Topographic features around Zhongshan Station,southeast of Prydz Bay

Considering the complex topographic features of the southeast of Prydz Bay where China's Zhongshan Station is located,three types of geomorphologic units can be identified,i.e., submarine slopes,canyons,and terrains.The major topographic features in the study area are the submarine canyon and trough system outside the calving ice front of Dalk Glacier.A 3.8 km×80 m fissure is found on the submarine terrain at Zhongshan Anchorage,which,once triggered by geological hazards such as earthquakes and ice falls,would be a threat to the usage and maintenance of the anchorage.

Ionospheric absorption at Zhongshan Station, Antarctica during magnetic storms in early May, 1998

In the paper the high latitude ionospheric absorption events, monitored by an imaging riometer at Zhongshan Station, Antarctica, are examined during magnetic storms in early May, 1998. The storm absorption at ~0639 UT on May 2 was mainly an equatorward progressing absorption event, which were associated with a strong negative bay of the magnetic H component and with a large Pc3 range pulsation. There was a time lag of about 1. 5 hours between the onset of the ionospheric disturbance and the IMF southward turning in the solar wind. The event at 2222 UT on May 2 was a typical midnight absorption spike event. The absorption region took the form of an elongated strip with the length of 100 - 150 km and the width of 30 - 40 km. The absorption during 0830 - 1200 UT on May 6 was a polar cap absorption (PCA) event,caused by intense precipitation of high-energy protons erupted after a large solar flare explosion.

Seasonal variations of sulfur aerosols at Zhongshan Station, East Antarctica

Observations of atmospheric methane-sulfonic acid（MSA） and non-sea-salt sulfate（nss-SO4^2-） from December 2010 to November 2011 at Zhongshan Station are presented in this paper. MSA and nss-SO4^2- average concentrations were 24.2 ± 37.9 ng·m^-3（0.5-158.3 ng·m^-3） and 53.0 ± 82.6 ng·m^-3（not detected [n.d.]） - 395.4 ng·m^-3）, respectively. Strong seasonal variations of MSA and nss-SO4^2-, with maxima in austral summer and minima in winter, were examined. The high concentrations of sulfur compounds in December may be attributed the dimethyl sulfide（DMS） emissions from the marginal ice zone, when open water near the sampling site was important in impacting the sulfur species of January and February at Zhongshan Station. In austral winter, there was almost no phytoplanktonic activity in offshore waters, and atmospheric sulfur compounds likely had long-range transport sources.

The high-latitude ionospheric phenomena observed by DPS-4 at Zhongshan Station, Antarctica

Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphcric phcnomena occurred in the cusp region. They are particle precipitation effects in the E region. F region magnetic noon phenomena, slant Es phenomena and lacuna. F layer irregularity zone (FLIZ) phenomena, and auroral oval identification. Typical examples of ionograms and ionogram sequences observed at Zhongshan Station are displayed in this paper.

Seasonal characteristics of F region in lower solar activity period at Zhongshan Station, Antarctica

Based on data of Digisonde Portable Sounder-4 (DPS-4 ) in 1995 -1997. we have analyzed the seasonal variations of F region at Zhongshan Station (69. 4°S,76. 4°E ). During the summer of Zhongshan Station, F region ionization is mainly controlled by the solar ultraviolet radiation. Similar to the phenomena in mid-latitude area, the value f0F2 is changed with local time. During equinox scasons, soft electron precipitation from the cusp/cleft region seems significant, f0F2 is changed with rnagnetic local time, and shows the magnetic noon phenomenon. In winter. the effect of the solar radiation on the F region is less than that of summer. Instead, F region is affected by particle precipitation from cusp/cleft region as well as polar plasma convection, there fore, the diurnal variation of f0F2 is more complex and shows two peaks. F region occurs all day in summer. and seldom appears at midnight in equinox.In winter, F region shows two minimums, one is at midnight and the other is at afternoon cusp. Further analysis of the F region spread indicates that in winter the aurora oval passes over the Zhongshan Station is at 1100 UT - 1500 UT.

SOME CHARACTERISTICS OF THE SURFACE RADIATION COMPONENTS AT ZHONGSHAN STATION

A preliminary analysis of some characteristics of the radiation components is made by using the surface radiation data obtained from February 1990 to January 1991 at Zhongshan Station. The result shows that the fluxes of direct radiation and global radiation are strong with higher atmospheric transparency, and the surface can absorb large amount of radiation energy in warm season. The surface loses heat energy in cold season due to the seasonal variations of the surface albedo and shortwave radiation. The variation of net longwave radiation is related to cloud amount and surface air temperature. The property of net radiation is similar to other Antarctic coastal stations but differs greatly from Antarctic inland area.

Prospect of China's Auroral Fine-structure Imaging System(CAFIS) at Zhongshan station in Antarctica

A new auroral imaging system is reported which is planned to be deployed at Zhongshan Station in Antarctica in the end of 2009. The system will focus on study of optical auroras in small scales and be called China＇ s Auroral Fine-structure Imaging System （CAFIS）. The project of CAFIS is carried out by support of ＇the tenth five-year plan for capacity building＇ of China. CAFIS will be a powerful groundbased platform for aurora observational experiments. Composing and advantages of CAFIS are introduced in this brief report. Some potential study topics involved CAFIS are also considered.

