Antarctic surveying, mapping and remote sensing is one of the important aspects of the Chinese Antarctic geoscience research program that stretch back over 25 years, since the first Chinese National Antarctic Research...Antarctic surveying, mapping and remote sensing is one of the important aspects of the Chinese Antarctic geoscience research program that stretch back over 25 years, since the first Chinese National Antarctic Research Expedition （CHINARE） in 1984. During the 1980＇s, the geodetic datum, height system and absolute gravity datum were established at the Great Wall and Zhongshan Stations. Significant contributions have been made by the construction of the Chinese Great Wall, Zhongshan and Kunlun Stations in Antarctica. Geodetic control and gravity networks were established in the King George Islands, Grove Moun- tains and Dome Argus. An area of more than 200 000 km2 has been mapped using satellite image data, aerial photogrammetry and in situ data. Permanent GPS stations and tide gauges have been established at both the Great Wall and Zhongshan Stations. Studies involving plate motion, precise satellite orbit determination, the gravity field, sea level change, and various GPS applications for atmospheric studies have been carried out. Based on remote sensing techniques, studies have been undertaken on ice sheet and glacier movements, the distributions of blue ice and ice crevasses, and ice mass balance. Polar digital and visual mapping tech- niques have been introduced, and a polar survey space database has been built. The Chinese polar scientific expedition manage- ment information system and Chinese PANDA plan display platform were developed, which provides technical support for Chi- nese polar management. Finally, this paper examines prospects for future Chinese Antarctic surveying, mapping and remote sens- ing.展开更多
The thickness and upper densification structure of an ice sheet are important parameters for dynamic ice sheet modeling and glacier mass balance studies.Seismic ambient noise methods,such as the horizontal-to-vertical...The thickness and upper densification structure of an ice sheet are important parameters for dynamic ice sheet modeling and glacier mass balance studies.Seismic ambient noise methods,such as the horizontal-to-vertical spectral ratio(H/V)method and ambient noise cross-correlation method,are becoming increasingly popular in glacier structure investigations.During China's 39th expedition to Antarctica,seismic ambient noise experiments were conducted to investigate the structure of the ice sheet at Kunlun Station,Dome A,using a seismic nodal system.We obtained a broad band(0.1–10 Hz)H/V curve with a 1-hour noise record from a seismic node.In addition,we extracted the Rayleigh wave dispersion curve with 5-day noise cross-correlation functions from a linear dense seismic array.Three clear peaks were observed in the H/V curve—a lower peak at~0.17 Hz and two higher frequency peaks at~3 Hz and~6 Hz.We inverted the ice sheet thickness using the lower frequency portion of the H/V curve and inverted the upper structure of the ice sheet using the higher frequency portion of the H/V curve jointly with the dispersion curve.Our estimations from ambient noise observations were consistent with those derived from the BedMachine ice sheet thickness dataset and the density profile determined by ground-penetrating radar investigations at the same site.展开更多
The year,2024,marks the 40th anniversary of Chinese research expeditions in the polar regions and the 25th anniversary of its Arctic research expeditions.China has conducted 14 national Arctic research expeditions.Wit...The year,2024,marks the 40th anniversary of Chinese research expeditions in the polar regions and the 25th anniversary of its Arctic research expeditions.China has conducted 14 national Arctic research expeditions.With the increase of understandings on the global impacts of the changes of Arctic climate system,especially on China’s weather and climate,and demands for commercial utilization of the Arctic sea routes,Chinese scientists have made great progresses on in site and remote sensing observation technologies for Arctic Ocean,interaction mechanisms between atmosphere,sea ice,and ocean,the connection mechanism between the Arctic Ocean and other regions,and have achieved a series of research results.This study summarizes the research achievements by Chinese scientists in the above-mentioned aspects or beyond,identifies knowledge gaps,and based on this,discusses prospects and provides suggestions.From a perspective of observation,improving the observation capabilities of the Arctic Ocean in winter and the ocean under the ice,as well as floe-scale processes of sea ice and mesoscale and submesoscale processes of the ocean,is an urgent task to be addressed.Strengthening international cooperation is necessary for building a monitoring network for the Arctic marine environment.From a perspective of numerical simulation,the descriptive ability and parameterization scheme of sub-grid processes based on observational evidence need to be developed.From a perspective of cross-sphere interactions,in addition to the multi-media coupling within the Arctic Ocean that this review focuses on,the interaction between the Arctic Ocean and land or ice sheet(Greenland),especially the water cycle process,is also a scientific domain that needs to be considered,in the context of Arctic warming and humidification.From a perspective of climate effects,the physical mechanisms that affect the robustness of teleconnection need to be clarified.展开更多
Information on the thickness distribution and volume of glacier ice is highly important for glaciological applications;however,detailed measurements of the ice thickness of many glaciers in the Chinese Altay Mountains...Information on the thickness distribution and volume of glacier ice is highly important for glaciological applications;however,detailed measurements of the ice thickness of many glaciers in the Chinese Altay Mountains remain lacking.Burqin Glacier No.18 is a northeast-orientated cirque glacier located on the southern side of the Altay Mountains.This study used PulseEKKO®PRO 100A enhancement ground-penetrating radar(GPR)to survey the ice thickness and volume of Burqin Glacier No.18 in summer 2018.Together with GPR surveying,spatial distributed profiles of the GPR measurements were concurrently surveyed using the real-time kinematic(RTK)global navigation satellite system(GNSS,Unistrong E650).Besides,we used QuickBird,WorldView-2,and Landsat TM to delineate accurate boundary of the glacier for undertaking estimation of glacier ice volume.GPR measurements revealed that the basal topography of profile B1-B2 was flat,the basal topography of profile C1-C2 presented a V-type form,and the basal topography of profile D1-D2 had a typical U-type topographic feature because the bedrock near the central elevation of the glacier was relatively flat.The longitudinal profile A1-A2 showed a ladder-like distribution.Glacier ice was thin at the terminus and its thickness increased gradually from the elevation of approximately 2620 m a.s.l.along the main axis of the glacier tongue with an average value of 80(±1)m.The average ice thickness of the glacier was determined as 27(±2)m and its total ice volume was estimated at 0.031(±0.002)km3.Interpretation of remote sensing images indicated that during 1989–2016,the glacier area reduced from 1.30 to 1.17 km2(reduction of 0.37%/a)and the glacier terminus retreated at the rate of 8.48 m/a.The mean ice thickness of Burqin Glacier No.18 was less than that of the majority of other observed glaciers in China,especially those in the Qilian Mountains and Central Chinese Tianshan Mountains;this is probably attributable to differences in glacier type and climatic setting.展开更多
Long-term,ground-based daily global solar radiation (DGSR) at Zhongshan Station in Antarctica can quantitatively reveal the basic characteristics of Earth’s surface radiation balance and validate satellite data for t...Long-term,ground-based daily global solar radiation (DGSR) at Zhongshan Station in Antarctica can quantitatively reveal the basic characteristics of Earth’s surface radiation balance and validate satellite data for the Antarctic region.The fixed station was established in 1989,and conventional radiation observations started much later in 2008.In this study,a random forest (RF) model for estimating DGSR is developed using ground meteorological observation data,and a highprecision,long-term DGSR dataset is constructed.Then,the trend of DGSR from 1990 to 2019 at Zhongshan Station,Antarctica is analyzed.The RF model,which performs better than other models,shows a desirable performance of DGSR hindcast estimation with an R^2 of 0.984,root-mean-square error of 1.377 MJ m^(-2),and mean absolute error of 0.828 MJ m^(-2).The trend of DGSR annual anomalies increases during 1990–2004 and then begins to decrease after 2004.Note that the maximum value of annual anomalies occurs during approximately 2004/05 and is mainly related to the days with precipitation (especially those related to good weather during the polar day period) at this station.In addition to clouds and water vapor,bad weather conditions (such as snowfall,which can result in low visibility and then decreased sunshine duration and solar radiation) are the other major factors affecting solar radiation at this station.The high-precision,longterm estimated DGSR dataset enables further study and understanding of the role of Antarctica in global climate change and the interactions between snow,ice,and atmosphere.展开更多
Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter da...Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.展开更多
This study examined the mass change of the Antarctic ice sheet(AIS) based on ICESat and CryoSat-2 observations. We estimated the AIS exhibited mass losses of-101±15 Gt·aduring the ICESat period(Sept–Nov 200...This study examined the mass change of the Antarctic ice sheet(AIS) based on ICESat and CryoSat-2 observations. We estimated the AIS exhibited mass losses of-101±15 Gt·aduring the ICESat period(Sept–Nov 2003 to Sept–Oct 2009) and-186±55 Gt·aduring the CryoSat-2 period(Jan 2011 to Dec 2015). Mass losses occurred mainly in the sectors of the Amundsen and Bellingshausen seas. Benefitting from the 30-d subcycle of CryoSat-2, we obtained monthly estimates of mass evolution. Considerable annual variations were observed in the mass evolution sequences and the climatological monthly mass evolution. Seasonal mass evolutions in the sectors of the Bellingshausen and Amundsen seas were found most representative of the annual variation. The geographical distribution characteristics of interannual AIS mass evolution were revealed by the annual average mass evolution sequences. During Jan 2011 to Dec 2015, the ice sheets in the sectors of the Bellingshausen and Amundsen seas, and the Totten Glacier, experienced increasingly rapid areal mass loss. An area of mass gain with a moderate rate of increase was found between Dronning Maud Land and Enderby Land. Rapid mass accumulation has occurred in a limited area of the Kamb Ice Stream.展开更多
Basal melting and calving are the main pathways for mass loss in Antarctic ice shelves.Basal channels,as detailed variations in basal melting,mutually promote basal melting and calving,thereby weakening the stability ...Basal melting and calving are the main pathways for mass loss in Antarctic ice shelves.Basal channels,as detailed variations in basal melting,mutually promote basal melting and calving,thereby weakening the stability of ice shelves.Therefore,it is necessary to calculate and statistically analyze basal melting,basal channels,and calving events across all Antarctic ice shelves and examine the correlation among these three factors.This study utilizes various data sources to calculate the Basal Channel Density(BCD)and average basal melt rate of all Antarctic ice shelves during 2010-2020,as well as the spatial correlation between basal melting,basal channels,and calving.We found that ice shelves along the Amundsen Sea and Bellingshausen Sea have higher basal melt rates and basal channel densities,while other sea areas have lower values.This is mainly influenced by seabed topography and Circumpolar Deep Water.Excluding(CDW)extreme calving events,there is a positive correlation among basal melting,basal channels,and calving in coastal ice shelves across different sea areas,with a correlation coefficient exceeding 0.67.This indicates that basal melting and basal channels are major factors causing ice shelf calving.Our results emphasize the importance of the impact of basal melting,basal channels,and calving on ice shelf stability,and they provide a significant reference for further research on ice shelf-ocean interactions.展开更多
Elevation change monitoring of the Antarctic ice sheet has been a key issue in global change research.Satellite altimetry has been proven to be effective in detecting ice sheet variations. With the development of ICES...Elevation change monitoring of the Antarctic ice sheet has been a key issue in global change research.Satellite altimetry has been proven to be effective in detecting ice sheet variations. With the development of ICESat-2, many elevation observations can be used to derive elevation changes. However, the large amount of multitemporal data may include anomalous data points, increasing the uncertainty of the results. In this work, we improved the traditional repeat track method by introducing the Institute of Geodesy and Geophysics Ⅲ(IGGⅢ) method to obtain high-accuracy estimates of elevation change. The improved method was applied to analyze elevation changes along the transect from Zhongshan Station to Dome A in East Antarctica via ICESat-2 satellite altimetry data. The results show that the improved and traditional methods yield consistent numerical and spatial elevation change distributions. The elevation change calculated via the traditional method is 0.033 ± 0.131 m/yr, whereas the elevation change estimated via the IGGⅢ robust estimation method is 0.033 ± 0.109 m/yr from March 2019 to December 2021.In terms of spatial distribution, elevation changes in inland areas remain close to equilibrium, whereas regions with steeper ice sheet margins exhibit positive accumulation trends in elevation changes. The improved method reduces the standard error of the adjustment function from 0.975 to 0.691 m/yr. The improvement is particularly remarkable in the area between 72°S and 77°S. The results demonstrate that the IGGⅢ method effectively reduces errors caused by the inclusion of anomalous data and maintains the high data utilization rate of repeat-orbit methods.展开更多
Lake 90°E in Antarctica encompasses an area of 2000 km2,ranking it the second largest subglacial lake identified in the country by area,following Vostok Subglacial Lake.In this study,the overlying ice thickness a...Lake 90°E in Antarctica encompasses an area of 2000 km2,ranking it the second largest subglacial lake identified in the country by area,following Vostok Subglacial Lake.In this study,the overlying ice thickness and lake elevation of Lake 90°E were determined using airborne radio-echo sounding across two survey lines,conducted by the International Collaborative Exploration of the Cryosphere by Airborne Profiling in Princess Elizabeth Land(ICECAP/PEL)campaign during the 32nd Chinese National Antarctic Research Expedition(CHINARE 32,2015-2016),and the depth of lake water was inversed by coupling with synchronous airborne gravity data.The analysis revealed a 15-m elevation increase in the ice sheet surface from the southeast to the northwest,correlating with a gradient in ice thickness that progresses from thin in the southeast to thick in the northwest.The maximum water depth of Lake 90°E is estimated as 320 m along the central line,bifurcated by a topographic ridge into two zones of varying depths,with exceptionally shallow water at its periphery.Thermodynamic modeling using data from two points along the survey lines indicated that melt rates at the ice-water interface have consistently been low over the last 400,000 years,varying between 0.56-0.95 mm/yr and 2.70-3.41 mm/yr,balanced by either basal freezing to the south or downstream water loss,thereby maintaining a thermodynamically stable state.Satellite imagery and altimetry data analyses identified no significant changes in the outline or elevation of the ice surface over the past 20 years.This study presents novel insights into the physiography and thermodynamic state of Lake 90°E,establishing a foundation for future drilling initiatives.展开更多
