Long-term trends in geomagnetic and climatic variability
Abstract
Causes leading to global mean sea surface temperature (GT) variability and to variations of the global circulation including the North Atlantic Oscillation (NAO) and El Niño (EN) events are examined. Statistically significant correlation coefficients between these variables were found and their relations are discussed with the aim to show possible causes leading to general year-to-year variability and to the global warming. At the same time, the results contribute to the verification of the hypothesis as given in our previous papers. We have suggested a link of processes generated by geomagnetic forcing that is followed by dramatic shifts in the atmospheric circulation patterns. At times of low geomagnetic activity in winter the meridional flow prevails contributing to the strong heat exchange of air between low and high latitudes. The arctic air penetrates from polar areas and participates in the cooling of middle latitudes; the NAO winter index (WI) is negative. At times of high geomagnetic activity the Icelandic low intensifies and influences the strengthening of the zonal flow in the Northern Hemisphere; the NAO WI is positive. A continuous zone of high pressure originates along middle latitudes and a little north-south motion of air takes place. In mid-latitudes above-normal temperatures occur while in polar areas the values are below normal. The strong Australian high at times of low geomagnetic activity seems to initiate EN events while the zonal flow in the Southern Hemisphere intensifies monsoon rains in the Indian Ocean when geomagnetic activity is high. EN and NAO events are shown to take part in the variability of GT. Controversial problems are discussed as well.
- Publication:
-
Physics and Chemistry of the Earth
- Pub Date:
- 2002
- DOI:
- 10.1016/S1474-7065(02)00022-0
- Bibcode:
- 2002PCE....27..427B