南极中山站-Dome A断面表层雪稳定同位素空间分布及环境影响因素分析

中山站-Dome A断面是表层雪稳定同位素组成分析的理想区域,沿线进行δ18O、δD和d的空间分布及环境影响因素研究对反映东南极地区的气候变化和物质来源具有关键意义。因而,本文基于线性回归及相关性分析方法,详细探究了断面上多种环境因素与表层雪稳定同位素分布的空间关系。结果表明,温度和地理因素与同位素比值之间有显著相关关系,且海拔是地理因素中的主要影响因素,随海拔上升表层雪的δ18O呈线性下降趋势。另外,通过断面上δ-T斜率与南极其他断面对比,发现斜率可能具有冰盖近岸和内陆地区较低的区域性特征,而造成这一现象的原因是水汽源区的改变和低温条件下水汽过饱和时的同位素动力分馏。最后,d的空间分布在沿海区域和内陆区域也有不同,推测主控因素分别是水汽源区条件和温度。     

A preliminary application GIS in glaciological research along the traverse route from Zhongshan Station to Dome A, Antarctica

GIS is applied in glaciological research along the traverse route from Zhongshan Station to Dome A, one of the key routes in ITASE project, to display, process, manage and analyze the data obtained mainly by the 3rd Chinese Inland Expedition, together with Antarctic databases provided by ADD and BEDMAP project. The ways of ADD data merging and clipping, and coordinate projection transformation of field data and BEDMAP data are introduced. Elevation data derived by GPS navigator are corrected using ADD and ArcView's contour interpolation. Sub ice topography and ice thickness along the route are extracted from BEDMAP database. Slope and aspect data are derived at each positioning station. GIS is a convenient and useful tool for us to record, query and display a variety of data in detail along the traverse route.     

Comparison of temperature extremes between Zhongshan Station and Great Wall Station in Antarctica

Although temperature extremes have led to more and more disasters, there are as yet few studies on the extremes and many disagreements on temperature changes in Antarctica. Based on daily minimum, maximum, and mean air temperatures(Tmin, Tmax, Tmean) at Great Wall Station(GW) and Zhongshan Station(ZS), we compared the temperature extremes and revealed a strong warming trend in Tmin, a slight warming trend in Tmean, cooling in Tmax, a decreasing trend in the daily temperature range, and the typical characteristic of coreless winter temperature. There are different seasonal variabilities, with the least in summer. The continentality index and seasonality show that the marine air mass has more effect on GW than ZS. Following the terminology of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC AR5), we defined nine indices of temperature extremes, based on the Antarctic geographical environment. Extreme-warm days have decreased, while extreme-warm nights have shown a nonsignificant trend. The number of melting days has increased at GW, while little change at ZS. More importantly, we have found inverse variations in temperature patterns between the two stations, which need further investigation into the dynamics of climate change in Antarctica.     

Variation of Stable Isotopes in Surface Snow along a Traverse from Coast to Plateau’s interior in East Antarctica and Its Climatic Significance

The variations of stable water isotopes of surface snow in east Antarctic Ice Sheet, are discussed by a total of 251 samples, which were taken along a 330 km traverse from Zhongshan Station to the outer edge of the Antarctic plateau and from four snow pits excavated along the route. Analyzing results of the samples showed the expected linear relationship between the parameters ?D and ?18O with slope S1 and intercept d1. When the data set was examined using a sliding window with a width of 5 samples, it was found that there were two areas with different ratios of S1 and d1. The boundary between these two areas occurred at an elevation of about 2,000 m, suggesting two different sources of water vapour. Nearly half (47%) of the fresh-snow samples had negative deuterium excess (d=?D? 8?18O) values, but few of the snow pit samples did, suggesting that variations of ? are quickly smoothed by isotopic diffusion in the near-surface firn. Analysis of the phase relationship between ?D and deuterium excess in the snow pit stratigraphies showed that they were mostly in phase from Jan. 1994 to Sept. 1995, but mostly out of phase from Sept. 1995 to Jan. 1997.     

