联合ERS-1和ICESAT卫星测高数据构建南极冰盖DEM          下载免费PDF全文

王泽民熊云琪  杨元德鄂栋臣 《极地研究》2013,25(3):211-217

南极冰盖DEM在南极研究中具有十分重要的作用,而构建南极冰盖DEM的主要数据源来自于卫星测高。在已有的测高卫星数据中,ERS-1/GM和ICESAT在空间分辨率和精度方面存在互补的关系,综合利用这两类数据,是获得南极冰盖高分辨率高精度DEM的前提。本文采用了数据联合的方法,利用ERS-1和ICESAT测高数据来构建南极冰盖DEM。采用ICESAT离散数据和RAMP/DEM v2对综合DEM进行精度评估,结果表明综合DEM高程精度在4 m左右。  相似文献   

Mass balance and near-surface ice temperature structure of Baishui Glacier No.1 in Mt. Yulong     

杜建括  何元庆  李双  王世金  牛贺文  辛惠娟  蒲焘 《地理学报(英文版)》2013,23(4):668-678

The accumulation and ablation of a glacier directly reflect its mass income and wastage, and ice temperature indicates glacier＇s climatic and dynamic conditions. Glaciological studies at Baishui Glacier No.1 in Mt. Yulong are important for estimating recent changes of the cryosphere in Hengduan Mountains. Increased glacier ablation and higher ice temperatures can cause the incidents of icefall. Therefore, it is important to conduct the study of glacier mass balance and ice temperature, but there are few studies in relation to glacier＇s mass balance and active-layer temperature in China＇s monsoonal temperate glacier region. Based on the field observations of mass balance and glacier temperature at Baishui Glacier No.1, its accumulation, ablation, net balance and near-surface ice temperature structure were analyzed and studied in this paper. Results showed that the accumulation period was ranged from October to the following mid-May, and the ablation period occurred from mid-May to October, suggesting that the ablation period of temperate glacier began about 15 days earlier than that of continental glaciers, while the accumulation period began about 15 days later. The glacier ablation rate was 6.47 cm d 1 at an elevation of 4600 m between June 23 and August 30, and it was 7.4 cm d 1 at 4800 m between June 26 and July 11 in 1982, moreover, they respectively increased to 9.2 cm d 1 and 10.8 cm d 1 in the corresponding period and altitude in 2009, indicating that glacier ablation has greatly intensified in the past years. The temperature of the main glacier body was close to melting point in summer, and it dropped from the glacier surface and reached a minimum value at a depth of 4-6 m in the ablation zone. The temperature then rose to around melting point with the depth increment. In winter, the ice temperature rose gradually with the increasing depth, and close to melting point at the depth of 10 m. Compared with the data from 1982, the glacier temperature has risen in the ablation zone in recent decades.  相似文献   

Spaceborne Microwave Remote Sensing of Arctic Sea Ice During Spring     

《The Professional geographer》2013,65(2):315-322

This paper outlines the fundamental roles sea ice plays during the spring Arctic climate, and it demonstrates the use of passive microwave remote sensing in measuring climatically important sea ice variables during the spring transitional period. It discusses the theoretical concepts underlying passive microwave remote sensing of sea ice, and it summarizes the historical use of satellite microwave radiometry in the Arctic region. In addition, this paper discusses the derivation of climatically important sea ice variables, including sea ice extent, concentration, multiyear ice fraction, and snow melt onset, with additional comments on the precision and accuracy of the remote sensing estimates. It also discusses interannual trends in sea ice extent and presents interannual trends in snow melt onset dates. Finally, this paper provides a brief discussion on the future directions in passive microwave remote sensing of climatically important sea ice variables during the spring transitional period.  相似文献   

