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| Titel |
GOAT (Global Oxygen And Temperature) Mapping |
| VerfasserIn |
T. G. Slanger, O. Kostko, D. A. Pejakovic, K. S. Kalogerakis |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061213
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| Zusammenfassung |
| The O2(b1Σg+ - X3Σg-) Atmospheric Band system has been studied extensively
since the days of Fraunhofer, who first showed that solar photoabsorption in the
762 nm region was caused by terrestrial oxygen; in this case, the 0-0 band of the
b - X system. The O2(b) state is generated by two different mechanisms in the
atmosphere: by O(3P ) atom recombination, where O2(b) is one of several excited O2
states produced, and by the energy transfer from O(1D) to O2, where the products
are O2(b, v = 0, 1). The latter is an ionospheric process and is the case of interest
here.
Recent studies at SRI International have demonstrated that O2(b, v = 1) is the
predominant product of the energy transfer, with the nascent [v = 1]/[v = 0] ratio being close
to 4 and temperature independent. Collisional quenching of b(1) by O2, to produce b(0),
proceeds six orders of magnitude faster than b(0) quenching [Slanger and Copeland, 2003].
As a consequence, the [b - X(1-1)]/[b - X(0-0)] intensity ratio as a function of
thermospheric altitude shows the degree to which b(1) has been converted to b(0), which
can be interpreted in terms of atmospheric composition. Of the three colliders —
O2, O(3P ), and N2 — it is the first two that control the b(1) - b(0) relaxation
rate.
To observe the b(v = 0, 1) emission requires space-based measurements in the 755-780
nm region of the 0-0 and 1-1 bands. In addition to the varying intensity ratio of the two bands,
the shapes will differ as a function of temperature as the rotational temperature changes.
Thus, observations of the shapes and the relative intensities of the two bands will
simultaneously lead to information on temperature and on the [O2] + [O(3P )] densities as a
function of altitude. The technique is relevant to the dayglow and to the portion of the night
when O(1D) is still detectable.
T. G. Slanger and R. A. Copeland, Chem. Rev. 103, 4731-65, 2003.
Supported by NASA ITM Grant NNX10AL08G and NSF Aeronomy Grant
AGS-0937317. |
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