake) proton pitch angle distributions to butterfly proton pitch angle distributions. That has allowed to determine unequivocally and precisely the anisotropy dynamics of the proton pitch angle distribution in the given concrete case. It is shown, that with increase of the geomagnetic activity Kp-index the boundary of isotropic proton pitch angle distribution comes nearer to the Earth, reaching L ≈ 3.6 at Kp = 7+

Analysis of Relationship Between Ionospheric and Solar Parameters Using Graphical Models

AbstractFor the investigation of time variations of critical frequency (foF2), solar radiation flux at 10.7 cm wavelength (F10.7 index) and geomagnetic activity index Kp, we use conditional independence graphical models which describe and transparently represent the structure of relationships in the time series. We employ multivariate statistic methods applied to daily observational data obtained from midlatitude ionosondes within the period 1994–2009 (23rd Solar Cycle). It is demonstrated that conditional independence graphical models represent a robust method of multivariate statistical analysis, useful for finding a relation between one of the main ionospheric parameters and space weather conditions. This method appears to be more appropriate than correlation analysis between foF2 and the main geomagnetic and solar indices, especially for long‐term data for which the model characteristics may change or time series can be interrupted. We compare the results obtained by the graphical models method with cross‐correlation analysis. We found that the method is suitable for the analysis of the dependence between foF2 values and time‐shifted F10.7 time series. In particular, we clearly identified +0 day shift in all cases, and +1‐, +2–3‐, and +4–5‐day shifts in European, American, and East Asia sector, respectively. The conditional independence graphs method can be applied even in the case when classical parametric methods are not convenient.

Periodic variations of the geomagnetic activity indices Ap and Kp

Yearly averages of geomagnetic activity indices Kp and Ap for the years 1984 to 2018 be compared to the relevant averages of VxBs, where V is the solar wind velocity and Bs is the southward interplanetary magnetic field (IMF) component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap and Kp with V and Bs separately. We found that, during the declining phase of solar cycle, V and during the ascending phase Bs have more influence on Ap and Kp indices. According to this observation the 27 days and semiannual, Ap and Kp variations be analysed discretely for years after and before sunspot minima. The time intervals prior to sunspot minima with a significant 27-day recurrent period of the IMF structure and those intervals after sunspot minima with a significant 28 to28.5 day recurrent phase of the structure be used. The averaged spectra of the two Ap and Kp data sets obviously show a period of 27 days before and a period of 28 to 29 days after sunspot minimum.

The interconnection and phase asynchrony between the geomagnetic indices’ periodicities: A study based on the interplanetary magnetic field polarities 1967–2018 utilizing a cross wavelet analysis

In this article, we investigate the interconnection and phase asynchrony between the periodicities of geomagnetic activity indices Kp, Ap, aa, and Dst according to the interplanetary magnetic field (IMF) polarities, toward (T) or away (A), during the time interval 1967–2018. For this purpose, the daily data of Kp, Ap, aa, and Dst indices during the considered period have been sorted into two groups (T and A) according to the IMF polarities. The wavelet transform (WT), the cross-wavelet transform (XWT), and the wavelet coherence (WTC) have been applied on the monthly averages of T and A groups for each geomagnetic index. Moreover, the correlation analyses (linear and running correlations) between the annual averages of T and A groups of each geomagnetic index have been investigated. The results of XWT and WTC revealed the existence of a long-term periodicity in the frequency range 8–16 yr for the monthly averages of T and A groups for aa, Kp, and Ap indices existed during the entire period. In contrast, the Dst index revealed this periodicity during the period 1980–2018. In addition, during this frequency band, both T and A groups of each geomagnetic index revealed a highly positive correlation and nearly in-phase relationship behavior. Furthermore, during the frequency band 4–8 yr, the XWT displayed a prominent periodicity that occurred for the monthly averages of T and A groups of each geomagnetic index, revealing a phase change during some time intervals. Periodicity in the range 2–4 yr for the monthly averages of T and A groups of aa, Kp,Ap, and Dst occurred in the intervals; 1967–2009 for aa and Kp, 1967–2007 for Ap, and 1976–1995 for Dst. The annual periodicity is also identified for all considered indices. Both T and A groups of Dst shared a semiannual periodicity (~187 days) during different intervals in the entire period. On the other hand, a periodicity around 0.25-yr (~90 days) appeared only near the times of solar activity maxima in the case of the T and A groups of aa, Kp, and Ap indices.

