Seasonal variations in aerosol compositions at Great Wall Station in Antarctica

High volume aerosol samplers at Great Wall Station in Antarctica were used to collect 73 aerosol samples between January 2012 and November 2013. The main ions in these aerosol samples, Cl^-, NO3-, SO4^2-, Na＋, K＋, Ca2＋, Mg2＋, NH4＋, as well as methane sulfonic acid, were analyzed using ion chromatography. Trace metals in these samples, including Pb, Cu, Cd, V, Zn, Fe, and Al, were determined by inductively-coupled plasma mass spectrometry. Results showed that sea salt was the main component in aerosols at Great Wall Station. Most ions exhibited significant seasonal variations, with higher concentrations in summer and autumn than in winter and spring. Variations in ions and trace metals were related to several processes（or sources）, including sea salt emission, secondary aerosol formation, and anthropogenic pollution from both local and distant sources. The sources of ions and trace metals were identified using enrichment factor, correlation, and factor analyses. Clearly, Na＋, K＋, Ca2＋, and Mg2＋were from marine sources, while Cu, Pb, Zn, and Cd were from anthropogenic pollution, and Al and V were mainly from crustal sources.

EXPERIMENT OF SHORT WAVE COMMUNICATION AND THE INVESTIGATION OF THE PROPAGATION BEARINGS BETWEEN THE GREAT WALL STATION AND XINXIANG

The distance from the Great Wall Station (62.2°S, 58.9°W) to Xinxiang (35.3°N, 113.8°E) is 16981 km. The path passes through the polar cap absorption region and the auroral absorption zone, and it is across the equator.In this paper firstly the effects of short wave communication and usable time blocks and frequency ranges between the Antarctic Great Wall Station and Xinxiang from December 1985 to March 1986 are introduced. The comparison between the usable frequency ranges with the estimated MUF is made. The upper limit of frequency ranges of communication along the short great circle path basically agrees with the MUF but there is difference between them along the long great circle path.Secondly, the result of the propagation bearings experiment in January to February 1986 is introduced in more detail, The propagation along the great circle path from the Great Wall Station to Xinxiang is the main propagation mode. But the propagation along non great circle paths occurs at times between Great Wall Station and Xinxiang. The non great circle path propagation varies with time because the ionospheric absorption and other conditions which support the non great circle path propagation are the function of the time. So the courses of the non great circle path propagation may be different in the different time. The mechanism of the constructing non great circle path propagation has been analysed. We preliminarily think the main cause of propagation along non great circle path is the ground scatter. The stronger radialization of the side lobes of the antenna and the less absorption of the ionosphere contribute to forming non great circle path propagation.

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

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

Features of visibility variation at Great Wall Station,Antarctica

The variation of visibility at Great Wall Station （GWS） was analyzed using manual observational data for the period of 1986 to 2012. Results show that the frequencies of occurrence of high （≥ 10 km） and low visibility （0-1 km） are 61.0% and 8.0%, respectively. Visibility at GWS shows an evident seasonal variation： The highest visibility between November and March, and the lowest visibility from June to October. Sea fog and precipitation are the main factors for low visibility during summer, whereas frequent adverse weather, such as falling snow, blowing snow, or blizzards, are responsible for low visibility in winter. The frequency of occurrence of low visibility has decreased significantly from 1986 to 2012. Conversely, the frequency of occurrence of high visibility has shown a significant increasing trend, especially during winter. The decreasing tendencies of fog, blowing snow, and snowfall have contributed to the increasing trend of high visibility during winter. Visibility at GWS exhibits significant synoptic-scale （2.1 to 8.3 d）, annual, and inter-annual periods （2 a, 4.1 a, and 6.9 a to 8.2 a）, among which the most significant period is 4.1 a. The visibility observed during 2012 indicates that instrumental observation can be applied in the continuous monitoring of visibility at GWS.

