Average vertical attenuation coefficients, K(av), for irradiance calculated by linear regression of ln E(z) on z through the euphotic zone or from two irradiance values in a certain depth interval, are useful but somewhat arbitrary procedures for estimating these important apparent optical properties of the ocean. A more fundamental approach is to calculate an irradiance-weighted coefficient, K...

Abstract We propose a new method to construct rigid G -automorphic representations and $${\widehat{G}}$$ G ^ -local systems for reductive groups . The construction involves the notion of euphotic , proof rigidity geometry certain Hessenberg varieties.

Silicon isotope tracers were used to examine the relative magnitude of silica dissolution and silica production in the Monterey Bay, California, upwelling system. A diatom bloom dominated by Skeletonema costatum and Chaetoceros spp. was encountered under conditions of moderate upwelling. Profiles of silica production and dissolution rates were obtained at seven stations that sampled both inside...

Quantification of hyperspectral downwelling vertical attenuation coefficient (Kd) and irradiance (Ed) in the euphotic depth (Zeu) in 2005 (falling) and 2006 (rising waters) in Amazonian waters showed that Kd is higher in the blue (5-9 m), decreasing towards the green (4-7 m) and red (3-5 m) part of the spectra. Further, Kds are generally higher in white waters than in black and clear waters. A ...

EisenEx—the second in situ iron enrichment experiment in the Southern Ocean—was performed in the Atlantic sector over 3 weeks in November 2000 with the overarching goal to test the hypothesis that primary productivity in the Southern Ocean is limited by iron availability in the austral spring. Underwater irradiance, chlorophyll a (Chl a), photochemical efficiency, and primary productivity were ...

In the seasonally stratified Gulf of Aqaba Red Sea, both NO 2 release by phytoplankton and NH þ 4 oxidation by nitrifying microbes contributed to the formation of a primary nitrite maximum (PNM) over different seasons and depths in the water column. In the winter and during the days immediately following spring stratification, NO 2 formation was strongly correlated (R 2 = 0.99) with decreasing ...

We show that the isotopic composition of oxygen (delta18O) in dissolved inorganic phosphate (Pi) reveals the balance between Pi transport and biological turnover rates in marine ecosystems. Our delta18Op of Pi (delta18Op) measurements herein indicate the importance of cell lysis in the regeneration of Pi in the euphotic zone. Depth profiles of the delta18Op in the Atlantic and Pacific Oceans ar...

The problem of the vertical distribution of phytoplankton is considered in the presence of gravitational settling, turbulent mixing, population growth due to cell division and a constant rate of loss due to predation and natural death. Nutrients are assumed to be plentiful so that the production rate depends only on the light available for photosynthesis. The non-linear saturation of plankton g...