Rights statement: Copyright 2000 by the American Geophysical Union
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Excitation of the primary tropospheric chemical mode in a global three-dimensional model
AU - Wild, O
AU - Prather, M J
PY - 2000/10/27
Y1 - 2000/10/27
N2 - Coupling of local chemical processes over the globe by atmospheric transport leads to the existence of chemical modes that are a fundamental characterization of global atmospheric chemistry and provide a true description of the atmospheric response to small changes in trace-gas emissions. Such coupled chemistry-transport modes in global tropospheric chemistry are an inherent feature of three-dimensional chemical transport models (CTMs). In CTMs these modes cannot be solved for explicitly, as they have been for the case of low-order, fully linearized systems, but they are investigated here through a series of perturbation experiments. When using meteorological fields that recycle every year, the long-lived modes are readily seen as seasonal decay patterns that e-fold each year. An important application of chemical modes is the study of how emissions of CO and NO excite perturbations to the CH4-like mode, the longest-lived (primary) mode found in tropospheric chemistry (i,e., with fixed stratospheric composition). Perturbation experiments are conducted with the University of California, Irvine, three-dimensional tropospheric CTM to identify this primary tropospheric mode and to determine its five-dimensional structure. The previous demonstrations of a long-lived chemical mode with 1.5 times the lifetime of CH4 are corroborated. The ability of emissions of CO and NO to excite this mode is then demonstrated, and a quantitative evaluation of the indirect effect of CO emissions on the greenhouse gases CH4 and tropospheric O-3 is made, showing that 100 kg of CO is equivalent to 5-6 kg of CH4 emissions.
AB - Coupling of local chemical processes over the globe by atmospheric transport leads to the existence of chemical modes that are a fundamental characterization of global atmospheric chemistry and provide a true description of the atmospheric response to small changes in trace-gas emissions. Such coupled chemistry-transport modes in global tropospheric chemistry are an inherent feature of three-dimensional chemical transport models (CTMs). In CTMs these modes cannot be solved for explicitly, as they have been for the case of low-order, fully linearized systems, but they are investigated here through a series of perturbation experiments. When using meteorological fields that recycle every year, the long-lived modes are readily seen as seasonal decay patterns that e-fold each year. An important application of chemical modes is the study of how emissions of CO and NO excite perturbations to the CH4-like mode, the longest-lived (primary) mode found in tropospheric chemistry (i,e., with fixed stratospheric composition). Perturbation experiments are conducted with the University of California, Irvine, three-dimensional tropospheric CTM to identify this primary tropospheric mode and to determine its five-dimensional structure. The previous demonstrations of a long-lived chemical mode with 1.5 times the lifetime of CH4 are corroborated. The ability of emissions of CO and NO to excite this mode is then demonstrated, and a quantitative evaluation of the indirect effect of CO emissions on the greenhouse gases CH4 and tropospheric O-3 is made, showing that 100 kg of CO is equivalent to 5-6 kg of CH4 emissions.
KW - OBSERVATORY PHOTOCHEMISTRY EXPERIMENT
KW - ORGANIC-COMPOUND EMISSIONS
KW - ATMOSPHERIC CHEMISTRY
KW - CARBON-MONOXIDE
KW - DIAGNOSTIC-TOOL
KW - ONLINE TRACERS
KW - TIME SCALES
KW - TRANSPORT
KW - OZONE
KW - O-3
U2 - 10.1029/2000JD900399
DO - 10.1029/2000JD900399
M3 - Journal article
VL - 105
SP - 24647
EP - 24660
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 0747-7309
IS - D20
ER -