The influence of large scale climate variability on winter precipitation extremes over the North America

The North America climate is strongly influenced by large scale climate variability, such as El Nino/Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO). The connections between seasonal precipitation totals over the region and those large-scale variability are relatively well understood. However, there are not many studies addressing the impacts of those large-scale variability on precipitation extremes. This study attemps to identify the statistical relationship between maximum daily precipitation in winter and large scale climate variability represented by ENSO, PDO, and NAO, by conducting extreme value modelling with ENSO, PDO, and NAO indices being co-variates. It was found that the ENSO, PDO, and NAO indeed have profound impacts on winter extreme precipitation. For exmaple, enhanced extreme precipitation occurs in the Pacific and Atlantic coasts of the North America in the El Nino years.