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The epidemics of cholera are impacted by many climatic and environmental factors such as precipitation, temperature, elevation and so on. The paper analyzed the suitable degree of V. cholerae in China using MaxEnt based on some geographic and climatic factors, and predicted the cholera risk in each district of China according to the suitable degree. The result shows that the areas in coastal southeast, central China and western Sichuan Basin are relatively suitable for V. cholerae and the suitable degree is higher in the Xinjiang Basin than in surrounding areas. The variables of precipitation, temperature and DEM are three main environmental risky factors that affecting the distribution of cholera in China. The variables of relative humidity, the distance to the sea and air pressure also have impacts on cholera, but sunshine duration and drainage density have little impact. The AUC value of MaxEnt based model is above 0.9 which indicates a high accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau using tree-ring records. Tree-ring samples were collected from the Hengduan Mountains in the southeastern part of the Qinghai-Tibet Plateau, China. A nearly 500-year chronology was developed using tree-ring width records. Correlation analysis shows moisture is the main factor limiting tree growth in this region. Ring-widths were significantly positively correlated with the Palmer Drought Severity Index (PDSI) and precipitation in many months. The highest correlation coefficient was found between the annual growth of trees and precipitation from the previous September to the current June (0.738). Based on this relationship, we reconstructed the precipitation history from 1509 to 2006. The reconstruction explains 54.4% ( R=53.5%, N=49, F=56.12) of the actual precipitation variation during the calibration period (1958-2006). During the reliable period of the reconstruction (1549-2006), some low-frequency climate signals are included, indicating this region has been getting wetter in the last 20 years. The reconstruction documents six apparently dry and five pluvial periods and the 17th century dry period lasted longer than any other. When compared with other recent studies, this study and these earlier reconstructions show a similar trend in the variation of drought and pluvial. Further spatial correlation analysis confirms that the reconstructed precipitation adequately represents the rainfall history of the entire Hengduan Mountain area. The Multi-taper method, a type of spectral analysis, reveals that precipitation in this area had significant ( P<0.01) spectral peaks at 3-5 a, 60 a and 79-85 a. [ABSTRACT FROM AUTHOR]

Climate and tectonism are both particularly intense in the Yarlung Zangbo (Tsangpo) Great Canyon in the eastern Himalayan syntaxis, which is characterized by the most rapid landscape evolution of anywhere in the world. Thus, the eastern Himalayan syntaxis is one of the best locations to study the interactions between climate and tectonics. This paper investigates the cooling ages of the Doxong La-Baibung profile using apatite fission track (AFT) dating on 11 bedrock samples at elevations ranging from 4210 to 710 m. There are topographic, climatic, metamorphic, and thermochronological gradients in the profile, providing good conditions to study interactions between climate and tectonics. AFT ages ranged from 4.6±0.6 Ma to 1.7±0.3 Ma, and the mean fission track lengths ranged from 11.0 to 12.4 µm. It was found that the cooling rates revealed by AFT ages increased with decreasing elevation. However, the tendency of the cooling rates revealed by the 40Ar-39Ar ages was different from that indicated by the AFT ages. Moreover, for most districts of the eastern Himalayan syntaxis, the compiled AFT age distribution correlates well with the annual average precipitation, indicating the coupling of the cooling and erosion rates of the near-surface rock and precipitation. The geothermal history modeling results indicate an obvious increase in the cooling and erosion rate between 1.0 and 0.5 Ma. This age is consistent with other research findings for this time, when the vapor channel of the Yarlung Zangbo Great Canyon began to take effect. These evidences suggest that climate, especially precipitation, has acting as a key factor influencing the rapid cooling and erosion in the Yarlung Zangbo Great Canyon since 1-0.5 Ma. [ABSTRACT FROM AUTHOR]

This study analyses the decadal changes in winter precipitation and extreme precipitation in a warming environment in China. The results show that, together with a trend of winter warming in China, winter precipitation and extreme precipitation in the region are also increasing. In addition, concurrent with the decadal warming shift that occurred in the mid-1980s, precipitation and extreme precipitation both increased significantly. Quantitative analysis shows that precipitation and extreme precipitation increased at rates of 9.7% and 22.6% per 1°C of surface warming in China. This rate of precipitation increase is greater than the global mean, which indicates that precipitation in China is highly sensitive to climate warming and further highlights the importance of studying regional responses to climate warming. The fact that extreme precipitation is increasing at a higher rate than precipitation implies that winter precipitation in China will increasingly be of more extreme type in the context of global warming, which could partly explain why there have recently been a number of record-breaking extreme snowfall events in China. [ABSTRACT FROM AUTHOR]

