Antarctica South Pole

The discovery of ozone holes over Antarctica in the mid-1980s was strong observational evidence to support the Rowland and Molina hypothesis. The atmosphere over the south pole is complex because of the long periods of total darkness and sunlight and the presence of a polar vortex and polar stratospheric clouds. However, researchers have found evidence to support the role of CIO in the rapid depletion of stratospheric ozone over the south pole. Figure 11-3 shows the profile of ozone and CIO measured at an altitude of 18 km on an aircraft flight from southern Chile toward the south pole on September 21, 1987. One month earlier the ozone levels were fairly uniform around 2 ppm (vol). 

The catalytic cycle described earlier (reactions 8 and 9) cannot explain the rapid depletion of ozone over the South Pole, because reaction 9 requires free oxygen atoms, which are too scarce in the polar stratosphere to react at any appreciable rate with QO. Several catalytic cycles that do not require oxygen atoms have been suggested as being at work over Antarctica. 

Fig. 18-11 Records of atmospheric CO2 in Antarctica for the past 1000 years. Open circles are ice-core data from Law Dome, on the coast of east Antarctica (Etheridge et al., 1996). Plus signs are direct measurements of CO2 in air samples collected monthly at the South Pole (NOAA Climate Monitoring and Diagnostics Laboratory, Boulder, Colorado).

Fig. 18-17 Ice core records of N2O. (a) Data of Machida et al. (1995) from the H15 ice core, east Antarctica, for the time period 1750-1950, and monthly atmospheric N2O measurements at the South Pole from the NOAA Climate and Diagnostics Laboratory, Boulder, CO, for the period 1989-1998. (b) Data from Leuenberger and Siegenthaler (1992) from the Byrd ice core in West Antarctica.

After the first reports of this phenomenon, major field campaigns were launched, which clearly established a relationship between ozone destruction and chlorine chemistry. For example, Fig. 1.8 shows simultaneous aircraft measurements of ozone and the free radical CIO as the plane flew toward the South Pole. As it entered the polar vortex, a relatively well-contained air mass over Antarctica, 03 dropped dramati-... 

Figure 12.17 shows the ozone profiles over the U.S. Amundsen-Scott Station at the South Pole in 1993 on August 23 prior to formation of the ozone hole and on October 12 after the ozone hole had developed. The total column ozone decreased from 276 DU on August 23 to only 91 DU on October 12, and, in addition, there was essentially no ozone in the region from 14 to 19 km (Hofmann et al., 1994a). During the same period at the McMurdo Station in Antarctica, the total column ozone decreased from 275 to 130 DU (B. J. Johnson et al., 1995). While similar profiles have been observed since the discovery of the ozone hole, these data show some of the most extensive ozone destruction ever observed, although 1994 and 1995 showed almost as much 03... 

The first report of coal in Antarctica came from the Shackleton Expedition of 1907-09 during the first attempt to reach the South Pole. Seven coal beds were observed at Buckley Nunatak near the head of the Beardmore Glacier, and a small piece was brought back. David and Priestley (12) reported a dry, mineral free fixed carbon value of 83.7% for the sample, suggesting that the coal is high rank (low volatile) bituminous (I). 

In the winter of 1984, massive losses of stratospheric ozone were detected in Antarctica over the South Pole (Halley Bay). This ozone depletion is known as the ozone hole. We know now that it also forms over the Arctic, although not as dramatically as in the Antarctic. Stratospheric ozone protects life on the surface of the Earth by screening harmful UV radiation coming from the sun through a photodissociation mechanism (see Chapter 4). 

Frequent readings of the pressure drop across the filter or, at RAMP stations, across a fixed orifice, and of the temperature are submitted to EML along with the filters to permit the calculation of the volume of air that was sampled. The filters from most sites are returned to EML for analysis at the end of each month. Because of transportation difficulties, the samples collected at the South Pole Station, Mawson, Marion Island, Palmer and Marsh Antarctica during the winter months are retained at the sites until they can be shipped to EML. This adversely affects the detection and the precision of measurements of short-lived radionuclides in these filters. 

Each spring since 1979, researchers have observed a thinning of the ozone layer over Antarctica. Each spring (autumn in the Northern Hemisphere) beginning in 1983, satellite images have shown a hole in the ozone layer over the South Pole. During August and September 1987, a NASA research team flew a plane equipped with sophisticated analytical instruments into the ozone hole 25 times. Their measurements demonstrated that as the concentration of the chlorine oxide radicals, Cl—O increased, the concentration of ozone decreased. 