The auroral occurrence over Zhongshan Station, Antarctica

The auroral data observed by all sky TV camera during 1995 and 1997 at Zhongshan Station of Antarctica are used to analyze the statistic characteristics of the aurora over Zhongshan Station. Around postnoon (1200 - 1600UT ) and midnight (2000 - 0100 UT ), the aurora appears more frequently and stronger than those in evening (1600- 2000UT ). The corona type auroras mainly occur at poleward and overhead of Zhongshan Station during postnoon and around midnight. The hand type auroras mainly appear during postnoon. while during evening and around midnight only appear at equatorward. The active surges mostly appear around midnight,while the transpolar arcs mainly occur after midnight. Except for the transpolar arcs. the occurrences of the other three type auroras are related with Kp index. Usually Zhongshan Station enters the auroral oval at postnoon,the exact time depends on Kp index.

CH4 Monitoring and Background Concentration at Zhongshan Station, Antarctica

Background CH4 concentration and seasonal variations measured at Zhongshan Station (69°22'2''S, 76°21'49''E, 18.5 m) in Antarctica from 2008 through 2013 are presented and discussed. From 2008-2013 CH4 was measured in weekly flask samples and started on line measurement by Picarro CO2/CH4/H2O analyzer from March, 2010-2013. These CH4 measurements show the expected growth period of CH4 concentration during February (Antarctic spring) with a peak in September (fall). Irrespective of wind direction, CH4 concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1% of the data. The mean daily cycle of CH4 concentration in all four seasons is small. The monthly mean CH4 concentration at Zhongshan station is similar to those at other stations in Antarctica showing that CH4 observed in Antarctica is fully mixed in the atmosphere as it is transported from the northern through the southern hemisphere. The annual CH4 increase in recent years at Zhongshan station is 4.8 ppb·yr-1.

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

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

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.

Locating the Polar Cap Boundary of Postnoon Sector from Observations of 630.0 nm Auroral Emission at Zhongshan Station

We studied the ground observations of 630.0 nm auroral emission at Zhongshan Station to determine the polar cap boundary with the latitudinal profile of emission intensity. The open-closed field time boundary is assumed to lie at the boundary between polar rain and plasma sheet precipitation. We assume that nonprecipitation-dependent sources of 630.0 nm emission cause a spatially uniform luminosity in the polar cap and that auroral zone luminosity is also spatially uniform. Therefore we determine the location of the polar cap boundary of postnoon sector from the auroral emission data each time by finding the best fit of the observations to a step function in latitude and we produce a time series of the location of the polar cap boundary. The average error of the practice in the paper is less than 0.8 degree.

The extremely intense CNA events observed at Zhongshan Station in July, 2000

Using the ground observation data at Zhongshan Station of Antarctica during July 13 to 17, 2000, the intense absorption events associated with the activities of the solar active region R9077 are analyzed. It was shown that an intense polar cap absorption event lasted more than 3 days, which was caused by the solar proton event associated with the X5/3B major flare at 1024 UT on July 13. The polar cap event started at about 1040 UT on July 14, and lasted to about 1940 UT on July 17, with a typical day night variation. At the same time, the intense solar activities extremely disturbed the magnetosphere, therefore aurora substorms occurred frequently. The energetic particle precipitation from the magnetosphere caused several absorption spikes superposing on the background of polar cap absorption. One distinct event is the absorption enhancement that started at about 0300 UT on July 15, reached its peak of 26 dB at about 0645 UT and recovered at about 1110 UT on the same day, which was the strongest absorption event observed at Zhongshan Station since the imaging riometer installed in February, 1997. Another outstanding absorption spike with pulsation occurred at about 1753 UT on 14th, its peak reached to 6 dB.

Intensity variations of the postnoon auroral bright spots observed at Zhongshan Station, Antarctica on August 8, 1999

In this paper we use the high speed multi channel meridian scanning photometer data and all sky TV camera images to analyze the intensity variations of the postnoon auroral bright sports of 557.7 nm and 630.0 nm emissions. Several results can be obtained from this paper. (1) Bright spots are rather transient features lasting typically for only a few minutes. (2) The intensity of the postnoon bright spots of 557.7 nm emissions can surpass 11 kR. The occurrence of the bright spots seems rather frequent. (3) The ratios of I(427.8)/I(630.0) and I(427.8)/I(557.7) during the bright spots occurring time show a positive peak and negative peak respectively. It qualitatively indicates that the average precipitating electron energies along the meridianal scan above Zhongshan Station increased as the bright spot appeared. And the intensification of the spot mainly was caused by the increasing of high energy (3 10 keV) flux. (4) Usually the bright spots are accompanied with the magnetic pulsation and the occurrence of multi band arcs.

