A precise monitoring of snow surface height in the region of Lambert Glacier basin-amery Ice Shelf, East Antarctica

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1 100 Science in China Ser. D Earth Sciences 2005 Vol.48 No A precise monitoring of snow surface height in the region of Lambert Glacier basin-amery Ice Shelf, East Antarctica XIAO Cunde 1,2,3, QIN Dahe 3, BIAN Lingen 2, ZHOU Xiuji 1,3, I. Allison 4 & YAN Ming 5 1. Department of Atmospheric Science, Peking University, Beijing , China; 2. Chinese Academy of Meteorology Sciences, Beijing , China; 3. Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou , China; 4. Australian Antarctic Division and Antarctic Climate and Ecosystems CRC, Private Bag 80 Hobart, Tasmania, 7001, Australia; 5. Polar Research Center of China, Shanghai , China Correspondence should be addressed to Xiao Cunde ( cdxiao@cams.cma.gov.cn) Received April 14, 2003; revised February 21, 2004 Abstract The net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation and wind redistribution. We present a one-year record of hourly snow-height measurements at LGB69 (70 50 S, E, 1850 m a.s.l.), east side of Lambert Glacier basin (LGB), and 4 year record at G3 (70 53 S, E, 84 m a.s.l.), Amery Ice Shelf (AIS). The measurements were made with ultrasonic sensors mounted on automatic weather stations installed at two sites. The snow accumulation at LGB69 is approximately 70 cm. Throughout the winter, between April and September, there was little change in surface snow height (SSH) at the two sites. The negative SSH change is due to densification at LGB69, and is due to both ablation and densification at G3. The strongest accumulation at two sites occurred during the period between October and March (accounting for 101.6% at LGB69), with four episodic increasing events occurring during 2002 for LGB69, and eight events during for G3 (2 to 3 events per year). At LGB69, these episodic events coincided with obvious humidity pulses and decreases of incoming solar radiation as recorded by the AWS. Observations of the total cloud amount at Davis station, 160 km NNE of LGB69, showed good correlation with major accumulation events recorded at LGB69. There was an obvious anti-correlation between the lowest cloud height at Davis and the daily accumulation rate at LGB69. Although there was no correlation over the total year between wind speed and accumulation at LGB69, large individual accumulation events are associated with episodes of strong wind (>7 m/s), we estimate drift snow may contribute to total SSH up to 35%. Strong accumulation events at LGB69 are associated with major storms in the region and inland transport of moist air masses from the coast. Keywords: Antarctica, Lambert Glacier basin, Amery Ice Shelf, accumulation, katabatic wind. DOI: /03yd0127 Copyright by Science in China Press 2005

