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Validation of the global distribution of CO 2 volume mixing ratio in the mesosphere and lower thermosphere from SABER
Author(s) -
Rezac L.,
Jian Y.,
Yue J.,
Russell J. M.,
Kutepov A.,
Garcia R.,
Walker K.,
Bernath P.
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd023955
Subject(s) - thermosphere , mesopause , mesosphere , atmospheric sciences , environmental science , atmosphere (unit) , depth sounding , radiance , polar night , mixing ratio , climatology , stratosphere , remote sensing , meteorology , ionosphere , geology , physics , geophysics , oceanography
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 ~ 400 km to the Earth's surface since 2002. The kinetic temperatures and CO 2 volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3 µm under nonlocal thermodynamic equilibrium (non‐LTE) conditions. This paper presents results of a validation study of the SABER CO 2 VMRs obtained with a two‐channel, self‐consistent temperature/CO 2 retrieval algorithm. Results are based on comparisons with coincident CO 2 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 CO 2 VMRs are in agreement with ACE‐FTS observations within reported systematic uncertainties from 65 to 110 km. The annual average SABER CO 2 VMR falls off from a well‐mixed value above ~80 km. Latitudinal and seasonal variations of CO 2 VMRs are substantial. SABER observations and the SD‐WACCM simulations are in overall agreement for CO 2 seasonal variations, as well as global distributions in the mesosphere and lower thermosphere. Not surprisingly, the CO 2 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.