Solar forcing of the semi-annual variation of length-of-day

We study the evolution of the amplitude A of the semi‐annual variation of the length‐of‐day (lod) from 1962 to 2009. We show that A is strongly modulated (up to 30%) by the 11‐yr cycle monitored by the sunspot number WN. A and WN are anticorrelated, WN leading A by 1‐yr. A is therefore directly corr...

Ausführliche Beschreibung

Gespeichert in:

Bibliographische Detailangaben
Veröffentlicht in:	Geophysical research letters 2010-08, Vol.37 (15), p.n/a
Hauptverfasser:	Le Mouël, Jean-Louis, Blanter, Elena, Shnirman, Mikhail, Courtillot, Vincent
Format:	Artikel
Sprache:	eng
Schlagworte:	Annual variations Climate change Cosmic rays Cryosphere Earth Geodetics length of day Ocean-atmosphere interaction Sciences of the Universe semi-annual line Solar activity solar forcing
Online-Zugang:	Volltext
Tags:	Tag hinzufügen Keine Tags, Fügen Sie den ersten Tag hinzu!

Beschreibung
Zusammenfassung:	We study the evolution of the amplitude A of the semi‐annual variation of the length‐of‐day (lod) from 1962 to 2009. We show that A is strongly modulated (up to 30%) by the 11‐yr cycle monitored by the sunspot number WN. A and WN are anticorrelated, WN leading A by 1‐yr. A is therefore directly correlated with galactic cosmic ray intensity. The main part of the semi‐annual variation in lod is due to the variation in mean zonal winds. We conclude that variations in mean zonal winds are modulated by the solar activity cycle through variations in irradiance, solar wind or cosmic ray intensity.
ISSN:	0094-8276 1944-8007
DOI:	10.1029/2010GL043185