天山1号冰川厚度和冰下地形探测与冰储量分析

通过对天山乌鲁木齐河源 1号冰川的雷达回波探测 ,清晰地揭示出冰川底部冰 /岩界面的位置及其起伏变化特征 ,显示出雷达波对山地冰川良好的穿透能力和对冰下地形的高分辨能力 ,冰川雷达测厚的误差小于 1 .2 %。研究结果显示 ,1号冰川东支冰川平均厚度为 5 8.77m ,西支冰川平均厚度为 44.84m ,冰体厚度最大值发育于冰川中部趋于主流线位置。冰川冰储量计算表明 ,东支冰储量为 0 .0 5 1 868km3,西支冰储量为 0 .0 2 0 2 1 0km3。表面和底部地形有明显差异 ,主要因冰川动力过程对基岩强烈的地貌作用所致 ,意味着冰床的起伏地形对冰川浅层冰体的运动过程影响不显著。     

Potassium alum and aluminum sulfate micro-inclusions in polar ice from Dome Fuji,East Antarctica

Water-soluble trace constituents affect the physicochemical properties of polar ice. Their structural distribution provides important insights into the formation history of ice and inclusions. We report the first finding of KAl(SO₄)₂·12H₂O (potassium alum) and Al₂(SO₄)₃·nH₂O (aluminum sulfate) micro-inclusions in the Dome Fuji ice core, East Antartica, using a micro-Raman technique. Eutectic temperatures of these water-soluble species determined using thermal analysis were −0.4 °C for potassium alum and −8.0 °C for aluminum sulfate. Although the formation process of the aluminum-bearing sulfates remains unclear, the occurrence of these salts largely depends on ice depth.     

表层雪中稳定同位素季节变化及其与水汽输送的关系——以天山乌鲁木齐河源1号冰川积累区为例

根据2002年9月至2005年12月在天山乌鲁木齐河源1号冰川积累区采集的表层雪样品,揭示了该区表层雪中δ<'18>O值的季节变化特征,讨论了水汽输送对降水中δ<'18>O值变化的影响.研究表明,天山乌鲁木齐河源1号冰川表层雪中δ<'18>O值季节变化显著,变幅可达12.59‰左右,其变化趋势和气温的变化趋势基本一致,...     

南极拉斯曼丘陵中山站地区Rb含量初步调查

利用手持快速矿石分析仪(NITON XL3t-500S GOLDD)对拉斯曼丘陵中山站附近出露的基岩进行测试, 初步调查结果显示该地区有明显的Rb元素富集。测试了17个样品, 其中12个的Rb含量达到了0.04%, 1个样品的Rb含量达到0.1%以上。分析测试样品特征, 并结合拉斯曼丘陵地质特征发现, 拉斯曼丘陵地区Rb的富集与含黑云母的泛非期伟晶岩墙关系密切, 而且粒度越大Rb含量越高, 类比推测该区域Rb元素富集潜力巨大, 有必要继续开展相应的地质调查工作, 进一步探讨其富集成因和规律。     

Spatial distributions and interannual variations of snow cover over China in the last 40 years

By using the observational snow data of more than 700 weather stations,the interannual temporal and spatial characteristics of seasonal snow cover in China were analyzed.The results show that northern Xinjiang,northeastern China-Inner Mongolia,and the southwestern and southern portions of Tibetan Plateau are three regions in China with high seasonal snow cover and also an interannual anomaly of snow cover.According to the trend of both the snow depth and snow cover days,there are three changing patterns for the seasonal snow cover:The first type is that both snow depth and snow cover days simultaneously increase or decrease;this includes northern Xinjiang,middle and eastern Inner Mongolia,and so on.The second is that snow depth increases but snow cover days decrease;this type mainly locates in the eastern parts of the northeastern plain of China and the upper reaches of the Yangtze River.The last type is that snow depth decreases but snow cover days increase at the same time such as that in middle parts of Tibetan Plateau.Snow cover in China appears to have been having a slow increasing trend during the last 40 years.On the decadal scale,snow depth and snow cover days slightly increased in the 1960s and then decreased in the 1970s;they again turn to increasing in the 1980s and persist into 1990s.     

