Solar and geomagnetic activity effects on climate at regional and global scales: Case study-Romania

We analyze 100-150 years-long temperature and precipitation records from 14 meteorological stations in Romania, in connection with long-term trends in solar and geomagnetic activities. The comparison of solar (sunspot number) and geomagnetic (aa index) parameters with the mean air temperature over the Romanian territory, at interdecadal timescales, shows positive correlation coefficients, while the comparison with the mean precipitation shows negative correlation coefficients. The correlation of climatic parameters seems to be stronger for geomagnetic activity than for solar activity. The Romanian temperature series are examined in the context of other European stations and of averages on the European, northern hemisphere, and global scale, respectively. Long-term (interdecadal and centennial) trends and differences between local trends and average trends for larger areas are discussed. The study indicates that solar and geomagnetic activity effects are present on the 22-year Hale cycle timescale. The temperature variation on this timescale lags the solar/geomagnetic ones by 5-9 years. (C) 2008 Elsevier Ltd. All rights reserved.