2 Monitoring of snow surface height in Antarctica 101 Antarctica contains more than 90% of the total global land-based ice and therefore positive/negative changes in ice sheet mass balance can lead to lowering/rise of global sea level. It is still an open question whether polar ice sheets will grow or decay with a warming climate. It is estimated that the current contribution of Antarctic Ice Sheet to the global sea level change is approximately mm/a [1], the error, up to 100% 200%, is due to the imprecise measurement of surface mass balance, as well as the inadequate knowledge on the seasonal distribution of snow accumulation when modeling the moistures loading onto the ice sheet. As such, a thorough knowledge of the processes which govern snow accumulation in ice sheets is critical in calculating mass balance, interpreting proxy archives of climatic events and past atmospheric composition in ice cores, and will also be necessary for interpretation of the new generation of precise satellite altimetric measurements on ice sheets. Although there are over 90 automatic weather stations running over the Antarctic ice sheet, only at several sites on the ice sheet [2 5] or ice shelves [6] have the intra-annual measurements of surface height variations been made using automatic snow depth gauges or snow-stake arrays. The Lambert Glacier is one of the largest outlet glaciers in East Antarctic, draining a total area of million square kilometers, which includes 71 thousand square kilometers of floating ice in the Amery Ice Shelf [7]. The glacier is flanked along much of its length by the Prince Charles Mountains, and discharges into Prydz Bay via the Amery Ice Shelf (fig. 1). There are no prior data however for the region of Lambert Glacier basin-amery Ice Shelf (LGB-AIS), and to address this the Chinese National Antarctic Research Expedition (CHINARE) and the Australian Antarctic Cooperative Research Centre (CRC) plan to install a series of automatic weather stations (AWS) with snow depth gauges along the CHINARE inland traverse route from Zhongshan Station to Dome A. In this study, surface height variation data from the first AWS, installed at a site called LGB69, as well as previously installed AWS at G3 on Amery Ice Shelf, are discussed. 1 Characteristics of the site and the AWS On 22 January 2002, an AWS was installed at LGB69 (70 50 S, E, 1850 m a.s.l.), east side of LGB, east Antarctica (fig. 1) by the 18th CHINARE. This site is 160 km inland from the coast. The surface microrelief consists of sastrugi approximately 0.2 m high, oriented with their longitudinal axis at approximately 60 T, which is perpendicular to the contour line. During the past 5 years, several over-surface traverses have been made along the route from Zhongshan towards Dome A (fig. 1(a)) [8]. Fig. 2 shows the spatial distribution of the average surface accumulation rate for the initial 470 km of this route. LGB69 is located in a relatively high accumulation region with an accumulation rate of approximately 70 cm/a. A minimum in accumulation of about 20 cm/a occurs between 200 and 350 km (dotted square in fig. 2), possibly because there is a combination of less atmospheric moisture and strong wind-erosion. Southward from 350 km, the accumula tion decreases with increasing distance from the coast. G3 station (70 53 S, E, 84 m a.s.l.) was installed in January, G3 is located at the middle of Amery Ice Shelf, with smooth snow surface and flat topography. A snow stake array of 36 canes in a 6 6 matrix has been surveyed at LGB69 since January 1999 to characterize annual variability of snow accumulation over a 100 m 100 m area. The stakes are spaced at approximately 20 m intervals, and the location of the array relative to the AWS is shown in fig. 1(b). The array was installed and initial heights were measured on 29 January, 1999, a second height-reading was made on 21 January, 2002 and a third on December 17, Table 1 gives the annual snow accumulation observed at each stake as well as the mean and standard deviations. The mean annual snow accumulation for the three years of 1999, 2000 and 2001 for all stakes was 75 cm/a, with a maximum accumulation 83 cm/a, a minimum 59 cm/a and a standard deviation

3 102 Science in China Ser. D Earth Sciences Fig. 1. (a) CHINARE over-snow traverse route in Princess Elizabeth Land and location of AWS LGB69 and G3; (b) location of LGB69 snow stake array relative to the automatic weather station. 5.8 cm/a. For a mean density of the surface snow layer is 0.38 gcm 3, the average water equivalent accumulation is 28.5 cm/a. In 2002/03, a third measurement of the array was made (Qin Xiang, personal communication) for the 327-day period in 2002, accumulation averaged 47.7 cm with a maximum of 66 cm, a minimum of 33 cm and a standard deviation of 8.1 cm. The AWS at LGB69 and G3 are Series 098 stations, designed and built by the Australian Antarctic Division (AAD). The AWS provides hourly measurements of air temperature (at nominal 1 m, 2 m and 4 m

4 Monitoring of snow surface height in Antarctica 103 Fig. 2. The distribution of snow accumulation rate along the initial 470 km of the route. The dotted square represents the belt of minimum accumulation in East Antarctic Ice Sheet. Table 1 Mean annual accumulation (P m ) for and approximate accumulation for 2002 (P-02) at the LGB69 snow stake arrays Stake P m /cm a 1 P-02/cm Stake P m /cm a 1 P-02/cm Stake P m /cm a 1 P-02/cm Average St. Dev Stake height measurements were made on 29 January, 1999, 21 January, 2002 and 17 December, Fig. 1(b) shows the matrix of the stakes. levels), wind speed and direction, atmospheric pressure, relative humidity, solar radiation, surface snow height and subsurface temperatures at several depths in the surface 10 m snow layer. Data are relayed via the Argos system on U.S. National Oceanic and Atmospheric Administration satellites. Table 2 lists the major sensors and their resolutions. Snow-surface height was measured every hour with a Campbell Scientific SR50-45 ultrasonic distance sensor mounted on the 4-m arm of the AWS. The sensor has a field of view of approximately 22 and measures the distance to the closest object within this field of view (e.g., the top of a snow surface feature) with a resolution of 10 mm. Total snow accumulation is calculated as the difference between the originally installed height of the SR50-45 sensor above the surface and subsequent measured distances. Data- recovery from the surface height detector was better than 99%. Meteorological observations from the closest occupied station, Davis, are also used to investigate factors impacting the surface height changes at LGB69. These observations, made every 3 hours, include the total cloud covers (in oktas) and cloud heights (in metres). 2 Seasonal changes in snow surface height 2.1 Changes of snow surface height at LGB69 Changes in snow surface height (SSH) measured by the acoustic sounder are independent of changes due to ice flow, since the AWS moves with the ice. Densification occurs after the snowfall, and therefore