Generation of Non‐Substorm Pi2s at Low and Middle Latitudes

AbstractThis study analyzes the characteristics of non‐substorm Pi2 (impulsive pulsations [3–25 mHz]) from low and middle latitudes and investigates the trends of these oscillations. Pi2 events are identified from geomagnetic H‐component data from low and middle latitude observatories Hyderabad (HYB, L = 1.03) and Paratunka (PET, L = 2.1) respectively, during solar maximum period (2015–2016) for quietest geomagnetic conditions, with stringent criteria of interplanetary parameters and activity indices. Data from five high‐latitude stations from THEMIS ground magnetometer chain, covering all local time sectors are additionally analyzed to verify the absence of substorms, pseudo substorms, etc. which may also generate Pi2 signatures. Variation of non‐substorm Pi2 periods with geomagnetic activity index Kp and solar wind speed (Vsw) show inverse relations with Pi2 period at HYB. In addition, non‐substorm Pi2s are distributed equally in all local time sectors with ratio of second harmonic to fundamental Pi2 ranging within 1.3–2.2. These trends of non‐substorm Pi2s indicate plasmaspheric cavity resonance (PCR) as the dominant source at low latitude, confirmed using a theoretical model. In contrast, non‐substorm Pi2 periods do not show a steady trend with Kp and Vsw at midlatitude station PET. Local time variations show an increased period in the premidnight sector at PET. A close agreement between theoretical estimates and observed periods of non‐substorm Pi2‐s at PET, leads to the inference of Alfvenic nature of these modes, attributable to a resonant oscillation.

Statistical characteristics of the polar ionospheric scale height around the peak height of F2 layer with observations of the ESR radar: Disturbed days

In this paper, based on observations of the European Incoherent Scatter Svalbard Radar (ESR) between 1997 and 2008, we analyzed variations of HmF2, the ionospheric scale height around the peak height of F2 layer (hmF2) at high latitude with geomagnetic activities, as well as variations of the HmF2 with the local time (LT), season and solar activity under disturbed conditions (2<Kp≤5). We found that the HmF2 shows a significant increment with enhancements of geomagnetic activities. In addition, based on a linear regression, the correlation and fitting coefficients are shown, which quantitatively describe the correlations between polar HmF2 and geomagnetic activity index Kp. The HmF2 shows a diurnal variation with a maximum early in the morning and a minimum around noon in disturbed days (2<Kp≤5), which is more complex in comparison with that in quiet days. However, in summer and autumn, the HmF2 in disturbed days shows a bulge during 06:00–11:00 LT instead of the continuous decline under quiet condition. We consider that the ESR was under the cusp region during the period so that the bulge might be related to the high-energy particles precipitating into the ionosphere resulting in changes of the electron density profile. The HmF2 has the highest seasonal magnitude in summer and the lowest seasonal magnitude in winter generally. The seasonal magnitude of the HmF2 in autumn is lower than that in spring and larger than that in winter under low solar activity, while the HmF2 shows the same seasonal variations in spring and autumn under moderate and high solar activities.

Fractal characteristics of the ULF emissions along a meridian profile, based on the 210 MM stations data

Fractal analysis of magnetic records (1 Hz sampling rate) of 5 stations (Guam, Moshiri, Paratunka, Magadan, and Chokurdakh) located along the 210 magnetic meridian (210 MM) has been performed using the Higuchi method. The period of 22 months (October 1992 to July 1994) that embodies the date of the strong Guam earthquake of 8 August1993 has been considered. A comparison of the ULF emissions scaling parameters (spectral exponents β and fractal dimensions D) obtained at different latitudes has been made. Dependence of β and D on the Kp index of geomagnetic activity has been analyzed for each of the 24 local time intervals. It is revealed that D decreases ( β increases) with increasing geomagnetic activity at all stations, but the rates of decrease (increase) are different at different stations and in different time intervals. It is shown that the evening, night and early morning hours are preferable to study magnetospheric effects, whereas the noon hours are the most suitable for the analysis of lithospheric effects. A possibility of using the data of the 210 MM stations as reference materials for the Guam seismically active area is discussed.

