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On the basis of experimental and theoretical studies, this paper proposes a new mechanism that contributes to nocturnal 4.3 µm CO2 emissions. It suggests that collisions of ground state O atoms with highly vibrationally excited OH(v), produced by the reaction of H with O3, remove a substantial fraction of the OH(v) vibrational energy by a fast, spin-allowed, multiquantum vibration-to-electronic energy transfer (ET) process that generates O(1D): OH(v ≥ 5) + O(3P) → OH(0 ≤ v′ ≤ v − 5) + O(1D). The electronically excited O(1D) atom is subsequently deactivated by collisions with N2 in a fast spin-forbidden ET process that leaves the N2 molecule with an average of 2.2 vibrational quanta. Finally, the vibrational excitation of N2 is transferred by a fast, near-resonant vibration-to-vibration ET process to the asymmetric stretch (v3) mode of CO2, which promptly radiates near 4.3 µm.

We propose a remote-sensing technique to measure temperature in the lower thermosphere with a resonant Raman lidar. A ground-based pulsed laser operating at 630.0304 (636.3776) nm excites 3P2 (3P1) multiplet level of the ground electronic state of atomic oxygen in the atmosphere to the electronically excited 1D2 state and the back-scattered photons at 636.3776 (630.0304) nm, while the atom transitions to 3P1 (3P2), are detected. Using the backscattering Raman cross sections calculated here we show: (1) For the range of altitudes in the lower thermosphere where the fine-structure multiplets of atomic oxygen are in thermodynamic equilibrium with the local translational temperature (LTE) and the electronically excited intermediate state 1D2 remains relaxed primarily by collisions with N2 and O2, the ratio of the backscattered signal can be used to obtain temperature. (2) Higher up, for the range of altitudes where the fine-structure multiplets of atomic oxygen are in LTE and the electronically excited intermediate state 1D2 is relaxed primarily by spontaneous emission of a photon, the Stokes and anti-Stokes backscattered signal can be used to obtain the atomic oxygen density and local temperature. (3) Still higher up, for the range of altitudes where the fine-structure multiplets of atomic oxygen are not in LTE and the electronically excited intermediate state 1D2 is relaxed primarily by spontaneous emission of a photon, the Stokes and anti-Stokes backscattered signal can be used to obtain the density of the 3P2 and 3P1 multiplet levels of the ground electronic state of atomic oxygen. For a ground-based instrument a simulation with 3 km range gate is used to show that the relative error of temperature measurements from 100 to 250 km could be less than 30%. It is pointed out that this technique has the potential of providing unique data that addresses the modeling of satellite drag and the effects of space weather on the upper atmosphere. In addition, this technique may also permit the detection of the thickness of the temperature inversion layers as well as their temperature and density perturbations.

The Raman backscatter cross sections for a 355 nm light source for the three fine-structure components are calculated. The signal-to-noise considerations show that the determination of the densities of the three fine-structure components separately is a feasible experiment. Since these fine-structure components are calculated to be in local thermodynamic equilibrium up to at least 350 km altitude, this experiment also gives atmospheric temperature. It is pointed out that this experiment does not suffer from the drawbacks of the previous efforts to determine atomic oxygen density and should yield reliable results for this density as well as temperature.

Recent laboratory work has arrived at a value of the rate coefficient for the room temperature O atom vibrational relaxation of NO(ν=1) which is nearly one third the previously accepted value [Fernando and Smith, 1979]. Laboratory measurements have also established a new value for the rate coefficient for the photodissociation of NO which is ∼1.6 times the previously accepted value. Since the NO(ν=1→ν=0) emission, around 5.3 μm, is a very important cooling process in the lower terrestrial thermosphere, the new values of the two rate coefficients lead to a decrease in the amount of NO as well as the rate at which it cools. Using the global mean model [Roble, 1995] of the mesosphere, thermosphere, and ionosphere, we find that the new rate coefficients introduce large changes in the thermal and density structure of the atmosphere. The resulting model atmosphere appears unrealistic. We find that these large changes are moderated and the resulting neutral temperatures agree better with the Mass Spectrometer Incoherent Scatter (MSIS) model when the value of the CO 2 +O rate coefficient for excitation of the bending vibration is increased two fold to the value arrived at by modeling the 15 μm emission from CO 2 from the lower terrestrial thermosphere. Finally, we describe the results of a number of runs with the thermosphere/ionosphere/mesosphere electrodynamics general circulation model (TIME-GCM) to examine the global temperature, composition, and circulation changes that result from using the new rates for both NO and CO 2 .

The overtone vibration-rotation band (Δv=−2) limb-emission from NO around 2.7 µm observed by the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) at 120 km tangent altitude is shown to arise from the nascent molecule produced by the reactions of N(4S) and N(²D) atoms with O2. Measurement of the 2.7 µm emission from NO therefore permits modeling of the local rate of production of NO, a quantity important in odd nitrogen chemistry in the thermosphere. The 2.7 µm limb-radiance in the nonauroral region is observed, above the instrument noise level, only during the day and shows about a factor of 2 variation indicating a similar variation in the rate of production of NO. In the aurorally dosed region however the observations lead to about an order of magnitude variation in this rate.

