QBO in solar wind speed and its relation to ENSO

by Klemens Hocke

Abstract:

Corotating coronal holes of the Sun induce fluctuations of the solar wind speed in the vicinity of the Earth. The fluctuations of solar wind speed are closely correlated with geomagnetic activity. Solar wind speed has been monitored by satellites since the mid 1960s. The long-term series of solar wind speed show enhanced amplitudes at the solar rotation period 27.3 days and at its harmonics 13.6 and 9.1 days. The amplitude series are modulated by a quasi-biennial oscillation (QBO) with a period of 1.75a (21 months) as bispectral analysis reveals. A 1.75a QBO component is also present in the equatorial, zonal wind of the stratosphere at 30 hPa, in addition to the well-known QBO component at the period 2.4a (29 months). The solar wind QBO may influence the stratospheric QBO, the global electric circuit, and cloud cover by modulation of ionospheric electric fields, cosmic ray flux, and particle precipitation. For a further analysis, the series of solar wind speed fluctuations are bandpass-filtered at the period 1.75a. The filtered series provide the amplitude of the solar wind QBO as function of time. The maxima of the solar wind QBO series are correlated with those of the ENSO index. The analysis indicate that the solar wind QBO may trigger the ENSO activity. This result is speculative at the moment. However, the focus of the study is on the investigation of the long-term modulations of the short-term (4–45 days) oscillations of the solar wind speed which are quite unexplored yet.

According to a study in Geographical Research  published by Wiley-Blackwell, the droughts in eastern Australia are related to the solar magnetic phases and not the greenhouse effect.

The study titled “Exploratory Analysis of Similarities in Solar Cycle Magnetic Phases with Southern Oscillation Index Fluctuation in Eastern Australia” uses data from 1876 to the present to examine the correlation between solar cycles and the extreme rainfall in Australia.

It finds that the Southern Oscillation Index (SOI) – the basic tool for forecasting variations in global and oceanic patterns – and rainfall fluctuations recorded over the last decade are similar to those in 1914 -1924.

PHYSORG.com: ‘Researchers Use Sun Cycle to Predict Rainfall Fluctuations’

Exploratory Analysis of Similarities in Solar Cycle Magnetic Phases with Southern Oscillation Index Fluctuations in Eastern Australia

ROBERT G.V. BAKER, Division of Geography and Planning, University of New England, Armidale, NSW 2351, Australia.

KEYWORDS
Southern Oscillation Index • sunspot cycle • Hale Cycle • Gleissberg charting • rainfall patterns • drought prediction • climate change

ABSTRACT

There is growing interest in the role that the Sun’s magnetic field has on weather and climatic parameters, particularly the ~11 year sunspot (Schwab) cycle, the ~22 yr magnetic field (Hale) cycle and the ~88 yr (Gleissberg) cycle. These cycles and the derivative harmonics are part of the peculiar periodic behaviour of the solar magnetic field. Using data from 1876 to the present, the exploratory analysis suggests that when the Sun’s South Pole is positive in the Hale Cycle, the likelihood of strongly positive and negative Southern Oscillation Index (SOI) values increase after certain phases in the cyclic ~22 yr solar magnetic field. The SOI is also shown to track the pairing of sunspot cycles in ~88 yr periods. This coupling of odd cycles, 23–15, 21–13 and 19–11, produces an apparently close charting in positive and negative SOI fluctuations for each grouping. This Gleissberg effect is also apparent for the southern hemisphere rainfall anomaly. Over the last decade, the SOI and rainfall fluctuations have been tracking similar values to that recorded in Cycle 15 (1914–1924). This discovery has important implications for future drought predictions in Australia and in countries in the northern and southern hemispheres which have been shown to be influenced by the sunspot cycle. Further, it provides a benchmark for long-term SOI behaviour.

This paper is published in the December 2008 issue of Geographical Research Vol. 46 Issue 4.