FIRE EFFECTS ON SOIL HETEROGENEITY BENEATH CHAMISE AND REDSHANKS CHAPARRAL     

Susan W. Beatty 《自然地理学》2013,34(1):44-52

The origin of soil heterogeneity found in Adenostoma fasciculatum and A sparsifolium chaparral was investigated in the Santa Monica Mountains, California. Possibilities were that geologic and genetic processes created inherent variability in surface soils, and/or that chaparral vegetation generated this variability. Fourteen soil properties were assessed under 17 pairs of the two shrub species before (1984) and after (1985) a wildfire. Hypotheses were that, although magnitudes of soil properties may change with fire, the inherent soil patterns would remain, while vegetation-influenced patterns might either be accentuated or obliterated. All but one of the 14 soil properties changed after fire, and 8 of these changed in the same direction for both shrub species. Different magnitudes of change, as well as opposite changes in 5 soil properties, led to an elimination of most spatial heterogeneity after fire. Eleven soil properties showed significant pre-burn differences between shrub species, while only 3 did so after fire. Vegetation influence was responsible for the spatial soil heterogeneity in the mature stand of chaparral, apparently developing over one regeneration period of about 40 years. With the obliteration of fine-scale soil differences during each fire cycle, soil heterogeneity cannot play a role in determining vegetation regeneration patterns. The creation of a more uniform substrate after fire, however, may favor sprouting over seeding strategies in postfire succession. [Key words: chaparral, fire ecology, soil properties, California.]  相似文献   

MEASURED ALTITUDINAL PROFILES OF UV-B IRRADIANCE IN HAWAI'I     

Dennis Nullet  James O. Juvik 《自然地理学》2013,34(4):335-345

Erythemally weighted UV-B irradiance was measured between sea level and 4,205 m in several midday altitudinal transects and continuously for several months at sea level and 3,400 m on the Island of Hawai'i. Between sea level and 4,205 m, standardized UV-B increased 25% and 29% for solar zenith angles of 10° and 45°, respectively, under clear-sky conditions. The standardized diffuse component constituted 28% to 58% of the total as a function of optical path length. Under all sky conditions, the monthly average UV-B irradiance increased 50% in summer and 103% in winter from a cloudy, windward, sea-level location to a site at 3,400 m in generally clear skies above the trade-wind inversion. [Key words: solar radiation, ultraviolet-B irradiance, Hawai'i.]  相似文献   

3.4万年以来南极斯科舍海古生产力演变及其环境制约     

杨春丽  陈志华  肖文申  王湘芹  鞠梦珊  崔迎春  黄元辉  唐正 《海洋学报》2021,43(3):116-125

本文通过对南极斯科舍海东南部DC-11岩芯生物硅、有机氮、TFe₂O₃与有机氮同位素的年代学分析,重建了该海区3.4万年以来古生产力与环境演变历史。研究结果表明,生物硅、有机氮含量与南极温度变化基本一致,暖期高、冷期低;有机氮同位素值与南大洋海冰变化相吻合,暖期小、冷期大,冷期硝酸盐利用率大于暖期。从末次冰期、末次冰消期至全新世,研究区古生产力与环境变化显著,南极冷倒转等千年尺度的变化明显;海冰在气候、营养盐与古生产力之间起着重要的关联作用。冰期或冷期海冰的加强导致表层水层化加强,深层水及其营养盐的上涌减弱,表层海洋硝酸盐等相对匮乏,生产力降低。研究区现代与全新世铁供应充足,在风尘盛行的末次冰期和冰消期呈过剩状态,明显不同于亚南极。  相似文献   

Modelling the annual cycle of landfast ice near Zhongshan Station,East Antarctica     

Jiechen Zhao  Tao Yang  Qi Shu  Hui Shen  Zhongxiang Tian  Guanghua Hao  Biao Zhao 《海洋学报(英文版)》2021,40(7):129-141

A high resolution one-dimensional thermodynamic snow and ice(HIGHTSI) model was used to model the annual cycle of landfast ice mass and heat balance near Zhongshan Station, East Antarctica. The model was forced and initialized by meteorological and sea ice in situ observations from April 2015 to April 2016. HIGHTSI produced a reasonable snow and ice evolution in the validation experiments, with a negligible mean ice thickness bias of(0.003±0.06) m compared to in situ observations. To further examine the impact of different snow conditions on annual evolution of first-year ice(FYI), four sensitivity experiments with different precipitation schemes(0, half, normal, and double) were performed. The results showed that compared to the snow-free case,the insulation effect of snow cover decreased bottom freezing in the winter, leading to 15%–26% reduction of maximum ice thickness. Thick snow cover caused negative freeboard and flooding, and then snow ice formation,which contributed 12%–49% to the maximum ice thickness. In early summer, snow cover delayed the onset of ice melting for about one month, while the melting of snow cover led to the formation of superimposed ice,accounting for 5%–10% of the ice thickness. Internal ice melting was a significant contributor in summer whether snow cover existed or not, accounting for 35%–56% of the total summer ice loss. The multi-year ice(MYI)simulations suggested that when snow-covered ice persisted from FYI to the 10 th MYI, winter congelation ice percentage decreased from 80% to 44%(snow ice and superimposed ice increased), while the contribution of internal ice melting in the summer decreased from 45% to 5%(bottom ice melting dominated).  相似文献   

