The interdecadal trend and shift of dry/wet over the central part of North China and their relationship to the Pacific Decadal Oscillation （PDO）

Based on monthly precipitation and monthly mean surface air temperature (SAT),the dry/wet trends and shift of the central part of North China and their relationship to the Pacific Decadal Oscillation (PDO) from 1951 to 2005 have been analyzed through calculating surface wetness index (SWI). The results indicate that there was a prominent drying trend and an abrupt change in the analysis period. A per-sistent warming period with less precipitation from the mid and late 1970s to present was found,and a shift process exists from the wet to the dry in the central part of North China during 1951-2005. The transition is located in the mid to late 1970s,which should be related to the shift variation of large-scale climate background. The correlation analysis has brought about a finding of significant correlativity between PDO index (PDOI) and SAT,precipitation and SWI in this region. The correlation exhibits that the positive phase of PDOI (warm PDO phase) matches warming,less precipitation and the drought period,and the negative PDOI phase corresponds to low SAT,more precipitation and the wet period. The duration of various phases is more than 25 years. The decadal variation of sea surface temperature (SST) in the North Pacific Ocean is one of the possible causes in forming the decadal dry/wet trend and shift of the central part of North China.     

Regional characteristics of the interdecadal turning of winter/summer climate modes in Chinese mainland

Tomé and Miranda’s climate trend turning discriminatory model is used to identify the spatial-temporal characteristics of the interdecadal turning of winter/summer climate modes at stations and in eight sub-areas over Chinese mainland based on the 1961–2000 observations. It is found that the stations with close occurrence years of the interdecadal trend turning (ITT) and coincident trends after the ITT exhibit a zonal distribution. A view is accordingly proposed that the interdecadal turnings of climate modes in China have remarkably regional structures. The research results show that after the early 1980s, winter climate over Chinese mainland overall trends towards a “warm-wet” mode, while summer climate had an abrupt change into “warm wet” mode in the late 1980s, suggesting that the time of the “warm-wet” mode turning for winter climate is earlier than that for summer climate. The regional characteristics and test results of the ITTs in eight sub-areas suggest that winter climate exhibits a distinctive “warm-dry” trend in North China after the late 1970s, and a slight “warm-dry” trend in Northeast China, South China, and Southwest China after the late 1980s. A “warm-wet” trend appears in the rest four sub-areas (the middle and lower reaches of the Yangtze River and the Huaihe River Valley, briefly Jianghuai, the east of the Tibetan plateau, and the east and west of Northwest China) after the early 1980s. The summer climate trends towards a “warm-dry” mode in Northeast China, North China and the east of Northwest China after the late 1980s, but a “warm-wet” mode appears in Southwest China and the east of the Tibetan plateau after the middle 1970s, as well as in Jianghuai and the west of Northwest China after the early 1980s. Specially, summer climate in South China started a “cold-wet” trend in 1984.     

High-resolution geochemistry records of climate changes since late-glacial from Dajiuhu peat in Shennongjia Mountains,Central China

A peat core with depths of 297 cm was obtained from the Dajiuhu Basin(31°29′27″N,109°59′45″E,1760 m)in Hubei Province,Central China.10 AMS ages provide a time control and reveal that this core spans the past about 16.0 kaBP(calibrated age)(1 4C age:13.3 kaBP).Multi-proxy indexes analysis of geochemistry shows the following character of climate and environmental changes since about 16 kaBP:(1) The climate during the late-glacial period was cold and wet as a whole,but fluctuated continually.11.4- 12.6 cal.kaBP,12.6-15.2 cal.kaBP and 15.2-16 kaBP were corresponding respectively to the Younger Drays,Bφlling-Allerφd Warm Period and the Oldest Drays.(2)Inheriting the some climate characteristics of the late-glacial,the climate during the early-Holocene was wet and temperature increased gradually,during which an obvious dry event around 10.6 cal.kaB appeared.(3)The climate during the mid-Holocene was genarally warm and wet.During 9.2-7.5 kaBP,temperature increased gradually, precipitation was less comparatively and the 8.2 kaBP cold event which might be representative in the globe was reflected markedly.Then,multi-proxy records were relatively stable during 6.7-4.2 kaBP, which shows the best water and thermal condition in the Holocene Optimum.(4)Around 4.2 kaBP,the climate and environment transform from warm and wet to cool and dry,which may result in the collapse of the Neolithic Culture and midwifery the civilization of Xia Dynasty in this region.After 0.9 kaBP,the climate turned cool and wet.Climate and environmental changes archived in Dajiuhu peat respond to the global changes since the late-glacial period and can be contrasted to the changes recorded in other high-resolution archives from the East Asia Monsoon region,which take on the variety model that the monsoon strengthened abruptly after the late-glacial,was strong during the early Holocene,subse- quently declined and became weak after the middle Holocene with dry climate.According to our analysis,the driving mechanism should be the response of s     