This paper models the fundamental vibration-rotation band emission from NO around 5.3 μm observed by the interferometer aboard the cryogenic infrared radiance instrumentation for shuttle (CIRRIS 1A) during the sunlit terrestrial thermosphere. The four dominant contributions to the 5.3 μm emission are solar pumping, the inelastic collisions with O of NO(v=0), the reactions of N(2D) with O2, and the reactions of N(4S) with O2. The contribution to the chemiluminescence due to the reaction of N(4S) with O2 is calculated using the energy distribution function (EDF) of these atoms obtained by solving the time dependent Boltzmann equation. The calculated radiance is derived using two model atmospheres: (1) the model atmosphere obtained from the atmospheric ultraviolet radiance integrated code (AURIC) [Strickland et al., 1998] and (2) the model atmosphere obtained from the thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) [Roble and Ridley, 1994]. The calculated results reproduce gross features of the CIRRIS 1A observations, and disagreement by a factor of ∼2 in the total band radiance calls for a fine tuning of the model atmospheres and/or the underlying phenomenology. The cooling of the atmosphere at high altitudes due to chemiluminescence from the reaction of N(4S) with O2 is found to be comparable to that due to collisions of NO with O.

Room-temperature and temperature-dependent thermal rate constants are calculated for the state-to-state vibrational relaxation of NO(v ⩽ 9) by atomic oxygen using the quasiclassical trajectory method and limited ab initio information on the two lowest O + NO potential-energy surfaces which are responsible for efficient vibrational relaxation. Comparisons of the theoretical results with the available experimental measurements indicate reasonable agreement for the deactivation of NO(v = 2, 3) at 300 K and NO(v = 1) at 2700 K, although the calculated relaxation rate constant for NO(v = 1) at 300 K is approximately a factor of two below the measured value. The state-to-state relaxation rate coefficients involve the formation of long-lived collision complexes and indicate the importance of multiquantum vibrational relaxation consistent with statistical behaviour in O + NO collisions. The present results, combined with recent measurements of vibrational relaxation for NO(v = 2, 3), suggest that the current atmospheric models of NO cooling rates require higher atmospheric temperatures and/or an increase in the NO/O number densities.

Daytime line-of-sight rates of production of vibrationally excited CO, CO 2 (ν 3 ), and NO + and their rotational temperatures are derived for the lower terrestrial thermosphere from the CIRRIS 1A database and compared with those calculated by models assuming rotational local thermodynamic equilibrium (LTE). It is found that vibrationally excited CO is in rotational LTE, although the calculated rate of its production is about 3 times too small. The observed radiance in the 4.3 μm band of CO 2 is found to be in good agreement with the predictions of the rotational LTE model SHARC (strategic high altitude radiance code). The line-of-sight rotational temperature of this emission is, however, less than that calculated by SHARC, in agreement with earlier non-LTE model calculations. The reaction of N 2 + with O is shown to be the dominant mechanism for producing NO + above 140 km ; the experimental data are consistent with the production of N( 2 D) and rotationally and vibrationally non-LTE NO + as the main reaction channel.

A quantitative interpretation is given of the observed quiescent nighttime radiance of nitric oxide in the fundamental vibration-rotation band near 5.3 μm. The radiance measured in the space shuttle experiment Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) is known to have two components, one characterized by a thermal population of rotational levels and the other by a highly excited rotational population. The analysis presented here confirms that the thermal population is due to impact excitation of NO by atomic oxygen and attributes the highly excited distribution to the reaction of N(4S) atoms with O2. The measured nighttime emission profile is compared with predictions for several model atmospheres. Both sources of excited NO depend upon the latitude, longitude, local time, and geomagnetic indices. The fraction of vibrationally excited NO produced by the reaction of N(4S) with O2 increases rapidly with altitude from 130 to 200 km and its contribution to cooling, though much less than that from inelastic excitation of NO(v=0) is, at higher altitudes, comparable to cooling produced by the atomic oxygen fine-structure line at 63 μm.

The rotational distribution of the “thermal” emission from the v = 1 vibrational level of NO, resulting from impacts of NO in the ground vibrational level (v=0) with oxygen atoms, is examined using the cryogenic infrared radiance for shuttle (CIRRIS-1A) database. A block of NO quiescent (nonauroral) nighttime limb radiances observed by the CIRRIS -1A interferometer and radiometer around 5.3 μm are inverted to obtain the local rotational envelopes of the 1→0 vibrational transition as functions of altitude for both spin components. It is found possible to describe these local rotational envelopes by Maxwell-Boltzmann distributions and to obtain rotational temperatures for each spin component of the vibrationally excited NO. The two spin components, within the accuracy of the measurements, are described by the same rotational temperature, which differs, however, from the mass spectrometer incoherent scatter (MSIS) model temperature at most altitudes. At low altitudes (≤110 km), the rotational temperature and the temperature describing the relative population of the spin states of the vibrationally excited NO approach each other, indicating the onset of thermodynamic equilibrium for the spin and the rotational degrees of freedom.

A fully quantal calculation of the excitation cross sections for the fine-structure levels of ground-state atomic oxygen, in collisions with oxygen atoms at low energies, is presented. The results are compared with the cross sections obtained in a previous calculation.