Climate extremes and changes in eastern China are closely related to variations of the East Asian summer monsoon and corresponding atmospheric circulations. The relationship between frequencies of temperature and precipitation extremes in China during the last half century is investigated using Singular Value Decomposition analysis. During 1980-1996, there was a typical pattern with fewer hot days and more precipitation extremes in the northern part of eastern China, and more hot days and fewer precipitation extremes in the southern part. This geographic pattern tended to reverse after 1997, with fewer hot days and more extreme precipitation days south of the Yangtze River and vice versa to the north. Differences in atmospheric circulation between the former and latter periods are presented. We conclude that a mid-level anomalous high/low, upper-level anomalous easterlies/westerlies over the north/south of eastern China, a weakened East Asian summer monsoon and associated upper-tropospheric center of cooling (30°N, 110°E) are all favorable for the changes in frequencies of temperature and precipitation extremes. [ABSTRACT FROM AUTHOR]

Climate change in the 21st century over China is simulated using the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3). The model is one-way nested within the global model CCSR/NIES/FRCGC MIROC3.2_hires (Center for Climate System Research/National Institute for Environmental Studies/Frontier Research Center for Global Change/Model for Interdisciplinary Research on Climate). A 150-year (1951-2100) transient simulation is conducted at 25 km grid spacing, under the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A1B scenario. Simulations of present climate conditions in China by RegCM3 are compared against observations to assess model performance. Results show that RegCM3 reproduces the observed spatial structure of surface air temperature and precipitation well. Changes in mean temperature and precipitation in December-January-February (DJF) and June-July-August (JJA) during the middle and end of the 21st century are analyzed. Significant future warming is simulated by RegCM3. This warming becomes greater with time, and increased warming is simulated at high latitude and high altitude (Tibetan Plateau) areas. In the middle of the 21st century in DJF, a general increase of precipitation is found in most areas, except over the Tibetan Plateau. Precipitation changes in JJA show an increase over northwest China and a decrease over the Tibetan Plateau. There is a mixture of positive and negative changes in eastern China. The change pattern at the end of the century is generally consistent with that in mid century, except in some small areas, and the magnitude of change is usually larger. In addition, the simulation is compared with a previous simulation of the RegCM3 driven by a different global model, to address uncertainties of the projected climate change in China. [ABSTRACT FROM AUTHOR]

Frequent winter snowstorms have recently caused large economic losses and attracted wide attention. These snowstorms have raised an important scientific question. Under scenarios of future global warming, will winter precipitation in China increase significantly and produce more snow in the north? Using Coupled Model Intercomparison Project phase 3 (CMIP 3) model projections under the Special Report on Emissions Scenario A1B scenario, we generated a possible future Arctic condition, the summer (September) 'ice-free Arctic' condition. We then used corresponding monthly sea surface temperature (SST) values and a set of CO concentrations to drive an atmospheric general circulation model (AGCM), for simulating East Asian climate change. The experimental results show that during the boreal winter (December-January-February; DJF), global surface air temperature would increase significantly under this scenario, producing substantial warming in Arctic regions and at high latitudes in Asia and North America. The Siberian High, Aleutian Low and East Asian winter monsoon would all weaken. However, because of increased transport of water vapor to China from the north, winter precipitation would increase from south to north. In addition, the significant increase in winter temperature might cause fewer cold surges. [ABSTRACT FROM AUTHOR]

