Atlantic multidecadal variability and inter-American rainfall
Abstract
Observations of North Atlantic sea surface temperature for 1856-1999 reveal a 65-80 year cycle with a 0.4C range, referred to as the Atlantic Multidecadal Oscillation (AMO). AMO warm phases occurred during 1860-1880 and 1940-1960, and cool phases during 1905-1925 and 1970-1990. Although the signal appears to be global in scope, with a positively correlated co-oscillation in parts of the North Pacific, it is most intense in the North Atlantic and covers the entire basin there. The relationship of the warm and cool phases of the AMO to decadally averaged rainfall over inter-American land regions is examined annually and as a function of season, and the phase influence on ENSO teleconnections is also examined. During AMO warmings most of the United States sees less than normal rainfall, including Midwest droughts in the 1930s and 1950s. Between AMO warm and cool phases, annual mean Mississippi River outflow has a 10% range, while the inflow to Lake Okeechobee, Florida varies by 40%. In some regions, but not in others, the winter patterns of interannual rainfall variability associated with El Niño-Southern Oscillation are significantly changed between AMO phases.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMOS51B0483E
- Keywords:
-
- 1860 Runoff and streamflow;
- 3339 Ocean/atmosphere interactions (0312;
- 4504);
- 3354 Precipitation (1854);
- 4522 El Ni