Basal melting is an important factor affecting the stability of the ice shelf.The basal channel is formed from uneven melting,which also has an important impact on the stability of the ice shelf.Therefore,it has impor...Basal melting is an important factor affecting the stability of the ice shelf.The basal channel is formed from uneven melting,which also has an important impact on the stability of the ice shelf.Therefore,it has important scientific value to study the basal channel changes.This study combined datasets of Mosaics of Antarctica,Reference Elevation Model of Antarctica(REMA) and Operation Ice Bridge to study the temporal and spatial changes of basal channels at the Getz Ice Shelf in Antarctica.The relationships between the cross-sectional area and width of basal channel and those of its corresponding surface depression were statistically analyzed.Then,the changes of the basal channels of Getz Ice Shelf were derived from the ICESat observations and REMA digital elevation models(DEMs).After a detailed analysis of the factors affecting the basal channel changes,we found that the basal channels of Getz Ice Shelf were mainly concentrated in the eastern of the ice shelf,and most of them belonged to the ocean-sourced basal channel.From 2009 to 2016,the total length of the basal channel has increased by approximately 60 km.Affected by the warm Circumpolar Deep Water(CDW),significant changes in the basal channel occurred in the middle reaches of the Getz Ice Shelf.The change of the basal channels at the edge of the Getz Ice Shelf is significantly weaker than that in its middle and upper reaches.Especially in 2005–2012,the eastward wind on the ocean wind field and the westward wind around the continental shelf caused the invasion and upwelling of CDW.Meanwhile,the continuous warming of deep seawater also caused the deepening of the basal channel.During from 2012 to 2020,the fluctuations of the basal channels seem to be caused by the changes in temperature of CDW.展开更多
Based on an ice concentration threshold of 90%,it has been identified that two polynya events occurred in the region north of Greenland during the 2017/2018 ice season.The winter event lasted from February 20 to March...Based on an ice concentration threshold of 90%,it has been identified that two polynya events occurred in the region north of Greenland during the 2017/2018 ice season.The winter event lasted from February 20 to March 3,2018 and the summer event persisted from August 2 to September 5,2018.The minimum ice concentration derived from Advanced Microwave Scanning Radiometer 2(AMSR2)observations was 72%and 65%during the winter and summer events,respectively.The occurrence of both events can be related to strengthened southerly winds associated with an increased east-west zonal surface level air pressure gradient across the north Greenland due to perturbation of mid-troposphere polar vortex.The relatively warm air temperature during the 2017/2018 freezing season in comparison with previous years,together with the occurrence of the winter polynya,formed favourable pre-conditions for ice field fracturing in summer,which promoted the formation of the summer polynya.Diminished southerly winds and increased cover of new ice over the open water were the dominant factors for the disappearance of the winter polynya,whereas increased ice inflow from the north was the primary factor behind the closure of the summer polynya.Sentinel-1 Synthetic Aperture Radar(SAR)images were found better suited than AMSR2 observations for quantification of a new ice product during the polynya event because the SAR images have high potential for mapping of different sea ice regimes with finely spatial resolution.The unprecedented polynya events north of Greenland in 2017/2018 are important from the perspective of Arctic sea ice loss because they occurred in a region that could potentially be the last“Arctic sea ice refuge”in future summers.展开更多
The decreasing of Arctic sea ice is projected to continue with global warming,which makes the summer navigation conditions of the Arctic improve.Based on the multi-source remote-sensing data with inter-sensor calibrat...The decreasing of Arctic sea ice is projected to continue with global warming,which makes the summer navigation conditions of the Arctic improve.Based on the multi-source remote-sensing data with inter-sensor calibration processing and the ship-based observational data from R/V Xuelong and M/V Yongsheng,the sea ice conditions of the Arctic Northeast Passage(NEP)during the 2002-2021 summer seasons were analyzed,and the navigability of the NEP between July and October from 2002 to 2021 was discussed.Inter-sensor calibration could effectively reduce the deviation from different passive microwave data.Sea ice extent and thickness in the NEP decreased annually,which resulted in the navigability of the NEP showing a potential tendency toward improvement in navigability.The navigation period was mainly concentrated in early August to early October.The middle part of the NEP was primarily affected by sea ice.This influence decreased over time,while the navigation period increased,especially in the Vilkitsky Strait,which is a key shipping area.This analysis of sea ice conditions and navigability in the past 20 years could provide a reference for future scientific investigations and aid in merchant ship navigation in the Arctic summer.展开更多
Marine geophysical survey by the Chinese National Antarctic Research Expedition （CHINARE） began with the first science expedition in 1984/1985, although only four cruises were performed in the vicinity of the Antar...Marine geophysical survey by the Chinese National Antarctic Research Expedition （CHINARE） began with the first science expedition in 1984/1985, although only four cruises were performed in the vicinity of the Antarctic Peninsula between then and 1991/1992. After a 20 year hiatus, Antarctic marine geophysical research was relaunched by the Chinese Polar Environmental Comprehensive Investigation and Assessment Programs （known simply as the Chinese Polar Program） in 2011/2012. Integrated geophysical surveys have been carried out annually since, in Prydz Bay and the Ross Sea. During the last 5 years, we have acquired about 5500 km of bathymetric, gravimetric, and magnetic lines; more than 1800 km of seismic reflection lines; and data from several heat flow and Ocean Bottom Seismometer （OBS） stations. This work has deepened understandings of geophysical features and their implications for geological tectonics and glacial history in Antarctica and its surrounding seas. Compiled Antarctic Bouguer and Airy isostatic gravity anomalies show different features of tectonics between the East Antarctic stability and West Antarctic activity. Calculated magnetic anomalies, heat flow anomalies and lithospheric anisotropy offshore of Prydz Bay may imply high heat capacity of mantle shielded by the continental shelf lithosphere, but high heat dissipation of mantle due to the Cretaceous breakup of Gondwana along the continent and ocean transition （COT）, where large sediment ridges would be brought about by the Oligocene ice sheet retreat and would enlarge free-air gravity anomalies. In the western Ross Sea, CHINARE seismic profiles indicate northern termination of the Terror Rift and deposition time of the grounding zone wedge in the northern JOIDES Basin.展开更多
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 ...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.展开更多