Surface ozone variations at the Great Wall Station,Antarctica during austral summer

Surface ozone(O3)is a secondary pollutant harmful to human health and a greenhouse gas which is one of the prime climate forcers.Due to the clean atmospheric environment of the Antarctic region and given the complexity of O3 chemistry,the observation of surface O3 variability in this region is necessary in the quest to better understand the potential sources and sink of polar surface O3.In this paper,we highlighted our observations on O3 variability at the Great Wall Station(GWS)during austral summer in December 2018 and January 2019.The continuous surface O3 measurement at the GWS,Antarctica was carried out using the Ecotech Ozone analyzer.To understand the roles of the meteorological conditions on the temporal variations of O3,meteorological data was obtained from the conventional auto-observational station at the GWS.The Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model was employed to investigate the air mass transport over the region.The observed austral summer surface O3 concentrations at the GWS exhibited variability and were significantly lower than those previously observed at other permanent coastal stations in Antarctica.The surface ozone variability at the GWS was strongly influenced by the synoptic change of air mass origin although the roles of photochemistry production and destruction were still uncertain.Marine characteristics and stable surface O3 characterized the air masses that reached the GWS.The unique characteristic of surface O3 at the coastal site of GWS was emphasized by its synoptic air mass characteristics,which displayed a significant influence on surface O3 variability.Air mass that traveled over the ocean with relatively shorter distance was linked to the lower O3 level,whereby the marine transport of reactive bromine(Br)species was thought to play a significant role in the tropospheric chemistry that leads to O3 destruction.Meanwhile,the diurnal variation indicated that the O3 background concentration levels were not strongly associated with the local atmospheric conditions.

A Case study of a snowstorm at the Great Wall Station,Antarctica

A case of a snowstorm at the Great Wall Station was studied using data of NCEP（National Centers for Environmental Prediction） analysis,in situ observations and surface weather charts.The storm occurred on August 29th, 2006,and brought high winds and poor horizontal visibility to the region.It was found that the storm occurred under the synoptic situation of a high in the south and a low in the north.A low-level easterly jet from the Antarctic continent significantly decreased the air temperature and humidity.Warm air advection at high level brought sufficient vapor from lower latitudes for the snowstorm to develop. The dynamic factors relating to strong snowfall and even the development of a snowstorm were deep cyclonic vorticity at middle and low levels,the configuration of divergence at high level and convergence at low level,and strong vertical uplift.There was an inversion layer in the low-level atmosphere during the later phase of the storm.This vertical structure of cold air at low levels and warm air at high levels may have been important to the longevity of the snowstorm.

MEDIUM-RANGE OSCILLATION OF METEOROLOGICAL ELEMENTS AT GREAT WALL STATION,ANTARCTICA

A method of multi-spectral analysis is used to study the spectral characteristics of surface and upper-level meteorological elements over the Great Wall Station (62°12'S, 58°57'W), Antarctica and their phasecorrelation, propagation of mean oscillation at 500hPa level in the Southern Hemisphere and their corresponding synoptic sense. the results are summed up as follows: 1. Over the sub-Antatctic zone, as in the Northern Hemisphere there generally exist quasi-weekly oscillation and quasi-biweekly oscillation. In different seasons the oscillations of meteorological elements are different: in winter season quasi-biweekly oscillation is dominant, while in summer season quasi-weekly oscillation is dominant. 2. From the Earth's surface to the lower stratosphere there is a distinct quasi-weekly oscillation at each isobaric surface, but the most intense oscillation appears at 200-300hPa, and the oscillations of height and temperature are propagated downward. 3. Both in winter and summer seasons the quasi-biweekly oscillation are propagated from west to east, and the mean velocity of its propagation is about 7-17 longtitude / day. 4. The quasi-biweekly oscillation and the quasi-weekly oscillation over the sub - Antarctic zone are closely related to the activity and intensity variation of polar vortex at 500hPa, while at 1000hPa they reflect an interaction between the circumpolar depression and the sub-tropical high. The quasi-biweekly oscillation may be a reflection of inherent oscillation of the polar vortex, where as the quasi-weekly oscillation is a result of forced oscillation by external disturbance.A large number of calculations and analysis made reveals the features of medium-range oscillation over the sub-Antarctic zone. The results are of significance for understanding the behaviour of synoptic dynamics and making the weather forecast.This work is supported by National Committee for Antarctic Research.

The climate background and synoptic situation of fog at Great Wall Station,Antarctica

Based on the observed and NCEP reanalysis data from 1985 to 2006, the climate background and synoptic situation of fog at Great Wall Station were analyzed.It is shown that the seasonal variation of fog is controlled by the change of general circulation and local pressure field.Three favorable typical synoptic situations for fog development arc found,the Front-of-A-Depression type,the Saddle-Shaped-Field type and the Passing-Weak-Cyclone type.The first one is the most important situation.Advection cooling fog is dominant at Great Wall Station,but there are other kinds of fog as well.As a result,some helpful principles for local fog forecasting are given.

