Research ArticleATMOSPHERIC SCIENCE

A previously unrecognized source of the O2 Atmospheric band emission in Earth’s nightglow

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Science Advances  20 Mar 2019:
Vol. 5, no. 3, eaau9255
DOI: 10.1126/sciadv.aau9255
  • Fig. 1 The OH Meinel and O2 AB systems are important features of the nightglow.

    (A) Astronomical night sky spectrum obtained using the Echelle Spectrograph and Imager on the Keck II telescope displays strong OH Meinel band emission (4 March 2000, 8:58 UT; λ/Δλ, ~7000; 50-min exposure) (14). The inset shows the weak (0,1) band of the O2 AB system near 864.5 nm. (B) Potential energy curve and vibrational levels of the OH ground state. The red arrow indicates a representative OH Meinel feature—the (8,4) band near 937 nm. (C) Observed OH vibrational population distribution in the nightglow (green) and nascent distribution from the H + O3 reaction (blue) (12, 14). (D) Low-lying electronic states of O2. The red arrow indicates the strong (0,0) O2 (b1g+X3g) emission near 762 nm that is absorbed by the atmosphere and is observable only from space.

  • Fig. 2 The OH(v) + O source of O2 AB emission depends on the altitude profile of the O-atom layer.

    (A and C) Measured (0,0) O2 AB volume emission rate as a function of altitude for ETON (gray circles) and NLTE-2 (black circles) and calculated contributions of the source from OH(v = 9) + O using the lower and upper limit rate constant values of 0 (blue) and 8 × 10−14 cm3 s−1 (green) for removal of O2(b, v = 0) by O atoms. (B) Measured atomic oxygen number density as a function of altitude for ETON (gray) and NLTE-2 (black). Note that despite the larger O-atom density during ETON, the better overlap of the O-atom profile with the OH layer during NLTE-2 leads to stronger O2 AB emission originating from OH(v = 9) + O.

  • Fig. 3 Estimated contributions from OH(v) + O and O + O + M to the O2 AB emission.

    (A and C) Measured (0,0) O2 AB volume emission rate profiles for the ETON and NLTE-2 datasets (gray and black circles, respectively) and calculated contributions from OH(v = 9) + O (green) and O + O + M (violet). The sum of the two contributions is also shown (orange) (see Methods for additional information). (B and D) As in (A) and (C) for O + O + M and assuming as an upper limit that OH(v = 5 to 8) produced from the H + O3 reaction exhibits a behavior similar to OH(v = 9) + O. OH(v) + O and O + O + M are assumed to be the only active sources of the O2 AB emission.

  • Table 1 Processes and relevant kinetics parameters used in the calculation of the contributions of OH(v = 9) + O multiquantum vibrational relaxation to the O2 AB emission.

    When a kinetics data compilation is available, that reference is shown for the sake of brevity. Additional details are provided in Methods.

    ProcessParameterValuef, g*Reference
    298 K (±%)k(T Kelvin)
    H + O3→OH(v) + O2kHO32.9 × 10−11 cm3 s−1 (±10%)1.4 × 10−10 × exp(−470/T)1.1, 40(31)
    Yield of OH(v = 9) from H + O3y90.47(12)
    O + O2 + M→O3 + MkOO2M6 × 10−34 cm6 s−1 (±10%)6 × 10−34 × (300/T)2.41.1, 50(31)
    O + O3→O2 + O2kOO38 × 10−15 cm3 s−1 (±10%)8 × 10−12 × exp(−2060/T)1.1, 200(31)
    OH(v = 9) + O2→productskOH9O22.2 × 10−11 cm3 s−1 (±14%)1.15 × 10−11 × exp(+195/T)(21, 25)
    OH(v = 9) + N2→productskOH9N27 × 10−13 cm3 s−1 (±14%)5.03 × 10−13 × exp(+100/T)(21, 25)
    OH(v = 9) + O→productskOH9O4 × 10−10 cm3 s−1 (±12%)6.2 × 10−10 × exp(−135/T)(21, 25)
    OH(v = 9) + O→OH(v = 3) + O(1D)kOH9NM3.2 × 10−10 cm3 s−1 (±16%)5.0 × 10−10 × exp(−135/T)(25, 26)
    O(1D) + N2→O(3P) + N2kODN23.1 × 10−11 cm3 s−1 (±10%)2.15 × 10−11 × exp(+110/T)1.1, 20(31)
    O(1D) + O2→O(3P) + O2kODO24.0 × 10−11 cm3 s−1 (±10%)3.3 × 10−11 × exp(+55/T)1.1, 10(31)
    Yield of O2(b) from O(1D) + O2yO2b0.8 (±25%)(31)
    O2(b, v = 0) + N2→O2 + N2kO2bN22.1 × 10−15 (±10%)1.8 × 10−15 × exp(+45/T)1.1, 100(31)
    O2(b, v = 0) + O2→O2 + O2kO2bO23.9 × 10−17 cm3 s−1 (±50%)1.5(31)
    O2(b, v = 0) + O→productskO2bO0/8.0 × 10−14 cm3 s−1(31)

    *The parameters f and g can be used to estimate the rate constant uncertainty from the expression: (T) = (298 K) × exp{abs[g × (1/T − 1/298)]}. The calculated uncertainty corresponds approximately to 1 SD (31).

    Supplementary Materials

    • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/3/eaau9255/DC1

      Fig. S1. Relevant information on the OH Meinel band emission from the ETON rocket P228H.

      Table S1. Processes and relevant kinetics parameters relevant to the generation of O2 AB emission from O + O + M association.

      Data S1. Data inputs and calculation outputs presented in the main text and Methods.

      References (52, 53)

    • Supplementary Materials

      The PDF file includes:

      • Fig. S1. Relevant information on the OH Meinel band emission from the ETON rocket P228H.
      • Table S1. Processes and relevant kinetics parameters relevant to the generation of O2 AB emission from O + O + M association.
      • References (52, 53)

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      Other Supplementary Material for this manuscript includes the following:

      • Data S1 (.pdf format). Data inputs and calculation outputs presented in the main text and Methods.

      Files in this Data Supplement:

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