A molecular theory of collision-induced fine-structure-level transitions in complex atoms is presented. The theory is applied to calculate the excitation cross sections for the fine-structure levels in the $^{3}$P ground state of atomic oxygen. We discuss and compare the theory presented here with previous molecular theories.

Cooling due to infrared emissions from O atom excited CO2and NO is a critically important process in the thermal budget of the terrestrial thermosphere. Increasing CO2density due to human activity makes the role of its emission particularly worthy of quantitative evaluation. Furthermore, the O atom excited 15 μm CO2emission has a unique role in the lower thermosphere of Venus where it is the only significant cooling mechanism; it is also an important process in the Martian thermosphere. The experimental and theoretical status of these rate coefficients is reviewed and the unsatisfactory current state of knowledge is pointed out.

A formalism is derived to include the effects of the long‐range attractive part of the interaction potential in the calculation of atom–diatom collision cross sections using the impulse approach (IA). These calculations have, until now, assumed the atom–diatom potential given by a sum of two atom–atom interactions, consequently yielding a poor representation of the long‐range attractive part. In the distorted wave impulse approach (DWIA) the long‐range attractive part, located at the center of mass of the diatom, is a spherically symmetric potential which ‘‘distorts’’ the incoming and outgoing waves. The DWIA formalism is used to calculate differential cross sections for the rotationally inelastic process Li++N2(v=0, j=2)→Li++N2(v’=0, j’), as a function of the final rotational level j’, at a relative kinetic energy of 4.23 eV and center of mass scattering angles of 49.2° and 37.1°. It is shown that differential cross sections calculated using the DWIA formalism are in much better agreement with experimentally measured ones than IA differential cross sections using atom–atom interactions expressed by either hard‐core, or exponential repulsive, functions.

This paper continues the study of inelastic and ballistic collisions for the CsF–Ar system using the impulse approximation (IA). The IA expresses the atom–diatom potential as the sum of the two atom–atom potentials. The atom–atom interaction is approximated by a hard core potential, and the laboratory differential cross sections are calculated for an initial relative translational energy of 1.0 eV as a function of the laboratory recoil velocity of CsF. The calculated differential cross sections are in excellent agreement with the experimental measurements for all eight laboratory scattering angles for which the data are available. While the calculated results show no significant dependence on the initial relative velocity or on the initial vibrational quantum number of CsF, they do show a systematic variation with the initial rotational quantum number—the ballistic effect is more pronounced than that observed experimentally for initial quantum rotational numbers less than 30 and is not pronounced enough f...

Ballistic collisions is a term used to describe atom-diatom collisions during which a substantial fraction of the initial relative translational energy is converted into the internal energy of the diatom. An exact formulation of the impulse approach to atom-diatom collisions is shown to be in excellent agreement with the experimental results for the CsF-Ar system at 1.1 eV relative translational energy for laboratory scattering angles of 30\ifmmode^\circ\else\textdegree\fi{} and 60\ifmmode^\circ\else\textdegree\fi{}. The differential cross section for scattering of CsF peaks at two distinct recoil velocities. The peak centered at the recoil velocity corresponding to elastic scattering has been called the elastic peak. This peak is shown to consist of several hundred inelastic transitions, most involving a small change in internal energy. The peak near the center-of-mass (c.m.) velocity is called the ballistic peak and is shown to consist of highly inelastic (ballistic) transitions. It is shown that transitions comprising the ballistic (elastic) peak occur when an Ar atom strikes the F (Cs) end of CsF. When one is looking along the direction of the c.m. velocity, the signal from a single transition, which converts about 99.99% of the relative translational energy into internal energy, may be larger than the signal from any other ballistic transition by as much as an order of magnitude. This property may be used to prepare state-selected and velocity-selected beams for further studies. It is also pointed out that the ballistic peak may be observed for any atom-molecule system under appropriate circumstances.

Starting with multipolar-multipolar interaction for intermolecular potential we have carried out a calculation of rate coefficients for transfer of one quantum of vibrational energy upon impact of O(2)(2 < or = v < or = 8) with O(2)(v = 0) as a function of temperature (150 K < or = T < or = 450 K). The equations for energy transfer, in the second order of perturbation theory, mediated by isotropic and anisotropic dispersion interactions, are derived. None of the parameters appearing in the calculation were adjusted to obtain agreement with the experimentally measured rate coefficients. The results of the calculation are compared with experimentally measured room temperature rate coefficients of the disappearance of O(2)(v) upon collision with O(2)(v = 0). The agreement is found to be good for the disappearance of O(2)(v = 3) and O(2)(v = 5). For O(2)(v = 2) the calculation gives a larger rate coefficient than the measured value, while for O(2)(v = 4) it gives a smaller value than obtained by measurement. For O(2)(v = 8) it agrees with one measurement and gives a value smaller than another measurement and a calculation.

