Atmospheric Heat Transport: Variability, Trends, and the Role of Orography

Abstract

Atmospheric heat transport (AHT) plays a key role role in Earth’s climate. It helps moderate the equator to pole temperature gradient and is instrumental in Earth’s hydrologic cycle. Despite this importance, there are numerous outstanding questions about AHT including what sets its magnitude in today’s climate, its variability over time, and its recent and future trends under global warming. In this dissertation I first show that total AHT is relatively invariant to the addition of large mid-latitude orography due to strong compensation between different components of AHT. I then analyze the temporal variability of AHT. I find that zonally-integrated AHT distributions are nearly Gaussian, with a limited role for extreme events. Lastly, I look at trends in AHT since 1980. I find a strengthening of climatological AHT in the Southern Ocean and less clear hemispheric scale signals in the Northern Hemisphere. Issues with reanalysis precipitation in the tropics creates unreasonable tropical AHT trends in atmospheric reanalysis datasets, with climate models doing a better job of accurately simulating the last 40 years of AHT changes. A principle of compensation emerges in all chapters of this work, where individual AHT components often vary in opposite-signed ways, such that total AHT varies less than individual AHT components.