scholarly journals Understanding Orographic Effects on Surface Observations at Macquarie Island

2016 ◽  
Vol 55 (11) ◽  
pp. 2377-2395 ◽  
Author(s):  
Zhan Wang ◽  
Danijel Belusic ◽  
Yi Huang ◽  
Steven T. Siems ◽  
Michael J. Manton

AbstractThe meteorological observations on Macquarie Island have become of increasing value for efforts to understand the unique nature of atmospheric processes over the Southern Ocean. While the island is of modest elevation (peak altitude of 410 m), the orographic effects on observations on this island are still not clear. High-resolution numerical simulations [Weather Research and Forecasting (WRF) Model] with and without terrain have been used to identify orographic effects for four cases representing common synoptic patterns at Macquarie Island: a cold front, a warm front, postfrontal drizzle, and a midlatitude cyclone. Although the simulations cannot capture every possible feature of the precipitation, preliminary results show that clouds and precipitation can readily be perturbed by the island with the main enhancement of precipitation normally in the lee in accordance with the nondimensional mountain height being much less than 1. The weather station is located at the far north end of the island and is only in the lee to southerly and southwesterly winds, which are normally associated with drizzle. The station is on the upwind side for strong northwesterly winds, which are most common and can bring heavier frontal precipitation. Overall the orographic effect on the precipitation record is not found to be significant, except for the enhancement of drizzle found in southwesterly winds. Given the strong winds over the Southern Ocean and the shallow height of the island, the 3D nondimensional mountain height is smaller than 1 in 93.5% of the soundings. As a result, boundary layer flow commonly passes over the island, with the greatest impact in the lee.

2005 ◽  
Vol 32 (2) ◽  
pp. 316-333 ◽  
Author(s):  
Malcolm Walker

Early explorers and sealers took home from the Southern Ocean tales of tempests, huge waves and massive icebergs. Many recorded in their logbooks and narratives observations of wind, weather and sea state. Meteorological measurements were made on some early voyages but were often of doubtful quality. Not until the 1840s were reliable meteorological observations made near the Antarctic continent. During the First International Polar Year, observations were made near Cape Horn and on South Georgia. From 1899 onwards, bases were established on the Antarctic continent and meteorological observing programmes organized. Extremely strong winds were discovered. Data sets of climatological value became available and data from aloft were obtained. After the First World War, wireless telegraphy was used increasingly to broadcast observations from ships and shore bases to distant analysis centres. During the Second International Polar Year, thousands of meteorological observations were made aboard ships on the Southern Ocean. After the Second World War, the pace of progress quickened, especially during the International Geophysical Year. Research stations and the International Antarctic Analysis Centre were established. Weather satellites, automatic weather stations, global telecommunication networks and powerful computers revolutionized Antarctic meteorology and climatology.


Author(s):  
Olga Mashtaler ◽  
Olga Mashtaler ◽  
Alexander Myasoedov ◽  
Alexander Myasoedov ◽  
Elizaveta Zabolotskikh ◽  
...  

The relevance of the polar lows (PLs) research is justified by their great destructive power and creation of threat to the safety of navigation in the high latitudes and along the Northern Sea Route. The most dangerous effects on maritime activities are strong winds, waves and icing. In addition, the study of the PLs acquires relevance due to the sharp decrease of the sea ice area in the Arctic in recent years and the emergence of areas of open water, suitable for the appearance and development of PLs. However, despite the importance of PLs, they are apparently not sufficiently studied. As there are no meteorological observations in the areas of their appearance, the main source of information about them are satellite observations. By using images on the SOLab SIOWS Arctic Portal from multiple satellites operating in the IR and visible ranges (e.g., MODIS and AVHRR), and using near-water wind fields from high resolution synthetic aperture radars (Sentine-1, ASAR) and low resolution scatterometers (ASCAT), we identify polar lows in various parts of the Arctic, revealing statistical regularities in the appearance of PLs, their distribution and intensity. Collected database of Pls and their characteristics will be used for further PLs forecasting model development.


Polar Record ◽  
2021 ◽  
Vol 57 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Mark Pharaoh

Abstract Sir Douglas Mawson is a well-known Antarctic explorer and scientist. Early in his career, he recognised opportunities for commerce in Antarctic and sub-Antarctic regions. While at Cape Denison, Antarctica, in 1913 on the Australasian Antarctic Expedition (AAE), the Adelie Blizzard magazine was produced. Mawson contributed articles about Antarctic natural resources and their possible use. Later, he advocated Australia be involved in pelagic whaling. He collected seal skins and oil for their commercial value to be assessed by the Hudson’s Bay Company. During the AAE, Mawson visited Macquarie Island where an oiling gang was killing southern elephant seals and royal penguins. Mawson was concerned that they were over-exploited and lobbied successfully to stop the killing. His plans for Macquarie Island included a wildlife sanctuary, with a party to supervise access, send meteorological observations to Australia and New Zealand, and be self-funded by harvesting elephant seals and penguins. Macquarie Island was declared a sanctuary in 1933. Although Mawson has been recognised as an early proponent of conservation, his views on conservation of living natural resources were inconsistent. They should be placed in their historical context: in the early twentieth century, utilisation of living natural resources was viewed more favourably than currently.


2018 ◽  
Vol 57 (2) ◽  
pp. 255-272 ◽  
Author(s):  
Fanglin Sun ◽  
Yaoming Ma ◽  
Zeyong Hu ◽  
Maoshan Li ◽  
Gianni Tartari ◽  
...  