An exact formulation of the impulse approach (IA), or quantum-mechanical spectator model, is applied to atom-diatom collisions. Results are compared with previous work on the IA, which has always involved the peaking approximation (PA). The PA is seen to overestimate (underestimate) differential cross sections for processes involving projectile atom energy loss (gain). The internal consistency of the IA is explored by subjecting it to semidetailed balancing. For small scattering angles the IA is seen to be an inadequate theory, probably due to the neglect of double- and higher-collision terms in the multiple-collision expansion of the three-body T matrix. For large scattering angles, where the IA does appear to describe the scattering process accurately, the exact calculation is shown to give the same results as when only the energy-conserving on-the-energy-shell two-body processes are considered. An accurate approximation method is also developed for rapid computation of inelastic differential cross sections. Finally, the calculated results are compared with the experimental measurements, and the need to explore two-body potentials more complicated than the hard-core potential is pointed out.

[1] The transfer of vibrational energy from chemiluminescent OH, produced predominately by the H + O3 → OH (v) + O2 reaction, is of importance in modeling the airglow from the atmospheres of Earth, Mars, and Venus. We have calculated the energy transfer probability per collision as function of temperature for the near-resonant processes OH (v) + CO2 (00001) → OH(v − 1) +CO2 (mnpqr) for v = 1, 8, and 9 in the 100 – 350 K temperature range. We show that the measured room temperature values of the removal rate coefficient of OH(v = 9, 8) and OH(v = 1) by CO2, are in agreement with the ones calculated for the vibration-to-vibration (VV) energy transfer (ET) processes OH (v) + CO2 (00001) → OH (v − 1) + CO2 (00011) and OH (1) + CO2 (00001) → OH (0) + CO2 (1001 n) n =1, 2, respectively. The emission from the latter levels of CO2 in the terrestrial mesosphere is not self-absorbed leading to the possibility that these levels may be important contributors to the 4.3 μm emission. Our calculation favors the “Collisional Cascade” model of vibrational energy transfer from OH to CO2 that predicts about 50 times more radiation in the Martian Meinel bands over that predicted by the “Sudden Death” model. These two models of Martian atmosphere predict vastly different steady-state populations of the vibrational levels of OH and should, because of the chemical reactions, of other trace species, e.g., H, O, and CO, as well.

The role of carbon dioxide in cooling the thermospheres of Earth, Venus, and Mars is well recognized (Gordiets et al, 1982; Dickinson, 1984; Dickinson et al, 1987; Dickinson and Bougher, 1986; Bougher and Dickinson, 1988). During a collision of CO{sub 2} with atomic and molecular species, some of the translational energy of relative motion (heat) is converted into vibrational energy of the lowest-lying mode, the bending mode, {nu}{sub 2}. This vibrational energy is subsequently radiated at 15 {mu}m. Many of these photons escape to space, cooling the atmosphere. A new value of the rate coefficient for the deactivation of the bending mode of carbon dioxide by atomic oxygen at low temperatures is derived from the observation of 15 {mu}m emission from the atmosphere of the Earth. This new value gives a cooling rate for the lower thermosphere that is two to three times the rate previously calculated, and it may resolve a long-standing problem in the Mars-Venus aeronomy.

Using an exact formulation of impulse approach (IA) to atom-diatom collisions, we assess its internal consistency. By comparing the cross sections in the forward and reverse directions for the vibrational-rotational inelastic processes, using the half-on-the-shell (post and prior) models of the two-body {ital t} matrix, we show that in both cases the IA leads to a violation of the semidetailed balance (SDB) condition for small scattering angles. An off-shell model for the two-body {ital t} matrix, which preserves SDB, is shown to have other serious shortcomings. The cross sections are studied quantitatively as a function of the relative translational energy and the mass of the incident particle, and criteria discussed for the applicability of IA.

[1] A comparative study of nitric oxide (NO) 5.3 μm emissions in the thermosphere measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectrometer and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) radiometer satellite instruments was conducted for nighttime data collected on 14 June 2003. The agreement between the data sets was very good, within ∼25% over the entire latitude range studied from −58° to + 4°. The MIPAS and SABER data were inverted to retrieve NO volume emission rates. Spectral fitting of the MIPAS data was used to determine the NO(v = 1) rotational and spin-orbit temperatures, which were found to be in nonlocal thermodynamic equilibrium (non-LTE) above 110 km. Near 110 km the rotational and spin-orbit temperatures converged, indicating the onset of equilibrium in agreement with the results of non-LTE modeling. Because of the onset of equilibrium the NO rotational and spin-orbit temperatures can be used to estimate the kinetic temperature near 110 km. The results indicate that the atmospheric model NRLMSISE-00 underestimates the kinetic temperature near 110 km for the locations investigated. The SABER instrument 5.3 μm band filter cuts off a significant fraction of the NO(Δv = 1) band, and therefore modeling of NO is necessary to predict the total band radiance. The needed correction factors were directly determined from the MIPAS data, providing validation of the modeled values used in SABER operational data processing. The correction factors were applied to the SABER data to calculate densities of NO(v = 1). A feasibility study was also conducted to investigate the use of NO 5.3 μm emission data to derive NO(v = 0) densities in the thermosphere.

[1] A calculation from first principles of the differential cross section for Rayleigh scattering shows that the contribution of polarizability anisotropy found in the literature is valid only in the high rotational quantum number limit of the vector coupling coefficients, that is, in the high-temperature or classical limit. The additional term in the total Rayleigh scattering cross section arising from the polarizability anisotropy is about four times smaller than what is called the King factor in the literature. These errors, resulting from ignoring the constraints imposed by the conservation of angular momentum, can lead to significant corrections in estimating populations from stratospheric and mesospheric measurements.

