Southern polar atmosphere

Why in Antarctica A minor reason is that the southern polar atmosphere is well contained during the... 

Because of the rotation of the Earth and because of the warm equatorial and cool polar regions, the atmosphere divides itself into six regions (roughly corresponding to the climatic zones). These atmospheric regions are called the northern and southern Polar, Ferrel, and Hadley cells (so called because they are roll cells ) see Figure 3.2. This division of the atmosphere tends to slow the mixing... 

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 macronutrient-rich surface waters of the equatorial upwehings and polar oceans are a particularly dynamic component of the global carbon cycle. In the Southern Ocean, for example, the nutrient-rich and C02-charged waters of the deep sea are exposed to the atmosphere and returned to the subsurface before the available nutrients are fuUy utilized by phytoplankton for carbon fixation. This incomplete utilization of upweUed nutrients aUows for the leakage of biologicaUy sequestered... 

Within the polar oceans involved in deep water formation, certain regions are more important than others. The Antarctic Zone, the most polar region in the Southern Ocean, is involved in the formation of both deep and intermediate-depth waters, making this region important to the atmosphere/ocean CO2 balance. The quantitative effect of the Subantarctic Zone on atmospheric CO2 is less certain, depending on the degree to which the nutrient status of the Subantarctic surface influences the preformed nutrient concentration of newly formed subsurface water (Antarctic Intermediate Water and Subantarctic mode water), but its significance is probably much less than that of the Antarctic. 

Several studies have been concerned with the penetration of liquids into latewood and earlywood (JJ, 16-23). Under atmospheric pressure, the penetration of nonpolar liquids into softwood latewood may be caused, in part, by capillary action in the very small lumens and passage through unaspirated pit membranes. In aspirated earlywood this penetration would not occur. Penetration of nonpolar liquids may also be through drying checks in the thick latewood cell walls. As the temperature and pressure of the liquid are raised, penetration of polar liquids in earlywood would be expected to increase because of softening of the pit structure and displacement of the pit membrane. Because the cell wall of earlywood is thinner than that of latewood, penetration into earlywood walls would be quicker and facilitated by swelling. Incrustation occurs in the pit membranes of southern pine latewood (24) this would retard liquid penetration. 

The concept of nutrient and O2 change along a surface of constant density in the upper ocean is illustrated in Fig. 6.18. When waters subduct (surface waters flow along density horizons into the thermo-cline) it is assumed that they carry with them O2 concentrations near saturation equilibrium with the atmosphere and preformed nutrient concentrations. The assumption of saturation equihbrium is not exactly correct but in most cases this is probably not a serious error because surface oxygen measurements indicate near-saturation equilibrium everywhere except in the Southern Ocean south of the polar front, where concentrations can be up to 10% undersaturated. As a water parcel moves along a constant-density surface into the upper thermocline, respiration consumes the O2 concentration while creating nutrients and AOU in the water mass. At any point in the ocean interior, preformed nutrient concentrations can be calculated if one knows the temperature, salinity (for determining [02 ), nutrient and O2 concentrations. 

From Mc2Hg data in surface sea water samples and in the corresponding marine atmosphere, a first estimation of the transfer of this compound from the Southern Ocean, the Arctic Ocean and the Atlantic Ocean was carried out by equation (1) (see Table 7.7) (45). This estimate was calculated under the questionable assumptions that the measured data were representative for the whole area and that no seasonal variation occurs. The great uncertainty in such calculations can also be inferred by the great variability in the data for the total biogenic Hg emission from all oceans, which range from 0.6 10 to 7700 10 g yr (66, 67). However, the calculated input of more than 0.2 10 g yr of Hg as Mc2Hg from each of the polar oceans is more than 10% of the total emission of this heavy metal species from the Atlantic Ocean. In addition, more recent data from Lindqvist et al. and... 

Figure 1. Maps of mixed layer depth in the global ocean as monthly averages for January (upper panel) and July (middle panel). The lower panel shows typical profiles of sigma-t (a measure of density) for a polar (Southern Ocean) versus tropical (Pacific) area of the ocean. The maps use global ocean temperature and salinity data sets compiled by the U.S. National Oceanic Atmospheric Administration as processed by Kara et al. [94].

The more complex dynamics of the Arctic vortex as compared to the Antarctic demand the application of sophisticated tools for analysis of ozone destruction. The greater wave activity of the Northern Hemisphere can enhance ozone losses even in winter by increasing the exposure of polar air to sunlight in the distortions caused by atmospheric waves as compared to the Southern Hemisphere (see e.g., Jones et al, 1990a). However, the same wave activity can warm the air and perhaps... 

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