Validation of the global distribution of COâ volume mixing ratio in the mesosphere and lower thermosphere from SABER
The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has been measuring the limb radiance in 10 broadband infrared channels over the altitude range from ~â400âkm to the Earth's surface since 2002. The kinetic temperatures and COâ volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3âµm under nonlocal thermodynamic equilibrium (non-LTE) conditions. This paper presents results of a validation study of the SABER COâ VMRs obtained with a two-channel, self-consistent temperature/COâ retrieval algorithm. Results are based on comparisons with coincident COâ measurements made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and simulations using the Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM). The SABER COâ VMRs are in agreement with ACE-FTS observations within reported systematic uncertainties from 65 to 110âkm. The annual average SABER COâ VMR falls off from a well-mixed value above ~80âkm. Latitudinal and seasonal variations of COâ VMRs are substantial. SABER observations and the SD-WACCM simulations are in overall agreement for COâ seasonal variations, as well as global distributions in the mesosphere and lower thermosphere. Not surprisingly, the COâ seasonal variation is shown to be driven by the general circulation, converging in the summer polar mesopause region and diverging in the winter polar mesopause region.
document
https://n2t.org/ark:/85065/d7dz09r3
eng
geoscientificInformation
Text
publication
2016-01-01T00:00:00Z
publication
2015-12-15T00:00:00Z
Copyright 2015 American Geophysical Union.
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