Ionospheric effects caused by the series of geomagnetic storms of September 9–14, 2005

This study presents the ionospheric effects caused by the series of geomagnetic storms of September 9–14, 2005. The behavior of different ionospheric parameters over the Yakutsk, Irkutsk, Millstone Hill and Arecibo stations during the considered period have been numerically calculated, using a global self-consistent model of the thermosphere, ionosphere, and protonosphere (GSM TIP) developed at WD IZMI-RAN. The model calculations of disturbances of the ionospheric parameters during storms qualitatively agree with the experimental data at these midlatitude stations. We suggest that the causes of the quantitative differences between the model calculations and the observational data were the use of the 3-hour Kp index of geomagnetic activity and the dipole approximation of geomagnetic field in GSM TIP, with additional contributions from the effects of solar flares which are not considered in GSM TIP.

Ionospheric effects of geomagnetic storms at mid latitudes

Previously, we studied the ionospheric effects of the sequence of geomagnetic storms on September 9–14, 2005 using a global self-consistent model “Thermosphere-Ionosphere-Protonosphere” (GSM TIP). Differences between the predicted and observed effects of the ionospheric storms may be due to the use of the three-hour K p index of geomagnetic activity in modeling the time dependence of model input parameters, use of the dipole approximation of the geomagnetic field, and disregard in simulations for solar flares that occurred during this period. We tried to eliminate two of these three reasons. First, we used the A E index of geomagnetic activity with minute resolution in modeling the time dependence of the model input parameters. Second, we took into account the effects of solar flares. In addition, GSM TIP model was supplemented by an empirical model describing the precipitation of high-energy electrons. The results of the simulation of the behavior of various ionospheric parameters over the Yakutsk, Irkutsk, Millstone Hill, and Arecibo stations on September 9 and 10, 2005 in the new formulation of the problem, presented in the current work, are in better agreement with the available experimental data than the results of previous calculations.

Association of major earthquakes (magnitude &gt;= 6 Richter scale) with geomagnetic activity index KP during the period 2001-2007

A critical study of variation of geomagnetic activity index Kp for the period 2001-2007 have been made and its close association with major earthquakes (magnitude &gt;= 6 Richter scale) is presented. From statistical analysis it is confirmed that when Kp touches 0 or 0+ values, major earthquakes take place within 48 hours. This is also explained considering the motion of the molten metal inside the outer core of earth.

Rapid recovery of thermosphere density during the October 2003 geomagnetic storms

[1] Thermosphere densities from the CHAMP and GRACE satellites are utilized, for the first time, to study the recovery of the thermosphere as a function of latitude during the October 2003 storms. Our results show that the relaxation times, defined by the e-folding time of the poststorm recovery of thermosphere density, are about 6 and 8 h for two recovery phases of the October 2003 superstorms, respectively. Geomagnetic activity index Kp or ring current index Dst is incapable of describing the rapid recovery of thermosphere density. Moreover, a weak altitudinal dependence of the relaxation times was observed between the CHAMP and GRACE altitudes at middle and high latitudes, but no coherent latitudinal dependence was found. The MSISE00 and TIEGCM neutral densities are compared with the observations to assess their capability in predicting the thermosphere response during the recovery phase of extremely severe storms. Neither the MSISE00 nor the TIEGCM reproduced the rapid recovery of thermosphere densities seen in the CHAMP and GRACE, although the TIEGCM captured most of the salient features observed by CHAMP and GRACE when AMIE convection and precipitation patterns were used to specify the high-latitude drivers. The relaxation times of the MSISE00 and TIEGCM nighttime densities at 390 km are generally longer than those from the CHAMP observations by about 4 h, and even longer in the geographic latitudinal range of 25°N–50°N. The TIEGCM recovery times of thermosphere density are shorter on the dayside than on the nightside, whereas the MSISE00 densities show substantially longer relaxation times at low latitudes. Thus, not only are the relaxation times of the MSISE00 and TIEGCM densities longer than observed in the CHAMP and GRACE data, but they also show much larger day-night differences. No clear explanation can be found to fully understand the causes for the slower recovery of the thermosphere density simulated by the TIEGCM.