The temporal distribution characteristics of COSMIC occultation data are analyzed in detail, and the limitations in earthquake-ionosphere anomaly detection caused by the temporal distribution characteristics of COSMIC...The temporal distribution characteristics of COSMIC occultation data are analyzed in detail, and the limitations in earthquake-ionosphere anomaly detection caused by the temporal distribution characteristics of COSMIC occultation data are discussed using the example of the Wenchuan earthquake. The results demonstrate that there is no fixed temporal resolution for COSMIC occultation data when compared with other ionospheric observation techniques. Therefore, occultation data cannot currently be independently utilized in research studies but can only be used as a complement to other ionospheric observation techniques for applications with high temporal resolution demands, such as earthquake-ionosphere anomaly detection.展开更多
There are a number of ionospheric models available for research and application, such as the polynomial model, generalized trigonometric series function model, low degree spherical harmonic function model, adjusted sp...There are a number of ionospheric models available for research and application, such as the polynomial model, generalized trigonometric series function model, low degree spherical harmonic function model, adjusted spherical harmonic function model, and spherical cap harmonic function analysis. Using observations from more than 40 continuously operating stations across Antarctica in 2010, ifve models are compared with regard to their precision and applicability to polar regions. The results show that all the models perform well in Antarctica with 0.1 TECU of residual mean value and 2 TECU of root mean square error.展开更多
A comprehensive analysis of sea ice and its snow cover during the summer in the Arctic Pacific sector was conducted using the observations recorded during the 7th Chinese National Arctic Research Expedition(CHIANRE-20...A comprehensive analysis of sea ice and its snow cover during the summer in the Arctic Pacific sector was conducted using the observations recorded during the 7th Chinese National Arctic Research Expedition(CHIANRE-2016)and the satellite-derived parameters of the melt pond fraction(MPF)and snow grain size(SGS)from MODIS data.The results show that there were many low-concentration ice areas in the south of 78°N,while the ice concentration and thickness increased significantly with the latitude above the north of 78°N during CHIANRE-2016.The average MPF presented a trend of increasing in June and then decreasing in early September for 2016.The average snow depth on sea ice increased with latitude in the Arctic Pacific sector.We found a widely developed depth hoar layer in the snow stratigraphic profiles.The average SGS generally increased from June to early August and then decreased from August to September in 2016,and two valley values appeared during this period due to snowfall incidents.展开更多
This paper summarizes the progress of the Chinese Antarctic expedition in geodetic remote sensing. It describes the systems for continuous satellite navigation and positioning, and the tide gauges that have been estab...This paper summarizes the progress of the Chinese Antarctic expedition in geodetic remote sensing. It describes the systems for continuous satellite navigation and positioning, and the tide gauges that have been established at the Zhongshan and Great Wall stations in Antarctica. Advances in the investigation of plate motion, the gravity field, and sea level change as well as the application of GPS in atmospheric studies are reported. Details of the movements of ice sheets and glaciers, distributions of blue ice and ice crevasses, and mass balance studies based on remote sensing techniques are presented. The use of field, satellite, and photogrammetric data to produce topographic maps is described. Finally, the prospects for further Antarctic surveying and mapping are discussed. In the near future, we will establish a high-precision geodetic datum in the Chinese Antarctic expedition areas, monitor changes of Antarctic snow and ice, and develop a platform for sharing Antarctic resource and environment information.展开更多
The snow depth on sea ice is an extremely critical part of the cryosphere.Monitoring and understanding changes of snow depth on Antarctic sea ice is beneficial for research on sea ice and global climate change.The Mic...The snow depth on sea ice is an extremely critical part of the cryosphere.Monitoring and understanding changes of snow depth on Antarctic sea ice is beneficial for research on sea ice and global climate change.The Microwave Radiation Imager(MWRI)sensor aboard the Chinese FengYun-3D(FY-3D)satellite has great potential for obtaining information of the spatial and temporal distribution of snow depth on the sea ice.By comparing in-situ snow depth measurements during the 35th Chinese Antarctic Research Expedition(CHINARE-35),we took advantage of the combination of multiple gradient ratio(GR(36V,10V)and GR(36V,18V))derived from the measured brightness temperature of FY-3D MWRI to estimate the snow depth.This method could simultaneously introduce the advantages of high and low GR in the snow depth retrieval model and perform well in both deep and shallow snow layers.Based on this,we constructed a novel model to retrieve the FY-3D MWRI snow depth on Antarctic sea ice.The new model validated by the ship-based observational snow depth data from CHINARE-35 and the snow depth measured by snow buoys from the Alfred Wegener Institute(AWI)suggest that the model proposed in this study performs better than traditional models,with root mean square deviations(RMSDs)of 8.59 cm and 7.71 cm,respectively.A comparison with the snow depth measured from Operation IceBridge(OIB)project indicates that FY-3D MWRI snow depth was more accurate than the released snow depth product from the U.S.National Snow and Ice Data Center(NSIDC)and the National Tibetan Plateau Data Center(NTPDC).The spatial distribution of the snow depth from FY-3D MWRI agrees basically with that from ICESat-2;this demonstrates its reliability for estimating Antarctic snow depth,and thus has great potential for understanding snow depth variations on Antarctic sea ice in the context of global climate change.展开更多
基金supported by the National Administration of Surveying, Mapping and Geoinformation (Grant no.1469990324229)the National Natural Science Foundation of China (Grant nos.40806076, 41176172, 41176173)+2 种基金the National High Technology Research and Development Program of China (Grant no. 2008AA121702–5)the National Science and Technology Infrastructure Program of China (Grant no.2006BAB18B01)the Chinese Arctic and Antarctic Administration, SOA(Grant no. 20070206)
文摘Antarctic surveying, mapping and remote sensing is one of the important aspects of the Chinese Antarctic geoscience research program that stretch back over 25 years, since the first Chinese National Antarctic Research Expedition （CHINARE） in 1984. During the 1980＇s, the geodetic datum, height system and absolute gravity datum were established at the Great Wall and Zhongshan Stations. Significant contributions have been made by the construction of the Chinese Great Wall, Zhongshan and Kunlun Stations in Antarctica. Geodetic control and gravity networks were established in the King George Islands, Grove Moun- tains and Dome Argus. An area of more than 200 000 km2 has been mapped using satellite image data, aerial photogrammetry and in situ data. Permanent GPS stations and tide gauges have been established at both the Great Wall and Zhongshan Stations. Studies involving plate motion, precise satellite orbit determination, the gravity field, sea level change, and various GPS applications for atmospheric studies have been carried out. Based on remote sensing techniques, studies have been undertaken on ice sheet and glacier movements, the distributions of blue ice and ice crevasses, and ice mass balance. Polar digital and visual mapping tech- niques have been introduced, and a polar survey space database has been built. The Chinese polar scientific expedition manage- ment information system and Chinese PANDA plan display platform were developed, which provides technical support for Chi- nese polar management. Finally, this paper examines prospects for future Chinese Antarctic surveying, mapping and remote sens- ing.
