Discussion and Conclusion

Scientific questions often can be answered after some simplification of the problem and thus can give answers to some aspects only of the full problem. Here, we sought an alternative approach to solve the problems within the earth environmental system by (1) experimenting with a complex OGCM, and then (2) extracting a simple mechanistic model (Harte, 2002) from the view of thermodynamics in the oceanic ecosystem as a whole and solving the mechanistic model analytically. The OGCM experiments involve the dynamical influence of phytoplankton on geophysical fluid with ocean-biological processes embedded. The simple mechanistic model extracts the essence of complexity of thermodynamical interaction between the oceanic ecosystem and the external environmental fluids executed in numerical experiments with OGCMs.

By constructing a mechanistic process model, simple enough to mimic biologically generated anomalous geostrophic currents, we proposed potential feedback mechanism between oceanic phytoplankton and upper tropical equatorial ocean circulation. Since the flow of energy through the boundary is necessary for the balance of entropy for ecosystem as a whole (Tsuchida, 1982; Nakamoto et al., 2002), the feedback mechanism between the ecosystem and its environment is associated with biogeochemical processes involving with photosynthesis, metabolism, and food chain in the entire oceanic ecosystem. The ecosystem in the ocean interact with external physical environment through thermal energy exchange processes.

The OGCM experiments with annual mean chlorophyll pigment concentration demonstrated basin-scale warming of upper ocean in the entire globe. Biologically generated density gradient and rotating fluids-led dynamical interaction between oceanic living things and external fluid environments. Chlorophyll-dependent variable attenuation of solar radiation in a global circulation model exhibited shallower mixed layer throughout entire oceanic basins (due to more solar radiation energy trapped near the surface) than that of constant attenuation for clear water conditions without phytoplankton (Nakamoto et al., 2001; Ueyoshi et al. 2003). Such mechanism were expressed by simple radiation transfer of solar radiation and the geostrophic dynamics in the equatorial ocean. The two processes (the heat deposition from phytoplankton in the upper part of the ocean and the rotating fluid dynamics in the tropical ocean) play a role of connectivity of the ecosystem and its environment in the ocean, which leads to the enhancement of the EUCs and a colder spot of SST in the eastern equatorial Pacific.

The analytical solution of the simple mechanistic model corresponds with the phytoplankton-induced geostrophic currents hypothesized in the previous OGCM experiments (Nakamoto et al., 2001; Ueyoshi et al., 2003): the analytical solution shows an active role of phytoplankton on density modification and resultant flows that induce seawater conditions favorable to phytoplankton blooming in the eastern equatorial Pacific. Thus, the simple mechanistic model extracting the dynamical interaction of phytoplank-ton with surrounding water provides a condition of potential feedback mechanism between phytoplankton and upper ocean circulation relevant to basin-scale climate variations (Miller et al., 2003).

We proposed a simple mechanistic model with analytical solutions that extracts thermodynamical aspects of the interaction between ecosystem and its environment in the upper ocean as a whole. Our analytical model is "mechanistic (Harte, 2002)'' in the sense that the effect of entropy release as heat from phytoplankton was replaced with the space-varying water density anomalies, because living phytoplankton deposit more heat in the upper ocean than nonliving particulate and resolved materials. Our simple "mechanistic model'' was able to mimic and identify the cause-and-result relationship in the oceanic dynamical interaction process between living phytoplankton and ocean water environment as seen in numerical OGCM experiments.

It is worth noting that the choice of the annual averaged chlorophyll pigment concentration in the equation (1) is arbitrary because there was no need to use the exponentially decaying function for the chlorophyll pigment concentration in meridional direction. The essence in this exponentially decaying form exists in the fact that the chlorophyll pigment concentration in the equatorial Pacific decrease as the distance increase from the equator. The penetration of solar irradiance does not necessarily follow an exponential decline with depth. However, the analytical solution obtained in this study extracts the nature of solar radiation energy depositing in the upper ocean due to the existence of phytoplankton that convert solar energy to chemical energy and heat energy released to the physical environments in the upper ocean. A shallower mixed layer with the existence of phytoplank-ton is due to the release of biologically generated entropy as heat release to maintain lower entropy for the entire oceanic ecosystem which is surrounded by environmental physical fluids in the ocean.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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  • PANU
    What are the conclusion on carbon cycle?
    9 months ago

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