On the heating of the outer radiation belt to produce high fluxes of relativistic electrons: Measured heating rates at geosynchronous orbit for high‐speed stream‐driven storms

The heating rate of the outer electron radiation belt at geosynchronous orbit is determined for the interval from 36 to 72 h after the onset of high‐speed stream‐driven storms. Multisatellite measurements of the radiation belt temperature are used for 93 high‐speed stream‐driven storms. During the storms, the outer electron radiation belt temperature changes from ∼120 keV to ∼190 keV. The average heating rate of 32 keV d−1 is obtained. The heating rate during the storms is found to be positively correlated with the solar wind velocity and with the Kp index of geomagnetic activity and to be negatively correlated with the solar wind number density. When the solar wind velocity is held fixed, the correlation of the heating rate with Kp vanishes. Expressions for the change in the heating rate as function of the solar wind speed, the solar wind density, and the Kp index are fit to the data. The heating rate is uncorrelated with the amplitude of magnetic field fluctuations in the magnetosphere. Correlations between the heating rate and the level of velocity, density, and magnetic field fluctuations in the magnetosphere and in the solar wind are weaker than the correlations of the heating rate with the solar wind velocity and density. The heating rates correspond to a kinetic energy density change of 3.6 × 10−11 erg cm−3 d−1 at geosynchronous orbit, to a specific entropy change of 4.1 × 106 eV cm2 d−1 at geosynchronous orbit, and to a total heating rate of the geosynchronous orbit region of 5.3 × 106 Watts.

The relation between solar activity and orientation of the solar wind electric field relative to the Earth’s magnetic moment

The relation of the Kp index of geomagnetic activity to the solar wind electric field (ESW) and the projection of this field onto the geomagnetic dipole has been estimated. An analysis indicated that the southward component of the IMF vector (Bz < 0) is the main geoeffective parameter, as was repeatedly indicated by many researchers. The presence of this component in any combinations of the interplanetary medium parameters is responsible for a high correlation between such combinations and geomagnetic activity referred to by the authors of different studies. Precisely this field component also plays the main role in the relation between the Kp index and the relative orientation of ESW and the Earth’ magnetic moment.

Analysis of characteristic rhythms of heliogeomagnetic activity and their roles in synchronization of rhythms of biological objects

Rhythms of heliogeomagnetic activity and their dynamics in the solar activity (SA) cycles are analyzed. Heliogeomagnetic rhythms are the mixture of a periodic signal and noise component, which differs from a periodic signal by a substantial suddenness. Therefore, the filtering methods optimized for smoothness were used to analyze these rhythms and to separate rhythm periodic components. Short-period rhythms of the Kp index of geomagnetic activity and Wolf numbers (W) have been revealed. The rhythm dynamics in SA cycles has been indicated. Clearly defined near-seven-day, semi-seven-day, and other components, which are harmonics of the solar rotation period, are present in the rhythms of the Kp index in contrast to W. A comparison of the Kp and Dst rhythms indicates that the seasonal and annual variations in these indices are substantially similar. It has been indicated that the rhythms of heliogeomagnetic activity could be the external synchronizers of biological rhythms, having integrated into the endogenous temporal structure of these rhythms in the process of evolution, and that the dependence of the population macroparameters on W is much weaker than on Kp.

Correlation between Drosophila population sizes and solar activity parameters

The relationships between the time series of the changes in the sizes of experimental Drosophila melanogaster populations at the preimaginal stage and three heliogeophysical indices (Wolf numbers, 10.7-cm radio flux intensity, and the Kp index of geomagnetic activity) have been analyzed. The results demonstrate a significant relationship between the population dynamics and heliogeophysical factors and dependence of this relationship on the phase of the 11-year solar activity cycle. Factors related to solar activity may stimulate female fertility and egg survival.

Comparisons between EUV/IMAGE observations and numerical simulations of the plasmapause formation

Abstract. Simulations of plasmapause formation described in Pierrard and Lemaire (2004) predict the shape and equatorial distance of the plasmapause as a function of the geomagnetic activity index Kp. The equatorial positions predicted by this model are compared with the observations of EUV/IMAGE during the geomagnetic storm of 24 May 2000, substorm events of 10 June 2001 and 25 June 2000, and also during a prolonged quiet period (2 May 2001) when the plasmasphere was very extended. The formation of structures, like plumes and shoulders observed during periods of high geomagnetic activity, is quite well reproduced by the simulations. These structures are directly related to specific time sequences of Kp variations. The radial distances of the plasmapause are also reproduced, on average, by the model. Keywords. Magnetospheric physics (Plasmasphere; Storms and substorms; Solar wind magnetosphere interactions)