基金supported by the National Natural Science Foundation of China(NSFC),grant number 42076234the National Key Research and Development Program of China,grant number 2021YFC2801404。
文摘The thickness and upper densification structure of an ice sheet are important parameters for dynamic ice sheet modeling and glacier mass balance studies.Seismic ambient noise methods,such as the horizontal-to-vertical spectral ratio(H/V)method and ambient noise cross-correlation method,are becoming increasingly popular in glacier structure investigations.During China's 39th expedition to Antarctica,seismic ambient noise experiments were conducted to investigate the structure of the ice sheet at Kunlun Station,Dome A,using a seismic nodal system.We obtained a broad band(0.1–10 Hz)H/V curve with a 1-hour noise record from a seismic node.In addition,we extracted the Rayleigh wave dispersion curve with 5-day noise cross-correlation functions from a linear dense seismic array.Three clear peaks were observed in the H/V curve—a lower peak at~0.17 Hz and two higher frequency peaks at~3 Hz and~6 Hz.We inverted the ice sheet thickness using the lower frequency portion of the H/V curve and inverted the upper structure of the ice sheet using the higher frequency portion of the H/V curve jointly with the dispersion curve.Our estimations from ambient noise observations were consistent with those derived from the BedMachine ice sheet thickness dataset and the density profile determined by ground-penetrating radar investigations at the same site.
基金The National Natural Science Foundation of China under contract Nos 42325604 and 42276253the Program of Shanghai Academic/Technology Research Leader under contract No.22XD1403600the Fund of the Ministry of Industry and Information Technology of China under contract No.CBG2N21-2-1.
文摘The year,2024,marks the 40th anniversary of Chinese research expeditions in the polar regions and the 25th anniversary of its Arctic research expeditions.China has conducted 14 national Arctic research expeditions.With the increase of understandings on the global impacts of the changes of Arctic climate system,especially on China’s weather and climate,and demands for commercial utilization of the Arctic sea routes,Chinese scientists have made great progresses on in site and remote sensing observation technologies for Arctic Ocean,interaction mechanisms between atmosphere,sea ice,and ocean,the connection mechanism between the Arctic Ocean and other regions,and have achieved a series of research results.This study summarizes the research achievements by Chinese scientists in the above-mentioned aspects or beyond,identifies knowledge gaps,and based on this,discusses prospects and provides suggestions.From a perspective of observation,improving the observation capabilities of the Arctic Ocean in winter and the ocean under the ice,as well as floe-scale processes of sea ice and mesoscale and submesoscale processes of the ocean,is an urgent task to be addressed.Strengthening international cooperation is necessary for building a monitoring network for the Arctic marine environment.From a perspective of numerical simulation,the descriptive ability and parameterization scheme of sub-grid processes based on observational evidence need to be developed.From a perspective of cross-sphere interactions,in addition to the multi-media coupling within the Arctic Ocean that this review focuses on,the interaction between the Arctic Ocean and land or ice sheet(Greenland),especially the water cycle process,is also a scientific domain that needs to be considered,in the context of Arctic warming and humidification.From a perspective of climate effects,the physical mechanisms that affect the robustness of teleconnection need to be clarified.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20020102,XDA20060201)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0201)+1 种基金the National Natural Science Foundation of China(International cooperation and exchange projects)(41761134093)the National Natural Science Foundation of China(41771077)。
文摘Information on the thickness distribution and volume of glacier ice is highly important for glaciological applications;however,detailed measurements of the ice thickness of many glaciers in the Chinese Altay Mountains remain lacking.Burqin Glacier No.18 is a northeast-orientated cirque glacier located on the southern side of the Altay Mountains.This study used PulseEKKO®PRO 100A enhancement ground-penetrating radar(GPR)to survey the ice thickness and volume of Burqin Glacier No.18 in summer 2018.Together with GPR surveying,spatial distributed profiles of the GPR measurements were concurrently surveyed using the real-time kinematic(RTK)global navigation satellite system(GNSS,Unistrong E650).Besides,we used QuickBird,WorldView-2,and Landsat TM to delineate accurate boundary of the glacier for undertaking estimation of glacier ice volume.GPR measurements revealed that the basal topography of profile B1-B2 was flat,the basal topography of profile C1-C2 presented a V-type form,and the basal topography of profile D1-D2 had a typical U-type topographic feature because the bedrock near the central elevation of the glacier was relatively flat.The longitudinal profile A1-A2 showed a ladder-like distribution.Glacier ice was thin at the terminus and its thickness increased gradually from the elevation of approximately 2620 m a.s.l.along the main axis of the glacier tongue with an average value of 80(±1)m.The average ice thickness of the glacier was determined as 27(±2)m and its total ice volume was estimated at 0.031(±0.002)km3.Interpretation of remote sensing images indicated that during 1989–2016,the glacier area reduced from 1.30 to 1.17 km2(reduction of 0.37%/a)and the glacier terminus retreated at the rate of 8.48 m/a.The mean ice thickness of Burqin Glacier No.18 was less than that of the majority of other observed glaciers in China,especially those in the Qilian Mountains and Central Chinese Tianshan Mountains;this is probably attributable to differences in glacier type and climatic setting.