Changes in precipitation and extreme precipitation in a warming environment in China

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℃ 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.     

Response of water budget to recent climatic changes in the source region of the Yellow River

Discharge in the source region of the Yellow River significantly declined after 1990.China Meteorological Administration(CMA) data show that precipitation in this region was low in the 1990s but returned to above normal after 2002;in recent decades there has been rapid warming of surface air,moistening and wind speed decrease.To investigate the influences of recent climatic changes on the water budget,this study simulates the surface water budget at CMA stations within and surrounding the source region during 1960-2006,using an improved land surface model.Results indicate that the spatial pattern of precipitation change is an important factor(except for precipitation amount and intensity) in determining the response of runoff to precipitation changes.Low runoff in the 1990s was consistent with precipitation amount and intensity.The recovery of precipitation after 2002 is mainly from increased precipitation in the dry area of the source region.Evaporation was mainly limited by water availability in this dry area,and thus most of the precipitation increase was evaporated.By contrast,energy availability was a more important influence on evaporation in the wet area.There was more evaporation in the wet area because of rapid warming,although precipitation amount partly decreased and partly increased,contributing to the reduction of runoff after 2002.This control on evaporation and its response,together with the modified spatial pattern of precipitation,produced a water budget unfavorable for runoff generation in the source region during recent years.     

Environmental changes reflected by n-alkanes of lake core in Nam Co on the Tibetan Plateau since 8.4 kaB.P.

The n-alkanes are extracted from NMLC-1 core that was drilled in the Nam Co, central Tibet. They are measured by using Gas Chromatography and Mass Spectrometry （GC/MS） for componential and quantitative analyses. According to the constructed depth-age model, the component and concentration of n-alkanes, together with total organic carbon （TOC）, total nitrogen （TN） and carbonate are used to elucidate palaeoenvironmental changes of Nam Co during the past 8.4 ka. The results indicate that Holocene environment performs three stages in the lake area. In the stage of 8.4-6.7 kaB.P., it was warmer while precipitation slightly increased. This stage was ended by an obvious cold/dry event. During 6.7-5.8 kaB.P., temperature increased rapidly and reached its maximum values at about 6.0 kaB.P. The environments were warm/wet optimum for the blooming of terrestrial plants and submerged aquatic plants. After that, temperature decreased continuously and showed the lowest values at about 3.0 kaB.P. From 2.9 kaB.P, to the present, temperature rose again but alternated with cold and warm. The lake area tended to be dry after 1.4 kaB.P. During 600-400 aB.P., the environmental feature was the reflection of ＂Little Ice Age＂.     

Environmental changes reflected by n-alkanes of lake core in Nam Co on the Tibetan Plateau since 8.4 kaB.P.

The n-alkanes are extracted from NMLC-1 core that was drilled in the Nam Co, central Tibet. They are measured by using Gas Chromatography and Mass Spectrometry (GC/MS) for componential and quantitative analyses. According to the constructed depth-age model, the component and concentration of n-alkanes, together with total organic carbon (TOC), total nitrogen (TN) and carbonate are used to elu- cidate palaeoenvironmental changes of Nam Co during the past 8.4 ka. The results indicate that Holo- cene environment performs three stages in the lake area. In the stage of 8.4―6.7 kaB.P., it was warmer while precipitation slightly increased. This stage was ended by an obvious cold/dry event. During 6.7― 5.8 kaB.P., temperature increased rapidly and reached its maximum values at about 6.0 kaB.P. The environments were warm/wet optimum for the blooming of terrestrial plants and submerged aquatic plants. After that, temperature decreased continuously and showed the lowest values at about 3.0 kaB.P. From 2.9 kaB.P. to the present, temperature rose again but alternated with cold and warm. The lake area tended to be dry after 1.4 kaB.P. During 600―400 aB.P., the environmental feature was the reflection of "Little Ice Age".     

