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This paper estimates air pollution spillover effects in Chinese cities. Estimation of this spillover effect is complicated because neighboring cities share similar business/pollution cycles, and changes in wind direction can be frequent. To circumvent these empirical challenges, we propose a new approach exploiting spatial and temporal variations in PM2.5 concentrations for major cities in China's Eastern Monsoon Region during the monsoon season. We find large pollution spillover effects. Estimates based on our preferred model specification suggest that a city's average PM2.5 concentration increases by 0.33 (or 0.26) units during the winter (or summer) monsoon season, if PM2.5 concentrations in cities upwind of this city increase by one unit. Estimated spillover effects in plain and non-plain regions are 14%–16% larger and 45%–71% smaller, respectively, than the baseline estimates. The percentage contributions of PM2.5 pollution from upwind cities to local PM2.5 levels vary by region and can be as large as 50%. [ABSTRACT FROM AUTHOR]

The present paper provides a scientific assessment of the inter-decadal variability of the Asian summer monsoon and its significant effect on precipitation patterns in China. The paper consists of four parts. The first part shows the observed inter-decadal weakening of the Asian summer monsoon since the end of 1970s. The second part describes the impact of the weakening Asian summer monsoon on precipitation in China, which caused the major monsoon rainbelt to shift southward from North China to South China over about 30 years, with a 60-80 oscillation dominating. The third part projects the future change of the Asian summer monsoon in the warmer climate by using IPCC AR4 climate models. It has been found that major monsoon rainfall belts in East Asia will move northward in the 2040s, with summer precipitation in North China increasing considerably and stably. Finally, in the fourth part, the implication of the adaptation to the above climate change and related water management will be discussed including the water transport engineering project from the Yangtze River to the Yellow River and North China. [ABSTRACT FROM AUTHOR]

Observations at the Shiquanhe and Gaize meteorological stations provide data for analysis of δ18O and δD variations in precipitation for the Ngari (Ali) region, western Tibetan Plateau. Temperature controls δ18O in precipitation in this area. δ18O in precipitation positively correlates with air temperature at the Shiquanhe and Gaize stations, especially for precipitation weighted monthly mean δ18O. The δ18O -- T correlation gradually strengthens from south to north across the western Tibetan Plateau and adjacent regions, with gradual weakening of southwest monsoon activity. The strongest correlation is found at Hetian. There is a poor correlation between δ18O and air temperature in the south at New Delhi because the moisture derives predominantly from the Indian Ocean in summer. The Ngari region exhibits a close relation between δD and δ18O in precipitation samples, similar to stations in adjacent regions and the global meteoric water line. The summer seasonal averaged deuterium excess (d) values increase gradually from south to north across western Tibetan and adjacent areas, resulting from southwest monsoon activity gradually weakening to the north. [ABSTRACT FROM AUTHOR]