5 104 Science in China Ser. D Earth Sciences Table 2 Sensor types and resolution for the AWSs at LGB 69 and G3 Sensor Type Sensor resolution Air temperature FS23D thermistor (individually calibrated) 0.02 Relative humidity Vaisala HMP45D 3% Wind speed AAD cup anemometer 0.2 m/s Wind direction Aanderra 3590 vane 6º Snow height Campbell Scientific SR cm Solar radiation Middleton EP MJ m 2 Pressure Paroscientific Digiquartz 6051A 0.1 hpa Snow temperature FS23D thermistor (individually calibrated) 0.02 Fig. 3. Cumulative snow surface height (SSH) at LGB69, The dashed line separates the 2002 and 2003 years. Numbers 1 4 and 1 denote five episodic increases of SSH. the change of snow surface height is not equal to net snow accumulation. The snow may also be redistributed by the wind (e.g. dune migration). But in this study, in the absence of specific observations on these processes, we assume that they are relatively small over a longer period and that variations of SSH provide a record of seasonal variability of net accumulation. After quality-control checks of the data, cumulative SSH changes and daily increase in SSH were calculated and plotted (fig. 3). Monthly means of these data for the 12-month deployment are shown in table 3. The overall characteristics of the seasonal changes of SSH are as follows. (1) An initial decrease in net SSH during the 10 days after installation of the AWS. This is probably due to wind erosion of a softer layer of surface snow used to refill and level the pit dug for the AWS base. Table 3 Monthly changes of snow surface height from 1 February, 2002 to 31 January, 2003 at the LGB69 AWS Month Monthly SSH/m Departure from mean/m Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan., Lower density and higher porosity of the inhomogeneous snow favors stronger erosion. In the following discussion, this period is ignored and we focus on the data collected from 1 February, 2002 to 28 February, %

6 Monitoring of snow surface height in Antarctica 105 (2) The major accumulation period is between October and March the next year. Further, the snow accumulation process at this site is episodic, with most of the annual accumulation being associated with only four events (table 4). Abrupt increases of SSH occurred on 7 to 15 February (event 1), 11 to 23 March (event 2), 4 to 21 October (event 3) and 28 November to 9 December (event 4) 2002, as well as 27 January to 7 February (event 1 ) The SSH change for the five events (4 in 2002 and 1 in 2003) ranges between 0.13 and 0.24 m, partly depending on the time that the event lasted. The rate of daily change was between 1.4 and md 1. Braaten [4] also found periodic increases of surface height during only five events at a site in West Antarctica (AGO2, S, W) in 1996/97. While it is likely that other precipitation events such as condensation or clear-sky precipitation may sometimes occur, it is not possible to quantify the frequency of occurrence or magnitude of these inputs due to snow transport by winds and the resolution limitations of the sensor. The positive snow-surface height changes may be associated with precipitation or wind-blown transport of snow into the target area. The surface height measurements alone cannot tell which process, or what combination of the two, causes the change, but, as discussed further below, we believe that precipitation is probably the dominant factor. Little increase in SSH occurs between the episodic events, even during the accumulation period from October to March. (3) The net SSH remains relatively unchanged during the austral winter. This could be a result of either very little precipitation and slight snow redistribution, or offset of any precipitation by wind erosion and sublimation. But sublimation at LGB69 will be small and will mainly occur during warm and windy periods in summer. For inland regions more than 150 km from the coast, sublimation is near zero [9]. As discussed below, during the study period the mean accumulation rate was greater during stronger winds. Therefore for snow redistribution, this site is probably an accumulating area rather than a wind-erosion one, and the constant SSH during winter is probably due to only rare precipitation during the period. Table 3 shows monthly SSH changes, departures from the mean monthly change for the year between 1 February, 2002 and 31 January, 2003 (0.57 m) and monthly changes as a percentage of the annual change. The annual SSH change is 0.68 m which, for a mean density of the annual accumulation layer of 0.38 g cm 3, is equivalent to 0.26 m water equivalent. This is similar to the mean annual accumulation Table 4 Change of SSH associated with identified snow accumulation events at the LGB69 and G3 AWS Event Month and year Julian days Number of days Change of SSH/m Rate of SSH change/md 1 LGB69 at LGB 1 Feb., Mar., Oct., Nov. Dec., Jan. Feb., * G3 at Amery Ice Shelf 1 Mar., Oct., Jan., May, Oct., Jan. Feb., Oct. Nov., Apr., * Shown as days (since Jan.1, 2002) in figs. 3 and 5.

