Drake G.W.F. (editor) Handbook of Atomic, Molecular, and Optical Physics

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Aeronomy 84.5 Neutral, Ion and Electron Temperatures 1283

ally larger than T

,butT

begin to diverge from T

slightly higher altitudes. The energy source for the elec-

trons on the dayside is largely photoionization, which,

as discussed above, produces electrons with average

energies in the 15 to 20 eV range. In slowing down,

these energetic electrons lose their energy in inelas-

tic processes with neutrals until E ≈ 1–2 eV. At this

point, elastic scattering by the thermal electron popu-

lation becomes the dominant energy loss process for

the suprathermal electrons and the major source of

heat for the thermal electrons. Other electron heat-

ing mechanisms include deactivation of electronically

or vibrationally excited species, and, for the terres-

trial planets, quenching of the ﬁne structure levels

of O.

As for the neutrals, heat in the electron gas is re-

distributed by conduction at a rate that depends on the

electron thermal conductivity. This quantity is inversely

proportional to the sum of the momentum transfer colli-

sion frequencies of electrons with ions, neutrals, and

ambient electrons. Cooling mechanisms for thermal

electrons include Coulomb collisions with ions, rota-

tional excitation of molecules, and, for the terrestrial

planets, excitation of the ﬁne structure levels of O. Be-

cause of the large mass difference, elastic collisions

between neutrals and electrons are not effective in trans-

ferring kinetic energy.

1400

1200

1000

800

600

400

200

800

700

600

500

400

300

200

100

2500

2000

1500

1000

500

1000

Temperature (K)

0 2000 3000 4000

0 200 400

600

800 10001200 1400 1600

Temperature (K) Temperature (K)

Altitude (km)

Altitude (km) Altitude (km)

Neutral

Ion

Electron

a) b) c)

Fig. 84.14a–c Ion and electron temperature proﬁles. ( a) Neutral (dot-dashedcurve), ion (dashed curve) and electron

(solid curve) temperatures for the terrestrial ionosphere from the International Reference Ionosphere for equinox, noon

and low and high solar activities. The electron temperature is found not to vary substantially with solar activity. After

Bilitza and Hoegy [84.82] with kind permission from Elsevier Science Ltd., Kidlington UK.

(b) Smoothed median ion

(dashed curve) and electron (solid curve) temperatures in the Venus ionosphere as measured by the PV retarding potential

analyzer and the Langmuir probe, respectively. The electron temperature proﬁle is essentially constant with solar zenith

angle. The ion temperature proﬁle applies to solar zenith angles between 0 and 90

◦

. After [84.83]. (c) Computed electron

and ion temperatures for the ionosphere of Titan, including only solar photoionization as the source of electron heating.

After [84.84]

in the ionosphere is elevated above T

at high

altitudes principally because of Coulomb collisions

with energetic electrons. Another potentially important

source of heat input to the ions near the ion peak is

exothermic ion–neutral reactions, including quenching

of metastable ions, such as O





, by neutrals. In

the presence of electric ﬁelds, joule heating may be

important and can cause T

to exceed T

The ions cool in elastic collisions and resonant

charge transfer with neutral species, which are charac-

terized by lower temperatures than the ions. The cooling

rate for elastic collisions is

=−2n

−T

). (84.67)

Collisions between ions and neutrals (other than their

parents) are dominated by the ion-induced-dipole inter-

action. The momentum transfer collision frequency is

thus given by (84.58). Resonant charge transfer between

an ion and its parent neutral, such as

+∗

+O → O

∗

, (84.68)

leads to very effective ion cooling, which dominates at

sufﬁciently high temperatures.

Examples of T

and T

proﬁles are shown in

Fig. 84.14a–c for Earth, Venus and Titan. The Interna-

tional Reference Ionosphere (IRI) temperatures proﬁles

Part G 84.5

1284 Part G Applications

for the terrestrial thermosphere show the close coupling

between the electrons, ions and neutrals at low altitudes

and the ions and electrons at high altitudes. T

increases

with increasing solar activity at low altitudes and ap-

proaches T

at high altitudes. The values of T

and T

are

about 3000 K at 1000 km [84.82]. Electron and ion tem-

peratures in the terrestrial ionosphere are discussed in

Rees [84.44], Banks and Kockarts [84.72], and Whitten

and Popoff [84.85].

and T

in the Venus atmosphere were measured by

instruments on the Pioneer Venus spacecraft. T

,which

approaches values of 2000–2500 K at high altitudes, has

been found to be insensitive to solar zenith angle, except

near the antisolar point, where it increases to values of

5000–6000 K [84.83]. T

also does not vary appreciably

with solar zenith angle; the high altitude values are in

the range 4000–6000 K [84.86].

The retarding potential analyzer (RPA) on the Viking

spacecraft found that T

on Mars decouples from the T

near 180 km, and approach values of about 3000 K at

high altitudes [84.66]. T

is predicted to diverge from

the T

in the lower ionosphere, and to approach values

of 3000–4000 K at high altitudes [84.87].

There are no measurements of plasma tempera-

tures in the ionospheres of the outer planets. The

plasma temperatures on Titan have been predicted by

a model [84.84]. The computed T

are grater than T

near

the n

maximum near 1000 km, but approach values of

about 300 K at high altitude. For the solar source only,

increases rapidly to a constant value of about 800 K

near 1200 km. Electrons from Saturn’s magnetosphere

may interact with the Titan ionosphere during the part

of its orbit that is within the magnetosphere, and in this

case T

up to about 5000 K near 2000 km are predicted.

