Morphology of nightside precipitation

Newell, P. T.; Feldstein, Y. I.; Galperin, Yuri I.; Meng, C.‐I.

doi:10.1029/95ja03516

Cited by 257 publications

(310 citation statements)

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“…The UV-intensity curves tend to be more peaked than the total flux curves. The most equatorward boundary of the DMSP precipitation categorization system is the zero-energy convection boundary (le, i) [Newell et al, 1996]. As zeroenergy particles do not curvature or gradient drift, the Earthward edge of their drift trajectories is controlled purely by the E x B drift.…”

Section: Description Of the Data Setmentioning

confidence: 99%

“…The 5pol marks the poleward boundary of the discrete oval (excluding the diffuse zone observed occasionally poleward of 5e and 5i). For more details about the boundary definitions, see Newell et al [1996]. At 5pol the precipitating energy flux of either electrons (Se) or ions (5i) typically drops by about an order of magnitude within _< 2 ø in magnetic latitude.…”

Section: Description Of the Data Setmentioning

confidence: 99%

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Size of the auroral oval: UV ovals and precipitation boundaries compared

Kauristie¹,

Weygand²,

Pulkkinen³

et al. 1999

J. Geophys. Res.

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Abstract. The oval boundaries in 44 Viking UV images are compared with three critical boundaries as defined from simultaneous DMSP particle precipitation data. The particle boundaries are the equatorward boundary of the particle oval (often associated with the earthward edge of the main plasma sheet), the boundary between smooth and structured precipitation, and the poleward boundary of the particle oval (close to the open-closed field line separatrix). The UV oval is characterized by the latitude of maximum UV intensity, equatorward boundary, and poleward boundary which are the latitudes corresponding to the half values of the maximum intensity. Differences between the UV and particle boundaries are quantified in various magnetic local time sectors and at different activity levels. The study shows that the poleward boundary of the particle oval is often at _>2 ø higher latitudes than the most intense UV luminosity. Large differences are typical especially in the midnight and morning sectors. The present results suggest that caution is needed in interpreting the dramatic poleward expansion of the oval in the UV images, or more generally in using UV images to compute changes in the amount of open flux under different states of substorm activity.

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Section: Description Of the Data Setmentioning

confidence: 99%

Section: Description Of the Data Setmentioning

confidence: 99%

Size of the auroral oval: UV ovals and precipitation boundaries compared

Kauristie¹,

Weygand²,

Pulkkinen³

et al. 1999

J. Geophys. Res.

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“…As noticed by Newell et al (1996), the use of the same terms to describe the precipitation patterns observed by di erent instruments can often lead to disagreement in the interpretation. In this paper we use the terms`d iscrete aurora'' and``discrete auroral arcs'' to describe well-isolated narrow (>100 km) auroral forms having a well-de®ned border corresponding to the low-altitude edge of the form.…”

Section: Introductionmentioning

confidence: 99%

“…The discussion on the sources of auroral precipitation has a long history (see e.g. the reviews by Feldstein and Galperin, 1985;Galperin and Feldstein, 1991;Feldstein and Elphinstone, 1992;Weiss et al, 1992;Elphinstone et al, 1995;Newell et al, 1996). All authors generally agree that the source region of the di use aurora is the inner, near-Earth plasma sheet; it is the origin of the discrete auroras that is a main subject of discussion.…”

Section: Introductionmentioning

confidence: 99%

Magnetospheric source region of discrete auroras inferred from their relationship with isotropy boundaries of energetic particles

et al. 1997

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Abstract. According to observations, the discrete auroral arcs can sometimes be found, either deep inside the auroral oval or at the poleward border of the wide (socalled double) auroral oval, which map to very di erent regions of the magnetotail. To ®nd common physical conditions for the auroral-arc generation in these magnetotail regions, we study the spatial relationship between the di use and discrete auroras and the isotropic boundaries (IBs) of the precipitating energetic particles which can be used to characterise locally the equatorial magnetic ®eld in the tail. From comparison of ground observation of auroral forms with meridional pro®les of particle¯ux measured simultaneously by the low-altitude NOAA satellites above the ground observation region, we found that (1) discrete auroral arcs are always situated polewards from (or very close to) the IB of >30-keV electrons, whereas (2) the IB of the >30-keV protons is often seen inside the di use aurora. These relationships hold true for both quiet and active (substorm) conditions in the premidnight-nightside (18± 01-h) MLT sector considered. In some events the auroral arcs occupy a wide latitudinal range. The most equatorial of these arcs was found at the poleward edge of the di use auroras (but anyway in the vicinity of the electron IB), the most poleward arcs were simultaneously observed on the closed ®eld lines near the polar-cap boundary. These observations disagree with the notion that the discrete aurora originate exclusively in the nearEarth portion of plasma sheet or exclusively on the PSBL ®eld lines. Result (1) may imply a fundamental feature of auroral-arc formation: they originate in the current-sheet regions having very curved and tailwardstretched magnetic ®eld lines.

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“…Results bear evidence for a strong connection between solar variability, the state of the magnetosphere, and the chemical climatological state of the middle and lower atmosphere. Newell and Meng (1992) and Newell et al (1996) discuss the morphology of nighttime precipitation and introduce a detailed scheme for quantitatively classifying the radiation belt impact in the low ionosphere. Assessment of radiation belts particle precipitation is useful for not only aeronomy but also lightning-related wave propagation research.…”

Section: Sources Outside the Cavitymentioning

confidence: 99%

A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

Simões¹,

Pfaff²,

Berthelier³

et al. 2011

Dynamic Coupling Between Earth’s Atmospheric and Plasma Environments

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Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earthionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and https://ntrs.nasa.gov/search.jsp?R=20120011991 2019-03-25T00:54:44+00:00Z atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

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Morphology of nightside precipitation

Cited by 257 publications

References 50 publications

Size of the auroral oval: UV ovals and precipitation boundaries compared

Size of the auroral oval: UV ovals and precipitation boundaries compared

Magnetospheric source region of discrete auroras inferred from their relationship with isotropy boundaries of energetic particles

A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

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