While not a true hole in the sense that some column ozone remains even in the most extreme depletions observed in the mid 1990s (when October ozone minima were near 100 Dobson Units over the South Pole, or depletion of about two-thirds of the historical levels, see Hofmann et al, 1997), the descriptor captures the fact that the peak depletion is sharply limited to Antarctic latitudes. Dobson (1968 and references therein) noted that there is less ozone naturally present over Antarctica than over the Arctic in winter and much of the spring, but this climatological difference between the natural ozone levels over the poles of the two hemispheres should not be confused with the abrupt decline that began near the mid-1970s as depicted in Figure 6.9. Newman (1994) discusses these and other historical measurements of total ozone and shows that the Antarctic ozone hole began only in the last few decades. 

Komhyr, W.D., R.D. Grass, and R.K. Leonard, Total ozone decrease at South Pole Antarctica, 1964-1985. Geophys Res Lett 13, 1248, 1986. 

FIGURE 5.18 Observations of the change in October total ozone profiles over Antarctica (WMO 1994). Historical data at South Pole and Syowa show changes in October mean profiles measured in the 1960s and 1970s as compared to more recent observations. Changes in seasonal vertical profiles are shown at the other stations. Isopleths mapped onto Antartica represent TOMS ozone column measurements on Oct. 5, 1987. 

The stratosphere is very dry and generally cloudless. The long polar night produces temperatures as low as 183 K (-90°C) at heights of 15 to 20 km, cold enough to condense even the small amount of water vapor present to form polar stratospheric clouds (PSCs). The lowest temperatures are more prevalent in the Antarctic, where the polar vortex is more stable than in the Arctic. The exceptional stability of the vortex at the South Pole may be a result of the almost symmetric distribution of ocean around Antarctica. The less-stable... 

At the Amundsen-Scott South Pole base station in Antarctica, when the temperature is — 100.0°F, researchers who live there can Join the "300 Club" by stepping into a sauna heated to 200.0°F then quickly running outside and around the pole that marks the South Pole. What are these temperatures in °C What are these temperatures in K If you measured the temperatures only in °C and K, can you become a member of the "300 Club" (that is, is there a 300.-degree difference between the temperature extremes when measured in °C and K) ... 

These voyages exposed the crews of his ships to frightful conditions caused by severe cold, violent storms, and dangerous pack ice along the coast. As a result of these hardships and based on what he had seen. Captain Cook reported that any land that may exist close to the geographic south pole was not worth the effort to explore (Stonehouse 2(X)2). In the years that followed Captain Cook s voyages, the ocean around Antarctica was frequented by a multitude of European and American whalers and seal hunters who were primarily interested in making a profit from the sale of whale oil and seal skins (Stonehouse 2002 Victor 1964). 

At the start of the twentieth century the exploration of Antarctica had progressed from observations of the coast to efforts to penetrate into the interior of the continent. More specifically, Robert F. Scott, Ernest H. Shackleton, and Roald Amundsen competed to become the first humans to reach the geographic South Pole. 

Fig. 1.9(a) Robert Falcon Scott (1868-1912) led two expeditions to Antarctica in 1901-1904 and 1910-1913. Although he reached the geographic South Pole in 1912, he and his men perished on the return trip to his base on Ross Island (Photo by the Scott Polar Research Institute, University of Cambridge, used here with permission) (b) Ernest Henry Shackleton (1874-1922) also led two expeditions to Antarctica in 1907-1909... 

Atkinson read a Burial Service after which the tent was collapsed and a large snow cairn was erected on top of it. The members of the search party returned to Cape Evans on November 26 and were greatly relieved that Campbell and his men had returned in their absence from their winter-over on Inexpressible Island. The Terra Nova arrived at Cape Evans on January 18,1913, but before the remainder of Scott s second Antarctic expedition left Cape Evans, Atkinson and a group of men erected a cross on the summit of Observation Hill located directly behind McMurdo Station in order to commemorate the five men who died after reaching the geographic South Pole of Antarctica. The cross in Fig. 1.16 carries the names of the men who went to the pole (Captain Scott, Wilson, Bowers, Oats, and Evans) and an inscription selected by Cherry-Garrard (Bull and Wright 1993) ... 

Fig. 1.18 Roeild Amundsen of Norway was not a man who smiled a lot. He was instead driven by his passion for exploration of the polar regions. Being a thorough and methodical person, he trained himself and his companions in the art of polar travel and planned meticulously in order to assure success without injury to the members of his team. This portrait of Amundsen is displayed in Oslo in the museum that houses the Pram, the ship in which he and his men traveled to Antarctica for the purpose of reaching the South Pole...

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