Physics of the Aurora and Airglow

Chamberlain, Joseph W.

doi:10.1029/sp041

Cited by 115 publications

(142 citation statements)

References 911 publications

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“…The intensity of the Na i doublet in the nightglow is on the order of 50 R (Chamberlain 1995); therefore, about 98% of the sodium line emission observed in the Lick spectra is from light pollution. It should be noted that the Na D2/D1 intensity ratio in the nightglow is on the order of 1.4-1.8 (Slanger & Osterbrock 2000), while in these pollution spectra it is unity, demonstrating the very large optical depth in these lines in the high-pressure sodium lamps.…”

Section: Absolute Intensitiesmentioning

confidence: 99%

“…The absolute intensity of the atomic lines can be roughly estimated by comparison to the nightglow O i l5577 line, for which a reasonable average figure is 150 R (Chamberlain 1995). In the units of the -axis of these spectra, that line has y an intensity of 18,000, the Na i ll5890, 5896 lines each have an intensity of 135,000, the Hg i l4358 line is 10,000, and the Hg i l5461 line is 7500.…”

Section: Absolute Intensitiesmentioning

confidence: 99%

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The High‐Resolution Light‐polluted Night‐Sky Spectrum at Mount Hamilton, California

Slanger

Cosby

Osterbrock

et al. 2003

PUBL ASTRON SOC PAC

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ABSTRACT. Sky spectra were recorded over San Jose at the Lick Observatory over the 3800-9200 Å spectral range, with a spectral resolution of 45,000. Strong atomic lines were detected from Al i, Ar i, Hg i, K i, Li i, Na i, Ne i, Sc i, Sc ii, Th i, Th ii, and from O i and OH nightglow features. Spectra are contrasted for observations over San Jose (west), the zenith direction, and the eastern sky. When observing in the easterly direction, the emission intensity is still 20%-30% of that seen toward the west. For a natural and stable terrestrial nightglow line, O i l5577, the intensity is comparable in either direction. A variety of line shapes are observed, reflecting the outputs of the mélange of pollution sources. A total of 177 identified light-pollution lines were observed, of which more than half are due to Sc i and Sc ii. The Sc i lines show a systematic shift to longer wavelengths from the expected positions, amounting to an average of 25 mÅ . This is presumably a consequence of their origin, high-pressure metal halide lamps. By comparing the intensity of the strongest pollution lines and continuum (from Na) with the nightglow O i l5577 line, a figure of merit for the pollution line intensity is the equivalent of 4 kR for the atmospheric conditions and viewing geometry investigated.

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Section: Absolute Intensitiesmentioning

confidence: 99%

Section: Absolute Intensitiesmentioning

confidence: 99%

The High‐Resolution Light‐polluted Night‐Sky Spectrum at Mount Hamilton, California

Slanger

Cosby

Osterbrock

et al. 2003

PUBL ASTRON SOC PAC

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“…[10] The spectroscopic data for this work are taken from Chamberlain [1961]. Hyperfine splitting gives rise to ten individual lines in the Na D system, four lines in the Na D 1 ( 2 P 1/2 À 2 S 1/2 ) transition near 589.76 nm and six lines in the Na D 2 ( 2 P 3/2 À 2 S 1/2 ) transition near 589.16 nm (vacuum wavelengths).…”

Section: Sodium Radiative Transfermentioning

confidence: 99%

Retrieval of global mesospheric sodium densities from the Odin satellite

Gumbel¹,

Fan²,

Waldemarsson³

et al. 2007

Geophysical Research Letters

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[1] Satellite observations of the Na D dayglow at 589 nm provide a global database for the climatology of the mesospheric sodium layer. More than five years of Na D limb observations are available from the Optical Spectrograph and InfraRed Imager System onboard the Odin satellite. We describe a robust retrieval method that provides individual sodium density profiles with a typical accuracy of 20% and altitude resolution of 2 km. Retrieved column abundances and density profiles are validated against sodium resonance lidar measurements at mid-latitudes. Examples of the seasonal and latitudinal variation of the sodium layer illustrate Odin's potential for climatological studies of mesospheric metals. Citation:

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“…[2] Being that discrete auroral displays contain prominent fine spatial structure with gradient scale length down to 1 km or less across magnetic field lines [e.g., Chamberlain, 1961], it is reasonable to assume that spatial inhomogeneities play a significant role in auroral particle dynamics, including finite gyroradii effects on the motion of ions, in particular at high altitude. Even a modest 5-km scale length at 100 km altitude and 70°magnetic latitude, when projected along dipolar field lines to, say, R = 6 R E , corresponds to a length ranging from about 30 to 240 km, depending on horizontal angle.…”

Section: Introductionmentioning

confidence: 99%

In situ Polar observation of transverse cold‐ion acceleration: Evidence that electric field generation is a hot‐ion finite gyroradii effect

Lennartsson

2003

J. Geophys. Res.

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[1] Recent results with the Polar TIMAS instrument (ion mass spectrometer) have revealed that earthward magnetic field-aligned and velocity-dispersed flows of 1-to 33-keV protons (and other ions) from the outer magnetosphere are inherently ''blast-like'' and exhibit a complex filamentary structure where transverse scale sizes may often be a few proton gyroradii. These velocity-dispersed protons (and accompanying hot electrons) have been found to have a close association with enhanced large pitch angle outflow of accelerated (sometimes to more than 10 keV) ionospheric ions (H + , O + , and He + ) at Polar. Theoretical considerations suggest a mechanism by which the difference in gyroradii between hot ions and electrons in earthward plasma bursts generates charge imbalance and strong transverse electric fields at density gradients, as the bursts move into an increasingly strong magnetic field, which in turn accelerate the ambient cold ions. Model electric fields greater than 1 V m À1 at Polar are readily generated with density gradient scale lengths of a few earth radii in an equatorial source region of the bursts, assuming that the magnetic moments of the burst protons are preserved. The nonadiabatic acceleration of cold ions may act to reduce these fields to the ca 0.1-V m À1 amplitude and few-second period fluctuations actually observed. Sample TIMAS data are shown to be consistent with the transverse acceleration of cold O + ions to keV energy on a timescale of less than a single gyroperiod.

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Physics of the Aurora and Airglow

Cited by 115 publications

References 911 publications

The High‐Resolution Light‐polluted Night‐Sky Spectrum at Mount Hamilton, California

The High‐Resolution Light‐polluted Night‐Sky Spectrum at Mount Hamilton, California

Retrieval of global mesospheric sodium densities from the Odin satellite

In situ Polar observation of transverse cold‐ion acceleration: Evidence that electric field generation is a hot‐ion finite gyroradii effect

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