Phytoplankton bloom and the vertical thermal structure of the upper ocean

Local heating rate within the oceanic mixed layer (ML) depends not only on the amount of solar radiation incident on the sea surface, but also on the vertical distribution of the irradiance in the water column. We have evaluated the effect of a phytoplankton bloom on mixed layer depth and temperature at a high latitude site near Iceland. The level 2½ version of the Mellor-Yamada (1982) turbulence scheme has been modified to include the vertical distribution of irradiance. This has allowed the investigation of the ML temperature and stability structure resulting from both physical and biological effects. An important part of the model is the parameterization of pigment-dependence which affects the spectral attenuation coefficient for downwelling irradiance as proposed by Morel (1988). Concurrent, high temporal resolution time series of physical and bio-optical data were used for the model. These data were acquired using a mooring deployed during the spring of 1989. We have estimated that the increase of phytoplankton abundance induced an increase of the sea surface temperature by about 0.2°C at the mooring site. This led to stronger near-surface thermal stratification and shallower mixed layers. The dependence of the upper layer thermal structure on biology is more important when vertical mixing is weaker and when phytoplankton concentrations are higher

Automated in situ observations of upper ocean biogeochemistry, bio-optics, and physics and their potential use for global studies

The processes controlling the flux of carbon in the upper ocean have dynamic ranges in space and time of at least nine orders of magnitude. These processes depend on a broad suite of inter-related biogeochemical, bio-optical, and physical variables. These variables should be sampled on scales matching the relevant phenomena. Traditional ship-based sampling, while critical for detailed and more comprehensive observations, can span only limited portions of these ranges because of logistical and financial constraints. Further, remote observations from satellite platforms enable broad horizontal coverage which is restricted to the upper few meters of the ocean. For these main reasons, automated subsurface measurement systems are important for the fulfillment of research goals related to the regional and global estimation and modeling of time varying biogeochemical fluxes. Within the past few years, new sensors and systems capable of autonomously measuring several of the critical variables have been developed. The platforms for deploying these systems now include moorings and drifters and it is likely that autonomous underwater vehicles (AUV's) will become available for use in the future. Each of these platforms satisfies particular sampling needs and can be used to complement both shipboard and satellite observations. In the present review, (1) sampling considerations will be summarized, (2) examples of data obtained from some of the existing automated in situ sampling systems will be highlighted, (3) future sensors and systems will be discussed, (4) data management issues for present and future automated systems will be considered, and (5) the status of near real-time data telemetry will be outlined. Finally, we wish to make it clear at the outset that the perspectives presented here are those of the authors and are not intended to represent those of the United States JGOFS program, the International JGOFS program, NOAA's C&GC program, or other global ocean programs

Modeling water column structure and suspended particulate matter on the Middle Atlantic continental shelf during the passages of Hurricanes Edouard and Hortense

The present contribution is motivated by the desire to elucidate the processes that contributed to the evolution of observed thermal structure and resuspension of particulate matter during and after the passages of two hurricanes, Edouard and Hortense, within a two-week period in late-summer 1996. A unique set of high temporal frequency measurements of the vertical structures of physical and optical properties was obtained at a mooring site near the Middle Atlantic Bight continental shelf-break (70 m water depth). These data provided insight and initial conditions for the physical model used for this study. The model accounted for wind and bottom current generated turbulence, surface waves, wave-current interactions, tides, and depth-dependent density-driven circulation. We find that the most important process controlling the thermal water column structure during and following the passage of Hurricane Edouard was the wind stirring. Differences between the model results and the observations of thermal structure may have been caused by advection, which is not included in this one-dimensional model. There is also clear evidence of internal tides in the observations, whereas the model could not reproduce this effect. A suspended particulate matter (SPM) model is included as a module of the physical model to examine sediment resuspension processes. It is concluded that wave-current bottom shear stress was clearly the most important process for sediment resuspension during and following both hurricanes. Discrepancies between modeled and observed SPM are attributed to the presence of biological material in the surface waters and changes in sediment properties (flocculation and de-flocculation) during and following the passages of the hurricanes

