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The present paper focuses on the analysis of dryness/wetness in the Yangtze River Basin from 1960 to 2005 using monthly precipitation data observed at 135 gauges uniformly distributed over the area. The spatial and temporal variation of dryness/wetness has been assessed by means of the Standardized Precipitation Index (SPI). The principal component analysis (PCA) and wavelet transform analysis were applied to the SPI series computed on both 6-month and 12-month time scales. The results demonstrated noticeable spatial patterns with three sub-regions characterized by different climatic variability: the southeastern downstream part of the basin, the midstream and the western upstream part of the study area. In the upstream and lower reaches of the Yangtze River Basin, an obvious trend towards wetter conditions has been detected from 1990 onward. In addition, inter-decadal changes are obvious, indicating 7–8 years fluctuation in most parts of the region sporadically distributed in the studied period in 95% confidence level. The results of this paper will be helpful for an efficient water resources management under different conditions. Furthermore, three sub-regions should be separately considered in the watershed planning process for mitigating the adverse impacts of future extreme drought or flood occurrences. [ABSTRACT FROM AUTHOR]

The Erdos Larus Relictus National Nature Reserve is the only internationally important lake wetland for the protection of the Larus Relictus and its breeding habitat. With Bojiang Lake shrinkage in the reserve in the last decade, the breeding ground had been seriously endangered. In order to investigate the dynamic changes and driving forces of the lake area, this paper studied the changes of the lake area from 1973 to 2013 using the Modified Normalized Difference Water Index from the Landsat remote sensing data, and then analyzed the relations between the lake area and the basin precipitation, temperature and vegetation by cumulative departure from the mean analysis and correlation analysis. The results suggested that Bojiang Lake area mainly experienced the three periods: the rapidly expanding period (1973–1979), the stable period (1980–1998) and the shrinking period (1999–2013). Bojiang Lake water area ranged from 0 to 13.38 km 2 . As the suitable breeding habitat for Larus Relictus, the lake area should be in the range of 5.49–11.31 km 2 . In the corresponding three periods, precipitation, temperature and vegetation changes had the different characteristics, and the correlations between lake area and precipitation, temperature and vegetation had obvious differences. Precipitation changes were the main factor of Bojiang Lake area variations in the period of 1973–1979 and 1980–1998, while vegetation changes were the main driving forces during 1999–2013. The influences of the other anthropogenic interventions (water consumption, the building of silt-trap dams, etc.) on the lake area variations should be further investigated. [ABSTRACT FROM AUTHOR]

Based on the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations, this paper evaluated the performance of the state-of-the-art climate models in simulating the interannual variability of the western North Pacific subtropical high (WNPSH), East Asian jet (EAJ) and East Asian summer rainfall (EASR), and further projected their potential changes in a future warmer world. The results show that the multimodel ensemble mean (MME) simulation has good ability to model the interannual variability of the WNPSH, EAJ and EASR, although some discrepancy exists among the individual models. The MME simulation can also reasonably capture the observed relationship of the EASR with the WNPSH and the EAJ. Under the RCP4.5 and the RCP8.5 scenarios, the interannual variability in WNPSH, EAJ and EASR is projected by the MME to increase in the 21st century. In addition, the WNPSH and EAJ would still be the dominant systems influencing the East Asian summer precipitation under global warming scenarios. But the linkage of the EASR to the WNPSH may be slightly weaker and that to the EAJ may be slightly stronger in the 21st century as compared to the present. [ABSTRACT FROM AUTHOR]

Based on the long-term trends analysis of five meteorological parameters (temperature, precipitation, wind speed, sunshine duration and relative humidity) in the four chosen stations of different settings, this paper attempts to reveal the characteristics of climate change in Urumqi City during 1960–2013. Our analytical results showed that both the temperature and precipitation in the Urumqi City have increased significantly since the middle 1980s. Autumn was the season when the temperature increased most drastically, and winter was the season when the precipitation increased most drastically. The average minimum temperature increased faster than the average maximum temperature, thus resulting in greatly reduced diurnal and annual temperature ranges. The wind speed was weakening significantly since the middle 1980s. The sunshine duration did not display any geographic coherence or consistency among different stations. The relative humidity has maintained more or less a constant, meaning that the absolute amount of water vapor has been increased under warming conditions. Comparatively, the Urumqi station (i.e., the urbanized area) had the most pronounced changes in temperature, precipitation and sunshine duration and the most pronounced changes were possibly due to the combined effects of natural and anthropogenic factors. Climate change in the mountainous area was synchronous with that in the plain area and the underlying surfaces and topographies, together with degrees of human activities, distinguished the regional climatic responses to global warming. [ABSTRACT FROM AUTHOR]

Based on the data of five observed meteorological elements (temperature, precipitation, wind speed, sunshine duration, and relative humidity) from 22 stations, the paper investigated the climate variations in northern Xinjiang over the past 50 years. The analytical results showed that both the temperature and the precipitation have increased significantly (0.35 °C/10 y, 11.2 mm/10 y) during the period of 1960–2011. An abrupt change was detected to have occurred in 1986 for temperature and in 1987 for precipitation. Autumn was the season when the temperature increased most dramatically, and winter and autumn were the seasons when the precipitation increased most dramatically. The twenty years after 1990 were the warmest and wettest two decades of the past ∼50 years, but the warming and wetting paces have slowed down during the same period. The results also showed that the mean annual minimum temperature increased more dramatically than the mean annual maximum temperature, resulting in a greatly reduced diurnal range. The reasons or mechanisms for rising trend of temperature during the past 50 years and also for the faster rising rate of the temperature in northern Xinjiang and the adjacent areas have been reasonably explored in published literature. However, the reasons or mechanisms for the rising trend of the past 50-year precipitation in northern Xinjiang and the adjacent areas have not been reasonably explored. This wetting trend has not extended further to the surrounding areas including Republic of Mongolia, major part of North China, and five republics of the former Soviet Union, and the need is thus pressing to explore the reasons or mechanisms behind this relatively “localized” wetting trend. [ABSTRACT FROM AUTHOR]

