Deuterium excess record in a southern Tibetan ice core and its potential climatic implications

Abstract

A 55-m long ice core, drilled close to bedrock from Mt. Noijin Kangsang on the southern Tibetan Plateau in summer 2007, was annually dated covering the period of 1864-2006 AD. The stable isotope ratios (d 18 O and dD) of the ice core were measured and thereby the deuterium excess (d) was calculated by d = dD -8*d 18 O for the individual ice samples. Results show that the d values of the ice samples were predominantly controlled by the moisture sources. The significant increasing trend of annual mean d values along the ice core is mainly related to the rapid warming of the tropical Indian Ocean, although the tendency is subjected to the modulation by the westernderived moisture. The decreasing Indian monsoon precipitation on the southern Tibetan Plateau, physically linked with the increasing tropical Indian Ocean SST, reduced the share of monsoon precipitation in the annual total accumulation, making an additional contribution to the significant increase of annual mean d in the Noijin Kangsang ice core with high values during the past 143 years.

Southern Tibetan Plateau ice core δ18O reflects abrupt shifts in atmospheric circulation in the late 1970s

“…From repeated 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 . From low-resolution measurements of δ 18 O and δD (220 merged samples), Zhao et al (2012) observed an increasing trend of deuterium excess. They attributed this signal to a decrease of Indian monsoon precipitation on the southern TP through the reduced fraction of annual mean accumulation provided by summer precipitation (associated with a low deuterium excess, Zhao et al 2012).…”

“…From low-resolution measurements of δ 18 O and δD (220 merged samples), Zhao et al (2012) observed an increasing trend of deuterium excess. They attributed this signal to a decrease of Indian monsoon precipitation on the southern TP through the reduced fraction of annual mean accumulation provided by summer precipitation (associated with a low deuterium excess, Zhao et al 2012). Here, we expand the investigation of the NK water stable isotope record through our new high-resolution δ 18 O data.…”

“…Field observations report no sign of surface wind mixing. Zhao et al (2012) describes in details the ice core drilling and analytical procedures. Below 16 m depth, the ice core density gradually increases to 0.9 g/cm 3 , with no indication of melt or stratigraphic perturbation.…”

“…A number of studies have attributed recent increasing trends in south TP ice core δ 18 O to regional warming (Thompson et al 2000;Yao et al 2006a;Zhao et al 2012), while process-based studies have stressed the importance of changes in precipitation amount and Indian monsoon intensity (Vuille et al 2005;Kaspari et al 2007;Joswiak et al 2010). Some authors have also stressed that spatial patterns are related to changes in air mass trajectories and moisture sources (Tian et al 2003;Johnson and Ingram 2004;Breitenbach et al 2010).…”

Remote Sensing of Glacier Change in the Central Qinghai-Tibet Plateau and the Relationship with Changing Climate

“…On large spatial scales, climate change over the QTP may also be tele-connected with hemispheric or global atmospheric circulations including North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO) [20]. Previous studies suggested that ENSO influences climate over the southern QTP through the link of IM [21,22], while NAO is associated with climate fluctuations over the northern QTP through modulation of westerlies [20,23]. Whether such teleconnections exist over the mid-latitude central QTP and how they affect local climate and glacier variability remain unclear.…”