Simulation and application of the emission line O19P18 of O2(a1Δg) dayglow near 1.27 µm for wind observations from limb-viewing satellites.

The O2(a1Δg) emission near 1.27 µm has relatively bright signal and extended altitude coverage and provides an important means to remotely sense the compositional structures and dynamical features of the upper atmosphere globally. In this paper, we report the simulation and application of O2(a1Δg) dayglow near 1.27 µm for wind observations from limb-viewing satellites. A line by line radiative transfer model of the O2(aΔ1g,υ'=0)→O2(XΣ3g,υ″=0) band is developed by taking both multiple scattering radiative transfer and nonlocal thermal equilibrium (non-LTE) models into account. The emission line O19P18 (7772.030 cm-1) with weak self-absorption, bright radiation intensity, and large spectral separation range is proved to be suitable for limb-viewing wind detection, due to its advantages of significantly lower cost, risk, and platform requirements. In order to ascertain the wind precision of O19P18, observations by a DASH-type (the Doppler asymmetric spatial heterodyne) instrument are simulated. The simulated results indicate a wind measurement precision of 1-2 m/s over an altitude range of 40 to 70 km in general, and possibly to 2-4 m/s due to a strong dependence on the spectral interference of the scattered sunlight background.