Haifeng Zhu

A 3585-YEAR RING-WIDTH DATING CHRONOLOGY OF QILIAN JUNIPER FROM THE NORTHEASTERN QINGHAI-TIBETAN PLATEAU

This article documents the development of a precisely dated and well-replicated long regional tree-ring width dating chronology for Qilian juniper (Juniperus przewalskii Kom.) from the northeastern Qinghai-Tibetan Plateau. It involves specimens from 22 archeological sites, 24 living tree sites, and 5 standing snags sites in the eastern and northeastern Qaidam Basin, northwestern China. The specimens were cross-dated successfully among different groups of samples and among different sites. Based on a total of 1438 series from 713 trees, the chronology covers 3585 years and is the longest chronology by far in China. Comparisons with chronologies of the same tree species about 200 kin apart suggest that this chronology can serve for dating purposes in a region larger than the study area. This study demonstrates the great potential of Qilian juniper for dendrochronological research.

Tree ring-dated fluctuation history of Midui glacier since the little ice age in the southeastern Tibetan plateau

Fluctuation history of Midui glacier in the southeastern Tibet since the Little Ice Age (LIA) was reconstructed by the dating of lateral and terminal moraines using tree rings. Four conversions of glacier advance/stabilization to retreat were identified at around 1767, 1875, 1924 and 1964. The glacier reached its LIA maximum position at 1767. The fluctuations are consistent with those of other glaciers from the Tibetan Plateau, the Rockies and the Alps, suggesting high spatial coherency of glacier fluctuations in the Northern Hemisphere. Comparison with the summer temperature reconstruction in the southeastern Tibetan Plateau indicated that the Midui glacier fluctuation may be related to temperature variation on the centennial timescale. On the decadal scale, the fluctuation could correspond to cold/warm variation with an 8-year lag on average.

Influence of the Indian Ocean Dipole on tree-ring δ18O of monsoonal Southeast Tibet

We present a newly developed, annually resolved tree-ring cellulose δ18O chronology for the southeastern Tibetan Plateau (TP) from Sikkim larch (Larix griffithii), spanning between 1684 and 2012. Comparisons with local and regional climate data reveal strong positive correlations with monthly sunshine hours, temperature and daily temperature amplitude as well as strong negative correlations with relative humidity, vapor pressure, rain days per month and cloud cover of August. Relationships with local and regional tree-ring δ18O chronologies are stable and highly significant. Over the 20th century, we find no long-term climatic trends. This is consistent with other tree-ring δ18O chronologies of other tree species south of the Himalayas, but contrasts with results from isotope studies north of the Himalayas. This suggests stable macroclimatic flow patterns throughout the last centuries for the southern tree stands. In terms of large-scale climate dynamics, we find evidence of a significant 30-year wave influencing our tree-ring oxygen chronology, most probably induced by the Indian Ocean Dipole and influencing tree-ring oxygen isotope chronologies along the southeastern Himalaya and the southeastern rim of the TP. This pattern is spatially and temporarily consistent among the chronologies and has apparently strengthened during the last century. During periods of strong positive dipole mode activity, the dipole mode index shows positive correlations with the δ18O of tree-rings on the southeastern TP.

Air mass origin signals in δ (18)O of tree-ring cellulose revealed by back-trajectory modeling at the monsoonal Tibetan plateau.

A profound consideration of stable oxygen isotope source water origins is a precondition for an unambiguous palaeoenvironmental interpretation of terrestrial δ18O archives. To stress the influence of air mass origins on widely used δ18O tree-ring chronologies, we conducted correlation analyses between six annually resolved δ18O tree-ring cellulose (δ18OTC

Climatic implications of a 3585-year tree-ring width chronology from the northeastern Qinghai-Tibetan Plateau

\delta ^{18}\textit {O}_{TC}

Millennial temperature reconstruction based on tree-ring widths of Qilian juniper from Wulan, Qinghai Province, China

) chronologies and mean annual air package origins obtained from backward trajectory modeling. This novel approach has been tested for a transect at the southeastern Tibetan plateau (TP), where air masses with different isotopic composition overlap. Detailed examinations of daily precipitation amounts and monthly precipitation δ18O values (δ18OP

August temperature variability in the southeastern Tibetan Plateau since AD 1385 inferred from tree rings

\delta ^{18}\textit {O}_{P}

Tree ring-based February-April temperature reconstruction for Changbai Mountain in Northeast China and its implication for East Asian winter monsoon

) were conducted with the ERA Interim and Laboratoire de Météorologie Dynamique General Circulation Model (LMDZiso) data, respectively. Particularly the southernmost study sites are influenced by a distinct amount effect. Here, air package origin δ18OTC

Early summer temperature reconstruction in the eastern Tibetan plateau since ad 1440 using tree-ring width of Sabina tibetica

\delta ^{18}\textit {O}_{TC}

Little Ice Age glacier fluctuations reconstructed for the southeastern Tibetan Plateau using tree rings

relations are generally weaker in contrast to our northern located study sites. We found that tree-ring isotope signatures at dry sites with less rain days per year tend to be influenced stronger by air mass origin than tree-ring isotope values at semi-humid sites. That implies that the local hydroclimate history inferred from δ18OTC