7 106 Science in China Ser. D Earth Sciences rate (0.28 ma 1 w. e.) determined from the stake-array. The SSH change from October 2002 to March 2003 was 0.69 m, which is equal to 101.6% of the total annual change, while the SSH change from April to September 2002 was only 0.07 m, accounting for 1.6% of the annual SSH. Negative changes to the surface may be due to wind erosion of surface snow, surface sublimation, and/or metamorphic changes and densification of the firn. 2.2 Changes of SSH at G3 The same quality-control check was dedicated for the four-year s SSH record at G3, and the daily SSH change is plotted in fig. 4. In contrasting with that at LGB69, the process of snow accumulation at G3 is much simpler. The major characteristics is: (1) The increase of SSH is attributable to 2 to 3 episodic increasing events per year. Total 8 increasing events were seen for the four-year SSH records. The accumulation season, like at LGB69, is also austral summer, while in winter a stable SSH was observed for the years 1999 and 2000, and a decreasing SSH was found for 2001 and 2002, which may be due to the strong ablation occurring at the end of the summer and/or densification after snowfall. A much more stable snow surface was seen over the ice shelf than ice sheet between every two episodic events. (2) Bigger amplitude of inter-annual SSH variation was found at G3 compared to LGB69 on the ice sheet. For instance, the annual SSH from 1999 to 2002 at G3 was respectively 0.32 m, 0.14 m, 0.54 m and 0.02 m, probably depending on the different amounts of annual precipitation occurring. But the extremely low SSH in 2002 may be due to ablation, as can be Fig. 4. (a) Cumulative SSH variations at G3, Amery Ice Shelf, 1999 through The dashed vertical lines are dividing lines between different years. Numbers 1 8 denote episodic increases of SSH; (b) enlarged SSH change in 2002 so as to compare with fig. 3.