AbstractThe seasonal variability of strong afternoon winds in a northern Himalayan valley and their relationship with the synoptic circulation were examined using in situ meteorological data from March 2006 to February 2007 and numerical simulations. Meteorological observations were focused on the lower Rongbuk valley, on the north side of the Himalayas (4270 m MSL), where a wind profile radar was available. In the monsoon season (21 May–4 October), the strong afternoon wind was southeasterly, whereas it was southwesterly in the nonmonsoon season. Numerical simulations were performed using the Weather Research and Forecasting Model to investigate the mechanism causing these afternoon strong winds. The study found that during the nonmonsoon season the strong winds are produced by downward momentum transport from the westerly winds aloft, whereas those during the monsoon season are driven by the inflow into the Arun Valley east of Mount Everest. The air in the Arun Valley was found to be colder than that of the surroundings during the daytime, and there was a horizontal pressure gradient from the Arun Valley to Qomolangma Station (QOMS), China Academy of Sciences, at the 5200-m level. This explains the formation of the strong afternoon southeasterly wind over QOMS in the monsoon season. In the nonmonsoon season, the colder air from Arun Valley is confined below the ridge by westerly winds associated with the subtropical jet.


1981 ◽  
Vol 57 (7) ◽  
pp. 333-335 ◽  
Author(s):  
I. R. Morgan ◽  
H. A. Westbury ◽  
I. W. Caple ◽  
J. Campbell

Polar Record ◽  
2009 ◽  
Vol 46 (2) ◽  
pp. 136-145
Author(s):  
Stephen Harris ◽  
Geof Copson ◽  
Louisa d'Arville

ABSTRACTCaves of marine origin occur in tectonically uplifted stacks on the coastal terrace and in plateau edge cliffs at a number of locations around Macquarie Island. Some of the caves have been located and their distributions mapped. Four of the best known caves are mapped in detail. Aspects of their geology, structure and biology, including speleothem development, clastic deposits, faunal remains and subfossil deposits are explored. Many of these caves contain deposits, which may have the potential to be investigated, as beach and peat deposits have been, for dating key time periods in the island's evolution. The palaeoenvironmental research potential of the sea caves on Macquarie Island has yet to be exploited. Further knowledge about these caves will assist in the understanding of the processes that have acted on Macquarie Island and other polar and sub-polar islands.


2012 ◽  
Vol 6 (4) ◽  
pp. 841-857 ◽  
Author(s):  
W. Thiery ◽  
I. V. Gorodetskaya ◽  
R. Bintanja ◽  
N. P. M. Van Lipzig ◽  
M. R. Van den Broeke ◽  
...  

Abstract. In the near-coastal regions of Antarctica, a significant fraction of the snow precipitating onto the surface is removed again through sublimation – either directly from the surface or from drifting snow particles. Meteorological observations from an Automatic Weather Station (AWS) near the Belgian research station Princess Elisabeth in Dronning Maud Land, East-Antarctica, are used to study surface and snowdrift sublimation and to assess their impacts on both the surface mass balance and the surface energy balance during 2009 and 2010. Comparison to three other AWSs in Dronning Maud Land with 11 to 13 yr of observations shows that sublimation has a significant influence on the surface mass balance at katabatic locations by removing 10–23% of their total precipitation, but at the same time reveals anomalously low surface and snowdrift sublimation rates at Princess Elisabeth (17 mm w.e. yr−1 compared to 42 mm w.e. yr−1 at Svea Cross and 52 mm w.e. yr−1 at Wasa/Aboa). This anomaly is attributed to local topography, which shields the station from strong katabatic influence, and, therefore, on the one hand allows for a strong surface inversion to persist throughout most of the year and on the other hand causes a lower probability of occurrence of intermediately strong winds. This wind speed class turns out to contribute most to the total snowdrift sublimation mass flux, given its ability to lift a high number of particles while still allowing for considerable undersaturation.


Polar Record ◽  
1991 ◽  
Vol 27 (162) ◽  
pp. 245-248 ◽  
Author(s):  
K. Townrow ◽  
P. D. Shaughnessy

AbstractFur seals were exterminated from Macquarie Island about 20 years after discovery of the island in 1810. Their specific identity is unknown. Few fur seals were reported at the island until it was occupied by the Australian National Antarctic Research Expeditions in 1948. Fur seal numbers are now increasing. An archaeological excavation at a sealers' quarters at Sandy Bay in 1988 revealed the fragmented skull of a young Antarctic fur sealArctocephalus gazella1.1 m below the surface in a layer dated in the 1870s and 1880s. This period coincides with the recovery of fur seal populations in the South Atlantic Ocean following earlier harvesting. Elsewhere it has been argued that the Antarctic fur seal is unlikely to have been the original fur seal at Macquarie Island because few individuals of that species are ashore in winter, which is the season when the island was discovered and fur-seal harvesting began. It is concluded that the Sandy Bay skull is from a vagrant animal.


1991 ◽  
Vol 18 (3) ◽  
pp. 249-254 ◽  
Author(s):  
David J. Slip ◽  
Harry R. Burton

Sections of coastline of Heard and Macquarie Islands were surveyed for marine debris in the summer of 1987–88 and 1989, respectively. These surveys were carried out at the same sites as previous surveys in 1986–87 at Heard Island, and in 1988 at Macquarie Island. The minimum rate of artefact accumulation was 13 objects per km of shoreline per year for Heard Island, and 90 objects per km of shoreline per year for Macquarie Island. Drift-cards, released from known locations and collected on the two islands, show a similar artefact catchment area.Plastic litter was a major component of the debris at both islands. Fisheries-related debris accounted for 40% of all artefacts on Heard Island, compared with 29% on Macquarie Island. Entanglement of Fur Seals appears to be more common at Heard Island, while plastic ingestion by seabirds appears to be more common at Macquarie Island.


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