ESTABLISHMENT OF SURVEYING SYSTEM OF THE GREAT WALL STATION

It is the main task of the antarctic surveying expedition to establish the surveying system. In three times of the antarctic surveying research expeditions, a complete and accurate surveying system has been established in the Chinese Great Wall Station area. The surveying system includes geodetic coordinate system, elevation system and gravity reference system. In this paper, the surveying methods and the mathematical models for establishing these systems are discussed, and the accuracy of results is analysed.

^(210)Pb distribution characteristics in the lake sediment core at Great Wall Station,Antarctica

The results of 210 Pb measurements in the lake sediment core from Antarctica are reported: the relative specific activities of 210 Pb in the lake sediment were found to decrease exponentially with the depth in the study area; the sedimentation rate of the lake is about 0.072 cm/a. This paper shows that 210 Pb method is applicable to Antarctic lake sediment ,and during the 1960's the atmospheric nuclear tests have an effect on the rate of 210 Pb deposition in Antarctica.

ON CHEMICAL WEATHERING OF WEATHERING CRUST AT THE GREAT WALL STATION REGION, ANTARCTICA

The chief aim of this study is to investigate the chemical weathering process of the weathering crust in Great Wall Station region of China (in Fildes Peninsula), Antarctica by the method of sedimentology.CW,SW,GW,TW,WE weathering crusts developed on volcanic clastic rock, gray aptitic basalt with tuff or basaltic bedrock. On change of minerals, geochemical behaviors of elements, migration and enrichment regularities of elements, Correlation between element geochemical behaviors, change of weathering potential of rocks in chemical weathering process are studied by us.We can see that the sequence fo weathering strengths of the abovementioned sections, from high to low, should reflected in TW, GW, CW and SWT and basical correspond with that calculated from the enrichment and differentiation indexes.

MASS MOVEMENT IN THE GREAT WALL STATION AREA, ANTARCTICA

This paper deals with the mass movement processes on the Fildes Peninsula, King George Island. Based on numerous field investigation, the authors consider that the slope mass movement and periglacial form on the peninsula have an internal relationship in genesis, reflecting in there main aspects. 1, All patterns of mass movement are developed on the slope surface; 2, different -order mass movement and periglacial type show their space-time distribution rules (their development stages); 3, The slope mass movement are developed from the periglacio - geomorphic processes. More detailed works have been done, such as fixed reapeated surveying whose results are concord and with the typical characteristics above mentimed very well.

THE PRELIMINARY STUDY ON THE PRECIPITATION CHEMISTRY AT THE CHINESE GREAT WALL STATION,ANTARCTICA IN 1998

This paper reports the analysis results (including pH,conductivity and ion concentrations) of the precipitation samples collected at the Chinese Great Wall Station,Antarctica (62°13′S, 58°58′W,ASL10.0 m) in 1998.The average pH value and conductivity were 5.62 and 85.16 μS/cm,respectively.The pH value and conductivity of precipitation were higher during autumn, but lower during other seasons.The major ions in the precipitation were C1- and Na+,followed by SO_4^(2-),Mg^(2+),Ca^(2+),K^+,NO_3^-,NH_4^+ with the lower concentrations in order.The positive correlation significantly existing between the major ions,except NO_3^- and NH_4^+,indicated that those major ions might come from same sources.The fact that the relative abundances of ions in precipitation were very close to that of seawater of Antarctic Ocean indicated that marine aerosol was the dominant source of the ions of precipitation.However,there were yet other sources which may contribute to Ca^(2+) ion in the precipitation.The precipitation at the area was characterized by marine type chemically.

The pigmental composition and the absorption spectral analysis of Ulothrix sp．and benthic diatoms in the intertidal zone of Great Wall Station，Antarctica

This paper reports the results of the absorption spectral analysis of Ulothrix sp. attached to the rocks from the intertidal zone in front of Great Wall Station,Antarctica in February 1989,and the benthic diatoms growing on small stones and on the edge of swamps of that zone.Six kinds of pigments were separated and identified in benthic diatoms.They are carotene, chlorophyll-a, fucoxanthin, chlorophyin, neoxanthin and chlorophyll-c. Nine kinds of pigments were identified in Ulothrix sp.. They are carotinoid, pheophytin, chlorophyll-a, -b, chlorophyllin, chlorophyllide-a, neoxanthin, chlorophyll-c and pheophytin-c. The intertidal benthic diatoms and Ulothrix sp. have specific absorption spectra and there are also marked differences in the composition of algal pigments they contain. Since the pigments of marine algae show differences in their absorption spectra, the absorption spectrum can be used to identify the species of marine algae.

