Fhe application of electromagnetic-induction on the measurement of sea ice thickness in the Antarctic

As an important component of the cryosphere, sea ice is very sensitive to climate change. The study of sea ice physics needs accurate sea ice thickness. This paper presents an electromagnetic induction （EM） technique which can be used to measure the sea ice thickness distribution efficiently and its successful application in the Antarctic Neila Fjord. Based on the electrical properties of sea ice and seawater and the application of electromagnetic field theory, this technique can accurately detect the distance between the EM instrument and the ice/water interface to measure the sea ice thickness. Analyzing the apparent conductivity data obtained by the electromagnetic induction technique and drill-hole measurements at same location allows the construction of a transform equation for the apparent conductivity and sea ice thickness. The verification of the calculated sea ice thickness using this equation indicates that the electromagnetic induction technique is able to determine reliable sea ice thickness with an average relative error of only 5.5%. The ice thickness profiles show the sea ice distribution in Neila Fjord is basically level with a thickness of 0.8 - 1.4 m.

The variation features of the Antarctic sea ice (Ⅱ)

In this paper, on the basis of the Antarctic sea ice data from 1972 to 1989 issued by the America JointIce Center, the distribution features of the Antarctic sea ice is analyzed, the net sea ice area indexes are calculated,and the long-range variation periods of the sea ice area index are analyzed with the maximum entropy spectrum, finally the distribution pattern of the Antarctic sea ice and its variation features are obtained.According to its spatial distribution feature, the Antarctic Sea ice is divided into three large regions. Region Ⅰ(0°～120°E) is a zonal area which includes the Prydz Bay area, and sea ice area extending from the Weddell Sea,Region Ⅱ (120°E～120°W) mainly includes the Ross Sea area, and Region Ⅲ (120°W～0°) mainly the WeddellSea area. Of all the regions, the ice area in Region Ⅲ is the largest, and that in Region Ⅰ is the smallest.In the Antarctic,the seasonal changes of the sea ice are very obvious, during summer, in February, there isleast sea ice in the Southern Ocean, the net sea ice area (not include the area of open water) is about 3 190 000 km2,during winter, in September, there is most sea ice in the Southern Ocean, the area index is about 16 840 000 km2,nearly 5. 3 times of that in February. The seasonal change of sea ice is one month lag of the changes of the air temperature, but almost synchronous with that of SST.Of all the three regions divided above, there are some points both common and uncommon in their sea icechange cycles, the common features are that there exist one and a half years, one year and ten-months secondaryperiods in all three regions, but their main periods are not the same, they are about 5, 11 and 6 a in Regions Ⅰ,Ⅱ,and Ⅲrespectively. The main periods of the sea ice change in Regions Ⅰand Ⅱ are very close because the ice areaextended eastward from the Weddell Sea ice area of Region Ⅲ is one of the main components of the Region Ⅰ. It isalso worth pointing out that in Region Ⅱ, southward extension of the Pacific Ocean, there exist not only a 11-yerasmain period but also a 2-yeras secondary period, which does not exist in the other two regions.

A study on the Antarctic circumpolar wave mode-A coexistence system of standing and traveling wave

The Antarctic circumpolar wave （ACW） has become a focus of the air-sea coupled Southern Ocean study since 1996, when it was discovered as an air-sea coupled interannual signal propagating eastward in the region of the Antarctic Circumpolar Current （ACC）. In order to analyze the mechanism of discontinuity along the latitudinal propagation, a new idea that ACW is a system with a traveling wave in the Southern Pacific and Atlantic Ocean and with a concurrent standing wave in the southern Indian Ocean is proposed in this paper. Based on the ideal wave principle, the average wave parameters of ACW is achieved using a non-linear approximation method, by which we find that the standing part and the traveling part possess similar radius frequency, proving their belonging to an integral system. We also give the latitudinal distribution of wave speed with which we could tell the reason for steady propagation during the same period. The spatial distribution of the propagation reveals complex process with variant spatial and temporal scales--The ENSO scale oscillation greatly impacts on the traveling process, while the result at the south of Australia indicates little connection between the Indian Ocean and the Pacific, which may be blocked by the vibration at the west of the Pacific. The advective effect of ACC on the propagation process should be examined clearly through dynamical method.

