The changes of pigment contents and their environmental implications in the lake sediments of Ny-(A)lesund, Svalbard, the Arctic

According to palaeoclimatic and modern instrumental data, numerous studies have indicated that the Arctic climate has undergone a significant warming during the past 100 years, and this may lead to significant impact on the fragile lake ecosystem. In this study, we collected a lake sediment core from the Ny-(A)lesund of Svalbard and determined the concentrations of four pigments including chlorophyll derivatives, total carotenoids, oscillaxanthin and myxoxanthophyll in the sediments. Combined with other physical and chemical proxies such as calcium carbonate, total organic carbon, biogenic silicon etc., we have reconstructed the historical changes of lacustrine primary productivity in Ny-(A)lesund, especially for the past 100 years. The results showed that during the period of Little Ice Age (LIA), the climate was unfavorable for the growth of the lake algae, and thus the lacustrine productivity declined. This result was supported by the relatively low contents of pigment and biogenic silica in the sediments. In contrast, the contents of total organic carbon (TOC) and sediment pigments increased significantly in the upper 5 cm (~1890AD), reflecting the rapid growth of the lake algae, thus the great increase of lacustrine primary productivity, corresponding to the warming climate after LIA. However, the biogenic silica in the upper sediments still had a relatively low level, and this might be related to the growth competition with other algae species. Over the past 100 years, the ratio of Osc/Myx in the sediments decreased continuously, indicative of durative increase of myxoxanthophyll in blue-green algal pigments, and this might imply that the human activity had enhanced the nutrition level of the lake in the Arctic region.     

Characteristics of carbonaceous aerosol in a two-week campaign at Ny-Alesund

The concentrations of organic carbon (OC) and elemental carbon (EC)in total suspended particle (TSP) were investigated at Ny-(A)lesund, Svalbard in a two-week campaign. The levels of OC and EC are 0.86 ±0.27 μgm-3 (mean±standard deviation) and 0. 19±0.10 μgm-3 , respectively. Back trajectory analysis of air masses arriving at Ny-(A)lesund reveals that long-range transport of polluted air play insignificant role in OC and EC levels, to which the potential influence of the local contamination were ascribed. The average OC/EC ratio is 5.41,suggesting the presence of the secondary organic aerosols. The estimated secondary organic carbon (SOC) in TSP is 0.59 μg/m3 , accounting for 64% of the total organic carbon.     

Analyses of structure of planetary boundary layer in ice camp over Arctic ocean

The vertical structure of Planetary boundary layer over Arctic floating ice is presented by using about 50 atmospheric profiles and relevant data sounded at an ice station over Arctic Ocean from 22 August to 3 September,2003.It shows that the height of the convective boundary layer in day is greater than that of the stability boundary layer in night.The boundary layer can be described as vertical structures of stability,instability and multipling The interaction between relative warm and wet down draft air from up level and cool air of surface layer is significant,which causes stronger wind shear,temperature and humidity inversion with typical wind shear of 10 m/s/100 m,intensity of temperature inversion of 8 ℃/100 m.While the larger pack ice is broken by such process,new ice free area in the high latitudes of arctic ocean.The interactions between air/ice/water are enhanced.The fact helps to understanding characteristics of atmospheric boundary layer and its effect in Arctic floating ice region.     

Inter-hemispheric comparisons of geospace environment in the polar regions—A proposed cooperative research program between China and Norway

1　ＩｎｔｒｏｄｕｃｔｉｏｎＧｅｏｓｐａｃｅｄｅａｌｓｗｉｔｈｔｈｅＥａｒｔｈ’ｓｍｉｄｄｌｅａｎｄｕｐｐｅｒａｔｍｏｓｐｈｅｒｅ ,ｔｈｅｒｍｏｓｐｈｅｒｅ/ｉｏｎｏ ｓｐｈｅｒｅａｎｄｍａｇｎｅｔｏｓｐｈｅｒｅ .Ｔｈｉｓ“ｇｅｏｓｐａｃｅｅｎｖｉｒｏｎｍｅｎｔ”ｉｓｏｆｇｒｅａｔｓｃｉｅｎｔｉｆｉｃａｎｄｐｒａｃｔｉ ｃａｌｉｎｔｅｒｅｓｔ,ｐａｒｔｉｃｕｌａｒｌｙａｓｉｔｉｓｏｆｔｅｎｓｕｂｊｅｃｔｔｏｄｉｓｔｕｒｂａｎｃｅｓ.Ａｂｌａｓｔｗａｖｅｆｒｏｍｔｈｅｓｕｎｃａｎｃｏｍｐｒｅｓｓｔｈｅｍ…     