[1] The spectrally resolved nighttime 5.3 μm emission from NO observed by the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) experiment aboard space shuttle Discovery at 195 km tangent altitude during a strong auroral event is modeled using a first-principles kinetics model. An appropriate SHARC (Strategic High Altitude Radiance Code) Atmospheric Generator (SAG) is dosed with an IBC class III aurora. The spectrally resolved fundamental vibration-rotation band emissions from NO around 5.3 μm resulting from impacts of ambient NO with O as well as reactions of N atoms with O2 are calculated under steady state conditions. The calculated results, using a local translational temperature derived from the observed spectrum, are in excellent agreement with the CIRRIS-1A observations, validating our model. The importance of the accurate nascent vibrational and rotational distribution of chemically produced NO as well as the collisonally induced rotation-to-vibration relaxation of rotationally hot NO is pointed out.

[1] Aurorally enhanced 5.3 μm emission from nitric oxide was observed by the MIPAS instrument on board the ENVISAT satellite during the solar storm of October/November 2003. Spectral modeling of the NO(Δv = 1) fundamental band emissions was performed in order to determine the NO rotational and spin-orbit distributions. In the thermosphere, NO(v = 1) is produced by collisional excitation of NO(v = 0) by O atoms and also by the chemical reactions of N(4S) and N(2D) atoms with O2. There are no measurements of the nascent spin-orbit distribution of NO produced by the reaction of N atoms with O2. Auroral activity leads to increased production of N(4S) and N(2D) atoms, resulting in enhanced chemical formation of NO. In the MIPAS data taken during the solar storm, strong NO signal levels and increased rotational temperatures indicated high levels of auroral activity. A comparison of the data from October/November 2003 with data taken during a quiescent period in June 2003 showed that NO(v = 1) produced by N + O2 has a hotter spin-orbit distribution than NO(v = 1) produced by O atom collisional excitation. The results imply that the spin-orbit ratio may be useful for identifying different sources of NO in the thermosphere. In addition, the NO(v = 1) spin-orbit distributions were found not to be in local thermodynamic equilibrium (non-LTE) for both quiescent and auroral conditions. The non-LTE effects must be taken into account in order to accurately retrieve atmospheric NO concentrations from 5.3 μm emissions.

In an attempt to explain the observed nightglow emission from OH(v=10) in the mesosphere that has the energy greater than the exothermicity of the H+O(3) reaction, potential energy surfaces were calculated for reactions of high lying electronic states of O(2)(A (3)Sigma(u) (+) and A' (3)Delta(u)) with atomic hydrogen H((2)S) to produce the ground state products OH((2)Pi)+O((3)P). From collinear two-dimensional scans, several adiabatic and nonadiabatic pathways have been identified. Multiconfigurational single and double excitation configuration interaction calculations show that the adiabatic pathways on a (4)Delta potential surface from O(2)(A' (3)Delta)+H and a (4)Sigma(+) potential surface from O(2)(A (3)Sigma(u) (+))+H are the most favorable, with the zero-point corrected barrier heights of as low as 0.191 and 0.182 eV, respectively, and the reactions are fast. The transition states for these pathways are collinear and early, and the reaction coordinate suggests that the potential energy release of ca. 3.8 eV (larger than the energy required to excite OH to v=10) is likely to favor high vibrational excitation.

The concept of determining the density (particles/unit volume) of atomic and molecular species at high altitudes (100-600 km) by passive remote sensing of the Rayleigh and Raman limbscattered solar radiation is explored. Using Rayleigh scattering the dominant contributors to atomic (O) and molecular (N2, O2) scattering may be distinguished by their differing scale heights and polarizabilities. Using simulated data total densities were recovered to within 5%. With Raman scattering it may be possible to extract the kinetic temperature of the thermosphere from the Ring effect in the Fraunhofer solar spectrum.

The dramatic solar storm events of April 2002 deposited a large amount of energy into the Earth's upper atmosphere, substantially altering the thermal structure, the chemical composition, the dynam ...

[1] Differential cross sections for Raman scattering between the multiplet levels of the ground electronic state of atomic oxygen are calculated from first principles. The calculated cross sections are in order-of-magnitude agreement with the available experimental measurements. The use of a Raman LIDAR (Light Detection and Ranging) has the potential of giving a three-dimensional map of the density of each of the three fine structure levels of atomic oxygen. Since it was established earlier that the fine structure levels are in local thermodynamic equilibrium (LTE) up to at least 350 km altitude, the Raman LIDAR therefore also has the potential of giving a three-dimensional map of the temperature of the atmosphere.