Measurement of NO_2 and analysis of relationship between stratospheric NO_2 and O_3 over Zhongshan Station,Antarctica

We have already continually taken the measurement of total column amount of O 3, NO 2 as well as stratospheric O 3, NO 2 over Zhongshan Station,Antarctica. This paper analyzes the seasonal variation of NO 2 and its relationship to O 3 during the Antarctic Ozone Hole in 1993～1995 and points out that the decrease of atmospheric NO 2 is one of the important reason to the strengthening of Antarctic Ozone Hole.

Simultaneous observations of Syowa East HF radar and Zhongshan Station optical aurora associated with the solar wind negative pressure impulse

The field of views of the Syowa East HF radar covers over Zhongshan Station (magnetic latitude ~ 74. 5°S). We examined the relation between HF radar signatures and optical aurora by using the data obtained on 3 Augusl 1997. A geomagnetic negative sudden impulse (SI- ) occurred at ~ 1432 UT on 3 August 1997associated with the sudden decrease of solar wind plasma density. From the behavior of the optical aurora observed by all-sky TV camera and scanning photometers at Zhongshan Station, a sudden enhancement of auroral emission intensity and poleward moving signature occurred associated with the negative SI. It is intcresting that the temporal and spatial variations of the HF radar backscatter power showed one to one correlations with optical aurora data. The details of this event are examined and compared with the data onboard WIND sate1lite and from ground based magnetometers.

Seasonal variation of atmospheric elemental carbon aerosols at Zhongshan Station,East Antarctica

Elemental carbon(or black carbon)(EC or BC)aerosols emitted by biomass burning and fossil fuel combustion could cause notable climate forcing.Southern Hemisphere biomass burning emissions have contributed substantially to EC deposition in Antarctica.Here,we present the seasonal variation of EC determined from aerosol samples acquired at Zhongshan Station(ZSS),East Antarctica.The concentration of EC in the atmosphere varied between 0.02 and 257.81 ng·m^(-3)with a mean value of 44.87±48.92 ng·m^(-3).The concentration of EC aerosols reached its peak in winter(59.04 ng·m^(-3))and was lowest(27.26 ng·m^(-3))in summer.Back trajectory analysis showed that biomass burning in southern South America was the major source of the EC found at ZSS,although some of it was derived from southern Australia,especially during winter.The 2019–2020 Australian bush fires had some influence on EC deposition at ZSS,especially during 2019,but the contribution diminished in 2020,leaving southern South America as the dominant source of EC.

The characteristics of Pi2 pulsations at Zhongshan Station ofAntarctica

In this paper Pi2 pulsations at Zhongshan Station of Antarctica are analyzed from October 1 - 31, 1996. Their characteristics e. g. occurrence frequency,frequency, and polarization are studied. The characteristics of Pi2 pulsations are summerized as follows: (1 ) Pi2 pulsations at Zhongshan Station usually take place from 2000 MLT to 0200 MLT; the main frequencies are between 6. 79 mHz and 13. 58mHZ; (2 ) Pi2 pulsations with low frequencies are dominent. The range of main frequencies becomes narrow at midnight; (3) The Polarization of Pi2 pulsations are almost linear; (4) About the orientation of major axes the NW-SE direction is dominent before 2200 MLT and NE-SW is dominent after 2200 MLT. The generation mechanism of Pi2 pulsations at Zhongshan Station is discussed theoretically.

Polarization characteristics of Pc3 pulsations at Zhongshan Station of Antarctica

In this paper the data of geomagnetic pulsations at Zhongshan Station from February 3 to Novernber 30 in 1996 are analyzed in ordcr to study polarization characteristics of Zhongshan Station Pc3 pulsations which comprises the cusp Pc3 pulsation and the nightside Pc3 pulsation. For the cusp Pc3 pulsation. the right-handed polarization is always dominant. But their orientation of major axes of polarizations changes with season, NW-SE is dominant in summer and NE-SW in winter. For the nightside Pc3 pulsation,the right-handed with NE-SW is always dominant before midnight. But the left-handed with the mixing orientation of major axes is dominant in summer and the NE-SW with the mixing polarization sense is dominant in winter after midnight. It means that the two types of Zongshan Station Pc3 pulsations have different sources.

Surface Ozone Monitoring and Background Concentration at Zhongshan Station, Antarctica

The background surface O3 concentrations and seasonal changes observed at the Zhongshan Station (69°22'2''S, 76°21'49''E;18.5 m), east Antarctica from 2008 to 2013 are presented. Irrespective of wind direction, surface O3 concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1.1% of the data. These O3 exhibit the expected lowest in summer, with a peak in winter. The daily range of average O3 in all four seasons is small. The monthly mean O3 is similar to that of other stations in Antarctica, with seasonal CO2 amplitudes in the order of 15 ppb to 35 ppb. Surface O3 significantly negatively correlated with UVB in the spring and autumn, with correlation coefficients of 0.50 and 0.57 under the 0.01 significance test. Furthermore, the surface O3 concentration during polar nights was 1 - 2 times higher than that during polar days. Thus, the chemical effect of the aurora lights was the dominant cause of ozone destruction, showing that surface O3 observed in Antarctica has a small interferences from human activities in the atmosphere as it moves from the north through the southern hemisphere.