A glacial stalagmite chronology from Nanjing has been established by the TIMS-U series dating and annual band counting methods. The annually layering sequence spanning the 3000-year period from 18179 to 14900 calendar...A glacial stalagmite chronology from Nanjing has been established by the TIMS-U series dating and annual band counting methods. The annually layering sequence spanning the 3000-year period from 18179 to 14900 calendar years before the present (aBP) was analyzed for evidence of East Asian summer monsoon precipitation variability during the Last Glacial Maximum (LGM). Power spectral analysis of the sequence shows a distinct interannual (2—7 years) band of enhanced variability suggestive of El Ni駉-Southern Oscillation (ENSO) teleconnections into East China during the LGM when climatic boundary conditions were different from those of today. The lower frequency bands (4—7 years) variability becomes weaker from 18179 to 14900 aBP, sup-porting the precession forcing model. The reappearance of the ENSO band in the coldest climatic boundary conditions during the Heinrich Event 1, however, suggests the stimula-tion of the enhanced East Asia winter monsoon to the El Ni駉 events.展开更多
A 3000-year-long stalagmite chronology from Hulu Cave near Nanjing was established by counting annual layers under microscope. Based on the 230Th age, this chronology covers the period 24-21 kaBP, within the Last Glac...A 3000-year-long stalagmite chronology from Hulu Cave near Nanjing was established by counting annual layers under microscope. Based on the 230Th age, this chronology covers the period 24-21 kaBP, within the Last Glacial Maximum (LGM). Two proxies, annual layer thickness and gray level were measured along the growth axis of the stalag-mite profile in order to establish a high-resolution East Asian monsoon history during the LGM. The high correlation coefficient (r = 0.55) between the two proxies suggests that both of them were controlled by a common factor, possibly reflecting changes in the strength of summer monsoon circulation and its pre-cipitation. Low frequency variations of the annual layer thickness, ranging from centennial to millennial scales, are approximately in agreement with the 10Be-flux recorded in the Greenland ice core, indi-cating that changes in East Asian monsoon strength might be forced by solar outputs during the LGM pe-riods. In support of this, Fourier power spectrum analysis of the annual layer thickness showed certain decadal to centennial-scale cycles that agree well with the periodicities of solar activity.展开更多
基金the National Natural Science Foundation of China (Grant No. 40225007)
文摘A glacial stalagmite chronology from Nanjing has been established by the TIMS-U series dating and annual band counting methods. The annually layering sequence spanning the 3000-year period from 18179 to 14900 calendar years before the present (aBP) was analyzed for evidence of East Asian summer monsoon precipitation variability during the Last Glacial Maximum (LGM). Power spectral analysis of the sequence shows a distinct interannual (2—7 years) band of enhanced variability suggestive of El Ni駉-Southern Oscillation (ENSO) teleconnections into East China during the LGM when climatic boundary conditions were different from those of today. The lower frequency bands (4—7 years) variability becomes weaker from 18179 to 14900 aBP, sup-porting the precession forcing model. The reappearance of the ENSO band in the coldest climatic boundary conditions during the Heinrich Event 1, however, suggests the stimula-tion of the enhanced East Asia winter monsoon to the El Ni駉 events.
文摘A 3000-year-long stalagmite chronology from Hulu Cave near Nanjing was established by counting annual layers under microscope. Based on the 230Th age, this chronology covers the period 24-21 kaBP, within the Last Glacial Maximum (LGM). Two proxies, annual layer thickness and gray level were measured along the growth axis of the stalag-mite profile in order to establish a high-resolution East Asian monsoon history during the LGM. The high correlation coefficient (r = 0.55) between the two proxies suggests that both of them were controlled by a common factor, possibly reflecting changes in the strength of summer monsoon circulation and its pre-cipitation. Low frequency variations of the annual layer thickness, ranging from centennial to millennial scales, are approximately in agreement with the 10Be-flux recorded in the Greenland ice core, indi-cating that changes in East Asian monsoon strength might be forced by solar outputs during the LGM pe-riods. In support of this, Fourier power spectrum analysis of the annual layer thickness showed certain decadal to centennial-scale cycles that agree well with the periodicities of solar activity.
