Changes in upper stratospheric CH4 and NO2 as measured by HALOE and implications for changes in transport
Authors:
- 1 April 1998
- journal article
- Published by American Geophysical Union (AGU) in Geophysical Research Letters
- Vol. 25 (7) , 987-990
Abstract
Measurements from HALOE indicate that there has been a significant decrease in CH4 in the middle to upper stratosphere from 1991–1997. Two dimensional model calculations suggest that a decrease in the tropical upwelling is the most plausible explanation for the CH4 decrease. The changes in CH4 resulting from solar cycle variations or changes in tropospheric CH4 and CFC emission rates are shown to be much smaller than the measured variations from ∼35–65 km. The HALOE measurements of NO2 in the lower stratosphere near the equator also show an increase which is consistent with a reduction in the upward transport rate. Above ∼40 km the NO2 measurements appear to be consistent with the net effect of opposing solar and dynamical trends.Keywords
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