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Stratospheric CO at tropical and mid‐latitudes: ATMOS measurements and photochemical steady‐state model calculations
Author(s) -
Rinsland C. P.,
Salawitch R. J.,
Osterman G. B.,
Irion F. W.,
Sen B.,
Zander R.,
Mahieu E.,
Gunson M. R.
Publication year - 2000
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 - 10.1029/1999gl011184
Subject(s) - mixing ratio , latitude , tropopause , atmospheric sciences , stratosphere , environmental science , middle latitudes , climatology , ozone , troposphere , meteorology , physics , geology , geodesy
We characterize the spring and fall stratospheric distribution of CO at 49°N‐55°S latitude from ATMOS profiles measured during 4 shuttle flights. Measured mixing ratios increase with potential temperature (θ) from 12 ppbv (10 −9 per unit volume) at 525 K, to 30–40 ppbv at 1750 K with only minor variations with latitude and season at a θ level. Evidence for some confinement near 1150 K in the developing November 1994 vortex is indicated from comparison of CO and N 2 O horizontal gradients. Measured CO mixing ratios at the tropical tropopause are a factor of 10 higher than values calculated with a steady‐state model using standard photochemistry constrained by correlative temperatures and pressures, and ATMOS measurements including CH 4 as inputs. Differences decrease with latitude at constant θ and are <20% at 800 K and all latitudes, where the CO photochemical lifetime is 40–50 days.