Enhancement of hydromagnetic emissions after geomagnetic storms

Wentworth, R. C.

doi:10.1029/jz069i011p02291

Cited by 75 publications

(54 citation statements)

References 3 publications

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“…As can be seen from this figure the EMIC wave activity is essentially enhanced starting on 6 May, during the late recovery phase of this geomagnetic storm. It is consistent with the statistical observational data reported by Wentworth (1964). A detailed analysis of the wave activity zone morphology and dynamics was presented in papers (Khazanov et al, 2002(Khazanov et al, , 2003.…”

Section: Emic Waves and Core Plasma Characteristicssupporting

confidence: 88%

The nonlinear coupling of electromagnetic ion cyclotron and lower hybrid waves in the ring current region: the magnetic storm 1-7May 1998

Khazanov

Krivorutsky

Gamayunov

et al. 2004

Nonlin. Processes Geophys.

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Abstract. The excitation of lower hybrid waves (LHWs) is a widely discussed mechanism of interaction between plasma species in space, and is one of the unresolved questions of magnetospheric multi-ion plasmas. In this paper we present the morphology, dynamics, and level of LHW activity generated by electromagnetic ion cyclotron (EMIC) waves during the 2-7 May 1998 storm period on the global scale. The LHWs were calculated based on a newly developed selfconsistent model (Khazanov et. al., 2002) that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes the evolution of EMIC waves. It is found that the LHWs are excited by helium ions due to their mass dependent drift in the electric field of EMIC waves. The level of LHW activity is calculated assuming that the induced scattering process is the main saturation mechanism for these waves. The calculated LHWs electric fields are consistent with the observational data.

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Section: Emic Waves and Core Plasma Characteristicssupporting

confidence: 88%

The nonlinear coupling of electromagnetic ion cyclotron and lower hybrid waves in the ring current region: the magnetic storm 1-7May 1998

Khazanov

Krivorutsky

Gamayunov

et al. 2004

Nonlin. Processes Geophys.

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“…In spite of a fairly good understanding of the properties and generation mechanisms of these pulsations their relation to other geomagnetic perturbations is still insuciently investigated. The results obtained by Wentworth (1964), Plyasova-Bakounina and Matveeva (1968), and Feygin et al (1970) show that the majority of pearl pulsations was observed during the recovery phase of a magnetic storm. The relation of temporal variations in Pc1 pulsations to geomagnetic activity was studied in detail by Fraser (1968).…”

Section: Introductionmentioning

confidence: 91%

Nonstationary pearl pulsations as a signature of magnetospheric disturbances

Feygin

Клейменова

Pokhotelov

et al. 2000

Annales Geophysicae

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Abstract. We analyse long-lasting (several hours) Pc1 pearl pulsations with decreasing, increasing or constant central frequencies. We show that nonstationary pearl events (those with either decreasing or increasing central frequency) are observed simultaneously with increasing auroral magnetic activity at the nightside magnetosphere while the stationary events (constant central frequency) correspond to quiet magnetic conditions. Events with decreasing central frequency are observed mostly in the late morning and daytime whereas events with increasing central frequency appear either early in the morning or in the afternoon. We explain the diurnal distribution of the nonstationary pearl pulsations in terms of proton drifts depending on magnetic activity, and evaluate the magnetospheric electric ®eld based on the variation of the central frequency of pearl pulsations.

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“…From a study of 25 isolated magnetic storms over a 3-year period, Wentworth [1964a] observed a strong tendency for emissions to occur in the interval 3 to 7 days after the beginning of the storm (fig. 11).…”

Section: Occurrence 2-8 Days After the Beginning Of A Magnetic Stormmentioning

confidence: 99%

Regular oscillations near 1 c/s observed at middle and low latitudes

Tepley¹

1965

J. RES. NATL. BUR. STAN. SECT. D. RAD. SCI.

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A review is presented of so me of th e more important prope rti es of Pc 1(0.2-5 cIs) e missions observed at middle and low lati tud es . Special attention is give n to fin e s tru c ture d regular osci ll ati ons referred to b y various workers as pearls, tYIJe A osc ill a tio ns, and h ydromagne ti c (hm) e mi ss ions. Th e fo ll ow· in g aspects of th ese oscillations are d isc ussed.(a) Signal appearance. Th e e mi ss ions are co nsid ere d fro m both th e ir a mplitud e· time (wave· fo rm) appearance observ ed o n c ha rt reco rd s a nd th e ir freq ue ncy-tim e ({t) c ha rac te ri s ti cs observed on so nagra ms. The various t ypes of {t fin e s tru c ture are discussed (ri sing a nd fa lling freq uency e le· me nt s, fan s ha ped e le me nts, e tc.).(b) SimuLtaniet y of ocwrrence at widely separated locations. A hi g h degree of similarity is often found in th e ap peara nce of {t s tru ctura l e leme nt s of hm e mi ss ions reco rd ed simult a neo usly a t wide ly se parate d s tati ons. Attention is give n to the time-s hifts be twee n th ese e le me nts at st ati ons in th e sa me he mi sp he re a nd in oppos it e he mi s phe res.(c) Time of occurrence. Co rre lati ons are co nsid e red be twee n tim es of occurrence of hm e mi ssio ns a nd other geop hys ica l effects s uc h as c ha rged parti c le even ts, magneti c s torm s, a nd variations of the io nos ph eric para me te r F oF2.(d) Latitude effects. Various latitude dependent e mi ss ion c hara c te ri s ti cs a re di sc ussed. These include latitude variations of e mi ss ion fre qu e ncy, fin e s tru c ture repetiti on pe ri od , a nd signa l a mplitude.In addition to th e aspects of th e Pc 1 emission s outlined above, properties of two oth er typ es of e mi ss ions are brie fl y discussed. One of these signals, referred to he re as a "continu ous e miss ion" also lies in th e Pc 1 category. It is often obsuved co ntinuous ly throu g hout th e ni ght and is c haracterized by a slow variation of J.t c haracte ri s ti cs. Th e other signal, whi c h might be pl aced in a P c 1-Pi 1 tran siti on ca tego ry, is observed durin g magneti ca ll y di sturbe d periods. On so nagram s it is c haracte rize d by an irregularly spaced ri sin g freq ue ncy fin e-s tru c ture. When monitore d aurally on ti me· co mpressed magnet ic tap e (speed-up fa cto r of 1000 to 2000), it is c hara cterized by a so und simil ar to bubbles blown unde r wate r.

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Enhancement of hydromagnetic emissions after geomagnetic storms

Cited by 75 publications

References 3 publications

The nonlinear coupling of electromagnetic ion cyclotron and lower hybrid waves in the ring current region: the magnetic storm 1-7May 1998

The nonlinear coupling of electromagnetic ion cyclotron and lower hybrid waves in the ring current region: the magnetic storm 1-7May 1998

Nonstationary pearl pulsations as a signature of magnetospheric disturbances

Regular oscillations near 1 c/s observed at middle and low latitudes

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