A preliminary analysis of the pigments from ice algae in theadjacentwatersofGreatWallStation，Antarctica

This paper reports the results of separation and identification of the pigments from ice algae in the adjacent waters (62°12′30″S～62°14′30″S, 58°53′W～ 58°57′W) of Great Wall Station, Antarctica during the icing Pened (from June 1988～ December 1988) and the discussion is also made on the composition and seasonal variations of the pigments of ice algae in that area as well as their roles in marine ecosystems. The results indicate that 15 kinds of pigments have been separated from ice algae, of which 13 kinds can be identified. They are respeCtively: carotene, pheophytin-a, chlorophyll-a, -b, -c, xanthophyll, fucoxanthin, chlorophyllide-a, violaxanthin, pheophorbide-a, chlorophyllin-a, derivative of chlorophyll-c (diadinoxanthin), but two kinds of pigments can not be identified. There are distinct seasonal variations in the pigments of ice algae at that sea area.

The separation and identification of phytoplankton pigments from the adjacent waters of Great Wall Station，Antarctica

This paper presents separation and identification of the pigments of the phytoplankton samples collected from the adjacent waters (62°12. 5'S, 58°53' W～62°14. 5' S, 58°57' W) of Great Wall Station, Antarctica during March 1988～February 1989 by using thin-layer chromatographic techniques. Of the 15 kinds of phytoplankton pigments separated, 13 were identified according to the R. values of the various marine algal pigments. The features of seasonal variations of phytoplankton pigments in the studied area are also discussed.

A PRELIMINARY STUDY ON THE SURFACE THERMAL REGIME OVER THE GREAT WALL STATION IN ANTARCTICA

Concerning the thermal regime near the surface of Antarctica, the micrometeorological observations and experiments were carried out by both American and Japanese scientists in the east Antarctic continent. However, the west part of Antarctica has been rarely touched. In December 1987—February 1988, the boundary layer observation was carried out over the Great Wall Station (62° 13′ S, 58° 58′ W) in Antarctica. The

LANDFORM CHARACTERISTICS AND ENVIRONMENT VARIATION IN FELDES PENINSULA——GREAT WALL STATION OF CHINA, ANTARCTICA

The Feldes Peninsula is an ice-free area of the King George Island, which is the biggest one of South Sheltland archipelago. This ice-free area is 7—8 km long, and 2.5—4.5 km wide. The southern end of the Feldes Strait separates the Nelson Island (ice sheet) from the peninsula, the northeast is covered by main ice sheet of the King George Island. The sheet is 350 m thick. The average thickness is 100 m, and the highest elevation is 668 m a. s. 1.

On the problems concerned in“The subter－ranean electrical conductivity structure at the ChineseGreatWalStationonAntarctic（CG┐WSA）”byXiaopingZeng，YunfangLinandYuechenZhao

By means of the Capon spectral analysis technique calculated the frequency response of the geomagnetic transfer functions for the Chinese Great Wall Station on Antarctic, and made a preliminary inference for the underground electrical conductivity structure. In the present note, the writer considers that there are some problems concerned in their paper. Maybe it is worthwhile discussing these problems as below.

Space physics and astronomy research from Chinese polar stations: current and future directions

Space weather has a remarkable effect on modern human activities,e.g.,communication,navigation,space exploration etc.Space physics study from polar stations is as an important part of the entire solar-terrestrial space,and conducts quantitative research from the perspective of overall space plasma behavior.One of the most important issues is to identify the dominant processes that transfer plasma and momentum from the solar wind to Earth’s magnetosphere.Thus,it is necessary to carry out research for combination the observations from polar ground stations and spacecraft observations in the space.Observations at polar regions can be as a window to the space for satellite traffic controls.The operation of the observation chain―Zhongshan-Taishan-Kunlun Station could monitor polar space debris in a large area with high temporal and spatial resolution.Also,night-time measurements of astronomical seeing at Dome A in Antarctica make it less challenging to locate a telescope above it,thereby giving greater access to the free atmosphere because of a thinner boundary layer.