Spatial and temporal variations in the thermodynamics since the Last Glacial Maximum at Jutulstraumen drainage basin,East Antarctica

A flow-line model is coupled to a 2D temperature model to simulate the thermodynamic changes of Jutulstraumen drainage basin due to grounding line retreat and increased surface temperature since the Last Glacial Maximum (LGM). The basin consists of a plateau drained by an outlet glacier, and the simulated ice volume reductions are 1% and 2% respectively of the current grounded volume. The mountain ranges H.U. Sverdrupfjella and Neumayerskarvet fringing the plateau were not overridden by ice at the LGM, while the Nashornet nunataks closer to the grounding line were. Today the glacier is almost in balance with the current climate, with the highest thinning rate?<?5.0×10^?3 ma^?1 at the plateau. The simulated present-day thermal regime of the outlet glacier shows a basal layer at the pressure melting point and negative temperature gradients with depth due to horizontal advection of cold ice from the plateau. Sensitivity studies show that strain heating and horizontal advection are important for the basal temperatures in the fast flowing outlet glacier and for about half of the wide basin at the polar plateau. Increased strain heating and horizontal advection since the LGM control the response time required to readjust to the new conditions, and it controls the present-day volume.     

Temporal variations in the abundance and sinking flux of diatoms under fast ice in summer near Syowa Station, East Antarctica

To investigate the fate of ice algae released from sea ice, we investigated the abundance, species composition, and sinking flux of diatoms in the water column under fast ice near Syowa Station, Antarctica during the summer of 2005/2006. The diatom assemblage in the water column consisted of chain-forming planktonic species, in contrast to the under-ice assemblage dominated by pennate species reported from this site in the past; this dissimilarity suggests the presence of an unconsolidated platelet ice layer under the congelation ice, within which planktonic species can bloom. Among the dominant diatoms, Porosira pseudodenticulata and Pseudo-nitzschia cf. turgiduloides were dominant in the water column, and their water column stocks were higher than their mass sedimentation. These species apparently maintain their populations in the surface layer, as their production remains in the water column. In contrast, Fragilariopsis kerguelensis and Thalassiosira australis were scarce in the water column but rich in the flux, indicating active sinking and export of their production to the benthic ecosystem. This distinction in buoyancy control and sinking characteristics of the dominant diatoms on release from the fast ice influences the diatom species composition and carbon flow under the ice.     

东南极冰盖中山站-Dome A断面表层雪中SO_4~(2–)和MSA的空间分布特征

中山站-Dome A断面考察是国际横穿南极科学考察计划(ITASE)的核心考察路线之一,具有重要的科学意义,在国内外产生了广泛影响。中国第31次南极科学考察内陆冰盖考察期间,采集了中山站-Dome A断面上约10 km间隔的表层雪样品,通过离子色谱实验分析,得出了断面上含硫化合物(SO_4~(2-)与MSA)的含量。在整个断面上,nssSO_4~(2-)和MSA含量表现出微弱的递减变化趋势,呈现出区域性变化趋势。在内陆高原区域(Dome A区域),nssSO_4~(2-)与MSA存在较好的线性关系([MSA]=0.1158×[nssSO_4~(2-)]–1.1497,r~2=0.75)。MSA/nssSO_4~(2-)比值在断面上的变化范围为0.04—0.47,均值为0.14,比值表现为沿海区域高于内陆区域,与低温条件下MSA/nssSO_4~(2-)比值大相矛盾,原因是由于源区的不同或风场而造成的。通过对断面上含硫化合物的研究,为进一步利用冰芯SO_4~(2-)与MSA记录研究过去气候环境提供了科学依据。     