84.6 Luminosity

The luminosity that originates in the atmospheres of the

planets is generally classiﬁed as dayglow, nightglow, or

aurora. Dayglow is the luminosity of the dayside atmos-

phere that occurs as a more or less direct result of the

interaction of solar radiation with atmospheric gases.

Among the sources of dayglow are photodissociative

excitation and simultaneous photoionization and exci-

tation. Dayglow may also include scattering of solar

radiation by processes that are selective, such as reso-

nance scattering by atoms and ﬂuorescent scattering by

molecules, but the term generally excludes nonselective

scattering processes, such as Rayleigh scattering.

In resonance scattering, the absorption of a photon

by an atom in the ground state, causes a (usually dipole

allowed) transition to a higher electronic state:

A+hν → A

∗

, (84.69)

followed by the emission of a photon as the state decays

back to the ground state:

∗

→ A+hν. (84.70)

The wavelength of the emitted radiation is very nearly

the same as the wavelength of the radiation absorbed.

The cross section for absorption of a line in the solar

spectrum is

(ν) =



8πν

φ(ν) , (84.71)

where the subscript 1 indicates the lower state and 2 the

upper state,  is the statistical weight of the state and

ν = c/λ is the frequency of the transition. A

is the

Einstein A coefﬁcient for the transition, and φ(ν) is the

lineshape function, which in this equation is normalized

so that the integral over all frequencies is unity.

If the linewidth is determined by the spread of ve-

locities of the species, the lineshape φ(ν) is a Doppler

(Gaussian) proﬁle

(ν) =

uν

√

exp



−



ν −ν





(84.72)

where ν

is the frequency at line center. The variable u =

(2k

T/m)

1/2

is the modal velocity of a gas in thermal

equilibrium at temperature T. The width of the line at

half maximum, ∆ν

∆ν

2ν

(ln 2)

1/2

. (84.73)

If the linewidth is determined by the natural lifetime, the

proﬁle is a Lorentzian

(ν) =

∆ν

/2π



ν −ν





∆ν



, (84.74)

where ∆ν

= Γ

/2π is the line width at half maximum,

and

= Γ

+Γ

, (84.75)

where Γ

and Γ

are the inverse radiative lifetimes of

the levels 2 and 1, respectively. Collisional broadening

also results in a Lorentzian lineshape. If both Doppler

Part G 84.6

Aeronomy 84.6 Luminosity 1285

and natural broadening mechanisms are important, the

lineshape is a convolution of the two proﬁles, called

a Voigt proﬁle:

∞



−∞

(ν



)φ

(ν −ν



)dν



. (84.76)

The absorption cross section σ

integrated over all

frequencies is proportional to the absorption oscillator

strength f

∞



(ν) dν =

πe

, (84.77)

where m

is the mass of the electron. A

is related to

the oscillator strength through



8π



8π

cλ

. (84.78)

The excitation rate q

of an upper level 2 by reso-

nance scattering is given by

= F(ν)

πe

= F(λ)



8πc

, (84.79)

where F(ν) is the solar ﬂux in units of pho-

tons cm

−2

−1

and F(λ) is the ﬂux in units

of photons cm

−2

−1

per unit wavelength interval. It

should be noted that for radiative transfer purposes the

photon ﬂux that we have called F(ν) is sometimes de-

noted πF(ν). It is customary in aeronomy to deﬁne a

“g-factor,” which is the probability per atom that a pho-

ton will be resonantly scattered in a particular transition:

= q



, (84.80)

where the sum in the denominator is over all the lower

states i that are accessible from the upper state 2. The

g-factor for unattenuated solar radiation is often quoted

at the mean sun-earth distance or at a particular planet.

The volume emission rate ε

(z) for resonance scattering

of a solar photon is then given by

(z) = g

(z), (84.81)

where n

(z) is the number density of atoms in level 1.

In ﬂuorescent scattering, a photon is absorbed by

a molecule in a vibrational state v producing an excited

electronic state with a vibrational quantum number v



AB(v) +hν → AB

∗



). (84.82)

This is followed by emission, at wavelengths that are

usually the same as or longer than that of the absorbed

photon, to a range of vibrational levels v



of a lower

state

∗



) → AB(v



) +hν



. (84.83)

The volume emission rate of a transition from a level v



of the upper electronic state to a vibrational level v



a lower electronic state at an altitude z is given by





(z) = n(z)g





= n(z)q













, (84.84)

where A





is the transition probability, n(z) is the num-

ber density of the molecular species at altitude z,andq



is the excitation rate of vibrational level v



of the upper

electronic state from a range of lower states v. The latter

quantity is





F(λ)

πe



, (84.85)

where η

is the fraction of molecules in the v vibrational

level.

Dayglow also includes emissions that are the result

of the interaction of atmospheric species with the photo-

electrons produced in solar photoionization, either by

direct excitation

A+ e

∗−

→ A

∗

+ e

−

, (84.86)

or by simultaneous dissociation and excitation

AB + e

∗−

→ A

∗

+ B+ e

−

, (84.87)

or ionization and excitation

X + e

∗−

→ X

+∗

+ e

−

. (84.88)

Electron impact processes are particularly important in

producing excited states that are connected to the ground

state by dipole forbidden transitions, whereas resonance

and ﬂuorescent scattering are largely limited to transi-

tions that are dipole allowed. Dayglow emissions may

also result from prompt chemiluminescent reactions,

which occur when fragments or ions produced by dis-

sociation or ionization recombine with the emission of

a photon.

