HR: 17:30h
AN: H24B-07    [Abstracts]
TI: Observed trends in the hydroclimatology of Lake Superior from 1948 to 1999: A weakening seasonal cycle
AU: * lenters, J D
EM: jlenters@lssu.edu
AF: Lake Superior State University, School of Environmental and Physical Sciences 650 W. Easterday Ave., Sault Sainte Marie, MI 49783 United States
AB: Water levels in the Laurentian Great Lakes experience a fairly pronounced seasonal cycle as a result of seasonal variations in runoff, evaporation, and other water budget components. Significant changes have been observed in these seasonal lake level cycles since 1860, particularly for Lakes Erie and Ontario, which are rising and falling earlier in the year. A recent analysis of the Lake Superior water budget reveals that this largest of the Great Lakes has also undergone significant changes since 1948. In particular, the seasonal rising and falling of Lake Superior has weakened in amplitude by approximately 20 percent from 1948 to 1999. Changes of this magnitude for such a large lake reflect significant 51-year trends in the monthly mean flux of water into and out of the lake (up to 1360 m3/s). Much of these changes can be attributed to trends in runoff, precipitation, and evaporation, indicating that the regulation of Lake Superior water levels has played a minimal role in the observed changes. An analysis of trends in regional air and water temperatures indicates that regional warming, particularly in the spring and summer, may help to explain some of the observed changes in the seasonal hydrologic cycle.
DE: 1833 Hydroclimatology
DE: 1836 Hydrologic budget (1655)
DE: 1845 Limnology
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting