7.13                              Edward VII Land, Marie Byrd Land, and Ellsworth Land  

Edward VII Land, Marie Byrd Land, and Ellsworth Land together span approximately longitudes 160º W to 80º W (see Figure 7.13.1). From west to east, the stations/features specifically referred to in this section include:

·                         Russkaya Station                     (74° 46´ S, 136° 52´ W, 124 m AMSL);

·                         Mount Sidley                            (~77º S, ~126º W, peak elev. 4,181 m AMSL);

·                         Byrd Station                             (79º 59´ S, 120º 00´ W, 1,528 m AMSL);

·                         Amundsen Sea;

·                         Mount Seelig                            (~82º S, ~103º W, peak elev. 3,022 m AMSL);

·                         Patriot Hills Base                    (80^o 19´ S, 81^o 16´ W, 1,000 m AMSL);

·                         Teniente Parodi                       (80^o 08´ S, 81^o 16´ W, 855 m AMSL);

·                         Ellsworth Mountains               (peak elev. (Vinson Massif) 4,897 m AMSL);

·                         Siple Station                             (75° 54´ 00″ S, 83° 55´ 12″ W, 1,054 m AMSL).

West Antarctica appears to have held meteorological interest in so far as the higher ground might affect the weather at lower altitudes, over for example, the Ross Ice Shelf (see for example Bromwich et al., 1994). However, there are no stations currently operating year round and very few summer stations. And so, while some of the information presented below is of a limited nature it seems important to record what data are available.

Although not covered in detail here the USAP operated Siple Station for some years (see for example, Foster (1985), and Heide (1990)) but closed the station in the early nineties. According to Art. Cayette (personal communication) Siple Station appears to be in an area where decaying waves and associated occlusions stagnate. With a frequent flow off the ocean from these large–scale systems, an upslope of ice orography, and a continually cooling of the surface air layer as the air mass migrates inland it is understandable why the operation at Siple might close. Climatically Siple Station would appear to be in a location that is windy, with frequent low cloud/fog, and considerable blowing snow.

Cayette goes on to advise that the forecasting programme at McMurdo Station currently includes coverage of western Marie Byrd Land. However, for this area the McMurdo office has limited experience and the recent records are restricted to two seasons in the late nineties. The McMurdo office has come up with some conclusions, some limited forecasting tools, and lots of questions that they hope to answer in the near future.

The information supplied below on Byrd Station (now closed) is also of a limited nature but is included to at least give a first impression of the area and is included due to the dearth of available meteorological information on this part of Antarctica.

	Key to numbered stations/bases/features 1         Russkaya 2         Byrd Station 3         Teniente Parodi 4         Patriot Hills Base 5         Siple Station Figure 7.13.1     A map of Edward VII, Marie Byrd and Ellsworth Lands and adjacent areas. (Adapted from a map provided courtesy of the Australian Antarctic Division.)

7.13.1                            Russkaya Station  

7.13.1.1                      Orography and the local environment

Russkaya Station (opened on March 9, 1980, closed on March 12, 1990) was situated on Cape Berks (Hobs shore) at 74° 46´ S, 136° 52¢ W at an altitude of 124 m above sea level. The coast in the station area is a snow–glacial barrier with a height of 2 to 40 m. From the western side of Cape Berks the coastline turns sharply southward. In this sector of the Ruppert shore the slope of the continental glacial cover towards the pole is 300 m per 10 km. The 100 m contour is 3 km away from the coastline. In the vicinity of the station along the coastline there is a row of hills with heights of 125–145 m. The orographic features intensify the eastern winds in the surface layer.

The sea bottom in the area of the station has a sharp declination away from the station. The 50 m isobath is at a distance of 200 m from the shore, and the 20 m isobath is at a distance of 100 m from the shore. The ocean bed is of rocky type.

7.13.1.2                      Operational requirements and activities relevant to the forecasting process

During its 10 years of operation Russkaya Station was the only scientific base in the immense coastal area between the Ross Sea and Antarctic Peninsula. Therefore the scientific observations carried out there are of great importance. In addition, Russkaya Station is remarkable amongst the coastal Antarctic stations due to the extraordinary values of some meteorological characteristics.

During its period of operation a wide variety of hydro–meteorological, geophysical, astronomical medico–physiological and others observations were carried out at the station. The weather forecast information for crucial activities at the station was provided by the forecasting group at Molodezhnaya Station.

7.13.1.3                      Data sources and services provided

Russkaya Station is currently closed.

7.13.1.4                      Important weather phenomena and forecasting techniques used at the location

General overview

Typically for a station in this area, extremely severe weather conditions occur because of a combination of low temperatures and very strong winds. The mean–annual air temperature recorded over the 10–year period of station occupation was –12.4ºC. The warmest month was January; the coldest was August. The absolute temperature minimum recorded during the occupation of the station was –46.4ºC, and the absolute maximum was +7.4ºC. In the station area blizzards were often observed (about 150 days a year) accompanying by snowfall and by restriction of visibility. Due to orographic factors, easterly winds prevail. The atmospheric circulation in the Pacific sector of Antarctic is characterized by high variability. Cyclogenesis is more prevalent in the cold period of the year and less common in November – January. The maximal frequency of mobile cyclonic eddies occurs in the area of 60–70º S, and the area of intensive cyclogenesis is located south of Tasmania and New Zealand in the area of 50–60º S. Most cyclonic eddies move along zonal trajectories, but some systems move along meridional trajectories from the above–mentioned areas toward the Hobs shore. Such tracks are associated with the development of blocking tropospheric highs, orientating north of the Amundsen Sea. The high frequency of depressions north of the station leads to a climatological low north of the Hobs shore, especially for cold period of the year. In contrast, there is a climatological high–pressure area over Marie Byrd Land.

Surface wind and the pressure field

Table 7.13.1.4.1 (in Appendix 2) shows mean–monthly MSLP values at Russkaya Station. It may be seen from this table that the mean–annual pressure at sea level (981 hPa) is the lowest pressure registered at any Antarctic coastal station. The annual pressure variation is characterized by a maximum value in January and minimum in October. The absolute pressure maximum was 1019.1 hPa. The absolute pressure minimum of 923.4 hPa was lower than any absolute pressure minimum values previously registered at a coastal station. The annual pressure variation amplitude of monthly mean data at Russkaya Station is much higher also, than at other Antarctic station.

The severity of the wind regime is a peculiarity of the climate of the Russkaya Station region. The mean annual wind speed experienced was 12.9 m s^–1 (~25 kt). The monthly mean wind speed maximum of 18.1 m s^–1 (~35 kt) was registered in March, the minimum of 9.6 m s^–1 (~19 kt) in January. The wind speed maximum (excluding January and February) fluctuated between 46–61 m s^–1 (~89–118 kt). The highest registered wind gust was 77 m s^–1 (~150 kt) – it was impossible to register stronger wind gusts due to the destruction of the wind anemometer. There was one situation when the wind had speeds of 50–60 m s^–1 (~97–116 kt) blowing continuously for 16 days. On an average during the year the number of days with wind speed exceeding 15 m s^–1 (~30 kt) was 264 days and there were 136 days a year with wind speed exceeding 30 m s^–1 (~60 kt). All the hurricane force winds registered at the station were of cyclonic origin with directions in the range 75–85º. The downslope southeasterly winds, which are typical for other areas of Antarctic coastline with marked glacial valleys, are not found here. To the west of cyclonic disturbances the wind direction has a west–southwesterly direction, because of the orientation of the shore

All cases of hurricane force winds were associated with the approach of a very active cyclones moving from the northwest to the Marie Byrd Land coastline. Their trajectory was dictated by a blocking high over the Amundsen Sea. In such a situation the centres of the lows were located over the ocean west of Russkaya Station and fronts were orientated along the coastline. Hurricane force winds occur because of the above synoptic situation and the particular orography along the coastline.

For successful forecasting of such situations it is necessary to have satellite imagery not less than twice a day. This allows the estimation of the movement of lows. The synoptic maps can give additional information, but they may be poor here due to lack of meteorological data.

It is possible also to predict the wind speed increases up to hurricane force with the help of meteorological observations carried out at the station. The approach of an active cyclone towards the coast is accompanied usually by cirrostratus and altostratus cloud 6–12 hours before the wind speed increase. At the same time a fall of pressure and an increase in temperature of 5–10ºC are registered. The subsequent wind turn towards 75–85º precedes the wind speed increase if the wind direction was different earlier. The turn of wind towards the northeast accompanied by a wind speed decrease does not always indicate the end of a storm, because it can be connected with the passage of a front, followed by another cyclone. Sometimes, there is the possibility of two and more cyclonic disturbances passing within a period of about a day, which is the reason for long periods of stormy conditions. Usually the wind drops fully with a turn to the southwest.

Upper wind, temperature and humidity

No specific information on forecasting has been obtained.

Clouds

No specific information on forecasting has been obtained.

Visibility: blowing snow and fog

No specific information on forecasting has been obtained.

Surface contrast including white–out

No specific information on forecasting has been obtained.

Horizontal definition

No specific information on forecasting has been obtained.

Precipitation

No specific information on forecasting has been obtained.

Temperature and chill factor

No specific information on forecasting has been obtained; however, Table 7.13.1.4.2 (in Appendix 2) shows mean–monthly temperatures at Russkaya Station.

Icing

No specific information on forecasting has been obtained.

Turbulence

No specific information on forecasting has been obtained.

Hydraulic jumps

No specific information on forecasting has been obtained.

Sea ice

The main feature of the ice regime in the area of Russkaya Station is the annual wide, solid strip of fast ice and chain of stationary polynyas, formed along the coastline in the summer period. The typical feature of fast ice is its increased stability. Each year it achieves the same maximum size of about 100 km, bounded by shelf area. In the spring–summer period about half of the fast ice is destroyed. In the station area the fast ice breaks down once every three to four years. In the case of breakdown of multiyear fast ice the frequent hurricane force winds block (prevent) the formation of stable ice for a long time.

Due to heavy ice conditions the disembarkation at Russkaya Station was carried out by helicopters only.

Wind waves and swell

No specific information on forecasting has been obtained.

7.13.2                            Byrd Station

7.13.2.1                      Orography and the local environment

Byrd Station (camp) is located at 80º S, 120º W, at an elevation of 1,530m (5,020ft) on the lower plateau of West Antarctica. The camp is some 350 km distant from the Executive Committee Mountain Range (high point being Mount Sidley at 4,181 m AMSL (~13,718 ft) and 400 km away from the Whitmore Mountains located to the southeast of the station, (the highest point being Mount Seelig, 3,022 m AMSL (~9,915 ft). Byrd Station is thus southwest of the ridgeline that links these two mountain ranges. The station is also approximately 600 km east–northeast of the Ross Ice Shelf; and some 800 km south–southwest of the Amundsen Sea.

7.13.2.2                      Operational requirements and activities relevant to the forecasting process

No specific information on requirements has been obtained.

7.13.2.3                      Data sources and services provided

Forecast services are available from McMurdo Station.

7.13.2.4                      Important weather phenomena and forecasting techniques used at the location

General overview

At a relatively low altitude (1,530 m (~5,020 ft)), Byrd Station (and all camps within the general area) is greatly affected by the intrusion of migratory mid–latitude cyclones. Climatology shows a mean wind from GRID west at 5 m s^–1 (10 kt), making blowing snow a major flight restriction. Winds are from the sector GRID235 to GRID275 nearly 63% of the time, and strong winds have essentially the same direction as the mean winds. Mean sky cover is near 4.8 oktas. This high degree of cloudiness is due to the ease with which cyclones can penetrate into the area. Fog banks and blowing snow often move into Marie Byrd Land with little or no warning, due to the poor surface and horizon definition and lack of visual markers to highlight their approach.

Table 7.13.2.4.1 (from Phillpot, 1967) in Appendix 2 provides limited monthly–mean temperature, station–level pressure and cloud data for Byrd Station while Table 7.13.2.4.2, also in Appendix 2 presents wind frequency data (also from Phillpot, 1967). Figure 7.13.2.4.1 provides a schematic of weather types that may be associated with wind direction.

Surface wind and the pressure field

Table 7.13.2.4.2 (in Appendix 2) is a limited record of surface winds at Byrd. It is evident that orography has a controlling influence of the surface wind at Byrd. Low–pressure centres of 976 hPa or higher in the vicinity or west of Cape Colbeck give Byrd Station good weather, as moisture is drawn off Marie Byrd Land and toward the Ross Ice Shelf. Deeper lows, however, will advect moist air over Marie Byrd Land on the eastern edge of the low, and produce moderately bad weather for Byrd Station and vicinity. Deep lows between Cape Colbeck and Byrd Station produce the worst weather, as significant moisture is advected over West Antarctica. These synoptic patterns can be related to wind directions and speeds as follows:

·                         Weak or moderate surface winds from GRID235 to GRID275 bring good weather unless the barometer begins a marked drop (in which case expect gusts exceeding 20 m s^–1 (~40 kt).

·                         Surface winds from GRID130 to GRID225 are accompanied by cloudiness, fog and/or snow. Winds from GRID215 to GRID225 may be frequently strong. Winds from other directions in this group are normally light. Visibility is seldom less than 900 m (~0.5 nm) or over 3,700 m (~2 nm).

·                         Surface winds between GRID275 to GRID045 are usually light and of short duration with no significant weather.

·                         Winds aloft from GRID north produce excellent weather.

·                         When winds from the surface to 500 hPa are from GRID southwest to west and above 13m s^–1 (~25 kt), look for blowing snow.

·                         If winds aloft between surface and 500 hPa are light/ variable and suddenly all line up from GRID southwest, expect storm conditions.

·                         Prolonged clear weather with low sun angles produces increasing downslope wind. High sun angles, strong winds, and thick clouds weaken the surface inversion, allowing the gradient winds aloft to have more influence on the surface.

Upper wind, temperature and humidity

No specific information on forecasting has been obtained.

Clouds

With the intrusion of mid–latitude migratory cyclones over Marie Byrd Land, Byrd Station can experience a wide variety of sky conditions. Stratus, altostratus, cirrus, cirrostratus, and altocumulus are all seen at Byrd Station.

Visibility: blowing snow and fog

Very few visibility markers exist at Byrd Station. Although visibility is generally good, obstructions to vision can move into the area virtually undetected due to poor horizon definitions.

Blowing snow is the primary flight restriction at Byrd Station. When the sun is high and no fresh snow has fallen, wind speeds above 13 m s^–1 (~ 25kt) are required to reduce visibility rapidly. With fresh snow, however, the critical speed for significant blowing snow drops to about 9 m s^–1 (~18 kt). When satellite imagery shows clouds streaking off the tops of the mountains to the GRID south and GRID west of Byrd Station, blowing snow can be forecast at Byrd Station with reasonable confidence.

The other restriction to visibility at Byrd Station is fog. During the summer, fog is most prevalent during the early morning when low sun angles strengthen the surface inversion.  "Camp Fog", as at Amundsen–Scott (South Pole) Station, can create IFR conditions at Byrd Station when temperatures are below –20°C (–4°F).

Surface contrast including white–out

No specific information on forecasting has been obtained except see Figure 7.13.2.4.1

Horizontal definition

No specific information on forecasting has been obtained.

Precipitation

Precipitation occurs with migratory cyclones.  The primary form of precipitation at Byrd Station is snow.

Temperature and chill factor

With light winds, a sudden clearing of the skies will result in a temperature drop of 7°C to 12°C (10°F to 20°F) within an hour. Likewise, a sudden clouding–over raises the temperature 7°C to 12°C (10°F to 20°F) within an hour. The temperature changes decrease as wind speed increases.

Icing

No specific information on forecasting has been obtained.

Turbulence

No specific information on forecasting has been obtained.

Hydraulic jumps

No specific information on forecasting has been obtained.

Sea ice

Not relevant at this location.

Wind waves and swell

Not relevant at this location.

7.13.3                            The Patriot Hills–Teniente Parodi 

7.13.3.1                      Orography and the local environment

The Patriot Hills are in the Heritage Range at the southernmost end of the Ellsworth Mountains, to the west of the Ronne Ice Shelf. From 1987, Adventure Network International (ANI) has operated a blue–ice runway during the summer season of November to February at their Patriot Hills Camp (also known as Base Camp) (80^o 19’ S, 81^o 16’ W, 1,000 m (~3,280 ft) elevation). In 1995 the Chilean Antarctic Institute and the Chilean Air Force established a field camp named Teniente Parodi at 80^o 08´ S, 81^o 16´ W, (855 m AMSL) that is close to the ANI site. The Teniente Parodi field camp is deployed about 1,000 m to the north of a blue–ice area located along the northern side of Patriot Hills, and that is used as runway for large wheeled aircraft.

7.13.3.2                      Operational requirements and activities relevant to the forecasting process

ANI use Hercules C–130 aircraft to fly to the Patriot Hills runway from Punta Arenas, Chile. They often have a meteorological observer at the station during the summer. Hourly METARs are available, although no forecasts are available. The Chilean Air Force requires weather forecasts for its air operations.

7.13.3.3                      Data sources and services provided

The Chilean Air Force obtains forecasts from the (Frei) Antarctic Meteorological Centre on King George Island: their Patriot Hills Station is occupied from early October to late January with there being a forecaster and an observer located at the station. The meteorological office prepares forecasts for the local area and for other areas of aviation interest. Forecasts for up to 24 hours ahead are prepared. TAFs are available from Patriot Hills by HF radio. Satellite imagery is available along with various meteorological charts. The ANI operation makes surface meteorological observations at the camp and has a satellite imagery receiver.

7.13.3.4                      Important weather phenomena and forecasting techniques used at the location

General overview

The Patriot Hills are well south of the circumpolar trough so there is not the constant passage of depressions that is found at more northerly stations. However, the area is often on the edge of depressions and some systems do reach the area. Depressions seem to arrive via two means. Firstly, a system passes from the Bellingshausen Sea across the base of the Antarctic Peninsula and onto the Ronne Ice Shelf. These systems give moderate winds, overcasts skies and some snow. Secondly, a more rare event involves a low tracking westwards from the eastern Weddell Sea, over the Ronne Ice Shelf towards the Patriot Hills. When this happens the system can stay in the Patriot Hills area until it fills, usually giving large quantities of snow.

As well as synoptic–scale depressions, the area can be affected by mesoscale lows that are a common feature on the Ronne Ice Shelf.

Surface wind and the pressure field

The Patriot Hills is a very windy area with the presence of blue ice indicating the strength and persistence of the surface winds. However, the area is also characterised by the highly variable nature of the wind, with some very marked local wind speed variations. At the ANI site there are reports of 17–18 m s^–1 (~34 kt) winds on the ice runway and less than 5 m s^–1 (~10 kt) at the camp, about 1 km directly downwind of the runway. This appears to be a very common occurrence. Moreover, katabatic winds can gust up to 50 m s^–1 (~100 kt) but more generally blow at a steady 5–8 m s^–1 (~10–15 kt).

After the passage of a weather system, observers at the ANI camp report that there would be a short period (half a day or so) of calm, clear weather. During this period snow could be observed blowing through the cols and off the peaks of the mountain ranges to the south and southwest. It would become apparent that strong winds were approaching and within a few hours the winds would pick up on the runway and then at the Patriot Hills camp itself. These winds could last for several days and clear skies were not uncommon.

Based on three years of record from Teniente Parodi the average wind direction at this camp prevails most of the time from the south-southwest (constancy above 0.85) with a mean speed about 5.3 m s^–1 (~10 kt). However, stronger wind events above 10 m s^–1 (~20 kt) were frequently observed at the camp (30% of the total time). On average, the wind speed decreases as the summer season becomes established.

The smoothed pressure behaviour (four-day running mean) indicates a synoptic-scale oscillation between maximum and minimum values on a five to six day cycle. Analysis of meteorological charts reveals that this behaviour is, in fact, associated with passing synoptic-scale cyclones (troughs) and ridges to the north of Patriot Hills, which affect the Bellingshausen and Weddell seas and surrounding areas.

Upper wind, temperature and humidity

No specific information on forecasting has been obtained.

Clouds

Cloud is highly variable in this area. Depressions can bring extensive cloud cover, but there are also long periods of cloud–free conditions. In addition, satellite imagery reveals non–frontal cloud can linger for long periods in the area.

Visibility: blowing snow and fog

Fog has been reported on a number of occasions. On one of these a large fog bank moved in from the south (and nearly forced an incoming flight to turn back). On occasions Patriot Hills camp would be clear but surrounded by fog, sheltered in the lee of the hills.

Surface contrast including white–out

Poor contrast is a regular feature of the Patriot Hills, particularly when under the influence of low–pressure systems.

Horizontal definition

No specific information on forecasting has been obtained.

Precipitation

Depressions can bring long periods of moderate or heavy snowfall to the area.

Temperature and chill factor

During the summer season temperatures are typically around –15^oC, but there are reports that temperatures can be as low as –30^oC in October and as high as –5^oC in December. Although no one has over–wintered in this area, winter temperatures are estimated to be around –40^oC.

Based on three years of record from Teniente Parodi the overall behaviour of the air temperature at the camp behaves as expected in that the temperature increases as direct solar radiation increases, in other words, as the summer approaches. The average daily oscillation in temperature at the camp is around 2ºC while the average linear increase of the temperature from the beginning of November to mid-December is around 0.5ºC per day.

Icing

No specific information on forecasting has been obtained.

Turbulence

Mechanical and lee turbulence can be experienced along the length of the blue–ice runway.

Hydraulic jumps

No specific information on forecasting has been obtained.

Sea ice/Wind waves and swell

Not relevant at this location.