This paper presents a new fossil pollen record from Tso Moriri (32°54′N, 78°19′E, 4512 m a.s.l.) and seeks to reconstruct changes in mean annual precipitation (MAP) during the last 12,000 years. This high-alpine lake occupies an area of 140 km 2 in a glacial-tectonic valley in the northwestern Himalaya. The region has a cold climate, with a MAP <300 mm, and open vegetation. The hydrology is controlled by the Indian Summer Monsoon (ISM), but winter westerly-associated precipitation also affects the regional water balance. Results indicate that precipitation levels varied significantly during the Holocene. After a rapid increase in MAP, a phase of maximum humidity was reached between ca. 11 and 9.6 cal ka BP, followed by a gradual decline in MAP. This trend parallels the reduction in the Northern Hemisphere summer insolation. Comparison of different palaeoclimate proxy records reveal evidence for a stronger Holocene decrease in precipitation in the northern versus the southern parts of the ISM domain. The long-term trend of ISM weakening is overlaid with several short periods of greater dryness, which are broadly synchronous with the North Atlantic cold spells, suggesting reduced amounts of westerly-associated winter precipitation. Compared to the mid and late Holocene, it appears that westerlies had a greater influence on the western parts of the ISM domain during the early Holocene. During this period, the westerly-associated summer precipitation belt was positioned at Mediterranean latitudes and amplified the ISM-derived precipitation. The Tso Moriri pollen record and moisture reconstructions also suggest that changes in climatic conditions affected the ancient Harappan Civilisation, which flourished in the greater Indus Valley from approximately 5.2 to 3 cal ka BP. The prolonged Holocene trend towards aridity, punctuated by an interval of increased dryness (between ca. 4.5 and 4.3 cal ka BP), may have pushed the Mature Harappan urban settlements (between ca. 4.5 and 3.9 cal ka BP) to develop more efficient agricultural practices to deal with the increasingly acute water shortages. The amplified aridity associated with North Atlantic cooling between ca. 4 and 3.6 and around 3.2 cal ka BP further hindered local agriculture, possibly causing the deurbanisation that occurred from ca. 3.9 cal ka BP and eventual collapse of the Harappan Civilisation between ca. 3.5 and 3 cal ka BP. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents compilation of geological and geoarchaeological data, based on excavations at the Saqqara necropolis, to denote climate variability in Egypt during the late Old Kingdom (around 2200 BC). A change in climate in that time was expressed firstly by aridification and low floods of the Nile, but also by occasional heavy rainfalls in northern Egypt. Low Nile floods were probably a consequence of decreased summer precipitation in the Ethiopian Highlands that resulted in catastrophically low discharges into the Blue Nile drainage basin. These weaker summer monsoons in Ethiopia and gradual aridification in Egypt that started about 5000 cal BP, were coincident with a southward progressing shifting of the summer Intertropical Convergence Zone in Africa. Simultaneous intensive rainfalls resulted in wide-spread sheet-flood accumulations, attested by archaeological evidence in northern Egypt. These rainfalls could be triggered by the North Atlantic Oscillation. Both these reasons caused a rapid collapse of the Old Kingdom at about 4200 cal BP. [Copyright &y& Elsevier]

Abstract: Climate extremes in the Tibetan Plateau may cause serious regional and global consequences, but observation-based research over the western Tibetan Plateau is scarce. In this paper, recent changes in extremes of temperature and precipitation over the western Tibetan Plateau from 1973 to 2011 are investigated. A total of 24 indices that represent extreme climate events are selected and calculated by using daily maximum and minimum temperature and precipitation data. Results demonstrate that most cold-related indices of temperature extremes (frost and ice days, cool nights and cool days, and cold spell duration indicators) show a significant decrease, and that both the coldest night and coldest day have increased during the study period. Warm-related indices of temperature extremes such as summer days, the warmest night and the warmest day, warm nights and warm days, and warm spell duration indicators all have increased. The diurnal temperature ranges show a decreasing trend with statistical significance, whereas growing season lengths have increased significantly. The change trends of precipitation extremes are nonsignificant. Nonsignificant increasing trends are detected for most indices including annual total wet-day precipitation, maximum 1-day and 5-day precipitation, very wet and extremely wet day precipitation, and consecutive wet days. However, nonsignificant decreasing trends are found for the number of heavy precipitation days, consecutive dry days and simple daily intensity index. [Copyright &y& Elsevier]

Abstract: This paper investigated the spatial and temporal climate variations of the Kaidu River Basin in Xinjiang from 1961 to 2009. The annual and monthly temperature and precipitation data were collected from six meteorological stations in the river basin and analyzed by a Mann–Kendall test and linear trend estimation. The results showed that: (1) temperature increased significantly in oasis areas over the past 49 years, while it does not display an increasing trend in mountainous areas over the same period; (2) precipitation exhibited a steep increasing trend in mountainous areas over the past 49 years, while the increasing trend in oasis areas is not significant; (3) with regard to seasonal variation, temperatures increased the most in spring and summer in the northern part of the mountainous area (Baluntai) and in the southern part of the oasis area (Yanqi County). The mean annual precipitation and the mean summer precipitation showed the largest increases in the northwestern part of the mountainous area (Bayinbuluke) and the largest decreases in the northern part of the oasis area (Hejing and Heshuo Counties). Temperature and precipitation increased from 2006 to 2009, showing a warming and wetting trend. [Copyright &y& Elsevier]