Tailward propagation of Pi2 waves in the Earth's magnetotail lobe

Volwerk, M.; Nakamura, R.; Baumjohann, W.; Уозуми, Т.; Yumoto, K.; Balogh, A.

doi:10.5194/angeo-26-4023-2008

Cited by 9 publications

(8 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the same time, these large waves are accompanied by smaller Pi2-like pulsations, often in the form of standing Alfvén waves in the tail lobe, which are one-to-one correlated with pulsations in the polar cap (Keiling et al 2005). We also note the study by Volwerk et al (2008) who reported Pi2-like oscillations in the tail lobe that traveled tailward, which are consistent with this propagation path, if they are interpreted as waves reflected off the ionosphere.…”

Section: Observationssupporting

confidence: 78%

Review of Pi2 Models

2011

View full text Add to dashboard Cite

More than half a century after the discovery of Pi2 pulsations, Pi2 research is still vigorous and evolving. Especially in the last decade, new results have provided supporting evidence for some Pi2 models, challenged earlier interpretations, and led to entirely new models. We have gone beyond the inner magnetosphere and have explored the outer magnetosphere, where Pi2 pulsations have been observed in unexpected places. The new Pi2 models cover virtually all magnetotail regions and their coupling, from the reconnection site via the lobes and plasma sheet to the ionosphere.In addition to understanding the Pi2 phenomenon in itself, it has also been important to study Pi2 pulsations in their role as transient manifestations of the coupling between the magnetosphere and the ionosphere. The transient Pi2 is an integral part of the substorm phenomenon, especially during substorm onset. Key questions about the workings of magnetospheric substorms are still awaiting answers, and research on Pi2 pulsations can help with those answers. Furthermore, the role of Pi2 pulsations in association with other dynamic magnetospheric modes has been explored in the last decade. Thus, the application of Pi2 research has expanded over the years, assuring that Pi2 research will remain active in this decade and beyond.Here we review recent advances, which have given us a new understanding of Pi2 pulsations generated at various places in the magnetosphere during different magnetospheric modes. We review seven Pi2 models found in the literature and show how they are supported by observations from spacecraft and ground observatories as well as numerical simulations. The models have different degrees of maturity; while some enjoy wide acceptance, others are still speculative.

show abstract

Section: Observationssupporting

confidence: 78%

Review of Pi2 Models

2011

View full text Add to dashboard Cite

show abstract

“…The overall spectrum becomes rather broadband during the local CD, suggesting the possibility of plasma instabilities with different spatiotemporal characteristic as well as distinct frequency bands, e.g., ballooning (mainly Pi2), the TCS mode (Pi1), and the CCI (above and possibly overlap with the upper edge of the Pi1). During this most active period of substorms there are also other viable mechanisms generating Pi1/Pi2 waves (e.g., Holter et al, 1995;Volwerk et al, 2008). Those instability/wave processes may coexist and cooperate, driving the current sheet into a turbulence state (Lui, 2002;Cheng, 2004).…”

Section: Discussionmentioning

confidence: 99%

In-situ observation of ULF wave activities associated with substorm expansion phase onset and current disruption

et al. 2009

View full text Add to dashboard Cite

Abstract. In this paper we present two substorm events with coordinated ground-based and in-situ THEMIS observations, and focus our interest on the wave activities in Pi1 and Pi2 bands from minutes before the substorm expansion phase (EP) onset to minutes after the local current disruption (CD). We find that Pi2 band (40-100 s) wave appears 1-2 min before the substorm onset and last over the entire EP interval, while higher-frequency wave within Pi1 band (10-30 s) emerges within few tens of seconds after the EP onset, intensifies during the local CD, and fades afterwards. The pre-onset Pi2 waves are attributed to a ballooning mode which acts as the seed perturbation to the substorm EP onset process. The azimuthal wavenumber estimated from the Doppler shift nature of the ballooning mode is consistent with the longitudinal "wavelength" inferred from the onset auroral structures. The Pi1 waves appearing within few tens of seconds after the EP onset are interpreted as supportive of a two-fluid instability mode of thin current sheet investigated in an accompanying paper . During the local CD, broadband wave activities from Pi2 band to well above the ion gyrofrequency are observed, suggesting the coexistence of various plasma instabilities featuring different frequency ranges.

show abstract

“…In order to better show the wave power and polarization characteristics of the Pc2 waves observed by Cluster 3, a wavelet analysis is used to obtain the wave power for leftand right-hand polarized components (B l = B t1 − i B t2 and B r = B t1 + i B t2 ) (Volwerk et al, 2008). Figure 5 presents the wavelet spectrograms for Cluster 3 during the interval of 17:00-17:48 UT.…”

Section: Discussionmentioning

confidence: 99%

Energetic ions scattered into the loss cone with observations of the Cluster satellite

2016

View full text Add to dashboard Cite

Abstract. In this paper, we report in situ observations by the Cluster spacecraft of energetic ions scattered into the loss cone during the inbound pass from the plasma sheet into the plasmasphere. During the inbound pass of the plasma sheet, Cluster observed the isotropy ratio of energetic ions to gradually decrease from unity and the isotropic boundary extended to lower L value for higher-energy ions, implying that the field line curvature scattering mechanism is responsible for the scattered ions into the loss cone from the plasma sheet. In the outer boundary of a plasmasphere plume, Cluster 3 observed the increase of the isotropy ratio of energetic ions accompanied by enhancements of Pc2 waves with frequencies between the He + ion gyrofrequency and O + ion gyrofrequency estimated in the equatorial plane. Those Pc2 waves were left-hand circularly polarized and identified as electromagnetic ion cyclotron (EMIC) waves. Using the observed parameters, the calculations of the pitch angle diffusion coefficients for ring current protons demonstrate that EMIC waves could be responsible for the ions scattering and loss-cone filling. Our observations provide in situ evidence of energetic ion loss in the plasma sheet and the plasmasphere plume. Our results suggest that energetic ions scattering into the loss cone in the central plasma sheet and the outer boundary of the plasmaspheric plume are attributed to the field line curvature scattering mechanism and EMIC wave scattering mechanism, respectively.

show abstract

Tailward propagation of Pi2 waves in the Earth's magnetotail lobe

Cited by 9 publications

References 24 publications

Review of Pi2 Models

Review of Pi2 Models

In-situ observation of ULF wave activities associated with substorm expansion phase onset and current disruption

Energetic ions scattered into the loss cone with observations of the Cluster satellite

Contact Info

Product

Resources

About