Lake records and LGM climate in China

Chinese lake status database has provided systematic geological records of much higher lake level and fresher water than today at the LGM from western China. This wet condition was significant contrast with very dry conditions in eastern China. Together with lake studies from Eurasian continents, there was a wet-condition belt from the Mediterranean and the Middle East, Central Asia to western China. Palaeoclimate simulations confirmed that the wet conditions in western China were produced by decrease of the evaporation and increase of precipitation by positive anomaly of annual P-E of 70-95 mm/a between the LGM and today. The westerlies enhanced in the strength and shifted southwards-eastwards in the position, and the low thermal conditions in the Eurasian continent creating temperature 4-16℃ lower than today and relatively low evaporation, were the major two important climate conditions to yield cold-wet climates in western China.     

Interannual variation of annual precipitation and urban effect on precipitation in the Beijing region

The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2000 annual precipitation observations at 20 stations in the Beijing region.The results show that:the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of-1.197/10 yr,which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years;the local annual precipitation anomalies(percent of the normal 1960-2000)show a positive center near the urban area,i.e.urban precipitation island(UPI),whose intensity increases with the linear trend of 0.6621%/10 yr,opposite to the interannual trend of large scale precipitation over the Beijing region;changes in the UPI are also associated with the intensity of synoptic processes of precipitation,and when the synoptic processes are strong(wet years),the intensity of UPI strengthens,while the synoptic processes are weak(dry years),and the UPI disappears in the Beijing region.     

Sporopollen analysis of Core B10 in the southern Yellow Sea and the reflected characteristics of climate changes

Eight sporopollen zones have been divided based on the results of high-resolution sporopollen analysis of Core B10 in the southern Yellow Sea. Based on the results along with ^14C datings and the subbottom profiling data,climatic and environmental changes since the last stage of late Pleistocene are discussed. The main conclusions are drawn as follows: (1) the vegetation evolved in the process of coniferous forest-grassland containing broad-leaved trees→coniferous and broad-leaved mixed forest→coniferons and broad-leaved mixed forest-grassland prevailed by coniferous trees→coniferous and broad-leaved mixed forest-grassland containing evergreen broad-leaved trees→coniferons and broad-leaved mixed forest-grassland prevailed by broadleaved trees→deciduous broad-leaved forest-meadow containing evergreen broad-leaved trees→coniferous and broadleaved mixed forest-grassland prevailed by broad-leaved trees→coniferous and broad-leaved mixed forest containing evergreen broad-leaved trees; (2) eight stages of climate changes are identified as the cold and dry stage, the temperate and wet stage, the cold and dry stage, the warm and dry stage, the temperate and wet stage, the hot and dry stage, the temperate and dry stage, then the warm and dry stage in turn; (3) the sedimentary environment developed from land,to littoral zone, to land again, then to shore-neritic zone; and (4) the Yellow Sea Warm Current formed during early-Holocene rather than Atlantic stage.     

Climatic difference in dry and wet season under effect of the Longitudinal Range-Gorge and its influence on transboundary river runoff

Based on observed data of transboundary river runoffs in the Longitudinal Range-Gorge Region （LRGR） and those of precipitation and air temperature fields in Yunnan, climatic variability in dry and wet seasons under the impact of LRGR and its influence on transboundary river runoff are studied by means of statistical analysis and wavelet transforms. Results show that latitude variations of high correlation center for precipitation field and corresponding transboundary river runoff are not so notable due to the underlying topography of LRGR, while longitude variations are highly marked. In dry season, greater precipitation and slighter relative deviation are observed in the eastern part as compared to those in the western part of LRGR; while lower average temperature and greater standard deviation are found in the eastern part. In wet season, greater precipitation and slighter relative deviation are ob- served in the western part, while lower average temperature and similar standard deviation are found in the eastern part. Either in dry or wet season, relative deviation of eastern runoff is always greater than that of the western one. LRGR＇s barrier action is stronger for southwest monsoon but weaker for northeast one. Under the effect of LRGR, precipitation variations in the eastern and western parts are primarily found in smaller timescales, and the variations tend to be insignificant as timescales increase; whereas slighter temperature variations are observed In recent years, precipitation in wet season tended to increase, which in turn resulted in the greater runoff of transboundary rivers. While in the past decade, air temperature showed a climbing trend in both dry and wet season in the LRGR.     

