HR: 0800h
AN: PP11B-0533    [Abstracts]
TI: Lessons Learned From the Modern Monsoon Applied to Interpretation of Paleoclimate Records
AU: * Dayem, K E
EM: dayem@colorado.edu
AF: Department of Geological Sciences and Cooperative Institute for Research in Environmental Science University of Colorado, Campus Box 399, Boulder, CO 80309, United States
AU: Battisti, D S
EM: david@atmos.washington.edu
AF: Department of Atmospheric Sciences University of Washington, Box 351640, Seattle, WA 98195, United States
AU: Roe, G H
EM: gerard@ess.washington.edu
AF: Department of Earth and Space Sciences University of Washington, Box 351310, Seattle, WA 98195, United States
AB: Spatial correlations of modern climate records and a description of modern atmospheric dynamics in India and SE Asia illuminate differences between and within the Indian and SE Asian monsoon systems and may improve interpretation of paleoclimate records. Land-sea heating differences and tropical circulation lead to heavy rainfall during the Indian monsoon, whose onset is consistently in June, and whose strength depends on the length of the rainy season and the number of days of rain. The SE Asian monsoon, on the other hand, depends on both mid-latitude and subtropical dynamics. Interaction between the mid-latitude jet and the subtropical high appear to control onset and amounts of springtime rains in South China, shifting northward in summer to bring rains to northern China. Yearly and rainy season precipitation totals in Northern China (near Hulu cave), Southern China (near Dongge cave) and Eastern India are not well correlated. Thus, each paleoclimate record might only describe one part of a monsoon system. Furthermore, in principle, records that are spatially well-separated allow spatial variation within a monsoon system such as that in SE Asia to be interpreted from paleoclimate records. If, as has been suggested, oxygen isotope records from Hulu and Dongge caves record precipitation amount, we do not expect these two records to co-vary over short timescales. Modern temperature records at the two sites do correlate positively however, and short-term trends in oxygen isotope records may be expected to agree if the isotope signal is largely due to temperature variation. The lack of correlations in the oxygen isotope records at decadal to centennial time scales is consistent with the modern observational record. However at longer timescales, local Milankovitch forcing and global climate events appear to dominate the variability at both sites.
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 3354 Precipitation (1854)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting