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A Global Atmospheric Model of Meteoric IronThe first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+ concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.
Document ID
20140010040
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Feng, Wuhu (Leeds Univ. United Kingdom)
Marsh, Daniel R. (National Center for Atmospheric Research Boulder, CO, United States)
Chipperfield, Martyn P. (Leeds Univ. United Kingdom)
Janches, Diego (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hoffner, Josef (Liebniz-Institute of Atmospheric Physics Kuehlungsborn, Germany)
Yi, Fan (Wuhan Univ. China)
Plane, John M. C. (Leeds Univ. United Kingdom)
Date Acquired
July 23, 2014
Publication Date
August 27, 2013
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Volume: 118
Issue: 16
Subject Category
Geophysics
Report/Patent Number
GSFC-E-DAA-TN13254
Funding Number(s)
CONTRACT_GRANT: NSF ATM-05311464
CONTRACT_GRANT: NSF ATM-0525655
CONTRACT_GRANT: NSF ATM-0634650
CONTRACT_GRANT: NSF AST-0908118
CONTRACT_GRANT: NERC grant NE/G019487/1
Distribution Limits
Public
Copyright
Other
Keywords
meteoric inputfunction
Atmosphere
themesosphere