Bowen ratio

Eor saturated surfaces, the Bowen ratio can then be used to calculate evapotranspiration as a residual of the surface energy balance (Penman, 1948). Since direct measurement of ET is difficult and expensive, the energy balance method is fairly common. 

Meyers TP, Hall ME, Lindberg SE. 1996. Use of the modified Bowen ratio technique to measure fluxes of trace gases. Atmos Environ 30 3321-3329. 

Passerat de Silans, A., Monteny, B.A., and Lhomme, J.P. 1997. The correction of soil heat flux measurements to derive an accurate surface energy balance by the Bowen ratio method. I HydroL 188 453 65. 

Further support of rapid recovery of hydrological functions in secondary forest comes from the Zona Bragantina, east of Belem. Here, Holscher et al. (1997) used a Bowen ratio approach to measure evapotranspiration in a 2.5-3.5-year-old secondary forest on abandoned crop land, and found an average daily rate (3 9 mm d ) very close to that of mature forests receiving similar amounts of radiation. During the dry season, this secondary forest was absorbing water from below 3 m depth, and therefore had recovered a portion of its deep soil water uptake capacity. 

Methods based on spatial gradients in the direction of diffusion These include the standard gradient and Bowen-ratio methods of surface-layer flux measurement in micrometeorology. The key assumption is that terms I and II are small, so that the source term (j) (in this case identifiable with the flux at the surface) equals the flux f at a measurement height Z. ... 

Eulerian methods based on spatial gradients Gradient, aerodynamic, Bowen ratio in the direction of diffusion Surface flux Steady, horizontally uniform X = 1 km, T = 30 min... 

Boreal zone forest stands are also part of a patchy landscape at least in terms of tree age, size, and density, which determine stand structure. More commonly, though, the stands of trees are interspersed with herbaceous and shrubby vegetation and wetlands. On average, P is found to be 0.5 mm day less than ( = 2.3 mm day ) for forests in summer. Rainfall interception has been included in this comparison because E comprised wet and dry canopy evaporation rates except for the Yakutsk study by Kelliher et al. (1997). The difference between rainfall and evaporation rates is up to 2 mm day for the two oldest studies. These studies also report by far the highest evaporation rates. These E measurements were made using the Bowen ratio technique, which is notoriously difficult to employ over forests because of the small gradients in temperature and humidity there. Except for Lalleur (1992), who also used this technique, the other measurements were made directly by eddy covariance. 

The average annual ratio of sensible to latent heat loss at the surface is called the Bowen ratio. With —6 units of sensible heat loss and —23 units of latent heat loss, the Bowen ratio is —0.27. 

Although the relationship of sediment adsorption to water concentration appears to be a controlling feature of shallow water systems such as lakes and coastal shelf water, the open ocean is more likely to contain soluble plutonium which seems to be unaffected by particulate matter. This is particularly evident in two oceanographic studies. Bowen et al have discovered a stratum of plutonium in the North Pacific at about 500m that has not changed depth appreciably from 1973 to 1980. How it arrived at this depth is subject to conjecture but it appears to be soluble plutonium which is not settling(17). Fukai et al have delineated plutonium maxima in the Mediterranean Sea which seem to be due to soluble species(18). Comparison of americium to plutonium ratios in this... 

Figure 11.1 Ratio of particle velocity (Us) to maximum flow velocity (V ) as a function of the ratio of the particle to pore diameter for the zero-drag case [Bowen and Sharif, 1994]...

Bowen and Pells measured the ratio of light emission to chemical oxidation and concluded that at least one in 2000 molecules of P4 oxidized emits a quantum of visible light. 

With the aid of a dynamic apparatus, Bowen and Tietz studied the photochemical oxidation of gaseous ethanal at around 25°C. and for near-unity values of the ratio of concentration [OjJ/IRCHO]. The primary molecular product of the reaction is, as in the liquid phase, peracetic acid. The rate of this photooxidation is independent of the oxygen concentration and is proportional to the concentration of aldehyde and to the square root of the absorbed light intensity la- The total quantum yield of the reaction is of the order of magnitude of 100. ... 

Figure 4 The log of the ratio of the average chemical concentration of elements in the Earth s upper crust (mgkg ) to that of the solar system (mgkg ). Data on the geochemistry of the upper crust from Taylor and McLennan (1985, table 2.15) with supplemental data from Bowen (1979, table 3.3). The chemistry of the solar system...

Sulfur is the vital structural part of proteins and essential component of living matter. The concentration of sulfur in plant tissues is relatively small, 0.34% of dry biomass (Bowen, 1966). Sulfur concentration is much higher in animals and microbes due to higher content of proteins themselves. The C S ratio in protein is about 16, in carbohydrates 80, in terrestrial plants over 200, and in animals about 70. The average S content in the oceanic living matter is 1.20% of the dry weight. In marine plant C S ratio is around 50. 

A relation was developed in Figure 19 for effect of the hydroxyl to epoxy ratio on the initial rate of reaction. As the hydroxyl concentration rises, the initial rate of reaction increases this would probably hold true until dilution effects dominate. Similar relations have been developed by Bowen and Whiteside (29). It should be further noted that this curve represents isopropyl alcohol as the hydroxyl source. The slope would shift for other alcohols depending on their reactivity. 

---