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On the Relationship of Multiple Solutions in Tropospheric Photochemistry to Observable PhenomenaMultiple steady-state solutions are a fairly robust feature of simplified models of tropospheric photochemistry and have been reported for a range of different modeling assumptions. Multiple solutions occur through a bifurcation as changes in a control parameter induce a transition from low to high NO(x) conditions. The usual control parameters are the sources of NO and of CO, CH4 or non-methane hydrocarbons. Typically, with increasing NO source, bifurcations occur at NO(x). concentrations that are higher than would be expected of even heavily polluted conditions. However, there are other ways of inducing a low NO(x) - high NO(x) transition. In this paper the primary control parameter is solar zenith angle. This is varied throughout the year by computing noontime steady states on successive days. Background NO(x), varied by assuming different NO(x) sources values, is used as a secondary control parameter. It is found that bifurcations can occur from high to low NO(x) conditions, for reasonable background NO(x) levels, as the model progresses through spring and then from low to high NO,, during the progression through fall. A time dependent version of this model has been run for the same parameter values as in the steady state runs. This shows rapid spring and fall transitions between high and low NO(x) states. H2O2, for example, rises from sub-ppb levels to about 2 ppb over a five day period in spring and declines quickly, but less precipitously, in fall. This study supports the suggestions that the rapid change in peroxide concentrations between summer and winter conditions may be understood as a manifestation of different underlying steady-state behavior.
Document ID
20010048417
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Stewart, Richard W.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Einaudi, Franco
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Subject Category
Inorganic, Organic And Physical Chemistry
Meeting Information
Meeting: Fall AGU Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 15, 2000
End Date: December 19, 2000
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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