基金supported by the National Natural Science Foundation of China (Grant Nos.41941010,41771064 and 41776195)the National Basic Research Program of China (Grant No.2016YFC1400303)the Basic Fund of the Chinese Academy of Meteorological Sciences (Grant No.2018Z001)。
文摘Long-term,ground-based daily global solar radiation (DGSR) at Zhongshan Station in Antarctica can quantitatively reveal the basic characteristics of Earth’s surface radiation balance and validate satellite data for the Antarctic region.The fixed station was established in 1989,and conventional radiation observations started much later in 2008.In this study,a random forest (RF) model for estimating DGSR is developed using ground meteorological observation data,and a highprecision,long-term DGSR dataset is constructed.Then,the trend of DGSR from 1990 to 2019 at Zhongshan Station,Antarctica is analyzed.The RF model,which performs better than other models,shows a desirable performance of DGSR hindcast estimation with an R^2 of 0.984,root-mean-square error of 1.377 MJ m^(-2),and mean absolute error of 0.828 MJ m^(-2).The trend of DGSR annual anomalies increases during 1990–2004 and then begins to decrease after 2004.Note that the maximum value of annual anomalies occurs during approximately 2004/05 and is mainly related to the days with precipitation (especially those related to good weather during the polar day period) at this station.In addition to clouds and water vapor,bad weather conditions (such as snowfall,which can result in low visibility and then decreased sunshine duration and solar radiation) are the other major factors affecting solar radiation at this station.The high-precision,longterm estimated DGSR dataset enables further study and understanding of the role of Antarctica in global climate change and the interactions between snow,ice,and atmosphere.
基金The National Natural Science Foundation of China under contract No.42076235.
文摘Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.
基金funded by the Key Program of National Natural Science Foundation of China (Grant no. 41531069)the Chinese Polar Environment Comprehensive Investigation and Assessment Programs (Grant no. CHINARE2016-02-02)
文摘This study examined the mass change of the Antarctic ice sheet(AIS) based on ICESat and CryoSat-2 observations. We estimated the AIS exhibited mass losses of-101±15 Gt·aduring the ICESat period(Sept–Nov 2003 to Sept–Oct 2009) and-186±55 Gt·aduring the CryoSat-2 period(Jan 2011 to Dec 2015). Mass losses occurred mainly in the sectors of the Amundsen and Bellingshausen seas. Benefitting from the 30-d subcycle of CryoSat-2, we obtained monthly estimates of mass evolution. Considerable annual variations were observed in the mass evolution sequences and the climatological monthly mass evolution. Seasonal mass evolutions in the sectors of the Bellingshausen and Amundsen seas were found most representative of the annual variation. The geographical distribution characteristics of interannual AIS mass evolution were revealed by the annual average mass evolution sequences. During Jan 2011 to Dec 2015, the ice sheets in the sectors of the Bellingshausen and Amundsen seas, and the Totten Glacier, experienced increasingly rapid areal mass loss. An area of mass gain with a moderate rate of increase was found between Dronning Maud Land and Enderby Land. Rapid mass accumulation has occurred in a limited area of the Kamb Ice Stream.
基金The National Natural Science Foundation of China No.42406251the Fundamental Research Funds for the Central Universities under contract No.2042025kf0079 and 2042025kf0080+2 种基金the Postdoctoral Fellowship Program of CPSF under contract No.GZC20241257the Postdoctoral Fellowship Program of CPSF under contract No.GZC20241257the Key Laboratory of Polar Environment Monitoring and Public Governance(Wuhan University),the Ministry of Education Open Fund under contract Nos 202403 and 202405.
文摘Basal melting and calving are the main pathways for mass loss in Antarctic ice shelves.Basal channels,as detailed variations in basal melting,mutually promote basal melting and calving,thereby weakening the stability of ice shelves.Therefore,it is necessary to calculate and statistically analyze basal melting,basal channels,and calving events across all Antarctic ice shelves and examine the correlation among these three factors.This study utilizes various data sources to calculate the Basal Channel Density(BCD)and average basal melt rate of all Antarctic ice shelves during 2010-2020,as well as the spatial correlation between basal melting,basal channels,and calving.We found that ice shelves along the Amundsen Sea and Bellingshausen Sea have higher basal melt rates and basal channel densities,while other sea areas have lower values.This is mainly influenced by seabed topography and Circumpolar Deep Water.Excluding(CDW)extreme calving events,there is a positive correlation among basal melting,basal channels,and calving in coastal ice shelves across different sea areas,with a correlation coefficient exceeding 0.67.This indicates that basal melting and basal channels are major factors causing ice shelf calving.Our results emphasize the importance of the impact of basal melting,basal channels,and calving on ice shelf stability,and they provide a significant reference for further research on ice shelf-ocean interactions.
基金supported by the National Key Research and Development Program of China under grant number 2023YFC2809103the Fundamental Research Funds for the Central Universities under grant numbers 2042022kf1204, 2042022kf1069, 2042023gf0012, 2042022dx0001+1 种基金the Hubei Provincial Natural Science Foundation of China under grant number 2022CFB081the State Key Laboratory of Geodesy and Earth's Dynamics, Innovation Academy for Precision Measurement Science and Technology under grant number SKLGED2023-2-6
文摘Elevation change monitoring of the Antarctic ice sheet has been a key issue in global change research.Satellite altimetry has been proven to be effective in detecting ice sheet variations. With the development of ICESat-2, many elevation observations can be used to derive elevation changes. However, the large amount of multitemporal data may include anomalous data points, increasing the uncertainty of the results. In this work, we improved the traditional repeat track method by introducing the Institute of Geodesy and Geophysics Ⅲ(IGGⅢ) method to obtain high-accuracy estimates of elevation change. The improved method was applied to analyze elevation changes along the transect from Zhongshan Station to Dome A in East Antarctica via ICESat-2 satellite altimetry data. The results show that the improved and traditional methods yield consistent numerical and spatial elevation change distributions. The elevation change calculated via the traditional method is 0.033 ± 0.131 m/yr, whereas the elevation change estimated via the IGGⅢ robust estimation method is 0.033 ± 0.109 m/yr from March 2019 to December 2021.In terms of spatial distribution, elevation changes in inland areas remain close to equilibrium, whereas regions with steeper ice sheet margins exhibit positive accumulation trends in elevation changes. The improved method reduces the standard error of the adjustment function from 0.975 to 0.691 m/yr. The improvement is particularly remarkable in the area between 72°S and 77°S. The results demonstrate that the IGGⅢ method effectively reduces errors caused by the inclusion of anomalous data and maintains the high data utilization rate of repeat-orbit methods.
基金the National Natural Science Foundation of China under Grants 42376253,42201489,and 42474056Shanghai Science and Technology Development Funds under Grant 21ZR1469700.