广东汛期蒸发皿蒸发量变化趋势及气象影响因子的通径分析

选取广东省86个气象观测站的观测资料,采用气候趋势分析和通径分析方法,对广东省1961～2003年小型蒸发皿蒸发量及其相关气象影响因子进行了分析。结果表明:虽然汛期广东省整体平均蒸发量呈下降趋势,前汛期、后汛期线性倾向率分别为-15.86 mm/10a和-13.79 mm/10a;但变化趋势在广东省内空间分布并不均匀,前汛期、后汛期粤东、中部部分地区分别有16、12个站呈上升趋势;前汛期6种气象因子单独对蒸发的决定程度按大小依次为:日照时数>气温>风速>降水>饱和差>气温日较差,后汛期6种气象因子单独对蒸发的决定程度按大小依次为:日照时数>降水>饱和差>风速>气温>气温日较差,整个汛期日照时数与其它各要素的协同作用对蒸发皿蒸发量的决定作用都很大。日照时数和风速总体上的下降是导致广东省汛期蒸发皿蒸发量逐年减少的重要原因。     

Analyzing and forecasting climate change in Harbin City,Northeast China

Based on sounding data from 1975 to 2005 and TM/ETM+ remote sensing images in 1989, 2001 and 2007, the climate changes in Harbin City, Northeast China in recent 30 years were analyzed and forecasted. Results show that in the lower troposphere the meridional wind speed and mean annual wind speed decrease, and in the lower stratosphere the temperature decreases while the meridional wind speed increases significantly. In the study area, the climate is becoming warmer and wetter in the middle lower troposphere. The expansion of urban area has great effects on the surface air temperature and the wind speed, leading to the increase of the surface air temperature, the decrease of the surface wind speed, and the increase of the area of urban high temperature zone. The quantitative equations have been established among the surface air temperature, the carbon dioxide (CO₂) concentration and the specific humidity (the water vapor content). It is predicted that the future increasing rate of the surface air temperature is 0.85°C/10yr if emission concentration of CO₂ remains unchanged; if emission concentration of CO₂ decreases to 75%, 50% and 25%, respectively, the surface air temperature will increase 0.65°C/10yr, 0.46°C/10yr and 0.27°C/10yr, respectively. The rise of the surface air temperature in the study area is higher than that of the global mean temperature forecasted by IPCC.     

Spatio-temporal variation of spring phenology in Tibetan Plateau and its linkage to climate change from 1982 to 2012

The influence of climate change on vegetation phenology is a heated issue in current climate change study. We used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season (SGS) over the Tibetan Plateau (TP) from 1982 to 2012 and to analyze its relationship with temperature and precipitation. No significant trend was observed in the SGS at the regional scale during the study period (R ² = 0.03, P = 0.352). However, there were three time periods (1982-1999, 1999-2008 and 2008-2012) with identifiable, distinctly different trends. Regions with a significant advancing trend were mainly scattered throughout the humid and semi-humid areas, whereas the regions with a significant delaying trend were mostly distributed throughout the semi-arid areas. Statistical analysis showed that the response of the SGS to climate change varies spatially. The SGS was significantly correlated with the spring temperature and the start of the thermal growth season (STGS) in the relatively humid area. With increasing aridity, the importance of the spring temperature for the SGS gradually decreased. However, the influences of precipitation and winter temperature on the SGS were complicated across the plateau.     

