[1] Data from the Global Precipitation Climatology Project (GPCP) covering the period 1979 -2007 are examined for changes of precipitation extremes as a function of global mean temperature by using a new method which focuses on interannual differences rather than time series. We find that the top 10% bin of precipitation intensity increases by about 95% for each degree Kelvin (K) increase in global mean temperature, while 30%-60% bins decrease by about 20% K À1 . The global average precipitation intensity increases by about 23% K À1, substantially greater than the increase of about 7% K À1 in atmospheric water-holding capacity estimated by the Clausius-Clapeyron equation. The large increase of precipitation intensity is qualitatively consistent with the hypothesis that the precipitation intensity should increase by more than 7% K À1 because of the additional latent heat released from the increased moisture. Our results also provide an independent evidence in support for significant increases in the number and/or size of strong global tropical cyclones. However an ensemble of 17 latest generation climate models estimates an increase of only about 2% K À1 in precipitation intensity, about one order of magnitude smaller than our value, suggesting that the risk of extreme precipitation events due to global warming is substantially greater than that estimated by the climate models.

[1] Daily data from reanalyses of the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction (NCEP) are analyzed to study changes in precipitation intensity with respect to global mean temperature. The results are in good agreement with those derived from the Global Precipitation Climatology Project (GPCP) data by Liu et al. (2009), providing an independent verification for large changes in the precipitation extremes: about 100% increase for the annual top 10% heavy precipitation and about 20% decrease for the light and moderate precipitation for one degree warming in the global temperature. These changes can substantially increase the risk of floods as well as droughts, thus severely affecting the global ecosystems. Atmospheric models used in the reanalysis mode, with the benefit of observed wind and moisture fields, appear to be capable of realistically simulating the change of precipitation intensity with global temperature. In comparison, coupled climate models are capable of simulating the shape of the change in precipitation intensity, but underestimate the magnitude of the change by about one order of magnitude. The most likely reason of the underestimation is that the typical spatial resolution of climate models is too coarse to resolve atmospheric convection.

We attempted to identify Asian dust (AD) events between February 2002 and February 2007 in northern Taiwan using aerosol Al measurements. We subsequently used the results to propose a criterion for defining AD events. A total of 30 AD events were detected based on Al spiking concentrations, and these occurred frequently in 2002 and 2006. The dust plumes that were identified occurred between November and April, which were concentrated in February, March, and April. There were 35 dusty days, which accounted for 1.89% of the whole study period, and for 3.75% when considering only November through April. The seasonality of atmospheric Al is quite evident, reaching a maximum in spring and winter and a minimum in summer. This pattern is related to the long‐range transport of AD in the northeasterly monsoon and the cease of AD contributions, the efficient removal by heavy rain, and effective mixing in summer. According to air‐mass trajectory analysis, the primary dust regions are located in and around the Gobi Desert and Loess Plateau. The geometric mean concentration of the data set excluding the AD cases is 502 ng m−3 with a geometric standard deviation (GSD) of 2.8. On the basis of our success in identifying the major AD events, the “geometric mean ×2 GSD” (i.e., 2800 ng m−3 in our study area) is proposed as a straightforward criterion to define the significant AD event. As such, the statistic‐based criterion could be applicable for other areas.

Significant increases of heavy precipitation and decreases of light precipitation have been reported over widespread regions of the globe. Global warming and effects of anthropogenic aerosols have both been proposed as possible causes of these changes. We examine data from urban and rural meteorological stations in eastern China (1955China ( -2011 and compare them with Global Precipitation Climatology Project (GPCP) data and reanalysis data in various latitude zones to study changes in precipitation extremes. Significant decreases in light precipitation and increases in heavy precipitation are found at both rural and urban stations, as well as low latitudes over the ocean, while total precipitation shows little change. Characteristics of these changes and changes in the equatorial zone and other latitudes suggest that global warming rather than aerosol effects is the primary cause of the changes. In eastern China, increases of annual total dry days (28 days) and 10 consecutive dry days (36%) are due to the decrease in light precipitation days, thereby establishing a causal link among global warming, changes in precipitation extremes, and higher meteorological risk of floods and droughts. Further, results derived from the GPCP data and reanalysis data suggest that the causal link exists over widespread regions of the globe.

[1] Dichotomous (PM 2.5 -10 and PM 2.5 modes) and size-resolved marine aerosols collected during the northeastern monsoon on two wintertime cruises in the subtropical South China Sea (SCS) were analyzed for water-soluble ions. During the sampling periods the study region was under the influence of strong pollution originating primarily from the Asian continent. Elevated levels of non-sea-salt sulfate and ammonium ions of up to 4.5 and 1.2 mg/m 3 , respectively, were observed, indicating that the SCS is now substantially contaminated by massive amounts of air pollutants most likely from China and South/Southeast Asia. The non-sea-salt sulfate to nitrate mass ratios reaching 3.8 ± 1.9 are much larger than those (approximately 2) in and around East Asia and the western Pacific Ocean, suggesting that the Asian outflow aerosols measured in the SCS experienced different traveling history from those in the vicinity of source regions. High chloride depletion (Cl-depletion) measured in the SCS marine aerosols was, on average, 30% for coarse-mode particles and nearly 90% for fine-mode particles. Cldepletion is size-dependent, and maximizes in submicrometer particles (i.e., Cl has almost been completely lost). Acid displacement is responsible for the observed high Cldepletion: nitrate substitution accounts for the coarse-mode depletion, whereas sulfate substitution accounts for the fine-mode depletion. The acid displacement of sea salt aerosols may be related to a variety of factors, especially the substantial air pollution, which is discussed in detail in this paper. On cloudy/rainy days, fine-mode aerosol samples have moderate Cl-depletion (i.e., $40-50%), in contrast to nearly complete Cl loss on sunny days, presumably indicating that photochemical reactions would play a key role in the Cl-deficit; however, it merits further investigation as the available samples were limited.