Yetang Wang

A Comparison of Antarctic Ice Sheet Surface Mass Balance from Atmospheric Climate Models and In Situ Observations

AbstractIn this study, 3265 multiyear averaged in situ observations and 29 observational records at annual time scale are used to examine the performance of recent reanalysis and regional atmospheric climate model products [ERA-Interim, JRA-55, MERRA, the Polar version of MM5 (PMM5), RACMO2.1, and RACMO2.3] for their spatial and interannual variability of Antarctic surface mass balance (SMB), respectively. Simulated precipitation seasonality is also evaluated using three in situ observations and model intercomparison. All products qualitatively capture the macroscale spatial variability of observed SMB, but it is not possible to rank their relative performance because of the sparse observations at coastal regions with an elevation range from 200 to 1000 m. In terms of the absolute amount of observed snow accumulation in interior Antarctica, RACMO2.3 fits best, while the other models either underestimate (JRA-55, MERRA, ERA-Interim, and RACMO2.1) or overestimate (PMM5) the accumulation. Despite underestima...

Abundance and community of snow bacteria from three glaciers in the Tibetan Plateau

Bacterial abundance and diversity in snow of East Rongbuk, Laohugou and Hailuogou glaciers on the Tibetan Plateau were investigated through epifluorescence microscope and denaturing gradient gel electrophoresis. Cell abundance ranged from 4.0 x 10(3) to 290.2 x 10(3) cells/mL. The phylogenetic trees placed the 16S rRNA sequences in four major groups: Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Brevundimonas, Flavobacterium, Hymenobacter, Bacillus, Polaromonas, Rhodoferax and Streptomyces were widely distributed bacteria in glaciers from different cold regions. The remaining five genera of Hylemonella, Delftia, Zoogloea, Blastococcus and Rhodococcus were endemism, only recovered from our investigated glaciers. It is proposed that the three glaciers on the Tibetan Plateau provide a specific ecological niche for prolonging survival of diverse microbial lineages.

Possible recent warming hiatus on the northwestern Tibetan Plateau derived from ice core records.

Many studies have reported enhanced warming trend on the Tibetan Plateau (TP), even during the warming hiatus period. However, most of these studies are based on instrumental data largely collected from the eastern TP, whereas the temperature trend over the extensive northwestern TP remains uncertain due to few meteorological stations. Here we combined the stable isotopic δ18O record of an ice core recovered in 2012 from the Chongce glacier with the δ18O records of two other ice cores (i.e., Muztagata and Zangser Kangri) in the same region to establish a regional temperature series for the northwestern TP. The reconstruction shows a significant warming trend with a rate of 0.74 ± 0.12 °C/decade for the period 1970–2000, but a decreasing trend from 2001 to 2012. This is consistent with the reduction of warming rates during the recent decade observed at the only two meteorological stations on the northwestern TP, even though most stations on the eastern TP have shown persistent warming during the same period. Our results suggest a possible recent warming hiatus on the northwestern TP. This could have contributed to the relatively stable status of glaciers in this region.

Abundance and Diversity of Glacial Bacteria on the Tibetan Plateau with Environment

The relation of glacial microorganism and their living environment is concerned but less understood for both glaciologists and microbiologists. Here we present the results about glacial snow bacteria from 3 glaciers on the Tibetan Plateau. The concentrations and diversity of bacteria collected from snow pit samples of East Rongbuk, Laohugou and Hailuogou glaciers on the Tibetan Plateau were investigated by epifluorescence microscope, denaturing gradient gel electrophoresis and Shannon-Weaver index. Concentrations and community diversity of bacteria in the East Rongbuk glacier with lower concentration and smaller size of microparticle were lower than in the Laohugou with higher concentration and larger size of microparticle. Bacterial concentration in East Rongbuk Glacier was close to that in polar regions, suggesting that Mt. Everest is a bacterial background for remote regions away from direct influence of anthropogenic sources. In addition, altitude difference was another factor for higher concentrations and community diversity of bacteria in Hailuogou and Laohugou glaciers than in East Rongbuk Glacier. The highest concentrations and community diversity of bacteria in Hailuogou Glacier were attributed to its most diverse atmospheric circulations and highest temperature among the 3 glaciers. We suggest a complicated correlation between glacial bacteria and their regional living environments.

Enhanced Recent Local Moisture Recycling on the Northwestern Tibetan Plateau Deduced From Ice Core Deuterium Excess Records

Local moisture recycling plays an essential role in maintaining an active hydrological cycle of the Tibetan Plateau (TP). Previous studies were largely limited to the seasonal time scale due to short and sparse observations, especially for the northwestern TP. In this study, we used a two-component mixing model to estimate local moisture recycling over the past decades from the deuterium excess records of two ice cores (i.e., Chongce and Zangser Kangri) from the northwestern TP. The results show that on average almost half of the precipitation on the northwestern TP is provided by local moisture recycling. In addition, the local moisture recycling ratio has increased evidently on the northwestern TP, suggesting an enhanced hydrological cycle. This recent increase could be due to the climatic and environmental changes on the TP in the past decades. Rapid increases in temperature and precipitation have enhanced evaporation. Changes of land surface of plateau have significantly increased evapotranspiration. All of these have intensified local moisture recycling. However, the mixing model used in this study only includes a limited number of climate factors. Some of the extreme values of moisture recycling ratio could be caused by large scale atmospheric circulation and other climatic and weather events. Moreover, the potential mechanisms for the increase in local recycling need to be further examined, since the numeric simulations from climate models did not reproduce the increased contribution of local moisture recycling in precipitation.

Recent Kyagar glacier lake outburst flood frequency in Chinese Karakoram unprecedented over the last two centuries

Kyagar glacier lake outburst floods (GLOFs) have long been a serious nature hazard in Yarkant river basins of the Chinese Karakoram, threatening more than one million people. Between 1810 and 2018, 34 Kyagar GLOF events have been recorded, of which 26 occurred from 1960 onwards and their occurrence frequency reaches at least three times in each decade. An early warning system established in 2011 has successfully predicted the Kyagar GLOF events in 2015, 2016, 2017 and 2018, which provides an important reference for the monitoring and risk pre-evaluation of the GLOFs in Karakoram.

Corrigendum: Possible recent warming hiatus on the northwestern Tibetan Plateau derived from ice core records

This corrects the article DOI: 10.1038/srep32813.