| Although the existing research shows that the contribution of glaciers to sea-level is mainly attributed to the mid and high latitude mountain glaciers,the ice-storage of Antarctica and its potential regulatory role on climate will lead to a greater uncertainty in the future.Research on the dynamics response of the Antarctic ice sheets under the background of global climate change,has an important guiding significance for the quantitative analysis of global mean sea-level change and scientific decision-making.The research of Antarctica began with its geographical discovery,but the special geographical location and extreme weather conditions prevent human to further explore such a world with ice and snow.Compared with field wrok,the appearence of space earth observation technologies has led to a new era in which observations of the ice sheet can be conducted throughout the day and in any weather condition.In addition,radar altimetry over the continental ice sheet has proved to be a valuable tool for studying ice sheet changes by providing measurements of elevation changes over the past decades.Based on the high-precision altimetry observations,we can conduct all the researches of Antarctica systematically.However,the end of the observation missions of ICESat and the orbit adjustment of Envisat let the satellite altimetry task into dilemma.As ESA's first mission of glacier monitoring,CryoSat-2 is not just a continuation of radar altimeter mission.The unique track design and operation mode has brought a new perspective for polar observations.Enabling synthetic aperture technology and a second receiving antenna can provide a more accurate measurement in the sea ice region and themarginof the Antarctica.Just under such a background,the topic of application of CryoSat-2 over Antarctic icesheet is chosen in this article.The traditional application of radar altimetry is then introduced and analysed with the data of CryoSat-2.The mainly works and the innovations of this paperare as follows:(1)Two different DEM extraction methods are introduced in this article.With the classical theory,the DEM along the expedition route in PANDA transection and Antarcitca are extracted.The GPS,ICEBrdige and ICESat data is then used to check the accuracy of the DEM respectively.Moreover,a new DEM extraction method named "Interferometric swath processing" is then illuminated in detail.With this method,a high resolution DEM is extracted covering the region of PIG.Then ICEBrdige data is used to check the the accuracy of the DEM.(2)The adaptability of CryoSat-2 to crossover and repeat-track analysis is first analyzed in this article.The result shows that it is difficult to extract the elevation change over the whole Antarctica due to the specific orbit and operating mode based on the crossover analysis.To overcome the problem caused by sporadic repeat-track,an adaptive algorithm is proposed in this paper.The algorithm can not only increase the amount of the altimetry data used to calculate the elevation change,but also weaken the influence brought by difference of ascending/descending orbit and the fluctuation of backscatter.(3)The altimetry data is first used to detect the distribution of Wind Glaze areas based on the fluctuation of backscatter with the data of CryoSat-2 and Envisat in this paper.In order to verify the results,four different geophysical parameters are analyzed respectively.The result reveals the influence of wind and the distribution of this influence with the result of radar altimetry.(4)The monitor of subglacial lakes is also a main application of radar altimetry.With the data of CryoSat-2,the activity of subglacial LakeCookE2 is monitored from 2011 to 2015.In addition,the subglacial lakes are also detected based on the Shreveequation. |
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