近50年青藏高原东部冬季积雪的时空变化特征

选取青藏高原东部地区1961-2010 年64 个测站的积雪数据,分析了冬季积雪日数的空间分布和年代际变化特征,结果表明：高原东部冬季积雪空间分布差异较大,巴颜喀拉山、唐古拉山和念青唐古拉山多雪且变率大,藏南谷地、川西干暖河谷地带及柴达木盆地少雪且变率小,这样的空间分布是由周边大气环流系统及复杂局地地形共同造成的;高原东部冬季积雪表现出“少—多—少”的年代际变化特征,分别在80 年代末和20 世纪末发生由少到多和由多到少的两次突变,尤其是20 世纪末的突变更为显著;降雪和气温的变化是影响积雪日数的重要因素,其中降雪的影响更为显著;80 年代末高原冬季降雪由少到多的突变是造成积雪日数发生相应变化的主要原因;20 世纪末高原冬季气温和降雪分别发生由低到高和由多到少突变,其影响叠加导致积雪日数发生了更为显著的突变。     

Gravity measurements with a portable absolute gravimeter A10 in Syowa Station and Langhovde,East Antarctica

Absolute gravity values were measured with a portable absolute gravimeter A10 in East Antarctica, for the first time by the Japanese Antarctic Research Expedition. This study aims to investigate regional spatiotemporal variations of ice mass distributions and associated crustal deformations around Syowa Station by means of repeated absolute gravity measurements, and we obtained the first absolute gravity value in Southern Langhovde on the Antarctic Continent. The average absolute gravity value at the newly installed benchmark AGS01 in Langhovde (obtained on 3 February 2012) was 982535584.2 ± 0.7 μgal (1 [μgal] = 1 × 10^?8 [m/s²]), which was in agreement with the gravity values obtained by the past relative gravity measurements within 1 mgal. In addition, the average absolute gravity value obtained at AGSaux in Syowa Station was consistent with both previous absolute gravity values and those obtained by simultaneous measurements using an FG5 gravimeter, owing to adequate data corrections associated with tidal effects and time variations in atomic clock frequencies. In order to detect the gravity changes associated with the ice mass changes and other tectonic phenomena, we plan to conduct absolute gravity measurements at AGS01 again and at other campaign sites around Syowa Station as well in the near future, with careful attention paid to the impacts of severe environmental conditions in Antarctica on gravity data collection.     

Spatial variability of chemical tracers in surface snow along the traverse route from the coast to 1000 km inland at east Dronning Maud Land, Antarctica

We measured the spatial variability of Cl -, Na +, SO 2- 4, NO - 3 and 7Be concentrations in snow cover along the traverse route from S16 to Dome Fuji station in east Dronning Maud Land, Antarctica. The concentrations of Cl - and Na + at the coast exponentially decreased with distance from the coast up to 200 km inland. Between 200 1000 km inland, the concentrations of Na + were nearly constant. On the other hand, the concentrations of Cl - increased with distance beyond 750 km inland. Furthermore, the contribution factors between Cl - and Na + decreased and the Cl -/Na + ratio and the nssCl -/Cl - ratio increased toward the interior of the continent. These results indicate that sea salt aerosols are transported from the coastal region toward the inland region of the Antarctic continent, and that a source of Cl - other than sea salt exists in the inland plateau of Antarctica. The concentrations of SO 2- 4, NO - 3 and 7Be in snow were relatively high in the coastal region and the inland plateau region compared with those in the katabatic wind region.     

2000—2019年新疆积雪终日时空变化特征

基于Google Earth Engine（GEE）遥感云平台,利用2000—2019年MODIS积雪产品资料提取和计算新疆积雪终日信息,利用趋势分析,变异系数等方法分析了新疆积雪终日时空变化特征和变化趋势。结果表明：（1） 新疆积雪终日以天山为界,天山以北长于南部,山区为积雪终日的高值区,盆地为积雪终日的低值区。北疆准噶尔盆地和伊犁河谷积雪终日在75~114 d之间,南疆塔里木盆地在0~31 d之间属于低值区。阿尔泰山脉、天山山脉和昆仑山脉区域在224~365 d之间属于高值区。（2） 南疆和北疆积雪终日有明显的时空差异,2000—2019年北疆准噶尔盆地和高海拔山脉地区积雪终日有明显的推迟趋势,推迟幅度达到14 d,占新疆总面积的8%。南疆塔里木盆地和东疆区域有明显的提前趋势,提前幅度达到16 d约占新疆总面积的44%。塔里木盆地和准噶尔盆地具有相反的变化趋势。（3） 新疆积雪终日年际变化差异显著,天山中段和北疆积雪终日出现不稳定状况,天山中段2002—2009年总体上呈现“M”型的特点,即多年积雪消融日年均值中出现明显的波峰和波谷,北疆2009—2019年积雪终日有较大的年际变化呈现出不稳定状况,出现明显的波峰和波谷,年际变化较大。     