Assuming large signal-to-noise ratio and using the rotationally resolved fundamental vibration-rotation band emission from NO near 5.3 m we propose a scheme for remotely sensing temperature above the altitudes where the 15 m emission from CO 2 becomes very weak. We also find that the rotationally resolved 5.3 m emission can be used to remotely sense N( 4 S) atom, O 2 , and O densities in the terrestrial thermosphere – this being the only method for remotely sensing the first two species. Keywords: NO; infrared emission; remote sensing 1. INTRODUCTION The next few years promise to offer great opportunities to the atmospheric scientists. The data gathered by SABER (S ounding of the A tmosphere by B roadband E mission R adiometry) and MIPAS (M ichelson Interferometer for Passive A tmospheric Sounding) aboard the NASA satellite TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and D ynamics) and ESA satellite ENVISAT (Environmental Satellite), respectively, are yielding data which should put the models of atmospheric phenomenology, especially those involving the emission of infrared radiation, on a firmer footing. Furthermore, these data should permit retrieval of additional atmospheric parameters. This retrieval of additional parameters includes extending an already existing retrieval, e.g., retrieval of temperature to higher altitudes, or retrieving parameters for which no methods currently exist, e.g., N(

[1] The temperature dependence of the rate coefficient of the N(2D)+O2→NO+O reaction has been determined using ab initio potential energy surfaces (PES) and classical dynamics. The calculation agrees with the recommended rate coefficient at 300 K (∼110 km altitude). The rate coefficient is given by the expression k(T) = 6.2 × 10−12(T/300) cm3/s/molec. In contrast to the nearly temperature-independent value of this rate coefficient previously recommended, the value given here increases by almost a factor of about four as the altitude increases from 110 to 200 km. It is also shown that even though N(2D) atoms in the thermosphere are produced with large translational energies, using the value of the rate coefficient at the local temperature introduces negligible error in the amount of NO produced. The new value of this rate coefficient will significantly increase the amount of NO computed in the aeronomic models causing a re-evaluation of the heat budget and temperature and density structure of the thermosphere. In particular, implications of the larger rate coefficient for the recent observations of dramatically enhanced 5.3 μm emission from NO in the thermosphere due to solar storms are discussed.

Cooling due to infrared emissions from O atom excited CO2 and NO is a critically important process in the thermal budget of the terrestrial thermosphere. Increasing CO2 density due to human activity makes the role of its emission particularly worthy of quantitative evaluation. Furthermore, the O atom excited 15 microns CO2 emission has a unique role in the lower thermosphere of Venus where it is the only significant cooling mechanism; it is also an important process in the Martian thermosphere. The experimental and theoretical status of these rate coefficients is reviewed and the unsatisfactory current state of knowledge is pointed out.

[1] A model of the production and loss of odd nitrogen species (mainly, N(4S), N(2D), NO, and NO+) and the enhanced vibration-rotation band emission from NO in the infrared from the aurorally dosed terrestrial nighttime thermosphere is described. This model is assessed by analyzing the observations of the fundamental (Δv = −1, ∼5.3 μm) and overtone (Δv = −2, ∼2.7 μm) NO vibration-rotation band limb emissions made by a Michelson interferometer and radiometer, respectively, aboard the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) experiment on the space shuttle Discovery during an auroral event. The auroral dosing along the line of sight is inferred from the 2.7-μm radiance profiles using a self-consistent procedure. The dosing obtained is then used in the model to predict the spectrally resolved emission in the 5.3-μm region. The calculated overtone radiance profiles agree with the measured ones at lower tangent altitudes, where the signal-to-noise ratio is large. The calculation, however, underpredicts the observed radiance, both fundamental and overtone, at higher tangent altitudes by a factor of ∼3 and gives a colder rotational temperature for the rotationally hot component of the spectrally resolved emission from nascent NO. The causes of this discrepancy and its impact on the densities of the odd N species are discussed.

This paper proposes to remotely sense the translational temperature and the densities of important nocturnal radiators, viz., nitric oxide, carbon dioxide, and atomic oxygen, as functions of altitude in the quiescent nighttime terrestrial thermosphere. The densities of the excited states as functions of altitude are obtained by inverting the measured infrared limb emissions from nitric oxide near 5.3 micrometers , from carbon dioxide near 15 micrometers , and the fine structure lines of atomic oxygen at 63.2 micrometers and 145.5 micrometers . A knowledge of the excitation mechanisms then permits the calculation of the ground states densities.

Classical trajectory calculations have been performed to determine the rotational distribution of vibrationally excited nitric oxide from collisions with atomic oxygen. The reaction occurs on two electronic potential energy surfaces which must be considered for a realistic description of the O+NO collision dynamics. The results, which have been statistically averaged over both electronic potential energy surfaces, are in good agreement with the available experimental data for vibrational relaxation of NO(v less than or equal to 9), as well as the temperature dependence of NO(v equals 1). The state-to-state relaxation rate coefficients involve the formation of long-lived collision complexes and indicate statistical behavior in O+NO collisions. The present study confirms earlier analysis that the NO(v equals 1) rotational distributions can indeed by described by a Maxwell-Boltzmann distribution, albeit with a rotational temperature of approximately 75% of the initial translational temperature. Thus, it appears possible to establish a lower bound to, and an estimate of, the nighttime quiescent terrestrial thermosphere by measuring the rotational envelope of the 5.3 micrometer emission from NO.

Atmospheric infrared radiance fluctuations result from fluctuations in the density of atmospheric species, individual molecular state populations, and kinetic temperatures and pressures along the sensor line of sight (LOS). The SHARC-4 program models the atmospheric background radiance fluctuations. It predicts a two dimensional radiance spatial covariance function from the underlying 3D atmospheric structures. The radiance statistics are non-stationary and are dependent on bandpass, sensor location and field of view (FOV). In the upper atmosphere non-equilibrium effects are important. Fluctuations in kinetic temperature can result in correlated or anti-correlated fluctuations in vibrational state temperatures. The model accounts for these effects and predicts spatial covariance functions for molecular state number densities and vibrational temperatures. SHARC predicts the non-equilibrium dependence of molecular state number density fluctuations on kinetic temperature and density fluctuations, and calculates mean LOS radiances and radiance derivatives. The modeling capabilities are illustrated with sample predictions of MSX like experiments with MSX sensor bandpasses, sensor locations and FOV. The model can be applied for all altitudes and arbitrary sensor FOV including nadir and limb viewing.

The paper presents a distorted wave generalization of the S-matrix version of the Kohn variational principal developed by Zhang, Chu, and Miller J. Chem. Phys. 88, 10 (1988). For scattering in the presence of a long range interaction, the large-r asymptotic solution to the Schrodinger equation is built into the Kohn variational principal order by order in an effort to accelerate convergence of the short-range square integrable part of the basis set expansion. The improvement in the rate of convergence is demonstrated by applying the method to a long-range model potential. Multichannel scattering is discussed. (AN)

This paper describes the development of a new version of the SHARC code, SHARC-3, which includes the ability to simulate changing atmospheric conditions along the line-of-sight (LOS) paths being calculated. SHARC has been developed by the U.S. Air Force for the rapid and accurate calculation of upper atmospheric IR radiance and transmittance spectra with a resolution of better than 1 cm-1 in the 2 to 40 micrometers (250 to 5,000 cm-1) wavelength region for arbitrary LOSs in the 50 - 300 km altitude regime. SHARC accounts for the production, loss, and energy transfer processes among the molecular vibrational states important to this spectral region. Auroral production and excitation of CO2, NO, and NO+ are included in addition to quiescent atmospheric processes. Calculated vibrational temperatures are found to be similar to results from other non-LTE codes, and SHARC's equivalent-width spectral algorithm provides very good agreement with much more time-consuming `exact' line-by-line methods. Calculations and data comparisons illustrating the features of SHARC-3 are presented.

The analysis of CIRRIS 1A (Cryogenic InfraRed Radiance Instrumentation for Shuttle) interferometric and radiometric data obtained during the flight of STS-39 (28 Apr - 6 May 1991) reveals the presence of IR emission in the 400-900/cm (11-25 micron) region not attributable to atmospheric emission. In this paper, data are shown which identify the signal as nearfield water vapor present during all CIRRIS IA observations. Variability of the near-field water vapor emissions is characterized and compared to mass spectrometer data also obtained on STS-39 (QINMS). Further investigation indicates that the water is excited to extremely high effective temperatures, possibly in excess of 9000 K. The data presented support the theory that water outgassed from the shuttle tiles is highly excited by collisions with atmospheric O, classifying it as a type of shuttle-induced glow never before measured in the LWIR.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Progress made in the last ten years in understanding the daytime earthlimb emission around 2.7 microns is reviewed. It is pointed that the solar pumped emission from the earth's atmosphere consists of radiation primarily from carbon dioxide and from water vapor. Radiation from CO2 was the subject of a thorough investigation (Sharma and Wintersteiner, 1985). The radiation from water vapor is studied using the newly developed Strategic High-Altitude Radiance Code, and the results are compared with the SPectral Infrared Rocket Experiment. The next few years should see dramatic progress in the backgrounds models because of the global measurement made by the CIRRIS 1A.

The probability per collision P(T) of near-resonant vibration-to-vibration energy transfer (ET) of one quantum of vibrational energy from vibrational levels nu=8 and nu=9 of OH to N(2)(nu=0), OH(nu)+N(2)(0)-->OH(nu-1)+N(2)(1), is calculated in the 100-350 K temperature range. These processes represent important steps in a model that explains the enhanced 4.3 microm emission from CO(2) in the nocturnal mesosphere. The calculated energy transfer is mediated by weak long-range dipole-quadrupole interaction. The results of this calculation are very sensitive to the strength of the two transition moments. Because of the long range of the intermolecular potential, the resonance function, a measure of energy that can be efficiently exchanged between translation and vibration-rotation degrees of freedom, is rather narrow. A narrow resonance function coupled with the large rotational constant of OH is shown to render the results of the calculation very sensitive to the rotational distribution, or the rotational temperature if one exists, of this molecule. The calculations are carried out in the first and second orders of perturbation theory with the latter shown to give ET probabilities that are an order of magnitude larger than the former. The reasons for the difference in magnitude and temperature dependence of the first- and second-order calculations are discussed. The results of the calculations are compared with room temperature measurements as well as with an earlier calculation. Our calculated results are in good agreement with the room temperature measurements for the transfer of vibrational energy for the exothermic OH(nu=9) ET process but are about an order lower than the room temperature measurements for the exothermic OH(nu=8) ET process. The cause of this discrepancy is explored. This calculation does not give the large values of the rate coefficients needed by the model that explains the enhanced 4.3 microm emission from CO(2) in the nocturnal mesosphere.

