Upward flux

Following the method used above, we see that there will be an upward flux of momentum m the v-direetion,... 

Fig. 10-13. The links between the cycling of C, N, and O2 are indicated. Total primary production is composed of two parts. The production driven by new nutrient input to the euphotic zone is called new production (Dugdale and Goering, 1967). New production is mainly in the form of the upward flux of nitrate from below but river and atmospheric input and nitrogen fixation (Karl et al, 1997) are other possible sources. Other forms of nitrogen such as nitrite, ammonia, and urea may also be important under certain situations. The "new" nitrate is used to produce plankton protoplasm and oxygen according to the RKR equation. Some of the plant material produced is respired in the euphotic zone due to the combined efforts...

Figure Al(a) shows the constant value of porosity used in the analytic model (dashed curve), compared to the porosity distribution for a ID melt column in which the upward flux of melt is required to remain constant (see Spiegelman and Elliott 1993). The solid curves in Figure Al(b) show values of ct, calculated from equations (A12-A14) along the (dimensionless) length of the melting column for the decay chain with a constant porosity of 0.1% and solid upwelling velocity of 1 cm/yr.

In the literature a wide range of estimates regarding the influx of ozone from the stratosphere into the troposphere is presented, derived by many different methods. Some studies report an annual flux between 200-870 Tg 03 yr 1 globally, whereas other studies report a flux between 500 and 1000 Tg 03 yr 1 for the NH only. With our model we estimate for the NH a net downward flux from the stratosphere of 580 Tg 03 yr1, which is partly balanced by an upward flux of ozone from photochemical production in the troposphere of 210 Tg 03 yr1, yielding a net downward cross-tropopause ozone transport of 370 Tg 03 yr 1. Globally, these values are 950, 370 and 580 Tg 03 yr 1, respectively. (Note that the troposphere-to-stratosphere ozone flux in the... 

D. When the leaves are randomly distributed with respect to distance above the ground and the trees are 16 m tall, at what level does the maximum upward flux of CO2 occur when a PPF of 200 pmol m-2 s-1 is incident on the canopy ... 

D. The maximum upward flux of CO2 will occur for the level at the light compensation point (leaves below this level have a net evolution of C02)- At 200 pmol m-2 s-1 incident on the canopy, light compensation occurs at F= 4.6 (calculated in A). Because the leaf area index is 8.0, Fincreases by 1.0 every 2.0 m (16 m/8.0). Therefore, an F of 4.6 occurs at 9.2 m from the top of the canopy, or 6.8 m above the ground. 

There is also present in the stratosphere a particulate aerosol layer which can, at least temporarily, have an impact on the earth s radiation budget and climate. This layer is formed primarily through oxidation of sulphur-hearing precursor gases of tropospheric origin. Anthropogenic activities contribute to the upward flux of these gases. 

If this is an adequate description of the real low-latitude ocean, then the strength of its biological pump (the amplitude of the surface-deep gradient in inorganic carbon concentration) is controlled solely by (i) the carbon/nutrient ratio of the organic matter, and (ii) the nutrient content of the deep ocean (see Equation (5)). If the C/P ratio of export production increased or the [PO4 ] of the deep ocean increased, then biological production at the surface would drive an increase in the downward flux of carbon that is not at first matched by any change in the upward flux of carbon dioxide associated with surface-deep... 

To illustrate particle diffusion, consider a tall water-filled volume in which particles have settled until a steady-state vertical concentration profile has been attained. Under this steady-state condition, the downward flux density of particles must equal the upward flux density of particles at every depth. The downward flux density can be expressed as... 

The average upwards flux of pore water driven by compaction is the result of porosity reduction in the underlying compacting layers and the velocity is at a constant sedimentation rate less than the subsidence rate (Bjprlykke, 1993). We can therefore calculate the compaction-driven flux from a limited thickness of... 

Previously, oxygen and sulfide were observed to coexist over some finite depth (or density) region, and it was assumed that oxygen oxidized the upward flux of sulfide at the oxic-anoxic interface. For example, Vinogradov and Nal-bandov (17) summarized data from several cruises (1984-1989) and observed that the first appearance of sulfide was at af = 16.18 (range of 15.95-16.30) (Table II). This value is in excellent agreement with our density of a, = 16.15... 

Another difficulty with the metal oxide hypothesis is that the observed sum of the vertical electron equivalent gradients of Mn(II) and Fe(II) is much less than that of sulfide (Figure 7). In a simple vertical, steady-state system where the upward flux of Mn(II) and Fe(II) results in oxidized particulate metal oxides, which in turn settle to oxidize sulfide, the electron gradients of Mn(II) + Fe(II) would equal that for sulfide. The fact that they do not equal it suggests that the vertical flux of Mn(II) + Fe(II) would not produce sufficient particulate metal oxides. This problem would be solved if the particulate oxides were produced primarily at the boundaries and transported into the interior (40). 

The upward flux of nutrients across the halocline is accompanied by the transport of salt. In correspondence with that, phosphate as well as nitrate are closely correlated with salinity or density in the winter surface layer (Nehring, 1981, 1982b, 1984a). Thus, the intensity of the upward transport of deepwater seems to be responsible for periods with increasing and decreasing nutrient concentrations lasting for several years in the winter surface layer in recent decades. 

The evidence for fluxes between the lower and upper mantle is more contentious. Whilst there is clear evidence of the transfer of material from upper to lower mantle through the sinking of subducted slabs, the ultimate destination of this material is uncertain. More controversial, as the current debate on mantle plumes is demonstrating, is the upward flux, from a lower to upper mantle reservoir. 

To determine the upward flux F and the downward flux F in a one dimensional representation, an integration of Eqs. (4.69a,b) must be performed over all solid angles according to Eq. (4.5) and Eq (4.6). It is convenient to introduce the flux transmissivity ... 

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