As an example, the dayglow spectrum of the earth

from 1200 to 9000 Å is shown in Fig. 84.15. An ultra-

violet spectrum of Mars as measured by the Mariner 9

spectrometer is shown in Fig. 84.16a, and the UV day-

glow of Saturn and Uranus, which were measured by the

Voyager spacecraft, are compared in Fig. 84.16b.

Nightglow arises from chemiluminescent reactions

of species whose origin can be traced to species pro-

duced during the daytime or whichhave been transported

Part G 84.6

1286 Part G Applications

500

400

300

200

100

500

400

300

200

100

5000 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000

Rayleighs/Å

Dayglow

, Vegard–Kaplan

, LBH

(1216)

Ol (1304)

Ol (1356)

(1216)

Nll

(2143)

Oll

(2470)

Mgll

(2795)

(2972)

(3466)

Call

(3934)

Call

(3970)

Oll

(4351)

Oll

(4368)

Oll

(4415)

[Nl]

(5200)

, First negative

, Second positive

Wavelength (Å)

Rayleighs/Å

[Nl]

(5200)

[Ol]

(5577)

[Nl]

(5755)

[Ol]

(6300)

[Ol]

(6364)

[Oll]

(7320)

(7774)

(8446)

, First positive

, Atmospheric

Meinel

0.0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.10 0.11 0.12 0.13 0.14

1.151.141.131.121.111.101.91.81.71.61.51.41.31.21.11.0

2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15

3.4 3.5 3.6

0.0 0.1 0.2 0.3 0.4 0.5 0.6

1.0 1.1 1.3 1.4 1.5 1.6 1.7

0.0 0.1 0.2 0.3

1.41.31.21.11.0

2.0 2.1 2.2 2.3 2.4 2.5

3.63.53.43.33.23.1

0.0 0.1 0.2 0.3 0.4 0.5

1.71.61.51.41.31.21.11.0

2.82.72.62.52.42.32.22.12.0

3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

3.0

1.01.11.2 1.31.3 1.4 1.5 1.6 1.7 1.8 1.9

3.6

2.5

1.4

0.3

5.0

2.6

1.5

0.4

8.4

7.3

6.2

5.1

4.0

8.5

7.4

6.3

5.2

4.1

3.0

8.6

7.5

6.4

5.3

1.0

2.1

3.0

4.1

5.2

4.2

3.1

2.0

8.7

7.6

0.0

1.1

2.2

2.0

4.0

5.1

2.0

6.5

5.4

4.3

3.2

2.1

0.1

1.2

5.3

4.2

3.1

1.0

1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200

Fig. 84.15 Terrestrial dayglow spectrum measured in a single 32-second exposure by the Arizona Imager/Spectrograph on board

the Space Shuttle [84.88]

from the dayside. For example, on Venus, O and N pro-

duced on the dayside are transported by the subsolar to

antisolar circulation to the nightside, where they subside

and radiatively associate:

N+O → NO+hν,

(84.89)

producing emission in the δ and γ bands of NO (e.g.,

Stewart et al. [84.89]). The Venus UV nightglow spec-

trum is shown in Fig. 84.17. Similar phenomena have

recently been observed by the ultraviolet spectrometer

on the Mars Express spacecraft [84.90].

Auroral emissions are deﬁned here as those produced

by impact of particles other than photoelectrons. Al-

though aurorae are usually thought of as conﬁned to the

polar regions of the Earth and the outer planets, Venus,

which does not have an intrinsic magnetic ﬁeld, exhibits

UV emissions on the nightside that are highly variable

and cannot be explained as nightglow. It has been pro-

posed that the emissions are produced by precipitation

of soft electrons into the nightside thermosphere. Mars

has recently been observed to exhibit auroral emissions,

which are concentrated over magnetic ﬁeld anomalies

in the martian crust [84.91].

The intensities of airglow and aurora are usually

measured in units of brightness called Rayleighs. One

Rayleigh is an apparent column emission rate at the

source of 10

photons cm

−2

−1

integrated over all an-

gles, or 10

/4π photons cm

−2

−1

. A comparison

Part G 84.6

Aeronomy 84.7 Planetary Escape 1287

Fig. 84.16a,b Dayglow spectra of selected planets.

(a) Martian airglow spectrum recorded by Mariner 9 at 15 Å

resolution. After [84.92].

(b) Comparison of dayglow spec-

tra from Uranus (heavy line)andSaturn(thin line) recorded

by Voyager 2 [84.4]

1800 2000 2200 2400 2600 2800

Wavelength (Å)

Total counts

PV/ OUVS night airglow spectrum of Venus

CO Cameron

NO Gamma

NO Delta

Fig. 84.17 Far ultraviolet nightglow spectrum of Venus

obtained with the Pioneer Venus orbiter ultraviolet spec-

trometer. The predicted responses for three different band

systems are also shown. After [84.93]

of auroral and dayglow emissions as measured by the

Cassini UVIS as the spacecraft ﬂew by Jupiter is shown

in Fig. 84.18. (A. I. F. Stewart, private communication,

2004).

