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Reevaluating the Use of O 2 a 1 Δ g Band in Spaceborne Remote Sensing of Greenhouse Gases
Author(s) -
Sun Kang,
Gordon Iouli E.,
Sioris Christopher E.,
Liu Xiong,
Chance Kelly,
Wofsy Steven C.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077823
Subject(s) - airglow , remote sensing , nadir , sciamachy , spectrometer , stratosphere , spectral resolution , mesosphere , environmental science , absorption (acoustics) , atmosphere (unit) , spectroscopy , spectral bands , imaging spectrometer , atmospheric sciences , physics , satellite , spectral line , optics , geology , meteorology , astronomy
Although the O 2 a 1 Δ g band has long been used in ground‐based greenhouse gas remote sensing to constrain the light path, it is challenging for nadir spaceborne sensors due to strong mesosphere/stratosphere airglow. Spectroscopic simulations using upper state populations successfully reconstruct the airglow spectra with excellent agreement with SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY limb observations (residual root‐mean‐square <0.7%). The accurate knowledge of airglow spectrum enables retrieval of O 2 ( a 1 Δ g ) number density, volume emission rate, and temperature. For nadir spaceborne observations, the a 1 Δ g airglow will lead to a negative bias of ∼10% to O 2 column, if not considered. However, when properly included, the airglow spectral feature can be adequately separated from O 2 absorption (mean bias <0.1%) at the spectral resolution of modern spaceborne spectrometers.