Sensitivity of penman-monteith reference crop evapotranspiration in Tao’er River Basin of northeastern China

A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration （ET0） to perturbation of four climate variables in Tao＇er River Basin of the northeastern China. Mean monthly ET0 and yearly ET0 from 1961 to 2005 were estimated with the FAO-56 Penman-Monteith Equation. A 45-year historical dataset of average monthly maximum/minimum air temperature, mean air temperature, wind speed, sunshine hours and relative humidity from 15 meteorological stations was used in the analysis. Results show that： 1） Sensitivity coefficients of wind speed, air temperature and sunshine hours were positive except for those of air temperature of Arxan Meteorological Station, while those of relative humidity were all negative. Relative humidity was the most sensitive variable in general for the Tao＇er River Basin, followed by sunshine hours, wind speed and air temperature. 2） Similar to climate variable, monthly sensitivity coefficients exhibit large annual fluctuations. 3） Sensitivity coefficients for four climate variables all showed significant trends in seasonal/yearly series. Also, sensitivity coefficients of air temperature, sunshine hours and wind speed all showed significant trends in spring. 4） Among all sensitivity coefficients, the average yearly sensitivity coefficient of relative humidity was highest throughout the basin and showed largest spatial variability. Longitudinal distribution of sensitivity coefficients for air temperature, relative humidity and sunshine hours was also found, which was similar to the distribution of the three climate variables.     

THE REGIONAL AIR-SEA COUPLED OSCILLATION IN THE SOUTH CHINA SEA

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＳｏｕｔｈＣｈｉｎａＳｅａ (ＳＣＳ)ｉｓａｕｎｉｑｕｅｓｅｍｉ ｅｎｃｌｏｓｅｄｄｅｅｐｏｃｅａｎｂａｓｉｎｌｏｃａｔｅｄｎｅａｒｔｈｅｗｅｓｔ ｅｒｎｐｅｒｉｐｈｅｒｙｏｆｔｈｅＰａｃｉｆｉｃＯｃｅａｎ .Ｓｐｒｅａｄｉｎｇｆｒｏｍｔｈｅｅｑｕａｔｏｒｔｏ 2 0°Ｎａｎｄｓｐａｎｎｉｎｇｚｏｎａｌｌｙａｂｏｕｔ1 5°Ｎ ,ｔｈｅＳＣＳｌｉｅｓｂｅｔｗｅｅｎｔｈｅＳｏｕｔｈＣｈｉｎａｃｏａｓｔａｎｄｔｈｅｍａｒｉｔｉｍｅｃｏｎｔｉｎｅｎｔ.ＴｈｅＳＣＳｂｏｔｔｏｍｔｏｐｏｇｒ…     

Meteorological Features at 6523 m of Mt.Qomolangma （Everest） between 1 May and 22 July 2005

Introduction Mt. Qomolangma (Everest) (27°54'N, 86°54'E) (Hereafter Mt. Qomolangma) lies between China and Nepal (Figure 1), and is the highest peak in the world, 8844.43 m asl (As promulgated by News Of-fice of the Chinese State Council in October 2005…     

Seasonal Variation in Air Temperature and Relative Humidity on Building Areas and in Green Spaces in Beijing,China

The cooling and humidifying effects of urban parks are an essential component of city ecosystems in terms of regulating microclimates or mitigating urban heat islands(UHIs).Air temperature and relative humidity are two main factors of thermal environmental comfort and have a critical impact on the urban environmental quality of human settlements.We measured the 2-m height air temperature and relative humidity at the Beijing Olympic Park and a nearby building roof for more than 1 year to elucidate seasonal variations in air temperature and relative humidity,as well as to investigate the outdoor thermal comfort.The results showed that the lawn of the park could,on average,reduce the air temperature by(0.80±0.19)℃,and increase the relative humidity by(5.24±2.91)% relative to the values measured at the building roof during daytime.During the nighttime,the lawn of the park reduced the air temperature by(2.64±0.64)℃ and increased the relative humidity by(10.77±5.20)%.The park was cooler and more humid than surrounding building area,especially in night period(more pronounced cooling with 1.84℃).Additionally,the lawn of the park could improve outdoor thermal comfort through its cooling and humidifying effects.The level of thermal comfort in the park was higher than that around the building roof for a total of 11 days annually in which it was above one or more thermal comfort levels(average reduced human comfort index of 0.92)except during the winter.     

郑州地区全新世古气候变化初探

根据对Z_(37-2)孔的孢粉分析结果表明,郑州地区,自全新世以来,气候经历三次较大的波动,先是气候开始转暖,气温不高,温凉半湿润;二是气候继续升高,达到“最适宜”气候期,温暖湿润;最后是气候再度下降,降水减少,温凉偏干.本区气侯变化规律,与北京地区基本符合.依据气侯地层学的观点,并结合放射性碳年代测定,本区的全新世地层可以划分为三期:即全新世早期(距今11000～7500a),全新世中期(距今7500～2500a),全新世晚期(距今2500a至今).     