Simulation of the Influence of Ion-Produced NO_X and HO_X Radicals on the Antarctic Ozone Depletion with a One-Dimensional Model

A one -dimensional time-dependent photochemical model is used to simulate the influence of ion-produced NOx and HOx radicals on the Antarctic ozone depletion in polar night and polar spring at a latitude of 73 degrees south.Vertical transport and nitrogen-oxygen (NOx). hydrogen-oxygen (HOx) production by ionic reactions have been introduced into the model.NOx and HOx produced by precipitating ions are transported into the lower stratosphere by vertical motion and have some effects in the development of the Antarctic ozone depletion.From winter through spring the calculated ozone column decreases to 269.4 DU. However, this value is significantly higher than the total ozone observed at several Antarctic ozone stations.

Polar WRF V4.1.1.simulation and evaluation for the Antarctic and Southern Ocean

A recent version of the Polar Weather Research and Forecasting model(Polar WRF)has been upgraded to the version 4.X era with an improved NoahMP Land Surface Model(LSM).To assess the model performance over the Antarctic and Southern Ocean,downscaling simulations with different LSM(NoahMP,Noah),WRF versions(Polar WRF 4.1.1 and earlier version 4.0.3,WRF 4.1.1),and driving data(ERA-Interim,ERA5)are examined with two simulation modes:the short-term that consists of a series of 48 h segments initialized daily at 0000 UTC with the first 24 h selected for model spin-up,whereas the long-term component used to evaluate long-term prediction consists of a series of 38-41 day segments initialized using the first 10 days for spin-up of the hydrological cycle and planetary boundary layer structure.Simulations using short-term mode driven by ERA-Interim with NoahMP and Noah are selected for benchmark experiments.The results show that Polar WRF 4.1.1 has good skills over the Antarctic and Southern Ocean and better performance than earlier simulations.The reduced downward shortwave radiation bias released with WRF 4.1.1 performed well with PWRF411.Although NoahMP and Noah led to very similar conclusions,NoahMP is slightly better than Noah,particularly for the 2 m temperature and surface radiation because the minimum albedo is set at 0.8 over the ice sheet.Moreover,a suitable nudging setting plays an important role in long-term forecasts,such as reducing the surface temperature diurnal cycle near the coast.The characteristics investigated in this study provide a benchmark to improve the model and guidance for further application of Polar WRF in the Antarctic.

Journey to the Antarctic

本课是阅读和口语课的结合,补充阅读材料是老师提供的一篇题目为'The Race to the Pole'的短文。在课前,学生已经通过一课时学习了教材中的课文,练习了通过上下文猜测词义的阅读策略,并且提前泛读了老师布置的阅读材料。课上学生继续使用这一阅读策略精读补充材料,通过小组讨论的形式,分析两位主人公最后不同命运的成因,探讨成功的真正含义。并通过朗读Captain Scott写给妻子的遗书节选,引导学生思考什么才是生命中最重要的事情。

Analysis of recent Antarctic plate kinematics based on GNSS data

The research aims to study recent Antarctic plate kinematics based on Global Navigation Satellite System(GNSS)data.The research covers 60 continuous GNSS stations located on the Antarctic plate during 1994-2021.We determine the components of horizontal displacement vectors of these GNSS stations and construct the schematic map of their distribution.The results indicate that the direction of velocity vectors of horizontal displacements has a rotational nature in clockwise order.The analysis of deformation processes shows that a gradual decrease in the horizontal strain rates,maximum shear strain and area strain is taking place from west to east,in the direction of West Antarctica-the Transantarctic Mountains-East Antarctica.The absolute rotation pole of the Antarctic plate in the ITRF2014/IGS14 reference frame has been determined,and the obtained values are in good agreement with recent plate models.

The intermediate water in the Philippine Sea

The dimensional and temporal distribution of Antarctic Intermediate Water(AAIW)and North Pacifi c Intermediate Water(NPIW)in the Philippine Sea were explored using Argo profi les and gridded Argo data.As the salinity minimum of intermediate water from mid-high latitude of the southern and northern hemisphere of the Pacifi c Ocean,the properties of AAIW and NPIW merge at about 10°N with diff erent properties in the Philippine Sea.The core of AAIW is located below 600 dbar with potential density of 27≤σθ≤27.3 kg/m 3 and salinity of 34.5≤S≤34.55.The core of NPIW is located between 300–700 dbar with potential density of 26.2≤σθ≤27 kg/m 3 and salinity of 34≤S≤34.4.The volume of AAIW and NPIW during January 2004 to December 2017 is negatively correlated.The time series of AAIW and NPIW is dominated by signifi cant periods of 6 and 8 months,respectively.The variations of AAIW and NPIW are mainly aff ected by volume transport through a 130°E section by the North Equatorial Current(NEC)and North Equatorial Undercurrent(NEUC).