Climate Response to Solar Variation: Cyclic and Secular

Abstract

The radiation emitted by the Sun varies both cyclically and secularly. We first study in this thesis the response of the Earth's temperature to the 11-year solar cycle at the surface and in the troposphere. Then we study multi-century long climate response and attribute it to various causes, including the Sun. The solar variation is one of the many factors that cause climate change on Earth. However, the solar cycle response in the atmosphere has not been consistently identified due to its small amplitude compared to other climate variability. A comprehensive study of extracting the solar cycle signal from various global temperature records is presented in this dissertation. Specifically, a clean decadal solar cycle response is proved statistically to exist in the 150-year-long sea surface temperature with the contamination by other climate phenomena quantified small. The existence and the statistical significance of the zonal-mean global temperature response to the 11-year solar cycle are also established throughout the troposphere and parts of the lower stratosphere, which reveals a spatial pattern consistent with a "bottom-up" mechanism that explains the effects of solar forcing on the atmosphere. Evidence is also found that the Sun is not to blame for global warming. These observational findings can be used for calibrating models to improve their ability to make more reliable predictions on Earth's climate change.