An absolute-dated, bi-decadal-resolution, stalagmite oxygen-isotopic time series from Shigao Cave reveals the evolution of summer monsoon precipitation over the past 9.9 ka BP in northern Guizhou Province, Southwest China. The δO-inferred climate conditions are divisible into three distinct stages: (1) a maximum humid era from 9.9-6.6 ka BP; (2) a gradual declining precipitation interval between 6.6-1.6 ka BP; and (3) a relatively low precipitation time window after 1.6 ka BP. Consistency of contemporaneous stalagmite Holocene δO records between Shigao and other caves in the Indian and East Asian monsoon realms support the effect of primary orbital solar forcings on monsoonal precipitation. However, statistical analysis shows a significant spatial asynchroneity of the Holocene Optimum termination in the Asian monsoon territory. The Holocene Optimum ended at 7.2-7.4 ka BP in Oman, located in the Indian monsoon region, and at 5.6-5.8 ka BP in Central China, in the East Asian monsoon zone. In Southwest China, the termination occurred between these periods, at 6.6-7.0 ka BP, and was influenced by both monsoon systems. We propose that this spatially asynchronous ending of Holocene Optimum in Asia may be attributed to sea surface temperature changes in the western tropical Pacific, which is a primary moisture source for the East Asian monsoon. [ABSTRACT FROM AUTHOR]

We investigated the moisture origin and contribution of different water sources to surface runoff entering the headwaters of the Heihe River basin on the basis of NECP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) re-analysis data and variations in the stable hydrogen and oxygen isotope ratios (δD and δ18O) of precipitation, spring, river, and melt water. The similar seasonality in precipitation δ18O at different sites reveals the same moisture origin for water entering the headwaters of the Heihe River basin. The similarity in the seasonality of δ18O and d-excess for precipitation at Yeniugou and Urumchi, which showed more positive δ18O and lower d-excess values in summer and more negative δ18O and higher d-excess values in winter, indicates a dominant effect of westerly air masses in summer and the integrated influence of westerly and polar air masses in winter. Higher d-excess values throughout the year for Yeniugou suggest that in arid inland areas 18 of northwestern China, water is intensively recycled. Temporal changes in δ18O, δD, and d-excess reveal distinct contributions of different bodies of water to surface runoff. For example, there were similar trends for δD, δ18O, and d-excess of precipitation and river water from June to September, similar δ18O trends for river and spring water from December to February, and similar trends for precipitation and runoff volumes. However, there were significant differences in δ18O between melt water and river water in September. Our results show that the recharge of surface runoff by precipitation occurred mainly from June to mid-September, whereas the supply of surface runoff in winter was from base flow (as spring water), mostly with a lower runoff amount. [ABSTRACT FROM AUTHOR]

The features of the decadal evolution of different durations of continuous Meiyu precipitation and their possible cause from the viewpoint of the low-level intraseasonal oscillation (ISO) are examined in this study. It is found that the total frequency of Meiyu precipitation events of certain duration gradually decreases as the duration of the events increases, and the main center of the events moves from the northern Yangtze-Huaihe River Valley (YHRV) to the southern YHRV. The linear trends of different durations of continuous Meiyu precipitation indicate that longer-duration precipitation has become significantly less frequent since 2000, while 2-day and 3--4-day continuous precipitation processes have become more frequent. At the same time, a close relationship between the variation in the low-level ISO and the decadal evolution of frequency of longer-duration Meiyu precipitation is detected. Clearly, since 2000, the low-level ISO has significantly decreased, and a single peak of longer-duration events has been replaced by several peaks of shorter-duration events, which has resulted in a significant decrease in the frequency of longer-duration precipitation. Meanwhile, low-level baroclinicity increased (decreased) during each period, which is in accordance with the increasing (decreasing) frequency of longer-duration precipitation. It is confirmed that longer-duration precipitation has significantly decreased in recent years. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility (χ) of surface soils on the Chinese Loess Plateau (CLP) has strong positive correlation with mean annual precipitation. It is widely accepted that ultrafine magnetite/maghemite grains produced during pedogenesis are responsible for the enhancement of χ, and loess χ on the CLP has been widely used as a proxy for the intensity of the East Asian summer monsoon. However, few works have investigated mechanisms for the enhancement of χ in the case of surface aeolian sediments in westerly-dominated inland China, north of the Tibetan Plateau. Here detailed rock magnetism and grain size studies of 49 surface samples taken across the southern Tarim Basin for different rainfall/temperature/altitude conditions are presented. The results show that samples taken from desert have the lowest χ values and that χ of loessic sand and loess samples decreases with increasing altitude. In addition, the rock magnetism studies suggest that the magnetic properties of surface soils across the southern Tarim Basin are mainly controlled by the concentration of coarse aeolian ferrimagnetic minerals. The contribution of ultrafine pedogenically produced magnetic grains to χ is very limited. [ABSTRACT FROM AUTHOR]