文摘Lake 90°E in Antarctica encompasses an area of 2000 km2,ranking it the second largest subglacial lake identified in the country by area,following Vostok Subglacial Lake.In this study,the overlying ice thickness and lake elevation of Lake 90°E were determined using airborne radio-echo sounding across two survey lines,conducted by the International Collaborative Exploration of the Cryosphere by Airborne Profiling in Princess Elizabeth Land(ICECAP/PEL)campaign during the 32nd Chinese National Antarctic Research Expedition(CHINARE 32,2015-2016),and the depth of lake water was inversed by coupling with synchronous airborne gravity data.The analysis revealed a 15-m elevation increase in the ice sheet surface from the southeast to the northwest,correlating with a gradient in ice thickness that progresses from thin in the southeast to thick in the northwest.The maximum water depth of Lake 90°E is estimated as 320 m along the central line,bifurcated by a topographic ridge into two zones of varying depths,with exceptionally shallow water at its periphery.Thermodynamic modeling using data from two points along the survey lines indicated that melt rates at the ice-water interface have consistently been low over the last 400,000 years,varying between 0.56-0.95 mm/yr and 2.70-3.41 mm/yr,balanced by either basal freezing to the south or downstream water loss,thereby maintaining a thermodynamically stable state.Satellite imagery and altimetry data analyses identified no significant changes in the outline or elevation of the ice surface over the past 20 years.This study presents novel insights into the physiography and thermodynamic state of Lake 90°E,establishing a foundation for future drilling initiatives.
基金The National Natural Science Foundation of China under contract Nos 41941010 and 42006184the Independent Scientific Research Project of the State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing。
文摘Basal melting is an important factor affecting the stability of the ice shelf.The basal channel is formed from uneven melting,which also has an important impact on the stability of the ice shelf.Therefore,it has important scientific value to study the basal channel changes.This study combined datasets of Mosaics of Antarctica,Reference Elevation Model of Antarctica(REMA) and Operation Ice Bridge to study the temporal and spatial changes of basal channels at the Getz Ice Shelf in Antarctica.The relationships between the cross-sectional area and width of basal channel and those of its corresponding surface depression were statistically analyzed.Then,the changes of the basal channels of Getz Ice Shelf were derived from the ICESat observations and REMA digital elevation models(DEMs).After a detailed analysis of the factors affecting the basal channel changes,we found that the basal channels of Getz Ice Shelf were mainly concentrated in the eastern of the ice shelf,and most of them belonged to the ocean-sourced basal channel.From 2009 to 2016,the total length of the basal channel has increased by approximately 60 km.Affected by the warm Circumpolar Deep Water(CDW),significant changes in the basal channel occurred in the middle reaches of the Getz Ice Shelf.The change of the basal channels at the edge of the Getz Ice Shelf is significantly weaker than that in its middle and upper reaches.Especially in 2005–2012,the eastward wind on the ocean wind field and the westward wind around the continental shelf caused the invasion and upwelling of CDW.Meanwhile,the continuous warming of deep seawater also caused the deepening of the basal channel.During from 2012 to 2020,the fluctuations of the basal channels seem to be caused by the changes in temperature of CDW.
基金The National Key Research and Development Program of China under contract Nos 2018YFA0605903 and 2016YFC1402702the National Natural Science Foundation of China under contract Nos 41722605 and 41976219。
文摘Based on an ice concentration threshold of 90%,it has been identified that two polynya events occurred in the region north of Greenland during the 2017/2018 ice season.The winter event lasted from February 20 to March 3,2018 and the summer event persisted from August 2 to September 5,2018.The minimum ice concentration derived from Advanced Microwave Scanning Radiometer 2(AMSR2)observations was 72%and 65%during the winter and summer events,respectively.The occurrence of both events can be related to strengthened southerly winds associated with an increased east-west zonal surface level air pressure gradient across the north Greenland due to perturbation of mid-troposphere polar vortex.The relatively warm air temperature during the 2017/2018 freezing season in comparison with previous years,together with the occurrence of the winter polynya,formed favourable pre-conditions for ice field fracturing in summer,which promoted the formation of the summer polynya.Diminished southerly winds and increased cover of new ice over the open water were the dominant factors for the disappearance of the winter polynya,whereas increased ice inflow from the north was the primary factor behind the closure of the summer polynya.Sentinel-1 Synthetic Aperture Radar(SAR)images were found better suited than AMSR2 observations for quantification of a new ice product during the polynya event because the SAR images have high potential for mapping of different sea ice regimes with finely spatial resolution.The unprecedented polynya events north of Greenland in 2017/2018 are important from the perspective of Arctic sea ice loss because they occurred in a region that could potentially be the last“Arctic sea ice refuge”in future summers.
基金supported by the National Key Research and Development Program of China[grant number 2017YFA0603104]the National Natural Science Foundation of China[grant number 42076235]+1 种基金the Fundamental Research Funds for the Central Universities[grant number 2042022kf0018]the Special Fund for High Resolution Images Surveying and Mapping Application[grant number 42-Y30B04-9001-19/21]。
文摘The decreasing of Arctic sea ice is projected to continue with global warming,which makes the summer navigation conditions of the Arctic improve.Based on the multi-source remote-sensing data with inter-sensor calibration processing and the ship-based observational data from R/V Xuelong and M/V Yongsheng,the sea ice conditions of the Arctic Northeast Passage(NEP)during the 2002-2021 summer seasons were analyzed,and the navigability of the NEP between July and October from 2002 to 2021 was discussed.Inter-sensor calibration could effectively reduce the deviation from different passive microwave data.Sea ice extent and thickness in the NEP decreased annually,which resulted in the navigability of the NEP showing a potential tendency toward improvement in navigability.The navigation period was mainly concentrated in early August to early October.The middle part of the NEP was primarily affected by sea ice.This influence decreased over time,while the navigation period increased,especially in the Vilkitsky Strait,which is a key shipping area.This analysis of sea ice conditions and navigability in the past 20 years could provide a reference for future scientific investigations and aid in merchant ship navigation in the Arctic summer.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 41576069, 41306201, 41776189, 41706212 and 41706215)the Chinese Polar Environment Comprehensive Investigation & Assessment Programs (Grant Nos. CHINARE2017-01-03 and CHINARE2017-04-01)the Special Foundation of the Second Institute of Oceanography, SOA (Grant No. 14260-10)
文摘Marine geophysical survey by the Chinese National Antarctic Research Expedition （CHINARE） began with the first science expedition in 1984/1985, although only four cruises were performed in the vicinity of the Antarctic Peninsula between then and 1991/1992. After a 20 year hiatus, Antarctic marine geophysical research was relaunched by the Chinese Polar Environmental Comprehensive Investigation and Assessment Programs （known simply as the Chinese Polar Program） in 2011/2012. Integrated geophysical surveys have been carried out annually since, in Prydz Bay and the Ross Sea. During the last 5 years, we have acquired about 5500 km of bathymetric, gravimetric, and magnetic lines; more than 1800 km of seismic reflection lines; and data from several heat flow and Ocean Bottom Seismometer （OBS） stations. This work has deepened understandings of geophysical features and their implications for geological tectonics and glacial history in Antarctica and its surrounding seas. Compiled Antarctic Bouguer and Airy isostatic gravity anomalies show different features of tectonics between the East Antarctic stability and West Antarctic activity. Calculated magnetic anomalies, heat flow anomalies and lithospheric anisotropy offshore of Prydz Bay may imply high heat capacity of mantle shielded by the continental shelf lithosphere, but high heat dissipation of mantle due to the Cretaceous breakup of Gondwana along the continent and ocean transition （COT）, where large sediment ridges would be brought about by the Oligocene ice sheet retreat and would enlarge free-air gravity anomalies. In the western Ross Sea, CHINARE seismic profiles indicate northern termination of the Terror Rift and deposition time of the grounding zone wedge in the northern JOIDES Basin.