A discussion of terrestrial airglow and auroral emis-

sions can be found in Rees [84.44]. Meier [84.94]

has reviewed spectroscopy and remote sensing of the

terrestrial ultraviolet emissions. The airglows of Mars

and Venus have been discussed by Barth [84.19], by

Fox [84.95] and by Paxton and Anderson [84.40]. Air-

glow and auroral emissions on the outer planets have

been reviewed by Atreyaet al. [84.96], Atreya [84.2], and

2000 2500 3000

450

300

150

20 40 60 80 100 120

600 800 1000 1200 1400 1600

Intensity k Rayleigh/15 Å

Wavelength (Å)

Channel

Wavelength (Å)

2.0 1.0 0.0

0.1 0.2 0.3 1.5 1.6

1.0 0.0 0.1 0.2 1.4 1.5

–X

CO σ

–X

OI 2972 Å

–X

4.0 3.0 2.0 1.0

Raman Lyα

Solar Reflection

a–b

HI Rydberg

Counts/3840S

Strobel [84.4]. Airglow in the atmospheres of the planets

has been reviewed by by Slanger and Wolven [84.97].

84.7 Planetary Escape

Escape of species from atmospheres can occur by ther-

mal and nonthermal mechanisms. Thermal processes

include Jeans escape and hydrodynamic escape. Jeans

escape is essentially evaporation of the energetic tail

of the Maxwell–Boltzmann distribution, while hydro-

dynamic escape is a large-scale “blow-off” of the

atmosphere that occurs when the average molecular

velocity is near or above the escape velocity. Al-

though Jeans escape still occurs for light species in the

thermospheres of small planets, hydrodynamic escape

is thought to have occurred only in the early history of

the terrestrial planets when the solar ﬂux in the UV was

Part G 84.7

1288 Part G Applications

1000

0.100

0.010

0.001

1000

Wavelength (Å)

1200 1400 1600 1800

Cassini uvis – Jupiter flyby 30 Dec 00

k Rayleigh/Å

Atomic hydrogen Lyman series

beta alpha

Solar lines

CIV HeII CI SiII

Molecular hydrogen Lyman and Werner bands

Heavy: Northern aurora

Light: Equatorial airglow

Fig. 84.18 Spectra of the northern aurora (heavy line) and the equatorial airglow (light line) taken by the UVIS spec-

trometer the Cassini spacecraft on closest approach on 30 December 2000. In both spectra, the Lyman and Werner bands

of molecular hydrogen are prominent. They are excited by photoelectron impact in the airglow, and by primary and

secondary auroral electrons. Locations of some of the brighter bands are indicated by dotted lines. Also shown are the

Lyman-alpha and -beta lines of atomic hydrogen. At wavelengths longer than 1550 Å, the airglow spectrum is swamped

by reﬂected UV sunlight; some solar lines are indicated. At shorter wavelengths, UV sunlight is absorbed by methane

and acetylene, rather than reﬂected. The solar signal is much weaker in the auroral spectrum than in the equatorial, due

to the higher angles of incidence and emission in the former [84.99]

higher. Nonthermal escape mechanisms, which domi-

nate for heavy species on smaller bodies such as Mars

and Titan, and for all species on Venus and Earth, include

both photochemical and mechanical processes. A peda-

gogical discussion of escape processes can be found in

Chamberlain and Hunten [84.98]

Because of the exponential rate of change of den-

sity with altitude in atmospheres, escape is sometimes

assumed to occur only at and above the exobase. The

exobase is mathematically deﬁned as the altitude where

the mean free path l =(nσ

)

−1

(where σ

is the collision

cross section), is equal to the atmospheric scale height.

The probability that a particle, moving upward from

the exobase with sufﬁcient velocity will actually escape

without suffering another collision is 1/ e. The condition

l = H therefore reduces to nHσ = 1 or, equivalently,

to N = (σ

)

−1

,whereN is the column density. Since

a typical collision cross section is about 3 ×10

−15

the exobase is located near the altitude above which

the column density is about 3.3×10

−3

, although

the collision cross section and thus the location of the

exobase is different for different escaping species.

Whether the trajectory of a particle moving upward

at the exobase is ballistic (bound) or escaping (free) is

determined by its total energy E, which is the sum of its

kinetic and potential energies:

E =



∞

mG M

dr , (84.90)

where the symbols have the same meaning as in equation

(84.2), and the subscript c refers to the critical level

or exobase. If E < 0, the particle is bound. Expression

(84.90) reduces to

E =

−mg

(84.91)

Part G 84.7

Aeronomy 84.7 Planetary Escape 1289

where g

is the gravitational acceleration at the exobase.

The escape velocity at the exobase, v

esc

, is then deﬁned

by the condition v

esc

= (2g

)

1/2

. Particles with vel-

ocities greater than the escape velocity are assumed to

escape if their velocity vector is oriented in the upward

hemisphere and if they undergo no further collisions.

The radius, gravitational acceleration, escape velocities

and scale height at the equatorial exobases of the planets

are given in Table 84.10.