8 Monitoring of snow surface height in Antarctica 107 clearly seen from fig. 4(b). (3) We also see from table 3 that bigger amplitude of daily rates was observed during the abrupt SSH events, ranging from 0.5 to md 1, in contrasting with that at LGB69. 3 Meteorological assessment of accumulation events Precipitation at the coast of Antarctica is episodic and associated with synoptic scale confines organized storm systems to the coastal areas [9]. Routine measurement of precipitation amounts in Antarctica is a difficult and in many instances an impossible task using surface-based collection techniques since precipitation usually occurs in conjunction with strong surface wind. Studies of blowing snow over the polar ice sheet have been undertaken and some empirical functions have been established [2,10 13]. Traditional glaciological point estimates of the inter-annual precipitation variability often assume that the accumulation and precipitation rates vary in parallel. The precipitation over the ice sheet can be estimated by using a function developed by Oerlemans [14] : P=920 (0.3+14S h)/C (mm/a), (1) where S is the ice sheet slope, h, elevation (m) and C, degree of continentality, usually 1.5 for the coastal and 2 for inland region. Based on this function the annual precipitation at LGB69 is around 410 mm/a. This value is approximately equal to 60% of the total SSH in 2002, in other words, around 40% SSH increasing derived from non-precipitation processes such as drift snow. 3.1 Increase of SSH at LGB69 versus wind speed The accumulation events observed at LGB69 may be due to precipitation alone, windblown snow alone or some combination of the two. Measured wind speed during an event can offer some insights into the mechanism. The formation of snowdrifts by windblown snow requires the movement of snow grains along the surface in a process called saltation [15]. However, this process only occurs if the wind speed exceeds some threshold speed. Typically the threshold speed for the onset of drifting varies between 7 and 13 m/s depending on surface roughness [7]. Unfortunately the bearings of the AWS anemometer shaft freeze during very cold periods and the instruments give a zero reading. For LGB69 the 1-m anemometer did not operate between June 23 and September 25, 2002, whereas the 4-m anemometer was stopped between July 30 and September 16. A plot of surface wind speed versus wind direction at 4-m level for the periods from January 22 to July 29, 2002, and from September 16, 2002 to February 28, 2003 (not shown), indicates that the prevailing wind direction is around 60 true, from Princess Elizabeth Land towards the Amery Ice Shelf. For the 4-m level the time-weighted monthly mean wind speed for the 12 months in 2002 are respectively January (from 22nd), 8.3 m/s; February, 10.0 m/s; March, 8.2 m/s; April, 10.2 m/s; May, 11.1 m/s; June, 10.6 m/s; July, 10.4 m/s; August, no data; September (from 16th), 11.8 m/s; October, 9.6 m/s; November, 8.7 m/s and December, 7.1 m/s. The annual average wind speed based on these numbers is 9.6 m/s, with the daily average wind speed ranging between 0 and 17.7 m/s. Figure 5(a) shows the relationship between daily increases of SSH and wind speed at the 1-m level exceeding 7 m/s, for two periods when wind speed data are available (days 22 to 173 and day 269 to 424). We are concerned only with snow accumulation events, either due to precipitation or wind transport to the site, and not with subsequent firnification or wind erosion. Hence only positive daily changes in SSH are shown in fig. 4 and subsequent figures. It is apparent that higher wind speeds are associated with larger increases of SSH. LGB69 is located leeward of the transition zone [16,17] ( km from coast, fig. 1(b)), and receives both precipitation and driftsnow. Taking the total SSH change caused by windy days higher than 13 m/s as the low limitation of drift snow accumulation, it is calculated that this amount is equal to 24 cm, which is 36.5% of the total SSH in This result, however, is lower than that we derived from the above equation (1).

9 108 Science in China Ser. D Earth Sciences Fig. 5. (a) Relationship between daily change of SSH (only positive changes are shown) and wind speed higher than 7 m/s at the 1 m level (WM1) for the days 22 to 173 and days 269 to 424; (b) relationship between cumulative change of SSH and relative humidity higher than 70%; (c) relationship between cumulative change of SSH and total daily incoming solar radiation at LGB69, while (d) and (e) are the relationships of daily SSH change versus solar radiations respectively for the days 0 60 and in

10 Monitoring of snow surface height in Antarctica Increase of SSH at LGB69 versus humidity Atmospheric humidity is another potential indicator of meteorological phenomena such as precipitation, moisture convection and/or windblown [13]. Daily increases of SSH between spring and autumn show a close positive correlation with the daily variation of relative humidity (RH) at the AWS (fig. 5(b)). But since both precipitation and windblown snow can increase the humidity, RH alone is insufficient to identify precipitation events. However, the humidity sensor is mounted at a height of 4 m, above the level of saltation or drift snow due to katabatic wind, and high RH is probably related to precipitation events or storms. The overall character is that lower RH in winter while higher in summer, a gradual humidity-decreasing trend was seen from summer to winter. Fig. 5(b) shows the relationship between SSH and RH greater than 70%. It is clear that pulses of RH coincide with abrupt increases of SSH. 3.3 Increase of SSH at LGB69 versus cloudiness Figure 5(c) shows the SSH compared to daily total incoming short wave radiation measured at the LGB69 AWS, and fig. 5(d) and (e) show the short wave radiation compared to daily increases in SSH. There is no short wave radiation during the polar night (approximately days 120 to 240). There are also several other periods outside the polar night when the AWS records no incoming short wave radiation probably due to an instrumental fault. These are excluded from analysis. Fig. 6(b) and (c) show a tendency for the episodic increases in SSH, which occur mostly in autumn and spring, to be anti-correlated with shortwave radiation, indicating that the SSH increases occur during cloudy periods, and are hence likely to be precipitation events. However, because a dense cloud Fig day-smoothed changes of daily SSH (only positive changes are shown) at LGB69 versus 10-day-smoothed variations of fractional cloud cover (a) and the lowest cloud height (b) observed at Davis Station in 2002.

