Characterization of the 11-year solar signal using a multiple regression analysis of the ERA-40 dataset

Peer Reviewed

Crooks SA, & Gray LJ

Journal of Climate 18, Issue 7, pages 996-1015, 2005, 10.1175/JCLI-3308.1.

A multiple linear regression analysis of the ERA-40 dataset for the period 1979–2001 has been used to study the influence of the 11-yr solar cycle on atmospheric temperature and zonal winds. Volcanic, North Atlantic Oscillation (NAO), ENSO, and quasi-biennial oscillation (QBO) signatures are also presented. The solar signal is shown to be readily distinguishable from the volcanic signal. The main solar signal is a statistically significant positive response (i.e., warmer in solar maximum) of 1.75 K over the equator with peak values at 43 km and a reversed signal of similar magnitude at high latitudes that is seasonally dependent. Consistent with this is a statistically significant zonal wind response of up to 6 m s−1 in the subtropical upper stratosphere/lower mesosphere that is also seasonally dependent. The wind anomalies are westerly/easterly in solar maximum/minimum. In addition, there is a statistically significant temperature response in the subtropical lower stratosphere that shows similarity in spatial structure to the QBO response, suggesting a possible interaction between the solar and QBO signals in this region. The solar response in tropospheric zonal winds is small but significant, confirming previous studies that indicate a possible modulation of the Hadley circulation.

Keywords: Solar, North Atlantic Oscillation, NAO, El Niño Southern Oscillation, ENSO, Quasi-Biennial Oscillation, QBO
Categories: Antarctic, Arctic, Natural Science