EMIC Waves in the Outer Magnetosphere: Observations of an Off‐Equator Source Region

Abstract. Discrete ELF/VLF chorus emissions, the most intense electromagnetic plasma waves observed in the Earth's radiation belts and outer magnetosphere, are thought to propagate roughly along magnetic field lines from a localized source region near the magnetic equator towards the magnetic poles. THEMIS project Electric Field Instrument (EFI) and Search Coil Magnetometer (SCM) measurements were used to determine the spatial scale of the chorus source localization region on the day side of the Earth's outer magnetosphere. We present simultaneous observations of the same chorus elements registered onboard several THEMIS spacecraft in 2007 when all the spacecraft were in the same orbit. Discrete chorus elements were observed at 0.15–0.25 of the local electron gyrofrequency, which is typical for the outer magnetosphere. We evaluated the Poynting flux and wave vector distribution and obtained chorus wave packet quasi-parallel propagation to the local magnetic field. Amplitude and phase correlation data analysis allowed us to estimate the characteristic spatial correlation scale transverse to the local magnetic field to be in the 2800–3200 km range.

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Nonlinear Interactions Between Relativistic Electrons and EMIC Waves in Magnetospheric Warm Plasma Environments

Journal of Geophysical Research Space Physics ◽

10.1029/2020ja028089 ◽

2020 ◽

Vol 125 (12) ◽

Author(s):

Jiang Yu ◽

L. Y. Li ◽

Jun Cui ◽

J. B. Cao ◽

Jing Wang ◽

...

Keyword(s):

Relativistic Electrons ◽

Nonlinear Interactions ◽

Warm Plasma ◽

Emic Waves

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OBSERVATION AND SIMULATION OF TSUNAMIS INDUCED BY THE 2003 TOKACHI-OKI EARTHQUAKE (M 8.0)

Journal of Applied Geology ◽

10.22146/jag.7270 ◽

2015 ◽

Vol 2 (3) ◽

Author(s):

Tatsuo Ohmachi ◽

Shusaku Inoue ◽

Tetsuji Imai

Keyword(s):

Rayleigh Wave ◽

Water Pressure ◽

Near Field ◽

Source Region ◽

Tsunami Source ◽

Band Pass Filter ◽

Pass Filter ◽

Tsunami Simulation ◽

Sea Bed ◽

Band Pass

The 2003 Tokachi-oki earthquake (MJ 8.0) occurred off the southeastern coast of Tokachi, Japan, and generated a large tsunami which arrived at Tokachi Harbor at 04:56 with a wave height of 4.3 m. Japan Marine Science and Technology Center (JAMSTEC) recovered records of water pressure and sea-bed acceleration at the bottom of the tsunami source region. These records are first introduced with some findings from Fourier analysis and band-pass filter analysis. Water pressure disturbance lasted for over 30 minutes and the duration was longer than those of accelerations. Predominant periods of the pressure looked like those excited by Rayleigh waves. Next, numerical simulation was conducted using the dynamic tsunami simulation technique able to represent generation and propagation of Rayleigh wave and tsunami, with a satisfactory result showing validity and usefulness of this technique. Keywords: Earthquake, Rayleigh wave, tsunami, near-field

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SANTA BARBARA BASIN, CALIFORNIA FLOOD LAYER PROVENANCE: MAPPING FLOODING HAZARD BY SEDIMENT SOURCE REGION

10.1130/abs/2016am-285044 ◽

2016 ◽

Author(s):

Tiffany J. Napier ◽

◽

Ingrid Hendy ◽

Julia G. Bryce

Keyword(s):

Source Region ◽

Sediment Source ◽

Santa Barbara ◽

Santa Barbara Basin ◽

Flooding Hazard

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Spatial variations of local climate at Taylor Dome, Antarctica: implications for paleoclimate from ice cores

Annals of Glaciology ◽

10.1017/s0260305500016487 ◽

1994 ◽

Vol 20 ◽

pp. 219-225 ◽

Cited By ~ 4

Author(s):

E.D. Waddington ◽

D.L. Morse

Keyword(s):

Spatial Variability ◽

Source Region ◽

Ice Core ◽

Ice Cores ◽

Temperature Inversion ◽

Related Factors ◽

Local Climate ◽

Air Masses ◽

Air Temperatures ◽

Inversion Strength

10m firn temperatures are commonly used on the Antarctic plateau to estimate mean annual air temperatures. 10m firn temperatures measured at Taylor Dome (also referred to as McMurdo Dome in the literature), Antarctica, are influenced by a factor other than altitude and latitude that varies systematically across Taylor Dome. Some inter-related factors possibly contributing to the modern temperature variability are differences in sensible heat from warm or cold air masses, differences in wind strength and source region, differences in temperature inversion strength and differences in cloudiness. Our preliminary data are compatible with spatially variable katabatic winds that could control the winter temperature inversion strength to provide a large part of the signal. This has implications for paleoclimate studies.(1) Variations of the stable isotopes δ18O and δD from ice cores are a proxy for paleotemperature. The isotope thermometer is calibrated by comparing local isotope ratios with corresponding measured temperatures. In order to derive a useful isotope-temperature calibration, we must understand the processes that control the modern spatial variability of temperature. (2) In order to quantify past changes in local climate, we must understand processes that influence local spatial variability. If those processes differed in the past, ice-core climate reconstruction would be affected in two ways: through alteration of the geochemical record and through alteration of deep ice and firn temperatures.

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