东南极内陆地区和乌鲁木齐河源1号冰川表层雪内NO^—3沉积后过程差异

酸性气体成分（如ＮＯ－３）的强挥发性导致其在雪面沉降后,具有沉积后气／雪交换作用,即其在表层雪内是“可逆”沉降的。通过比较东南极内陆雪坑的ＮＯ－３剖面和乌鲁木齐河源１号冰川表层雪内ＮＯ－３的浓度变化,认为沉积后气／雪交换作用在东南极内陆较显著,而在乌鲁木齐河源１号冰川则不然。表层雪内ＮＯ－３存在方式的不同和沉降机制的差异应是导致两地ＮＯ－３沉积后过程差异的原因所在。     

2007—2020年西藏草面温度时空分布特征

利用2007—2020年西藏38个气象站点平均草面温度（简称草温）、平均气温、平均地表温度、云量、降水量等观测资料,采用气候统计诊断方法分析了西藏草面温度的时空分异特征及其影响因素,以期科学研究当地草地生态系统和开展专业气象服务。结果表明：西藏年平均草温呈自东南向西北递减的分布。草温与海拔高度存在显著的负相关,海拔高度每升高100 m,季平均草温降低0.44~0.70 ℃,年平均草温降低0.58 ℃;与纬度有着显著的曲线关系,29.3°N以南（北）地区,随着纬度增加,草温随之升高（降低）。各站草温呈一峰一谷的日变化特征,日最低值出现在07:00—08:00（北京时间）,日最高值均出现在14:00;草温月平均最低值都出现在1月,月平均最高值出现在6月或7月;76%的站点草温的变化为夏季>春季>秋季>冬季的气候特征。西藏草温年较差为21.4 ℃,较气温年较差偏大3.1 ℃;草温日较差达35.7 ℃,远高于气温日较差,偏大21.6 ℃。草温与气温之差以夏季最大,其次是春季、冬季两者比较接近;草温与地表温度之差以春季最大,夏季次之,冬季最小。在空间分布上,月平均草温与气温、地表温度均呈显著的正相关,与平均风速、积雪日呈显著的负相关;积雪深度对草温的影响,除冬季外二者存在显著的负相关;大部分月份平均草温与总云量、低云量、降水量的关系不显著。86.8%的站点5—9月平均逐小时草温与降水量存在显著的负相关关系。     

东南极夏季中山站邻近固定冰DMS、DMSP分布初探

中国第30次南极科学考察期间,在中山站邻近固定冰区采集了两支海冰冰芯并首次分析其中的DMS、DMSP含量。结果表明,两支冰芯上层均含有较高浓度的DMSP+DMS,分别高达114.93及134.41 nmol·L-1。冰芯中DMS、DMSP+DMS浓度随深度的增加而递减。两支冰芯顶部DMSP+DMS高值的成因不同,冰芯1主要受藻类活动影响而产生DMSP+DMS高值,冰芯2主要是由于雪层及薄冰层阻碍,致使DMS在冰芯顶部聚集产生DMS高值。因为海冰底部较高生物量的海冰融化进入水体,所观测的剩余海冰底部Chl a、DMSP+DMS值均较低。在海冰的融化过程中,卤道内的卤水可发生垂向运输,致使冰芯中Chl a、DMSP+DMS的垂直分布有所不同。冰芯的Chl a、DMSP+DMS总量分别为6.79和10.20、51.83和88.41μmol·m-2,与前人研究结果比较,在海冰融化过程中,海冰中Chl a、DMSP+DMS总量变化的总趋势是递减的。