Mixed layer dynamics

However, as pointed out by Sathyendranath and Platt (1994) and Sathyen-dranath etal. (1999), models that only consider mixed layer dynamics without taking into account changes in bio-optical properties of phytoplankton are probably insufficient to explain the occurrence of phytoplankton blooms in the Arabian Sea. Sathyendranath etal. (1999) provided evidence for significant seasonal changes in the parameters that describe the dependence of photosynthesis rate of phytoplankton on the amount of light available (P-I curves), viz. the assimilation number (PmB) and the initial slope of photosynthesis-light curve (aB), as well as in the specific absorption coefficient of phytoplankton (ac ). 

Sathyendranath, S. and Platt, T. (1994) New production and mixed layer dynamics. Proceedings of the Indian Academy of Sciences (Earth and Planetary Sciences), 103, 177-188. 

J. Kim and J. S. Kim, Modelling of lifted turbulent diffusion flames in a channel mixing layer by the flame hole dynamics. Combust. Theory Model. 10 21-37, 2006. 

Tumewitsch R, Springer BM (2001) Do bottom mixed layers influence dynamics in the abyssal nearbottom water column . Deep-Sea Res I 48 1279-1307... 

For phosphorus, Cdeep/C river = 3 0 and Csurface/Qver = 0.15, SO = 0.95. This means that if enough time has elapsed for the complete exchange of water between the two reservoirs, then 95% of the phosphorus that enters the surface box is removed in particulate form. Detailed studies of nutrient dynamics in the mixed layer indicate that the average atom is recycled 10 times before escaping as a sinking particle into the deep sea. 

Figure 8.9 Phase separation in a mixed layer of protein + surfactant from Brownian dynamic simulation. In the picture are cross-linked protein-like particles (black) and surfactant-like displacer particles (grey). Reproduced from Wijmans and Dickinson (1999b) with permission.

Both of the models presented here are based on the flow of nitrogen through ecosystems in one case a nearshore kelp-bed system and in the other a general offshore plankton community. The klep bed model was developed to explore the hypothesis that nitrogen flow is affected by horizontal water transport in shallow water marine systems here wave action or mixing associated with horizontal transport are likely to retain nitrogen in the photic zone and the benthic community is of fixed location so that boundaries of the system can be easily defined. In pelagic systems, on the other hand, the community tends to move horizontally with water in the mixed layer, and vertical transport into and out of the mixed layer is an important feature of the system dynamics. 

Fasham, M., Ducklow, H., andMcKelvie, S. (1990). A nitrogen-based model of plankton dynamics in the oceanic mixed layer. f. Mar. Res. 48, 591—639. 

Vincent, W. F. (1992). The daily pattern of nitrogen uptake by phytoplankton in dynamic mixed layer environments. Hydrobiologia 238, 37—52. 

Figure 16.18 Distribution, abundance and temporal dynamics of N2 fixing bacteria at Station ALOHA. (A) Vertical profiles of <10 pm (left) and >10 pm (right) nifH phylotypes in December 2002 relative to upper mixed-layer depth (dashed line) and 1 % surface radiance isopleth (dotted line). Error bars are 1SD of triplicate QPCR (45 cycles) reactions. From Church et al. (2005a).

The region of the atmosphere that is in direct contact with the surface (on a timescale of 1 h or less) is commonly referred to as the boundary layer or mixed layer. Technically, the boundary layer refers to the region of the atmosphere that is dynamically influenced by the surface (through friction or convection driven by surface heating). Less formally, the boundary layer is used to represent the layer of high pollutant concentrations in source regions. The top of the boundary layer in urban areas is characterized by a sudden decrease in pollutant concentrations and usually by changes in other atmospheric features (water vapor content, thermal structure, and wind speeds). 

Brenner, S., Rozentraub, Z., Bishop, J. and Krom, M. (1990) The mixed layer/thermocline cycle of a persistant warm core eddy in the Eastern Mediterranean. Dynamics of Atmospheres and Oceans, 15, AS1-A11. 

McCreary, J.P., Kundu, P.K. and Molinari, R.L. (1993) A numerical investigation of dynamics, thermodynamics and mixed-layer processes in the Indian Ocean. Progress in Oceanography, 31, 181-244. 

Keller, J.O., J.L. EUzey, R. W. Pitz, l.G. Shepherd, and J.W. Daily. 1988. The structure and dynamics of reacting plane mixing layers. Experiments Fluids 6 33-43. 

Strykowski, P. J., and D. L. Niccum. 1992. The influence of velocity and density ratio on the dynamics of spatially developing mixing layers. Physics Fluids 4 770-81. 

Dynamics of the Mixed Layer and Thermocline of the South China Sea... 

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