Long-term variability of the sharp thermocline in the Yellow and East China Seas

Based on observed temperature data since the 1950s, long-term variability of the summer sharp thermocline in the Yellow Sea Cold Water Mass (YSCWM) and East China Sea Cold Eddy (ECSCE) areas is examined. Relationships between the thermocline and atmospheric and oceanic forcing were investigated using multiyear wind, Kuroshio discharge and air temperature data. Results show that: 1) In the YSCWM area, thermocline strength shows about 4-year and 16-year period oscillations. There is high correlation between summer thermocline strength and local atmospheric temperature in summer and the previous winter; 2) In the ECSCE area, interannual oscillation of thermocline strength with about a 4-year period (stronger in El Ni o years) is strongly correlated with that of local wind stress. A transition from weak to strong thermocline during the mid 1970s is consistent with a 1976/1977 climate shift and Kuroshio volume transport; 3) Long-term changes of the thermocline in both regions are mainly determined by deep layer water, especially on the decadal timescale. However, surface water can modify the thermocline on an interannual timescale in the YSCWM area.     

Projections of wind changes for 21st century in China by three regional climate models

This paper examines the capability of three regional climate models(RCMs),i.e.,RegCM3(the International Centre for Theoretical Physics Regional Climate Model),PRECIS(Providing Regional Climates for Impacts Studies)and CMM5(the fifth-generation Pennsylvania State University-the National Center for Atmospheric Research of USA,NCAR Mesoscale Model)to simulate the near-surface-layer winds(10 m above surface)all over China in the late 20th century.Results suggest that like global climate models(GCMs),these RCMs have the certain capability of imitating the distribution of mean wind speed and fail to simulate the greatly weakening wind trends for the past 50 years in the country.However,RCMs especially RegCM3 have the better capability than that of GCMs to simulate the distribution and change feature of mean wind speed.In view of their merits,these RCMs were used to project the variability of near-surface-layer winds over China for the 21st century.The results show that 1)summer mean wind speed for 2020-2029 will be lower compared to those in 1990-1999 in most area of China; 2)annual and winter mean wind speed for 2081-2100 will be lower than those of 1971-1990 in the whole China; and 3)the changes of summer mean wind speed for 2081-2100 are uncertain.As a result,although climate models are absolutely necessary for projecting climate change to come,there are great uncertainties in projections,especially for wind speed,and these issues need to be further explored.     

Comparison Between Early and Late 21~(st)C Phytoplankton Biomass and Dimethylsulfide Flux in the Subantarctic Southern Ocean

Time-series of chlorophyll-a(CHL),a proxy for phytoplankton biomass,and various satellite-derived climate indicators are compared in a region of the Subantarctic Southern Ocean(40°-60°S,110°-140°E)for years 2012-2014.CHL reached a minimum in winter(June)and a maximum in late summer(early February).Zonal mean CHL decreased towards the south.Mean sea surface temperature(SST)ranged between 8℃and 15℃and peaked in late February.CHL and SST were positively correlated from March to June,negatively correlated from July to September.CHL and wind speed(WIND)were negatively correlated with peak WIND occurred in winter.Wind direction(WIRD)was mostly in the southwest to westerly direction.The Antarctic Oscillation index(AAO)and CHL were negatively correlated(R=−0.58),indicating that as synoptic wind systems move southwards,CHL increases,and conversely when wind systems move northwards,CHL decreases.A genetic algorithm is used to calibrate the biogeochemical DMS model’s key parameters.Under 4×CO2(after year 2100)Regional mean SST increases 12%-17%,WIND increases 1.2ms−1,Cloud Cover increases 4.8%and mixed layer depth(MLD)decreases 48m.The annual CHL increases 6.3%.The annual mean DMS flux increase 25.2%,increases 37%from day 1 to day 280 and decrease 3%from day 288 to day 360.The general increase of DMS flux under 4×CO2 conditions indicates the Subantarctic regional climate would be affected by changes in the DMS flux,with the potential for a cooling effect in the austral summer and autumn.     

