[1] The atmospheric water vapor transport for summer precipitation over the southeastern Tibetan Plateau (hereafter TP) during 1979-2002 is examined by using five precipitation data sets and three reanalysis data sets. The multidata ensemble mean shows that under climate mean conditions, TP is a moisture sink in summer, having a net moisture convergence of 4 mm/day. The climatological water vapor transport from the southern boundary, which originates from the Indian Ocean and the Bay of Bengal, dominates the summer precipitation over the southeastern TP. It is estimated that the water vapor from the western boundary along the southern edge of the TP is about 32% of that from the southern boundary. The summer precipitation over the southeastern TP exhibits strong interannual variability, with a standard deviation of 1.3 mm/day, but no significant long-term trend. The water vapor transport for the interannual variability of summer rainfall over the southeastern TP mainly comes from the western boundary of the TP, which is originally from lower latitudes. An excessive rainfall anomaly of 1 mm/day over the southeastern TP is associated with an anomalous water vapor input of 138 (104) kg/m/s from the western (southern) boundary. It is worth noting that the quantitative analysis in this study is determined by the setting of the domain. The interannual variability of summer precipitation over the southeastern TP is dominated by an anomalous anticyclone over the northern Indian subcontinent and the Bay of Bengal, which intensifies the water vapor transport along the southern edge of the TP and leads to more water vapor convergence over the southeastern TP, thus the excessive rainfall in the area.Citation: Feng, L., and T. Zhou (2012), Water vapor transport for summer precipitation over the Tibetan Plateau: Multidata set analysis,

Cryoconite in mountain glaciers plays important roles in glacial ablation and biogeochemical cycles. In this study, the composition and sources of dissolved organic matter (DOM) in cryoconite from the ablation regions of two Tibetan Plateau glaciers were determined using electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and fluorescence spectrometry. A marked absorbance between 300 and 350 nm in the DOM absorption spectra was observed which was consistent with microbe-derived mycosporine-like amino acids. Fluorescence excitation-emission matrices showed that DOM had intense signals at protein-like substance peaks and weak signals at humic-like substance peaks. The high-resolution mass spectra of FT-ICR-MS showed cryoconite DOM from both glaciers contained diverse lignins, lipids, proteins, and unsaturated hydrocarbons. The lipids and proteins were consistent with material from microbial sources, and the lignins and unsaturated hydrocarbons were probably from vascular plant material supplied in atmospheric aerosols and debris from around the glaciers. Almost one-third of the identified DOM molecules had low C/N ratios (≤20), indicating their high bioavailability. Using a conservative cryoconite distribution on Chinese mountain glacier surfaces (6%) and an average debris mass per square meter of cryoconite (292 ± 196 g m), we found that the amount of DOC produced in cryoconite on Chinese glaciers as much as 0.23 ± 0.1 Gg per cryoconite formation process. This dissolved organic carbon may absorb solar radiation, accelerate glacial melting, and be an important source of bioavailable DOM to proglacial and downstream aquatic ecosystems.