comparative study
; correlation
; decadal variation
; drought
; greenhouse gas
; isotopic composition
; oxygen isotope
; paleoenvironment
; sea surface temperature
; solar radiation
; speleothem
; tree ring
; Pacific Ocean
; Pacific Ocean (North)
英文摘要:
Precipitation in southwestern North America has exhibited significant natural variability over the past few thousand years. This variability has been attributed to sea surface temperature regimes in the Pacific and Atlantic oceans, and to the attendant shifts in atmospheric circulation patterns. In particular, decadal variability in the North Pacific has influenced precipitation in this region during the twentieth century, but links to earlier droughts and pluvials are unclear. Here we assess these links using δ 18 O data from a speleothem from southern California that spans AD 854-2007. We show that variations in the oxygen isotopes of the speleothem correlate to sea surface temperatures in the Kuroshio Extension region of the North Pacific, which affect the atmospheric trajectory and isotopic composition of moisture reaching the study site. Interpreting our speleothem data as a record of sea surface temperatures in the Kuroshio Extension, we find a strong 22-year periodicity, suggesting a persistent solar influence on North Pacific decadal variability. A comparison with tree-ring records of precipitation during the past millennium shows that some droughts occurred during periods of warmth in the Kuroshio Extension, similar to the instrumental record. However, other droughts did not and instead must have been influenced by other factors. Finally, we find a significant increase in sea surface temperature variability over the past 150 years, which may reflect an influence of greenhouse gas concentrations on variability in the North Pacific.
Department of Earth System Science, University of California, Irvine, CA 92697, United States; Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT 84112, United States; CIRES/ATOC, University of Colorado, Boulder, CO 80309, United States; Department of Earth Science, California State University, Dominguez Hills, Carson, CA 90747, United States; Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455, United States; Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China
Recommended Citation:
Mccabe-Glynn S.,Johnson K.R.,Strong C.,et al. Variable North Pacific influence on drought in southwestern North America since AD 854[J]. Nature Geoscience,2013-01-01,6(8)