In the Jeans process, escape occurs when particles in

the high energy tail of the Maxwellian distribution attain

the escape velocity. The escape ﬂux, Φ

is given by

√

(1+λ

) exp(−λ

), (84.92)

where u = (2k

T/m)

1/2

is the modal velocity and λ is

the gravitational potential energy in units of k

λ =

GMm

mgr

(84.93)

Table 84.10 Exobase properties of the planets

Planet r

esc,c

a,b

avg

(km) (cm s

−2

) (km s

−1

) (km)

Mercury

2439 378 4.29 –

Venus

6250 831 10.2 17

Earth

6878 842 10.8 71

Mars

3593 333 4.89 17

Jupiter

73 000 2236 57.2 250

Saturn

67 000 731 31.3 910

Uranus

31 800 561 18.9 66

Neptune

27 300 919 22.4 250

Titan

4175 51.4 2.07 116

Triton

2222 28.9 1.13 140

Values given are those at the equatorial exobase, and assume

that the thermosphere co-rotates with the planet.

Average value computed from H

avg

= k

T/m

avg

g, but does

not represent the local pressure scale height, except for cases

where there is one major constituent.

Exobase is at the surface.

Model from Hedin et al. [84.3]forF

10.7

=150, 45

◦

solar

zenith angle.

MSIS model for F

10.7

=150, equator, 45

◦

Solar Zenith

Angle [84.17].

Model from Nier and McElroy [84.8], and pertains to low

solar activity conditions.

Model from [84.2, 14].

Model from Atreya [84.2].

Model from [84.55].

Model from [84.56].

Model from Strobel et al. [84.10].

Model from Krasnopolsky et al. [84.15]

Sometimes a correction factor is applied to the expres-

sion for the escape ﬂux to account for the suppression

of the tail of the distribution due to the escape of the

energetic particles [84.100,101].

Photochemical processes that produce energetic

fragments include photodissociation and photodissocia-

tive ionization, photoelectron impact dissociation and

dissociative ionization, as well as exothermic chem-

ical reactions. The most important example of the latter

are dissociative recombination reactions, which are very

exothermic and tend to produce neutral fragments with

large kinetic energies. Charge transfer processes such as

+∗

+O → O

∗

(84.94)

can produce fast neutrals if the ion temperature is larger

than the neutral temperature, as is usually the case near

the exobase of a planet. In modeling these processes,

the kinetic energy distribution of the product species is

important, as well as the cross sections or reaction rates.

Physical or collisional escape mechanisms include

sputtering and “knock-on.” Sputtering can occur when

a heavy ion picked up by the solar wind collides with an

atmospheric species near or above the exobase, and in

the process produces a “back-splash” in which the ac-

celerated neutral may be ejected from the atmosphere.

In knock-on, hot atmospheric neutral species, such as

O atoms produced in exothermic chemical reactions

near the exobase can collide with a lighter species,

such as H, imparting sufﬁcient kinetic energy to allow

it to escape. Modeling these processes requires knowl-

edge of the ion–neutral or neutral–neutral collision cross

sections.

The escape rate of a light species from a planetary at-

mosphere may be controlled by diffusion of the species

from the lower atmosphere to the exobase, rather than

by the escape process itself [84.102]. The limiting up-

ward ﬂux, φ

of a species i with mixing ratio f

can be

estimated as

≈ b

, (84.95)

where H

is the average scale height of the atmosphere

and b

is the binary collision parameter introduced in

Sect. 84.2.2. Equation (84.95) above is usually eval-

uated at the homopause, with the mixing ratio taken

from a suitable altitude in the middle atmosphere, but

above the cold trap (where the species condenses), if

one exists. The limiting ﬂux obtains if and only if the

mixing ratio is constant with altitude. The effect of

photochemistry can be accounted for if all chemical

forms of the species are considered in the calculation

of f

Part G 84.7

1290 Part G Applications

5576

5000

4000

3000

2000

1000

Wavelength (Å)

5576.5 5577 5577.6 5578 5577.5

Relative intensity

Venus dark – Venus bright

HIRES

UT 20 Nov 99

15:59 – 16:08

500s

Airmass = 1.7

Velocity = 12.45 km/s

Venus

A = 4191

Γ = 0.103 Å

T = 5577.574 Å

Terrestrial

A = 3094

Γ = 0.103 Å

T = 5577.344 Å

Fig. 84.19 Spectrum of the oxygen green line taken on

the nightside of Venus taken by the Keck/HIRES on 20

November 1999. The individual terrestrial and Doppler-

shifted Venusian components are shown by the dashed lines

(from Slanger et al. 84.103)

Even if energetic particles released at the exobase

of a planet do not have enough energy to escape, they

may travel to great heights along ballistic orbits be-

fore falling back to the atmosphere. These particles are

said to form a hot atom “corona”. Hot H and O coronas

have been found to surround the Earth and Venus, and

have been predicted for Mars (Fig. 84.19). Reviews of

the H and O coronas of Venus have been presented by

Fox and Bougher [84.79] and by Nagy et al. [84.104].

See Chamberlain and Hunten [84.98] for a detailed

discussion of planetary coronal population processes.

References

84.1 U. von Zahn, S. Kumar, J. Niemann, R. Prinn: Com-

position of the Venus atmosphere. In: Venus,ed.

by D. M. Hunten, L. Colin, T. M. Donahue, V. I. Moroz

(Univ. Arizona Press, Tucson 1983)

84.2 S. K. Atreya: Atmospheres and Ionospheres of the

Outer Planets and Their Satellites (Springer, New

York 1986)

84.3 A. E. Hedin, H. B. Neimann, W. T. Kasprzak, A. Seiff:

J. Geophys. Res. 88, 73 (1983)

84.4 D. F. Strobel, R. V. Yelle, D. E. Shemansky,

S. K. Atreya: The upper atmosphere of Uranus.

In: Uranus, ed. by J. T. Bergstralh, E. D. Miner,

M. S. Matthews (Univ. Arizona Press, Tucson

1991)

84.5 S. K. Atreya, B. R. Sandel, P. N. Romani: Photo-

chemical and vertical mixing. In: Uranus,ed.by

J. T. Bergstralh, E. D. Miner, M. S. Matthews (Univ.

Arizona Press, Tucson 1991)

84.6 The U. S. Standard Atmosphere (National Oceanic

and Atmospheric Administration, U.S. Government

Printing Ofﬁce 1976)

84.7 R. V. Yelle, F. Herbert, B. R. Sandel, R. J. Vervack,

T. M. Wentzel: Icarus 104, 38 (1993)

84.8 A. O. Nier, M. B. McElroy: J. Geophys. Res. 82,4341

(1977)

84.9 R. J. Vervack Jr., B. R. Sandel, D. F. Strobel: Icarus

170, 91 (2004)

84.10 D. F. Strobel, M. E. Summers, X. Zhu: Icarus 100,512

(1992)

84.11 Y. L. Yung, M. Allen, J. P. Pinto: Astrophys. J. Suppl.

55,465(1984)

84.12 R. V. Yelle: private communication

84.13 R. V. Yelle, L. A. Young, R. J. Vervack, R. Young,

L. Pﬁster, B. R. Sandel: J. Geophys. Res. 101, 2149

(1996)

84.14 Y. H. Kim: The Jovian Ionosphere. Ph.D. Thesis

(State University of New York at Stony Brook, New

York 1991)

84.15 V. A. Krasnopolsky, B. R. Sandel, F. Herbert,

R. J. Vervack: J. Geophys. Res. 98, 3065 (1993)

84.16 D. F. Strobel, M. E. Summers: Triton’s upper at-

mosphere and ionosphere. In: Neptune,ed.by

D. Cruikshank, M. S. Matthews (Univ. Arizona Press,

Tucson 1996)

84.17 A. E. Hedin: J. Geophys. Res. 96, 1159–1172 (1991)

84.18 C. D. Keeling, T. P. Whorf: Atmospheric CO

records

from sites in the SIO sampling network. In: Trends:

A Compendium of Data on Global Change. Car-

bon Dioxide Information Analysis Center,ed.by

T. A. Boden, D. P. Kaiser, R. J. Sepanski, W. F. Stoss

(Oak Ridge National Laboratory, U.S. Department of

Energy, Oak Ridge, Tenn., U.S.A. 2004)

84.19 C. A. Barth, A. I. F. Stewart, S. W. Bougher,

D. M. Hunten, S. J. Bauer, A. F. Nagy: Aeronomy

of the current Martian atmosphere. In: Mars,

ed. by H. Kiefer, B. M. Jakosky, C. W. Snyder,

M. S. Matthews (Univ. Arizona Press, Tucson 1992)

84.20 J. S. Lewis, R. G. Prinn: Planets and their atmo-

spheres: Origin and Evolution (Academic Press,

Orlando 1984)

84.21 T. M. Donahue, R. R. Hodges Jr.: Geophys. Res. Lett.

20, 591 (1993)

84.22 V. A. Krasnopolsky, G. R. Gladstone: J. Geophys.

Res. 101, 15,765 (1996)

Part G 84

Aeronomy References 1291

84.23 V. A. Krasnopolsky, P. D. Feldman: Science 294,1914

(2001)

84.24 W. B. DeMore: Icarus 51, 199 (1982)

84.25 D. F. Strobel: The Photochemistry of Atmospheres:

Earth, the Other Planets, and Comets,ed.by

J. S. Levine (Academic, New York 1985)

84.26 H. B. Niemann: J. Geophys. Res. 103, 22,831 (1998)

84.27 K. Lodders, B. Fegley: The Planetary Scientist’s

Companion (Oxford, New York 1998)

84.28 R. Courtin, D. Gautier, D. Strobel: Icarus 123,37

(1996)

84.29 D. M. Hunten, M. G. Tomasko, F. M. Flasar,

J. R. E. Samuelson, D. F. Strobel, D. J. Stevenson: Ti-

tan. In: Saturn, ed. by T. Gehrels, M. S. Matthews

(Univ. Arizona Press, Tuscon 1984)

84.30 J. L. Elliot, M. J. Person, S. Qu: The Astronomical

Journal 126, 1041 (2003)

84.31 D. F. Strobel, B. C. Wolven: Astrophysics and Space

Science 277, 271 (2001)

84.32 J. Saur, D. F. Strobel, F. M. Neubauer: J. Geophys.

Res. 103, 19,947 (1998)

84.33 A. J. Kliore, D. P. Hinson. F. M. Flasar, A. F. Nagy,

T. E. Cravens: Science 277, 355 (1997)

84.34 D. M. Hunten, T. H. Morgan, D. E. Shemansky: The

Mercury atmosphere. In: Mercury, ed. by F. Vilas,

C. R. Chapman, M. S. Matthews (Univ. Arizona Press,

Tucson 1988)

84.35 X. Zhu, M. E. Summers, M. H. Stevens: Icarus 120,

266 (1996)

84.36 L. M. Lara, W. H. Ip, R. Rodrigo: Icarus 130, 16 (1997)

84.37 W. K. Tobiska: J. Atmos. Terr. Phys. 53, 1005 (1991)

84.38 D. Lummerzheim, M. H. Rees, H. R. Anderson:

Planet. Space Sci. 37, 109 (1989)

84.39 L. Herzberg: Solar optical radiation and its role

in upper atmospheric processes. In: Physics of

the Earth’s upper atmosphere, ed. by C. Hines,

I. Paghis, T. R. Hartz, J. A. Fejer (Prentice-Hall, En-

glewood Cliffs, NJ 1965)

84.40 L. J. Paxton, D. E. Anderson: Far ultraviolet remote

sensing of Venus and Mars. In: Venus and Mars:

Atmospheres, Ionospheres and Solar Wind Inter-

actions, Geophysical Monograph, Vol. 66, ed. by

J. G. Luhmann, M. Tatrallay, R. O. Pepin (American

Geophysical Union, Washington, D.C. 1992) pp. 113–

190

84.41 J. M. Valentine, S. C. Curran: Rep. Prog. Phys. 21,1

(1958)

84.42 C. B. Opal, W. K. Peterson, E. C. Beaty: J. Chem. Phys.

55, 4100 (1971)

84.43 W. E. Swartz, J. S. Nisbet, A. E. S. Green: J. Geophys.

Res. 74, 6415 (1971)

84.44 M. H. Rees: Physics and Chemistry of the Upper At-

mosphere (Cambridge Univ. Press, Cambridge 1989)

84.45 A. F. Nagy, P. M. Banks: J. Geophys. Res. 75,6260

(1970)

84.46 H. S. Porter, F. Varosi, H. G. Mayr: J. Geophys. Res.

92, 5933 (1987)

84.47 D. J. Strickland, R. E. Daniell, B. Basu, J. R. Jasperse:

J. Geophys. Res. 98, 21533 (1993)

84.48 S. C. Solomon: Geophys. Res. Lett. 20, 185 (1993)

84.49 S. J. Bauer: Physics of Planetary Ionospheres

(Springer, New York 1973)

84.50 S. G. Lias, J. E. Bartmess, J. F. Liebman, J. L. Holmes,

R. D. Levin, W. G. Mallard: Gas-phase ion, and neu-

tral thermochemistry, J. Phys. Chem. Ref. Data 17,

Suppl. 1 (1988)

84.51 F. L. Nesbitt, G. Marston, L. J. Stief, M. A. Wickra-

maaratchi, W. Tao, R. B. Klemm: J. Phys. Chem. 95,

7613 (1991)

84.52 J. L. Fox, A. Dalgarno: J. Geophys. Res. 84, 7315

(1979)

84.53 G. R. Gladstone: private communication (2004)

84.54 J. I. Moses, S. F. Bass: J. Geophys. Res. 105, 7013

(2000)

84.55 F. Herbert, B. R. Sandel, R. V. Yelle, J. B. Holberg,

A. L. Broadfoot, D. E. Shemansky: J. Geophys. Res.

92, 15093 (1987)

84.56 J. R. Lyons, private communication

84.57 M. Summers, D. F. Strobel: private communication

(2005)

84.58 D. F. Strobel, B. C. Wolven: Astrophys. Space Sci. 277,

271 (2001)

84.59 T. Su, M. T. Bowers: Classical ion-molecule collision

theory. In: Gas Phase Ion Chemistry,Vol.1,ed.by

M. T Bowers (Academic, New York 1979)

84.60 V. G. Anicich: Astrophys. J. Suppl. Ser. 84, 215–315

(1993)

84.61 Y. Ikezoe, S. Matsuoka, M. Takabe, A. Viggiano: Gas

Phase Ion-Molecule Rate Constants Through 1986

(Maruzen Co., Tokyo 1986)

84.62 D. R. Bates, A. Dalgarno: Electronic recombina-

tion. In: Atomic and Molecular Processes,ed.by

D. R. Bates (Academic, New York 1962) pp. 245–

271

84.63 M. H. G. Zhang, J. G. Luhmann, A. J. Kliore: J. Geo-

phys. Res. 95, 17095 (1990)

84.64 D. P. Hinson and the Mars Radio Science team:

Public access to MGS RS Standard electron density

proﬁles, http://nova.stanford.edu/projects/mgs/

eds-public.html (2003)

84.65 C. Y. Johnson: J. Geophys. Res. 71, 330 (1966)

84.66 W. B. Hanson, S. Sanatani, D. R. Zuccaro: J. Geo-

phys. Res. 82, 4351 (1977)

84.67 A. N. Maurelis, T. E. Craveus: Icarus 154, 350 (2001)

84.68 J. R. Lyons: Nature 267, 648 (1995)

84.69 A. D. Richmond: The ionosphere. In: The Solar Wind

and the Earth, ed. by S.-I. Akasofu, Y. Kamide

(Terra Scientiﬁc Publishing Co., Tokyo 1987)

84.70 A. Dalgarno, M. R. C. McDowell, A. Williams: Phil.

Trans. Roy. Soc. London, Ser. A 250,411(1958)

84.71 R. W. Schunk, A. F. Nagy: Rev. Geophys. Space Phys.

18,813(1980)

84.72 P. M. Banks, G. Kockarts: Aeronomy (Academic,

New York 1973)

Part G 84

1292 Part G Applications

84.73 R. W. Schunk, A. F. Nagy: Ionospheres: Physics,

Plasma Physics and Chemistry (Cambridge Univ.