Glacial bedforms in the Northwind Abyssal Plain,Chukchi Borderland     

Zhongyan Shen  Tao Zhang  Jinyao Gao  Chunguo Yang  Qingsheng Guan 《海洋学报(英文版)》2021,40(5):114-119

A series of sub-parallel linear glacial scours are identified on the crest of the Baoshi Seamount in the Northwind Abyssal Plain by compiling new multibeam data acquired during the 9th Chinese Arctic Research Expedition (CHINARE-Arc9) in 2018 and previously published data. The new data reveal scours that developed at water depths of 850–1 030 m with an orientation of about 75°/255°. The maximum water depth occurs in the southernmost scour and is deeper than that from previous investigations, which showed a maximum scouring depth of about 900 m on the seamount. The topographic and geomorphological characteristics suggest that these scours resulted from erosion by the ice shelf extending from the Chukchi margin and/or Laurentide Ice Sheet that grounded on the crest of the seamount and moved in a NE–SW direction. Other possibilities of their genesis include armadas of large icebergs/multi-keel icebergs calved from the Chukchi Shelf or the Laurentide Ice Sheet. The new data provide new constraints for assessing the extent and volume of the ice sheet in the Chukchi area during glacial maxima.  相似文献   

Evaluation of vertical crustal movements and sea level changes around Greenland from GPS and tide gauge observations     

Jiachun An  Baojun Zhang  Songtao Ai  Zemin Wang  Yu Feng 《海洋学报(英文版)》2021,40(1):4-12

To better monitor the vertical crustal movements and sea level changes around Greenland, multiple data sources were used in this paper, including global positioning system(GPS), tide gauge, satellite gravimetry, satellite altimetry, glacial isostatic adjustment(GIA). First, the observations of more than 50 GPS stations from the international GNSS service(IGS) and Greenland network(GNET) in 2007–2018 were processed and the common mode error(CME) was eliminated with using the principal component analysis(PCA). The results show that all GPS stations show an uplift trend and the stations in southern Greenland have a higher vertical speed. Second, by deducting the influence of GIA, the impact of current Gr IS mass changes on GPS stations was analysed, and the GIA-corrected vertical velocity of the GPS is in good agreement with the vertical velocity obtained by gravity recovery and climate experiment(GRACE). Third, the absolute sea level change around Greenland at 4 gauge stations was obtained by combining relative sea level derived from tide gauge observations and crustal uplift rates derived from GPS observations, and was validated by sea level products of satellite altimetry. The results show that although the mass loss of Gr IS can cause considerable global sea level rise, eustatic movements along the coasts of Greenland are quite complex under different mechanisms of sea level changes.  相似文献   

Quantitative analysis of Arctic ice flow acceleration with increasing temperature     

Zemin Wang  Boya Yan  Songtao Ai  Kim Holmén  Jiachun An  Hongmei Ma 《海洋学报(英文版)》2021,40(1):22-32

This study explores the ice flow acceleration(21.1%) of Pedersenbreen during 2016–2017 after the extremely warm winter throughout the whole Arctic in 2015/2016 using in situ data and quantitatively analyses the factors contributing to this acceleration. Several data sets, including 2008–2018 air temperature data from Ny-?lesund,ten-year in situ GPS measurements and Elmer/Ice ice flow modelling under different ice temperature scenarios,suggest that the following factors contributed to the ice flow acceleration: the softened glacier ice caused by an increase in the air temperature(1.5℃) contributed 2.7%–30.5%, while basal lubrication contributed 69.5%–97.3%.The enhanced basal sliding was mostly due to the increased surface meltwater penetrating to the bedrock under the rising air temperature conditions; consequently, the glacier ice flow acceleration was caused mainly by an increase in subglacial water. For Pedersenbreen, there was an approximately one-year time lag between the change in air temperature and the change in glacier ice flow velocity.  相似文献