Vertical eddy diffusivity

Order-of-magnitude values for the vertical eddy diffusivity in the atmosphere and the ocean are shown in Fig. 4-15. The values for the viscous layers represent molecular diffusivities of a typical air molecule like N2. 

The inadequacy of the two-box model of the ocean led to the box-diffusion model (Oeschger et al, 1975). Instead of simulating the role of the deep sea with a well-mixed reservoir in exchange with the surface layer by first-order exchange processes, the transfer into the deep sea is maintained by vertical eddy diffusion. In... 

Under neutral conditions the atmospheric lapse rate is adiabatic. Close to the ground the vertical eddy diffusivity profile can be based on Monin-Obukhov similarity theory, in which case = 1 and = ku,z- With this formulation, increases without limit—clearly a physically unrealistic situation. Myrup and Ranzieri (1976) proposed a set of empirical roll off functions for altitudes above the surface layer ... 

A solution of Eq. (9.36) has been obtained by Huang (1979) in the case when the mean wind speed and vertical eddy diffusivity can be represented by the power-law expressions ... 

The relative importance of gas-phase and surface resistances depends on the nature of the pollutant and the surface as well as the meteorology (Shaw, 1984 Unsworth et al., 1984 Chameides, 1987 Wesely and Hicks, 1999). The gas-phase resistance (rgas) is determined by the vertical eddy diffusivity, which depends on the evenness of the surface and the meteorology, for example, wind speed, solar surface heating, and so on. The surface resistance (rsur[) depends on the detailed characteristics of the surface (e.g., type, whether... 

If the lake is stratified, vertical transport is commonly the time-limiting step for complete mixing. This was the reason for applying the two-box model to the case of PCE in Greifensee (Illustrative Example 21.5). Now we go one step further. We consider a vertical water column of mean depth h with a constant vertical eddy diffusion coefficient Ez. The flux Fa/VJ of PCE escaping to the atmosphere is given by Eq. 20-la ... 

Imboden, D. M., and S. Emerson, Natural radon and phosphorus as limnological tracers Horizontal and vertical eddy diffusion in Greifensee , Limnol. Oceanogr., 23,77-90 (1978). 

Mechanisms and rates of transport of nuclear test debris in the upper and lower atmosphere are considered. For the lower thermosphere vertical eddy diffusion coefficients of 3-6 X 106 cm.2 sec. 1 are estimated from twilight lithium enhancement observations. Radiochemical evidence for samples from 23 to 37 km. altitude at 31° N indicate pole-ward mean motion in this layer. Large increases in stratospheric debris in the southern hemisphere in 1963 and 1964 are attributed to debris from Soviet tests, transported via the mesosphere and the Antarctic stratosphere. Most of the carbon-14 remains behind in the Arctic stratosphere. 210Bi/ 210Pb ratios indicate aerosol residence times of only a few days at tropospheric levels and only several weeks in the lower stratosphere. Implications for the inventory and distribution of radioactive fallout are discussed. 

Above 120 km. the atmosphere is essentially in diffusive equilibrium (34). For the altitude interval between 80 and 120 km. Colegrove et al. (6) estimated an average vertical eddy diffusion coefficient of 4 X 106 cm.2 sec."1 by a careful evaluation of the 0/02 concentration ratio profile over this altitude interval. Using their eddy diffusion coefficient and following the procedure of Kellogg (22) it is estimated that molecular... 

The pattern of eddy mixing in the mesosphere apparently may be highly nonisotropic, similar to that indicated for the lower thermosphere. The upper limit of vertical eddy diffusion coefficients for the mesosphere... 

In the real atmosphere horizontal motions along latitude and longitude must also be taken into consideration. Thus, the ozone concentration profile should show a significant derivation near the tropopause due to the downward transport of 03 from the expected profile without vertical eddy diffusion. 

Benitez-Nelson C, Buesseler KO, Crossin G (2000) Upper ocean carbon export, horizontal transport, and vertical eddy diffusivity in the southwestern Gulf of Maine. Cont Shelf Res 20 707-736... 

The large fluctuations with altitude that are frequently observed in tropospheric measurements of ozone and water number densities suggest that vertical eddy diffusion with a constant diffusion coefficient is not adequate. 

Bolin and Bischof (23) found a 25- to 30-day phase lag between the seasonal variations of carbon dioxide number densities at the tropopause and those at the surface layer. Assuming that vertical eddy diffusion is responsibl for the transport from the ground to the tropopause, they... 

The photodissociation rate coefficients are included as source and sink terms in a system of time-dependent continuity equations for the atmosphere. Modem values for vertical (eddy) diffusion and solar photon flux are utilized. The system of 2nd-order ordinary differential equations is solved by integration, and yields chemical species abundances as a function of time and altitude. The isotope atmospheric chemistry includes only SO2 isotopologue photodissociation reactions and production of SO isotopologues. Additional isotopic reactions such as SO2 oxidation by OH, SO photolysis, SO disproportionation during self-reaction, and SO dimmer formation, have been neglected. My objective here is to focus only on SO2 photolysis as a S-MIF mechanism. 

Broecker W. S., Cromwell J., and Li Y.-H. (1968) Rates of vertical eddy diffusion near the ocean floor based on measurements of the distribution of excess Rn. Earth Planet. Sci. Lett. 5, 101-105. 

Sarmiento J. L., Feely H. W., Moore W. S., Bainbridge A. E., and Broecker W. S. (1976) The relationship between vertical eddy diffusion and buoyancy gradient in the deep sea. Earth Planet. Sci. Lett. 32, 357-370. 

The distribution of a number of dissolved species (02, C-14, Ra-226, salinity) in the Central Pacific water column, at depths between 1 and 4 km, has been shown (11) to be consistent with a steady-state model of the water column in which the concentration-depth profiles are stationary and the concentrations at the boundaries 1 and 4 km are stipulated at their present values. The physical model of the water column is based on two transport mechanisms vertical eddy diffusion (eddy diffusion coefficient K — 1.3 cm2 sec"1) and upwelling of deep water (advection velocity U = 1.4 X 10 5 cm sec"1, or approximately 1 cm per day) (11). 

Lerman, A., Stiller, M., Vertical Eddy Diffusion in Lake Tiberias, ... 

In these expressions, Gq and G represent additional dissipative terms to be added to the thermodynamic equation (3.69). Kh represents the vertical eddy diffusion coefficient for heat, which is related to the vertical eddy diffusion coefficient for momentum and tracers (Eq. 3.78) by the Prandtl number Pr ... 

As indicated earlier, vertical exchanges associated with turbulent mixing such as that caused by gravity wave breaking below the homopause are often represented as eddy diffusion. When expressed in terms of number density in an atmosphere following hydrostatic equilibrium conditions, the effective vertical eddy diffusion velocity becomes... 

Table 1-7 summarizes vertical eddy diffusion coefficients for the troposphere and the lower stratosphere as derived from various observations, mainly of tracers. For the troposphere the Kz data of Davidson et al. (1966) are the least trustworthy, because they are based on tracers originating in the stratosphere. The best values probably are those of Bolin and Bischof (1970), derived from the seasonal variation of C02. Above the tropopause... 

Fig. 1-10. One-dimensional vertical eddy diffusion coefficient Kz derived from trace gas observations in the stratosphere (1) from nitrous oxide, (2,3) from methane. (1) Schmeltekopf el al. (1977), (2) Wofsy and McElroy (1973), (3) Hunten (1975).

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