Press, Cambridge 2000)

84.74 R. G. Roble, E. C. Ridley, R. E. Dickinson: J. Geophys.

Res. 92, 8745–8758 (1987)

84.75 J. L. Fox: Planet. Space Sci. 37, 36 (1988)

84.76 J. L. Fox, P. Zhou, S. W. Bougher: Adv. Space Res.

17, (11)203–(11)218 (1995)

84.77 J. H. Waite, T. E. Cravens, J. Kozyra, A. F. Nagy,

S. K. Atreya, R. H. Chen: J. Geophys. Res. 88, 6143

(1983)

84.78 R. G. Roble: Rev. Geophys. 21, 217–233 (1983)

84.79 J. L. Fox, S. W. Bougher: Space Sci. Rev. 55, 357 (1991)

84.80 S. W. Bougher, D. M. Hunten, R. G. Roble: J. Geo-

phys. Res. 99, 14609 (1994)

84.81 R. P. Wintersteiner, R. H. Picard, R. D. Sharma,

J. R. Winick, R. A. Joseph: J. Geophys. Res. 97, 18083

(1992)

84.82 D. Bilitza, W. R. Hoegy: Adv. Space Res. 10, (8)81–

(8)90 (1990)

84.83 K. L. Miller, W. C. Knudsen, K. Spenner, R. C. Whit-

ten, V. Novak: J. Geophys. Res. 85, 7759 (1980)

84.84 A. Roboz, A. F. Nagy: J. Geophys. Res. 99,2087

(1994)

84.85 R. C. Whitten, I. G. Poppoff: Fundamentals of

Aeronomy (Wiley, New York 1971)

84.86 R. F. Theis, L. H. Brace, H. G. Mayr: J. Geophys. Res.

85, 7787 (1980)

84.87 W. B. Hanson, G. P. Mantas: J. Geophys. Res. 93,

7538 (1988)

84.88 A. L. Broadfoot, B. R. Sandel, D. Knecht, R. Viereck,

E. Murad: Appl. Opt. 31, 3083 (1992)

84.89 A. I. F. Stewart, J.-C. Gerard, D. W. Rusch,

S. W. Bougher: J. Geophys. Res. 85, 7861 (1980)

84.90 J. L. Bertaux, F. Leblanc, S. V. Perrier, E. Quemerais,

O. Korablev, E. Dimarellis, A. Reberac, F. Forget,

P. C. Simon, B. Sandel: Nightglow in the upper at-

mosphere of Mars and implication for atmospheric

transport, Science 307(5709), 566–569 (2005)

84.91 J. L. Bertaux, F. Leblanc, O. Witasse, E. Quemerais,

J. Lilenstein, S. A. Stern, B. Sandel, O. Korablev:

Nature, 435(7043), 790–794 (2005)

84.92 C. A. Barth, C. W. Hord, A. I. Stewart, A. L. Lane:

Science 175, 309 (1972)

84.93 A. I. F. Stewart, C. A. Barth: Science 205, 59 (1979)

84.94 R. R. Meier: Space Sci. Rev. 58, 1–187 (1991)

84.95 J. L. Fox: Airglow and aurora in the atmospheres of

Venus and Mars. In: Venus and Mars: Atmospheres,

Ionospheres and Solar Wind Interactions, Geo-

physical Monograph, Vol. 66, ed. by J. G. Luhmann,

M. Tatrallay, R. O. Pepin (American Geophysical

Union, Washington, D.C. 1992) pp. 191–222

84.96 S. K. Atreya, J. H. Waite Jr., T. M. Donahue,

A. F. Nagy, J. C. McConnell: Theory, measurements,

and models of the upper atmosphere and iono-

sphere of Saturn. In: Saturn, ed. by T. Gehrels,

M. S. Matthews (Univ. Arizona Press, Tucson 1984)

84.97 T. G. Slanger, B. C. Wolven: Airglow processes in

planetary atmospheres. In: Atmospheres in the So-

lar System: Comparative Aeronomy, Geophysical

Monograph 130 (AGU, Washington, D.C. 2002)

84.98 J. W. Chamberlain, D. M. Hunten: Theory of Plane-

tary Atmospheres (Academic, New York 1987)

84.99 A. I. F. Stewart: private communication (2004)

84.100 J. W. Chamberlain: Planet. Space Sci. 11, 901 (1963)

84.101 D. M. Hunten: Planet. Space Sci. 30, 773 (1982)

84.102 D. M. Hunten: J. Atmos. Sci. 30, 1481 (1973)

84.103 T. G. Slanger, D. L. Huestis, P. C. Cosby, N. Chanover:

The Venus nightglow: Ground based observations

and chemical mechanisms, Icarus (2004) in press

84.104 A. F. Nagy, J. Kim, T. E. Cravens: Ann. Geophys. 8,

251 (1990)

Part G 84