Abstract:
The Atlantic Multi-decadal Variability (AMV) depicts the swings of North Atlantic basin-wide sea surface temperature (SST) between the warm and cold phases on a multi-decadal time scales. The 20th Century instrumental record indicates a relative cold period in the beginning of the 20th Century, a warm period in the 40s and 50s, another cold period in the 70s and 80s, followed by the recent warming period. There are limited understanding of the physical mechanisms that give rise to decadal and multidecadal climate variability, although it is often thought to be connected to the changes in Atlantic Meridional Overturning Circulation (AMOC). In this talk, I will give a brief overview of the AMV in observations and models and their climate impacts, particularly on North American drought and the Atlantic hurricane intensity.
The frequency and severity of droughts across North America has been modulated by the phase of the Atlantic Multidecadal Variability (AMV) over the historical period. The decadal oscillations in U.S. West hydroclimate (associated with ENSO) reach extreme severity during the warm and neutral phases of AMV, such as in the 1930s and the 1950s when the U.S. Great Plains and the Southwest experienced the extremely dry conditions of the Dust Bowl and the persistent Texas drought, respectively. Similarly, the Atlantic hurricane intensity responds to North Atlantic SST in a way that is much more effective than the anthropogenically forced warming, thus making AMV a very important contributor to the recent increased hurricane intensity in the Atlantic basin.
