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Earth environmental problems involve feedbacks between the ecosystem and the climate. Concerning global warming, one may assume that potential feedbacks between marine ecosystem and physical processes will increase or decrease the concentration of carbon dioxide in the atmosphere than the sum of the component systems themselves. Because of the complexity of the earth environmental problems in terms of scales in time and space as well as its interconnectivity between multidisciplines in contemporary sciences, providing answers to these questions is an enormous challenge.

The atmosphere and ocean continuously exchange carbon dioxide across sea surface. Within the top hundred meters of seawater, the carbon dioxide is taken up by phytoplankton quite rapidly (Kawabata et al., 2003; Otsuki et al., 2003). Absorption in the lower level of the ocean takes longer because the mixing of the upper ocean water with water at lower level requires up to several hundred years or so. It takes over thousands of years for the deep ocean to complete the same process.

Recent measurements of underwater solar energy absorption spectrum in the northwestern Pacific (see Fig. 3 of Sasaki et al., 2001) showed that living phytoplankton absorbs more light than detritus or other material without life activity do. Siegel and Dickey (1987) demonstrate that the attenuation of visible energy and photosynthetically available radiation (PAR) (Morel, 1978) are primarily functions of chlorophyll pigments. Iturriaga and

Siegel (1989) reported that phytoplankton abundance accounted for 50-70% of the particulate absorption at 440 nm.

Lewis et al. (1990) suggested that variations in the amount of irradiance penetrating through the mixed layer are due to changes in phytoplankton abundance, especially in the Pacific warm pool region. Using TOGA-COARE intensive observation data in January 1992, Siegel et al. (1995) showed that a nearly tripling of mixed-layer phytoplankton following a sustained westerly wind burst resulted in a reduction in the penetrative flux of nearly 6 W m-2 in the net solar radiation at 30 m and biologically mediated increase in the mixed-layer radiant heating rate of 0.13 K during the observation period.

By analyzing a three-dimensional numerical model experiment results of Ocean isoPYcnal coordinate (OPYC) general circulation model (Oberhuber, 1993), Nakamoto et al. (2001) showed that surface chlorophyll pigments in the equatorial Pacific not only influence vertical penetration of solar radiation, but also modify geostrophic flows in the Pacific basin scales. They used an empirical relation for a heating rate as a function of depth and of phytoplankton concentration retrieved from the satellite data (Morel and Antoine, 1994).

In their numerical model experiments, the biologically generated geo-strophic flows converge toward the equatorial undercurrent (EUC) in the western equatorial Pacific. The water masses converged into the EUC in the west are transported eastward. That induces an upwelling in the eastern equatorial Pacific, and leads to a biomass-related sea surface temperature (SST) anomalies, characterized by water colder than the case without phytoplankton in the ocean (Nakamoto et al., 2001).

Recent model experiments performed by Ueyoshi et al. (2003) using the MIT OGCM with Morel and Antoine's (1994) shortwave penetration scheme and SeaWiFs satellite-measured chloropyhll concentration data produced the results remarkably similar to those described by Nakamoto et al. (2001). In particular, the enhanced EUC and the colder ocean surface region of SST anomalies in the eastern equatorial Pacific were reproduced, indicating ocean dynamical interaction effects of phytoplankton in the equatorial Pacific.

Using coastal zone color scanner (CZCS) satellite-derived chlorophyll concentration data, Murtgudde et al. (2002) conducted ocean general circulation experiments similar to Nakamoto et al. (2000, 2001). Their control runs without phytoplankton were done with the attenuation depth of 17 m and these runs were compared with runs where the attenuation depth was computed from annual mean CZCS data (see the Fig. 1, p. 472 of Murtgudde et al., 2002). They argued that the large region of colder-than-observed SSTs in the eastern equatorial and coastal region is greatly alleviated in their ocean model with CZCS chlorophyll pigment data by stating that the model simulated SST with phytoplankton is as high as 1°C for the cold tongue region compared with the control run without phytoplankton (see Fig. 5a in

SeaWiFS Chlorophyll - a Concentration: Mean 1997 - 2004

SeaWiFS Chlorophyll - a Concentration: Mean 1997 - 2004


Figure 1: Biomass distribution from SeaWiFS satellite observations and the mathematical distribution function (mg m-3) given by equation (1). The coordinates x and y are normalized by 100 km (For colour version, see Colour Plate Section).

Figure 1: Biomass distribution from SeaWiFS satellite observations and the mathematical distribution function (mg m-3) given by equation (1). The coordinates x and y are normalized by 100 km (For colour version, see Colour Plate Section).

page of Murtgudde et al., 2002). Regarding the process occurring in their ocean model simulations with variable attenuation depths, they speculate that slight warming below the mixed layer with the presence of phytoplank-ton and the consequent weakening of the stratification leads dynamical feedbacks as described in their numerical model outputs (see p. 476 of Murtugudde et al., 2002).

Here, it is worth noting that Nakamoto et al. (2000, 2001) and Murtgudde et al. (2002) conducted two different numerical experiments with respect to the process of penetration of solar radiation due to phytoplankton in the upper ocean, i.e., Nakamoto et al. (2001) and Ueyoshi et al. (2003) employed a numerical scheme that allows solar energy shifting toward the ocean surface in the eastern equatorial ocean with phytoplankton, while Murtgudde et al. (2002) employed a numerical scheme allowing solar energy to penetrate deeper into the eastern equatorial subsurface ocean with phytoplankton compared to their control run without phytoplankton.

In this paper, we do not discuss the solar energy penetration process employed by Murtgudde et al. (2002). Instead, we study the hypothesis proposed by Nakamoto et al. (2001) to seek for an analytical approach to verify their bioclimate interaction hypothesis involving living phytoplankton and ocean circulation, by assuming that heat deposition due to phytoplankton occurs in the surface region rather than in the subsurface ocean if phyto-plankton concentration is given in the surface part of the ocean.

Question we address here is the following: Why does SST in the eastern equatorial Pacific become cooler in Nakamoto et al. (2001) and Ueyoshi et al. (2003), when phytoplankton is taken into account, despite phytoplankton-traped solar radiation near the ocean surface in Nakamoto et al. (2001) and Ueyoshi et al. (2003)? In order to answer this question, we focus our attention on the geophysical dynamics problem hypothesized by Nakamoto et al. (2001) based on their ocean general circulation model (OGCM) experiment. Now, a new question, "Does the geographical pattern of chlorophyll biomass concentration is the key in the biological interaction with the surrounding seawater in the tropical ocean?'' arises. More specifically, we may address the following question: "Do phytoplankton in the equatorial ocean generate subsurface westward-geostrophic currents, which eventually merge into the EUCs in the western equatorial Pacific?''

We illustrate the process via extracting a simple mechanistic model from numerical experiments with OGCMs . The goal of this paper is to motivate earth system modeling from the view of thermodynamics of life in oceanic ecosystem for understanding biological—chemical-physical feedback mechanism essential in the Earth System Sciences (Harte, 2002).

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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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