Continental mode

FIGURE 5.18 Winter season (JFM) overall difference of westerly wi nds ((7) at the sea level between the actual maritime climate mode starting in 1988 and a great part of the preceding continental mode (1948-1987) as derived from (NOAA, 2006) positive values (gray coloured) indicate increasing westerlies within the belt of the planetary frontal zone (40°-60°N) during the last 18 years. 

Average ratios for Si, Al, K, Ca, and Ti to Fe approximate earth crust ratios, indicated by arrows at left. These elements occur mainly in coarse particles (Figures 3 and 4). The Mn/Fe ratio is somewhat greater and Zn/Fe is 20 times greater than earth crust ratios. These two elements have appreciable fine-mode concentrations (Figure 4). All 8 elements may occur characteristically in continental air masses. 

Fine-mode Cl and K may be mainly pollution-derived, coarse-mode Cl typical of marine air, and coarse-mode K typical of continental air (Xinglong aerosol, March 16—19, 1980 means and standard deviations). 

Remote continental -104 Three modes centered at Dp - 0.02, 0.12, and 1.8 p, m includes products of gas-to-particle conversion and biological sources, e.g., pollens... 

Nonurban continental 103 Three modes similar to urban aerosol... 

Similar data for sulfate have been reported in many studies. Figure 9.36, for example, shows overall average sulfate distributions measured in marine areas as well as at continental sites (Milford and Davidson, 1987). The marine data show two modes, a coarse mode associated with sea salt and a fine mode associated with gas-to-particle conversion. Sulfate in seawater, formed, for example, by the oxidation of sulfur-containing organics such as dimethyl sulfide, can be carried into the atmosphere during the formation of sea salt particles by processes described earlier and hence are found in larger particles. The continental data show only the fine particle mode, as expected for formation from the atmospheric oxidation of the S02 precursors. 

Gillani, Leaitch, and co-workers (1995) carried out a detailed study of the fraction of accumulation mode particles (diameters from 0.17 to 2.07 /Am) that led to cloud droplet formation in continental stratiform clouds near Syracuse, New York. When the air mass was relatively clean, essentially all of the particles were activated to form cloud droplets in the cloud interior and the number concentration of cloud droplets increased linearly with the particle concentration. However, when the air mass was more polluted, the fraction of particles that were activated in the cloud interior was significantly smaller than one. This is illustrated by Fig. 14.40, which shows the variation of this fraction (F) as a function of the total particle concentration, Nun. In the most polluted air masses (as measured by large values of Nun), the fraction of particles activated was 0.28 + 0.08, whereas in the least polluted, it was as high as 0.96 + 0.05. The reason for this is likely that in the more polluted air masses, the higher number of particles provided a larger sink for water vapor, decreasing the extent of supersaturation. 

Buck R (1991) Modes of continental lithospheric extension. J Geophys Res 96(B12) 20,161-20,178 Carson MA (1976) Mass-wasting, slope development and climate. In Geomorphology and climate. Derbyshire E (ed) John Wiley and Sons, New York, p 101-136... 

Rey P, Vanderhaeghe O, Teyssier C (2001) Gravitational Collapse of the continental crust definition, regimes and modes. Tectonophysics 342 435-449... 

Catenas B., Marfil R., and de la Pena J. A. (1982) Modes of formation and diagnostic features of Recent gypsum in a continental environment. La Mancha (Spain). Est. Geol. 38, 345-359. 

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