基金The National Key R&D Program of China under contract No.2016YFC1402701the National Natural Science Foundation of China under contract Nos 41941010,41531069 and 41476162
文摘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.
基金supported by the National Science Foundation of China(41174029,41204028)Chinese Arctic and Antarctic Administration(20110205)the Fundamental Research Funds for the Central Universities(121001)
文摘The temporal distribution characteristics of COSMIC occultation data are analyzed in detail, and the limitations in earthquake-ionosphere anomaly detection caused by the temporal distribution characteristics of COSMIC occultation data are discussed using the example of the Wenchuan earthquake. The results demonstrate that there is no fixed temporal resolution for COSMIC occultation data when compared with other ionospheric observation techniques. Therefore, occultation data cannot currently be independently utilized in research studies but can only be used as a complement to other ionospheric observation techniques for applications with high temporal resolution demands, such as earthquake-ionosphere anomaly detection.
基金supported by the National Natural Science Foundation of China(Grant nos.41174029,41204028,41231064)the Open Research Fund of Key Laboratory for Polar Science of SOA(Grant no.KP201201)+1 种基金the Chinese Polar Environment Comprehensive Investigation and Assessment Programsthe Science and Technology Project of NASMG(Grant name Polar Geomatics Technology Test)
文摘There are a number of ionospheric models available for research and application, such as the polynomial model, generalized trigonometric series function model, low degree spherical harmonic function model, adjusted spherical harmonic function model, and spherical cap harmonic function analysis. Using observations from more than 40 continuously operating stations across Antarctica in 2010, ifve models are compared with regard to their precision and applicability to polar regions. The results show that all the models perform well in Antarctica with 0.1 TECU of residual mean value and 2 TECU of root mean square error.
基金The National Key Research and Development Program of China under contract No.2016YFC1402704the National Natural Science Foundation of China under contract No.42076235the Special Fund for High Resolution Images Surveying and Mapping Application System under contract No.42-Y30B04-9001-19/21
文摘A comprehensive analysis of sea ice and its snow cover during the summer in the Arctic Pacific sector was conducted using the observations recorded during the 7th Chinese National Arctic Research Expedition(CHIANRE-2016)and the satellite-derived parameters of the melt pond fraction(MPF)and snow grain size(SGS)from MODIS data.The results show that there were many low-concentration ice areas in the south of 78°N,while the ice concentration and thickness increased significantly with the latitude above the north of 78°N during CHIANRE-2016.The average MPF presented a trend of increasing in June and then decreasing in early September for 2016.The average snow depth on sea ice increased with latitude in the Arctic Pacific sector.We found a widely developed depth hoar layer in the snow stratigraphic profiles.The average SGS generally increased from June to early August and then decreased from August to September in 2016,and two valley values appeared during this period due to snowfall incidents.
基金supported by the Chinese Polar Environment Comprehensive Investigation and Assessment Programs (Grant no.CHINARE2017)Key Program of the National Natural Science Foundation of China (Grant no.41531069)National Basic Research Program of China (Grant nos.2012CB957701,2013CBA01804-04)
文摘This paper summarizes the progress of the Chinese Antarctic expedition in geodetic remote sensing. It describes the systems for continuous satellite navigation and positioning, and the tide gauges that have been established at the Zhongshan and Great Wall stations in Antarctica. Advances in the investigation of plate motion, the gravity field, and sea level change as well as the application of GPS in atmospheric studies are reported. Details of the movements of ice sheets and glaciers, distributions of blue ice and ice crevasses, and mass balance studies based on remote sensing techniques are presented. The use of field, satellite, and photogrammetric data to produce topographic maps is described. Finally, the prospects for further Antarctic surveying and mapping are discussed. In the near future, we will establish a high-precision geodetic datum in the Chinese Antarctic expedition areas, monitor changes of Antarctic snow and ice, and develop a platform for sharing Antarctic resource and environment information.
基金The National Natural Science Foundation of China under contract No.42076235the Fundamental Research Funds for the Central Universities under contract No.2042022kf0018.
文摘The snow depth on sea ice is an extremely critical part of the cryosphere.Monitoring and understanding changes of snow depth on Antarctic sea ice is beneficial for research on sea ice and global climate change.The Microwave Radiation Imager(MWRI)sensor aboard the Chinese FengYun-3D(FY-3D)satellite has great potential for obtaining information of the spatial and temporal distribution of snow depth on the sea ice.By comparing in-situ snow depth measurements during the 35th Chinese Antarctic Research Expedition(CHINARE-35),we took advantage of the combination of multiple gradient ratio(GR(36V,10V)and GR(36V,18V))derived from the measured brightness temperature of FY-3D MWRI to estimate the snow depth.This method could simultaneously introduce the advantages of high and low GR in the snow depth retrieval model and perform well in both deep and shallow snow layers.Based on this,we constructed a novel model to retrieve the FY-3D MWRI snow depth on Antarctic sea ice.The new model validated by the ship-based observational snow depth data from CHINARE-35 and the snow depth measured by snow buoys from the Alfred Wegener Institute(AWI)suggest that the model proposed in this study performs better than traditional models,with root mean square deviations(RMSDs)of 8.59 cm and 7.71 cm,respectively.A comparison with the snow depth measured from Operation IceBridge(OIB)project indicates that FY-3D MWRI snow depth was more accurate than the released snow depth product from the U.S.National Snow and Ice Data Center(NSIDC)and the National Tibetan Plateau Data Center(NTPDC).The spatial distribution of the snow depth from FY-3D MWRI agrees basically with that from ICESat-2;this demonstrates its reliability for estimating Antarctic snow depth,and thus has great potential for understanding snow depth variations on Antarctic sea ice in the context of global climate change.