Environmental adaptations and constraints on latest Cretaceous Arctic dinosaurs

The Arctic hosts an extraordinary wealth of terrestrial fossil biotas of Late Cretaceous age representing a diverse and highly productive near-polar ecosystem that has no modern analogue. Compared to the rest of the Late Cretaceous Maastrichtian plant diversity was at its lowest and the temperature regime the coolest,yet the semi-open forests supported a rich dinosaur fauna made up of a wide range of body sizes and feeding strategies.The combination of mild winter temperatures and continuous darkness lasting several months imposed severe constraints on primary productivity. Plant survival strategies involved almost universal winter loss of foliage,which in turn limited food supply for non-migratory overwintering herbivorous animals. A combination of leaf form and tree ring studies has been used to quantify year round variations in temperature and determine the timing of spring bud-break and autumnal leaf fall. While Maastrichtian winter temperatures were cold enough( down to- 10℃ for brief intervals) for frequent frosts and snowfall,summer temperatures were cool but highly variable and at ~ 83 ° N along the north Alaskan coast frequently fell below + 10 ℃. Theropod egg shell fragments at ~ 76 ° N in the Maastrichtian of Northeastern Russia may indicate that dinosaur reproduction took place in the Arctic ecosystem,as distinct from taking place at lower latitude breeding grounds reached by migration.This raises the question of nest management and specifically the maintenance of incubation temperatures,and the duration of incubation. Of critical importance to year-round residency is the timing of hatching and juvenile care before winter darkness set in,temperatures fell to near freezing and food resources became limited.     

近40年来中国大陆地表气温变化估算

 本文对近20年来中国地表气温变化估算方法进行了全面的总结,并对不同研究者所采用的资料、时间尺度及研究结果进行了对比分析。结合当前国际上应用较多的几种升温估算方法,本文以1970-2007年的气温数据为基础,分别应用直接算术平均法、逐站计算法、区域面积加权法、一级差分法和空间插值法,对中国大陆近40年的升温幅度分别进行了估算,从结果的对比分析中揭示中国地表气温变化估算中存在的不确定性:中国大陆地区近40年来的增温趋势在0.30~0.43℃/10a之间,升温幅度在1.16~1.56℃之间;冬季升温最为显著,夏季升温最少;整体上北方升温幅度高于南方。不同计算方法计算得到的增温速率在绝对值上有着一定差异,但整体趋势是相同的。     

A water movement study in Lianzhou Bay,Guangxi Province,China

This study investigates the physical conditions (water depth, current speed, salinity, temperature) in Lianzhou Bay, a shallow coastal bay in southern China, during two expeditions in the dry and wet seasons of 2011. Based on these expedition data, basic hydrodynamic parameters like Brunt-Väisälä Frequency, Richardson Number, Rossby radius, and Resonance Period are calculated. The results show that Lianzhou Bay is characterized by comparatively small quantity of freshwater input and weak stratification. Strong tides, which are spatially uniform within the bay, cause turbulent mixing. Residence time of the water is shorter in winter due to a stronger coastal current in that season. Consideration of the water movement may help to reduce the harmful ecological impact of aquaculture waste water discharge.     

A temperature inversion in "Chinese Arctic Research Expedition 1999

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Increasing Winter Conductive Heat Transfer in the Arctic Sea-ice-covered Areas:1979–2014

Sea ice is a quite sensitive indicator in response to regional and global climate changes. Based on monthly mean PanArctic Ice Ocean Modeling and Assimilation System(PIOMAS) sea ice thickness fields, we computed the conductive heat flux(CHF) in the Arctic Ocean in the four winter months(November–February) for a long period of 36 years(1979–2014). The calculated results for each month manifest the increasing extension of the domain with high CHF values since 1979 till 2014. In 2014, regions of roughly 90% of the central Arctic Ocean have been dominated by the CHF values larger than 18 Wm~(-2)(November–December) and 12 Wm~(-2)(January–February), especially significant in the shelf seas around the Arctic Ocean. Moreover, the population distribution frequency(PDF) patterns of the CHF with time show gradually peak shifting toward increased CHF values. The spatiotemporal patterns in terms of the trends in sea ice thickness and other three geophysical parameters, surface air temperature(SAT), sea ice thickness(SIT), and CHF, are well coupled. This suggests that the thinner sea ice cover preconditions for the more oceanic heat loss into atmosphere(as suggested by increased CHF values), which probably contributes to warmer atmosphere which in turn in the long run will cause thinner ice cover. This represents a positive feedback mechanism of which the overall effects would amplify the Arctic climate changes.