Toward closure of upwelling radiance in coastal waters

We present three methods for deriving water-leaving radiance Lw(λ) and remote-sensing reflectance using a hyperspectral tethered spectral radiometer buoy (HyperTSRB), profiled spectroradiometers, and Hydrolight simulations. Average agreement for 53 comparisons between HyperTSRB and spectroradiometric determinations of Lw(λ) was 26%, 13%, and 17% at blue, green, and red wavelengths, respectively. Comparisons of HyperTSRB (and spectroradiometric) Lw(λ) with Hydrolight simulations yielded percent differences of 17% (18%), 17% (18%), and 13% (20%) for blue, green, and red wavelengths, respectively. The differences can be accounted for by uncertainties in model assumptions and model input data (chlorophyll fluorescence quantum efficiency and the spectral chlorophyll-specific absorption coefficient for the red wavelengths, and scattering corrections for input ac-9 absorption data and volume scattering function measurements for blue wavelengths) as well as radiance measurement inaccuracies [largely differences in the depth of the Lu(λ, z) sensor on the HyperTSRB]. © 2003 Optical Society of America

Haploinsufficiency of the E3 Ubiquitin Ligase C-Terminus of Heat Shock Cognate 70 Interacting Protein (CHIP) Produces Specific Behavioral Impairments

The multifunctional E3 ubiquitin ligase CHIP is an essential interacting partner of HSP70, which together promote the proteasomal degradation of client proteins. Acute CHIP overexpression provides neuroprotection against neurotoxic mitochondrial stress, glucocorticoids, and accumulation of toxic amyloid fragments, as well as genetic mutations in other E3 ligases, which have been shown to result in familial Parkinson's disease. These studies have created a great deal of interest in understanding CHIP activity, expression and modulation. While CHIP knockout mice have the potential to provide essential insights into the molecular control of cell fate and survival, the animals have been difficult to characterize in vivo due to severe phenotypic and behavioral dysfunction, which have thus far been poorly characterized. Therefore, in the present study we conducted a battery of neurobehavioral and physiological assays of adult CHIP heterozygotic (HET) mutant mice to provide a better understanding of the functional consequence of CHIP deficiency. We found that CHIP HET mice had normal body and brain weight, body temperature, muscle tone and breathing patterns, but do have a significant elevation in baseline heart rate. Meanwhile basic behavioral screens of sensory, motor, emotional and cognitive functions were normative. We observed no alterations in performance in the elevated plus maze, light-dark preference and tail suspension assays, or two simple cognitive tasks: novel object recognition and spontaneous alternation in a Y maze. Significant deficits were found, however, when CHIP HET mice performed wire hang, inverted screen, wire maneuver, and open field tasks. Taken together, our data indicate a clear subset of behaviors that are altered at baseline in CHIP deficient animals, which will further guide whole animal studies of the effects of CHIP dysregulation on cardiac function, brain circuitry and function, and responsiveness to environmental and cellular stress

Tidally induced turbulence and suspended sediment

Nearly continuous data collected using novel methods are utilized to advance the understanding of turbulence and suspended particulate matter (SPM) dynamics under strong tidal flow conditions. Key instrumentation includes a single acoustic current profiler that provides nearly continuous, concurrent turbulence and SPM information with respect to depth near the seafloor and within the water column. Observations show a lag of about 1 hour in turbulence production between the bottom and 12 meters above the bottom (mab), and of about 1.5 hours for SPM. Estimates of eddy viscosity show values ranging between 10−3 and 10−2 m2 s−1, with an almost constant mean value of 3.5 × 10−3 m2 s−1 within the bottom 7 meters. The present observations and a previously reported theory show good agreement in both amplitude and phase for SPM and turbulence, when values of eddy viscosity ranging between 3.5 × 10−3 (mean) and 10−2 (maximum) are used. Our data set is valuable for evaluating, developing, and improving turbulence and SPM numerical models

