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| Titel |
The influence of global warming in Earth rotation speed |
| VerfasserIn |
R. Abarca del Rio |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 17, no. 6 ; Nr. 17, no. 6, S.806-811 |
| Datensatznummer |
250013778
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| Publikation (Nr.) |
 copernicus.org/angeo-17-806-1999.pdf |
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| Zusammenfassung |
The tendency of the atmospheric angular
momentum (AAM) is investigated using a 49-year set of monthly AAM data for the
period January 1949-December 1997. This data set is constructed with zonal wind
values from the reanalyses of NCEP/NCAR, used in conjunction with a variety of
operationally produced AAM time series with different independent sources and
lengths over 1976-1997. In all the analyzed AAM series the linear trend is found
to be positive. Since the angular momentum of the atmosphere-earth system is
conserved this corresponds to a net loss of angular momentum by the solid earth,
therefore decreasing the Earth rotation speed and increasing the length of day
(LOD). The AAM rise is significant to the budget of angular momentum of the
global atmosphere-earth system; its value in milliseconds/century (ms/cy) is
+0.56 ms/cy, corresponding to one-third of the estimated increase in LOD (+1.7
ms/cy). The major contribution to this secular trend in AAM comes from the
equatorial Tropopause. This is consistent with results from a previous study
using a simplified aqua-planet model to investigate the AAM variations due to
near equatorial warming conditions. During the same time interval, 1949-1997,
the global marine + land-surface temperature increases by about 0.79 °C/cy,
showing a linear correspondence between surface temperature increase and global
AAM of about 0.07 ms per 0.1 °C. These results imply that atmospheric angular
momentum may be used as an independent index of the global atmosphere's
dynamical response to the greenhouse forcing, and as such, the length of day may
be used as an indirect indicator of global warming.
Key words. Meteorology and atmospheric dynamics
(general circulation) · Geodesy |
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