Interannual variation of annual precipitation and urban effect on precipitation in the Beijing region

The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960—2000 annual precipitation observations at 20 stations in the Beijing region. The results show that: the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of -1.197/10 yr, which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years; the local annual precipitation anomalies (percent of the normal 1960—2000) show a positive center near the urban area, i.e. urban precipitation island (UPI), whose intensity increases with the linear trend of 0.6621%/10 yr, opposite to the interannual trend of large scale precipitation over the Beijing region; changes in the UPI are also associated with the intensity of synoptic processes of precipitation, and when the synoptic processes are strong (wet years), the intensity of UPI strengthens, while the synoptic processes are weak (dry years), and the UPI disappears in the Beijing region.     

Reconstruction of precipitation in the last 140 years from tree ring at south margin of the Tengger Desert, China

Based on the tree ring width index of Pinus tabulaeformis, precipitation in the last 140 years was reconstructed at south margin of the Tengger Desert. The results indicated that there were obvious fluctuations of dry-wet changes in precipitation： two wet periods occurred during 1868-1876 and 1932-1939, and two dry periods during 1877-1894 and 1924-1932, however, the years 1887 and 1888 were a little wet. There were small changes in precipitation during 1895-1923 and 1940-2000. As compared to the average, the maximum increasing range of precipitation amounted to 56% during the wet periods, and 42% during the dry periods. And the range of variability of precipitation exceeded 30% in 19 years. There was no obvious consistent drying or wetting trend in the last 140 years. But since 1940 fluctuating scope of precipitation tended to be smaller, while the frequency of the fluctuation tended to be larger. Power spectrum analyses suggested that precipitation of south margin of the Tengger Desert had significant periodicities of 2.46-2.64 a and quasi periodicity of 11.67 a.     

Hotspots of the sensitivity of the land surface hydrological cycle to climate change

Due to the shortage of the global observational data of the terrestrial hydrological variables,the understanding of how surface hydrological processes respond to climate change is still limited.In this study,the Community Land Model(CLM4.0)with high resolution atmospheric forcing data is selected to simulate the global surface hydrological quantities during the period 1948–2006and to investigate the spatial features of these quantities in response to climate change at the regional scales.The sensitivities of evaporation and runoff with respect to the dominant climate change factors(e.g.temperature and precipitation)derived from the concept of climate elasticity are introduced.Results show that evaporation has a declining trend with a rate of 0.7 mm per decade,while runoff shows a weak increasing trend of 0.15 mm per decade over the global land surface.Analyses of the hotspots in the hydrological cycle indicate that the spatial distributions for evaporation and runoff are similar over many areas in central Asia,Australia,and southern South America,but differ largely in high latitudes.It is also found that,the evaporation hotspots in arid regions are mainly associated with the changes in precipitation.Our sensitive analysis suggests that the hydrological quantities show a rather complicated spatial dependency of response of the water cycle to the different climate factors(temperature and precipitation).     

Core Competitiveness Construction of Clothing Brands in Low-Carbon Economy

The climate issue has become an environmental concern for all sectors of the world and the low-carbon economy has thus become a new economic development model to combat climate change. With the development of low-carbon economy era, the textile and clothing industry plays an important role in stabilizing the development of low-carbon economy and society, and China has put forward the development requirements of low-carbon transformation for the textile and clothing industry, and also it has an i...     