Observaciones oceanográficas interdisciplinares: nuevas tendencias

Oceanographic measurements, though difficult and expensive, are essential for effective study, stewardship, preservation, and management of our oceanic and atmospheric systems. Ocean sciences have been driven by technologiesenabling new observations, discoveries, and modelling of diverse interdisciplinary phenomena. Despite rapid advances inocean sampling capabilities, the numbers of disciplinary variables that are necessary to solve oceanographic problems arelarge and increasing. In addition, the time and space scales of key processes span over ten orders of magnitude; presently, there remain major spectral gaps in our sampling. Thus, undersampling presents the main limitation to our understanding of global climate change; variability in fish biomass and regime shifts; and episodic and extreme events. Fortunately, recentadvances in ocean platforms and in situ autonomous sampling systems and satellite sensors are enabling unprecedented rates of data acquisition as well as the expansion of temporal and spatial coverage. Consequently, improved sampling strategies will lead to a reduction in ocean forecasting error for predictions of a multitude of atmospheric and oceanic processes. Nonetheless, major challenges remain to massively increase the variety and quantity of ocean measurements and to effectively coordinate, synthesize, and distribute oceanographic data sets. In particular, numbers of measurements are limited by the costs of instruments and their deployment as well as data processing and production of useful data products and visualizations. Looking forward, many novel and innovative technologies involving computing, nanotechnology, robotics, information and telemetry technologies, space sciences, and molecular biology are being developed at a fast pace for numerous applications (Kaku, 1997; Kurzweil, 1999). It is anticipated that several of these can and will be transitioned to the ocean sciences and will prove to be extremely beneficial for oceanographers in the next few decades. Already, autonomous, ‘robotic’ in situsampling, high spectral resolution optical and chemical instrumentation, multi-frequency acoustics, and biomolecular techniques are being utilized by a limited number of oceanographers. Also, increased temporal and spatial sampling capabilities for expanding numbers of interdisciplinary variables are being accelerated thanks to both new technologies and utilization of data assimilation models coupled with autonomous sampling platforms. Data networks coupled with internet connectivity are rapidly increasing access to and utilization of data sets. In this essay, we review recent technological progress for solving some key oceanographic problems and highlight some of the foreseeable challenges and opportunities of ocean science technologies and their applications.Las medidas de parámetros oceanográficas son difíciles y caras de obtener, no obstante son esenciales para una eficaz conservación y gestión de los sistemas marinos y atmosféricos. Las ciencias marinas han avanzado a medida que la tecnología permitía nuevas observaciones y procesar modelos de fenómenos de diversa interdisciplinaridad. No obstante, el número de variables necesarias para resolver preguntas en el sistema marino es muy alto y el rango de las escalas de tiempo y espacio asociadas a procesos calve es de diez órdenes de magnitud. Actualmente todavía existen intervalos de este rango sin muestrear. Por tanto, la falta de medidas representa la mayor limitación para un buen conocimiento del cambio global, y de las causas que provocan la variabilidad de la pesca, de los regímenes de las corrientes marinas y de los eventos extremos. Afortunadamente, los avances recientes relacionados con sistemas automáticos de toma de muestras tanto in situ como remotamente han permitido mejorar tanto la rapidez en la adquisición como la cobertura espacial. Estas mejoras en las estrategias de muestreo nos ayudan a redicir el error en las predicciones de procesos oceánicos y atmosféricos. No obstante, el mayor reto continua siendo por un lado aumentar la diversidad y cantidad de medidas, y por otro conseguir una coordinación efectiva que permita la síntesis y distribución de los datos adquiridos. En particular el número de medidas están limitadas por el coste de los instrumentos, del tratamiento de los datos y de los métodos de visualización de éstos. Mirando hacia el futuro, las innovaciones en los campos de la informática, la nonotecnología, la biología molecular, la robótica y la telemetría aumentarán rápidamente y permitirán nuevas aproximaciones (Kabu, 1997, Lurzweil, 1999). Actualmente, un número limitado de oceanógrafos ya trabajan con sistemas automáticos de adquisición de datos que combinan técnicas acústicas, químicas, biomoleculares, etc. Además, la capacidad de toma de datos a distintas escalas de tiempo y espacio está continuamente aumentando gracias a las nuevas tecnologías y a la mejora de los sistemas de tratamiento de datos. En este trabajo nosotros revisamos el progreso de las tecnologías recientes para solucionar preguntas claves en la oceanografía y remarcamos algunos de los retos futuros, así como las tecnologías aplicadas a las ciencias del océano