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NO x production due to energetic particle precipitation in the MLT region: Results from ion chemistry model studies
Author(s) -
Nieder Holger,
Winkler Holger,
Marsh Daniel R.,
Sinnhuber Miriam
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019044
Subject(s) - thermosphere , ion , atmospheric chemistry , mesopause , mesosphere , ionization , chemistry , dissociation (chemistry) , atomic physics , analytical chemistry (journal) , atmospheric sciences , physics , ionosphere , ozone , environmental chemistry , organic chemistry , astronomy , stratosphere
Production of neutral species such as NO x (N, NO, and NO 2 ) during particle‐induced ionization events plays an important role in the chemistry of the mesosphere and lower thermosphere (MLT) region, especially in high latitudes. The effective production rate of NO x is composed of the direct production in reactions associated with the ionization or dissociation process and of indirect production during subsequent ionic reactions and recombination. A state of the art ion chemistry model is used to study the dependence of the effective production rate of NO x on several atmospheric parameters such as density, temperature, and abundance of atmospheric constituents and trace gases. The resulting effective production rates vary significantly, depending on the atmospheric state, and reach values between 1.2 NO x per ion pair in the lower mesosphere and 1.9 NO x per ion pair in the lower thermosphere. In this paper, an alternative approach to obtain realistic NO x production rates without running a full ion chemistry model is discussed; a database setup and readout system is used to replace ion chemistry calculations. It is compared to the full ion chemistry model and to a thermospheric reduced ion chemistry model combined with constant rate estimation below the mesopause. Database readout performs better than the constant estimate at all altitudes, where above 100km reduced ion chemistry better reproduces full ion chemistry, but database readout performs better in terms of numerical cost.