First principles model calculations of the vibration-to-vibration (VV) energy transfer (ET) processes NO(+)(nu=1)+N(2)(nu=n-1)--NO(+)(nu=0)+N(2)(nu=n)+(28.64n-14.67) cm(-1) and NO(+)(nu=n)+N(2)(nu=0)--NO(+)(nu=n-1)+N(2)(nu=1)+(32.52(n-1)+13.97) cm(-1) for n=1-3 in the 300-1000 K temperature range are performed. The VV ET probability is computed for three mechanisms: (1) The charge on NO(+) acting on the average polarizability of N(2) induces a dipole moment in N(2) which then interacts with the permanent dipole moment of NO(+) to mediate the energy transfer. (2) The charge on NO(+) acting on the anisotropic polarizability of N(2) induces a dipole moment in N(2) which then interacts with the permanent dipole moment of NO(+) to mediate the energy transfer. (3) The dipole moment of NO(+) interacts with the quadrupole moment of N(2) to mediate the energy transfer. Because the probability amplitudes of the second and third mechanisms add coherently the ET probability for these two mechanisms is given as a single number. The probability of energy transfer per collision is in the 5 x 10(-3) range. The results of this calculation are compared with the available experimental data. This calculation should help quantify the role of NO(+) in the energy budget of the upper atmosphere.

In an attempt to explain the observed nightglow emission from OH(v=10) in the mesosphere that has the energy greater than the exothermicity of the H+O3 reaction, potential energy surfaces were calculated for reactions of high lying electronic states of O2(AΣu+3andA′Δu3) with atomic hydrogen H(S2) to produce the ground state products OH(Π2)+O(P3). From collinear two-dimensional scans, several adiabatic and nonadiabatic pathways have been identified. Multiconfigurational single and double excitation configuration interaction calculations show that the adiabatic pathways on a Δ4 potential surface from O2(A′Δ3)+H and a Σ+4 potential surface from O2(AΣu+3)+H are the most favorable, with the zero-point corrected barrier heights of as low as 0.191 and 0.182eV, respectively, and the reactions are fast. The transition states for these pathways are collinear and early, and the reaction coordinate suggests that the potential energy release of ca. 3.8eV (larger than the energy required to excite OH to v=10) is likely...

Infrared radiative excitation in non-local thermodynamic equilibrium (non-LTE) regions of the Earth's atmosphere for the v3-mode vibrationally excited states of CO2 under sunlit conditions and the resulting 4.3-μm limb radiance are calculated using a line-by-line (LBL) radiative transfer model. Excited-state population densities and the corresponding vibrational temperature profiles are calculated for the important emitting states using a model which includes radiative absorption and emission as well as various collisional processes. The quenching of O(1D) by N2 has a greater impact on these population densities than has been previously reported in the literature. Integrated radiance in a limb view for the 4.3-μm bands is calculated from the model and compared with sunlit earthlimb measurements obtained by the Spectral Infrared Rocket Experiment (SPIRE). Solar pumping is the dominant excitation process for the 4.3-μm emitting states in the daytime. The major contribution to the total limb radiance for tangent heights of 55–95 km is made by the fluorescent states at approximately 3600 cm−1 which absorb sunlight at 2.7 μm and then emit preferentially at 4.3 μm. The predicted radiance is in good agreement with the SPIRE measurements for all tangent heights in the 50- to 130-km range. This is the first detailed comparison of results of a full line-by-line non-LTE radiative transfer calculation with 4.3-μm earthlimb radiance data.

We describe a new line-by-line (LBL) algorithm for radiative excitation in infrared bands in a non-local thermodynamic equilibrium (non-LTE) planetary atmosphere. Specifically, we present a predictive model for the terrestrial CO[sub 2] 15[mu]m emission that incorporates this generic algorithm, and validate the model by comparing its results with emission spectra obtained in a limb-scanning rocket experiment. The unique features of the reactive-excitation algorithm are discussed in this paper. These features contribute to accurate radiative transfer results and reliable atmospheric cooling rates. For altitudes above 40 km, we present results of model calculations of CO[sub 2]([nu][sub 2]) vibrational temperatures, 15-[mu]m limb spectral radiances, and cooling rates, for the main band and for weaker hot and isotopic bands. We calculate the excitation and deexcitation rates due to different processes. We compare the predicted limb radiance with earthlimb spectral scans obtained in the SPIRE rocket experiment over Poker Flat, Alaska, and get excellent agreement as a function of both wavelength and tangent height. This constitutes the first validation of a long-wavelength CO[sub 2] non-LTE emission model using an actual atmospheric data set and verifies the existence of certain aeronomic features that have only been predicted by models and constrains the previously unknown valuemore » of the very important rate constant for deactivation of the CO[sub 2] bending mode by atomic oxygen to the range of 5-6 [times] 10[sup [minus]12] cm[sup 3]/(mol s) at mesospheric and lower thermospheric temperatures. We discuss the significance of this large value for terrestrial and Venusian thermospheres and the convergence rate of the iterative scheme, the model's sensitivity to the background atmosphere, the importance of the lower boundary surface contribution, and the effects of the choice of the layer thickness and the neglect of line overlap. 86 refs., 20 figs., 5 tabs.« less