Thoughts on studies of China continental geology and tectonics

As an important part of the global continents, China continent has long been situated in the peculiar tectonic position and experienced extremely complicated activities, which resulted in the regional unique characteristics for China continent on the global common geological background. These characteristics contain abundant information regarding scientific key issues of modern geological frontier. Thus, China continent can be a natural laboratory and excellent arena for the modern geosciences. The modern earth sciences have started entering the era featured with earth systematic science and beyond plate tectonics. How to take the regional advantage and exploit the treasure resource to participate the new theoretical and methodological creation is a historic opportunity and great challenge we are facing. This paper generalizes research priorities in four fields on China continental geology and tectonics for discussion. They are: China continental tectonics and dynamics; Mesozoic-Cenozoic crustal deformation and deep-seated processes in China continent and the adjacent regions; deep-seated dynamic background and evolutionary trend of crustal tectonic activities on the time scale of human existence; deep-seated background and processes of conjunction and transformation of different tectonic systems.     

Deep-water Oligocene pollen record from South China Sea

Leg 184 of ODP recovered a record of deepwater sediments spanning the past 32.8 Ma from the South China Sea (SCS). The sediments of the Ofigocene (32.8-23.8 Ma) at Site 1148 contain relatively abundant fossil pollen. The pollen analysis at Site 1148 has established the first pollen assemblage sequence of deep-water Oligocene in the China Sea. The pollen assemblages of the Ofigocene are dominated by montane conifer tree pollen. The abundances of broad-leaved tree pollen are lower in the assemblages.Both of the montane conifer and broad-leaved tree pollen groups include mainly tropical-subtropical components. The pollen of cold and drought-enduring plants is present in lower content. The distinct change in pollen assemblage sequence of deep-water Oligocene of the SCS occurred at 32.0 Ma, indicative of an important shift of the Oligocene climate in the SCS region. The characteristics of the pollen flora of the deep-water Oligocene indicate the tropical montane ralnforest and lowland ralnforest developed on the areas around the SCS before 32.0 Ma, reflecting the warm and wet climatic condition. In the pollen flora of the Oligocene after 32.0 Ma, the temperate montane conifer and cool and drought-en- during deciduous tree taxa remarkably increased, indicating that the climate in the SCS region became comparatively cool and dry.     

Decadal variation of different durations of continuous Meiyu precipitation and the possible cause

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.     

Influence of variation in precipitation on the δD values of terrestrial n-alkanes on the southern Tibetan Plateau

A short lake sedimentary core and ice core were recovered from Lake Chen Co and Noijingangsang Glacier,respectively,in the Lake Yamdrok watershed of the southern Tibetan Plateau.Hydrogen isotope ratios of the ice core(δDice) and δD values of terrestrial n-alkanes(δDwax) in the sediments showed a linear correlation(R2 = 0.41,P = 0.047) over the past 80 years,indicating the effect of hydrogen isotope ratios of precipitation(δDp) on δDwax.However,apparent fractionation(εwax-p) values of δDwax relative to δDice increased with decreasing ice core accumulation(amount of precipitation;R2 = 0.65,P = 0.0051),revealing that dry or wet climate variation had a significant impact on δDwax.Thus,precipitation amount and δDp are both important in determining δDwax.     

Variations in the equilibrium line altitude of Urumqi Glacier No.1, Tianshan Mountains, over the past 50 years

The glacier ELA is one of the important parameters reflecting climate change.Based on observations of the equilibrium line altitude(ELA) of Urumqi Glacier No.1 in the Tianshan Mountains,we established a statistical model between ELA and its major influencing factors,warm season air temperature(air temperature averages for May,June,July and August) and annual precipitation.Result showed that,warm season air temperature was the leading climatic factor influencing ELA variations.The glacier ELA ascends(descends) 61.7 m when warm season air temperature increases(decreases) by 1°C,and ascends(descends) 13.1 m when cold season precipitation decreases(increases) by 10%.In the period 1959-2008,the glacier ELA showed a general increasing trend,ascending108 m and reaching its highest altitude in 2008 at 4168 m a.s.l.,close to the glacier summit.If future climate is similar to that in the past 50 years,the ELA of Urumqi Glacier No.1 will still ascend with a speed of 2.16 m/a.However,If future climate is similar to that in the period 2000-2008,the ELA will still ascend with a speed of 6.5 m/a before it is stable.As a result of ELA variation,the accumulation area ratio(AAR) of the glacier showed a decreasing trend during the past 50 years.