How good is the relationship of solar and interplanetary plasma parameters with geomagnetic storms?

Abstract

[1] Since the work of Snyder et al. (1963), who showed a possible link between interplanetary solar wind speed V and geomagnetic index Kp, such a relationship has been examined by many workers and found to be rather loose. In the present communication this relationship is rechecked for all data during . It was noted that moderate or strong geomagnetic storms occurred only when solar wind speed V was above $350 km/s. However, above this limit, the plots of Dst versus V showed a large scatter, and any value of V could be associated with any value of Dst in a wide range of a factor of $2, or any Dst value could be associated with any value of V in a wide range of a factor of $2, indicating a poor relationship between V and Dst. The scatter could be partly because not V but VB s (product of V and the southward component B s of interplanetary field B) is the appropriate variable relevant for Dst changes. This was checked. In the plot of Dst versus VB s it was noticed that the scatter was smaller and correlation better than that in the plot of Dst versus V. Since the relationship between V and Dst is poor, an estimate of V with some antecedence, as is done in a present-day prediction scheme ) V estimated from the lateral extension speed of side halo coronal mass ejections (CMEs) and assuming V 2 proportional to Dst magnitudes) is not likely to give reliable estimates of Dst magnitudes. However, estimate of V could certainly be useful to estimate the time when the storm would hit the Earth but remembering that 15% of the halo CMEs may miss the Earth.

Climate interaction mechanism between solar activity and terrestrial biota

“…Peaks shorter than 1 yr may be due to seasonal climatic phenomena. The ∼2 yrs period can be associated with the Quasi-Biennial Oscillation (QBO) in the stratosphere (Holton et al 1972;Dunkerton 1997;Baldwin et al 2001;Naujokat 1986;Holton et al 1980) and with the solar activity (Kane, 2005).The periodicities ∼3 and 4 yrs could be related to the El Niño-Southern Oscillation (ENSO) (Nuzhdina 2002;Njau 2006: Enfield 1992) that is a large-scale climatic phenomenon. The periodicities ∼5 yrs can be a harmonic of the 11-yrs solar cycle (Djurović & Páquet 1996).…”

Astrophysics in 2005

“…Subcycles with periods of 152-158 days were also noted from flare rates (Ballester et al 2004) or other solar indices (Kane 2005c). Such subcyles are also called Rieger periodicities and were even discovered on stars, e.g., with a 294-day cycle on UX Arietis, believed to be caused by equatorially trapped Rossbytype waves modulating the emergence of magnetic flux at the surface (Massi et al 2005).…”

“…However, a cycle is not simple in nonlinear dynamics; fluctuations in the Babcock-Leighton dynamo were actually shown to lead to period doubling and to transition to chaos (Charbonneau et al 2005b), possibly explaining the anomaly of the Maunder minimum (Charbonneau 2004(Charbonneau , 2005Charbonneau et al 2004). Spherical harmonic decomposition of magnetic field data revealed also intermittent oscillations with periods of 2.1-2.5 yr, 1.5-1.8 yr, and 1.2-1.4 yr (Knaack & Stenflo 2005;Kane 2005b), as similarly found in cosmic-ray modulations (Starodubtsev et al 2004). While we believed that the magnetic cycle of 22 years (Hale cycle) clocks everything on the Sun, correlations with the equatorial rotation rate actually reveal that the phase of the beginning of a 22 yr cycle in the latitudinal gradients is out of phase by 180Њ (Javaraiah et al 2005).…”

“…A large statistical study showed that just over a quarter of the 938 HCMEs observed by LASCO were associated with a forward shock near L1, suggesting that about half of the earthbound HCMEs are either deflected away from the Sun-Earth line or do not form a shock (Howard & Tappin 2005). Although "halo-CMEs" are considered as Earth-directed, a fraction of 15% miss the Earth (Kane 2005c). Given the maximum observed CME speeds of ≈3000 km s Ϫ1 , the shortest travel times of CME-driven shocks are expected to be no less than ≈0.5 days (Gopalswamy et al 2005b).…”

Variability of Geomagnetic Field with Interplanetary Magnetic Field at Low, Mid and High Latitudes

“…In this reference, we have considered different places on earth as well as storms of different intensities to know the nature of variation and amount of decrease at different places during different storms. Some studies have been conducted in the past to investigate how the variations in IMF during geomagnetic storm events cause the variations in the geomagnetic field like a cause-effect relationship [18].…”