11 110 Science in China Ser. D Earth Sciences cover does not necessarily result in precipitation, the correspondence between SSH peaks and radiation troughs is not one on one. Are major increases of SSH attributable to storms in the coastal region? In fig. 6 the daily change in SSH is compared with cloud observation at Davis station, 160 km NNE of LGB69. Fig. 6(a) shows the total cloud amount and fig. 6(b) shows the elevation of the lowest cloud layer. The correlation coefficient (r) is 0.29 between 10-day-smoothed cloud covers and SSHs and is 0.25 between 10-day-smoothed cloud heights and SSHs, with both confidence levels better than 99.9%. During summer the increase in SSH at LGB69 is associated with both a greater cloud fraction and lower level clouds at Davis. This relationship is less distinct in winter. However, individual accumulation events are really not quantitatively correlate to precipitation events, hence it is meaningless to apply statistical test for the correlation between accumulation events and meteorological conditions. Low level clouds ( m above surface) are the dominant source of precipitation. Synthesis of airflow into Antarctica suggests that upslope advection of warm air into the interior Antarctica is a frequent and persistent phenomenon [18]. This low level circulation in turn affects the accumulation on the coastal ice sheet. Ice core and meteorological studies suggest that the circum-polar trough, and especially cyclonic activity in the Indian Ocean in Prydz Bay to the north, may be responsible for the long-term variability of accumulation in Princess Elizabeth Land, Antarctica [17]. 3.4 Meteorological assessment of G3 SSH change Because SSH is free from katabatic wind, SSH change is most attributable to the precipitation and ablation/firnification. Abrupt SSH increasings coincide with humidity pulses but no clear coherence with winds speed. We also compare SSH change at G3 with cloud observation at Davis, there is no obvious correlation at all. Therefore, we judge that the climate system between the AIS and east side of LGB is different. For the complexity of climate regime over this region, we have analyzed it through ice core studies [17,19]. 4 Discussion and conclusions Automatic weather stations (AWS) was used to monitor snow surface height (SSH) in Lambert Glacier basin-amery Ice Shelf (LGB-AIS) region, Antarctica. Significant increases in the SSH both at LGB69 and G3 were episodic, with large increases at LGB69 being associated with only five events in the months between February 2002 and March 2003, and 2 to 3 events per year at G3 during 1999 through All events occurred between late spring and early autumn. At LGB69, The total initial increase in surface height that occurred during the events was 0.78 cm, which is greater than the total annual change of 0.68 m, but significant surface height decreases occurred subsequent to the events due to a combination of snow compaction, wind erosion and sublimation. During the winter months (April to September) individual SSH height increases were considerably smaller than during the spring and autumn episodes, and were typically followed by approximately equivalent SSH decreases: the net change to the surface height over the 6 winter months was only 0.07 m. Much more stable SSH was observed between episodic events at G3, in contrasting with LGB69, probably due to a weaker wind over the ice shelf. But processes such as ablation, sublimation and densification may result in more decreasings of SSH after snowfall than on the ice sheet, this is especially obvious for the records in 2001 and The Antarctic circum-polar low-pressure belt has the largest impact on Antarctic accumulation and temperature. For example, the variability of the Amundsen Sea low and the Bellingshausen Sea low exert major impact on the climate of west Antarctica and the Antarctic Peninsula, respectively [20]. The Antarctic circumpolar trough is at its deepest and most southerly location during the equinoxes, but for the sole year of record that we present here, the accumulation episodes are all on the summer side of the equinoxes. However, Xiao and others [17] use ice core records to show that a Southern Indian Ocean low in the Prydz Bay region governs inter-annual variability of the accumulation and decadal climate change in Princess Elizabeth Land. Longer records are required to

12 Monitoring of snow surface height in Antarctica 111 establish any links between accumulation seasonality, storminess, and the propagation and strength of the circum-polar trough. However, the seasonality of the accumulation at this site may not be the same over all of east Antarctica. For instance, the seasonality is similar for Wilkes Land, Mizuho Plateau, Dronning Maud Land [21 23], but is different for Kemp Land [19,24, 25] and for the west Antarctic ice sheet [4,6]. Our estimation of the percentage of windblown snow (35% 40%) to the annual SSH change at LGB69, although not precise, is close to the known verify- coefficient of precipitation at Mirny, Molodezhnaya and Novolazarevskaya (30%), as well as Vostok (37%) [26,27]. More precise system is required for the future designing of the monitoring stations. 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