Mark Abbott

Chlorophyll-temperature profiles were measured across Lake Tahoe about every 10 days from April through July 1980. Analysis of the 123 profiles and associated productivity and nutrient data identified three important processes in the formation and dynamics of the deep chlorophyll max-imum (DCM): turbulent diffusion, nutrient supply rate, and light availability. Seasonal variation in these three processes resulted in three regimes: a diffusion-dominated regime with a weak DCM, a variable-mixing regime with a pronounced, nutrient supply-dominated DCM, and a stable regime with a deep, moderate light availability-dominated DCM. The transition between the first two regimes occurred in about 10 days, the transition between the last two more gradually over about 3 weeks. The degree of spatial variability of the DCM was highest in the second regime and lowest in the third. These data indicate that the DCM in Lake Tahoe is constant in neither time nor space. A deep chlorophyll maximum (DCM) ...

Marine N 2 fixation by diazotrophic microorganisms is a key process in biogeochemical cycling and yields an important input of new nitrogen into the tropical and subtropical surface ocean. However, it is only poorly accounted for in current numerical models. We present a simple ...

... equipped with a water sampler and an optical package to study biologically active processes along the drifter track (see Abbott et al ... the intervening images (not shown) suggest that although there is considerable variability in their relative sizes, the anticyclonic eddy is dominant ...

Both the California Current System and the Antarctic Polar Front are characterized by mesoscale variability and meandering jets. These meanders lead to regions of strong vertical motion, on the order of several tens of meters per day. To study physical and biological scales of variability in these two systems, near-surface drifters were released in these two environments; twenty-six in the California Current and five in the Polar Front. Each drifter was equipped with a spectroradiometer to measure upwelled radiance at the ...

We use a 4-year time series of high-resolution coastal zone color scanner imagery to study mesoscale variability in phytoplankton pigment (as a surrogate for biomass) distributions off central Calfornia during the spring-summer upwelling season. We use empirical orthogonal functions to decompose the time series of spatial images into its dominant models of variability. Similarly, we analyze wind fields derived from

Abstract. Satellite ocean color data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) were used to examine distributions of chlorophyll concentration within the Southern Ocean for the period October 1997 through September 1998. Over most of the Southern ...

During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the resulting drifter trajectory data set has been analyzed in terms of its Eulerian and Lagrangian statistics. The CTZ drifter results show that the California Current can be characterized in summer and fall as a meandering coherent jet which on average flows southward to at least 30ºN, the southern end of the study domain. From 39ºN south to about 33ºN, the typical core velocities are of O(300 km) and the current meanders have alongshore wavelengths of O(100–200 km) and onshore-offshore amplitude of O(100–200 km). The lateral movement of this jet leads to large eddy kinetic energies and large eddy diffusivities, especially north of 36ºN. The initial onshore-offshore component of diffusivity ...

The proliferation of ocean observatories without internationally agreed-upon standards for instrument/user interfaces and observatory control functions is inhibiting interoperability and utilization of disparate datasets. This is in turn limiting the scientific impact of ocean observatories and increasing their operating costs. Hardware-based standards are not feasible given the different internal architectures of existing and planned ocean observatories. This paper proposes that

ABSTRACT Simplistic models relating global satellite ocean color, temperature, and light to ocean net primary production (ONPP) are sensitive to the accuracy and limitations of the satellite estimate of chlorophyll and other input fields, as well as the primary productivity model. The standard MODIS ONPP product uses the new semi-analytic chlorophyll algorithm as its input for two ONPP indexes. The three primary MODIS chlorophyll Q estimates from MODIS, as well as the SeaWiFS 4 chlorophyll product, were used to assess global and regional performance in estimating ONPP for the full mission, but concentrating on 2001. The two standard ONPP algorithms were examined with 8-day and 39 kilometer resolution to quantify chlorophyll algorithm dependency of ONPP. Ancillary data (MLD from FNMOC, MODIS SSTD1, and PAR from the GSFC DAO) were identical. The standard MODIS ONPP estimates for annual production in 2001 was 59 and 58 GT C for the two ONPP algorithms. Differences in ONPP using alternate chlorophylls were on the order of 10% for global annual ONPP, but ranged to 100% regionally. On all scales the differences in ONPP were smaller between MODIS and SeaWiFS than between ONPP models, or among chlorophyll algorithms within MODIS. Largest regional ONPP differences were found in the Southern Ocean (SO). In the SO, application of the semi-analytic chlorophyll resulted in not only a magnitude difference in ONPP (2x), but also a temporal shift in the time of maximum production compared to empirical algorithms when summed over standard oceanic areas. The resulting increase in global ONPP (6-7 GT) is supported by better performance of the semi-analytic chlorophyll in the SO and other high chlorophyll regions. The differences are significant in terms of understanding regional differences and dynamics of ocean carbon transformations.

Chlorophyll-temperature profiles were measured across Lake Tahoe about every 10 days from April through July 1980. Analysis of the 123 profiles and associated productivity and nutrient data identified three important processes in the formation and dynamics of the deep chlorophyll max- imum (DCM): turbulent diffusion, nutrient supply rate, and light availability. Seasonal variation in these three processes resulted in three

ABSTRACT Earth observing satellites represent some of the most valued components of the international Global Ocean Observing System (GOOS) and of the Global Climate Observing System (GCOS), both part of the Global Earth Observation System of Systems (GEOSS). In the United States, such satellites are a cornerstone of the Integrated Ocean Observing System (IOOS), required to carry out advanced coastal and ocean research, and to implement and sustain sensible resource management policies based on science. Satellite imagery and satellite-derived data are required for mapping vital coastal and marine resources, improving maritime domain awareness, and to better understand the complexities of land, ocean, atmosphere, ice, biological, and social interactions. These data are critical to the strategic planning of in situ observing components and are critical to improving forecasting and numerical modeling. Specifically, there are several stakeholder communities that require periodic, frequent, and sustained synoptic observations. Of particular importance are indicators of ecosystem structure (habitat and species inventories), ecosystem states (health and change) and observations about physical and biogeochemical variables to support the operational and research communities, and industry sectors including mining, fisheries, and transportation. IOOS requires a strategy to coordinate the human capacity, and fund, advance, and maintain the infrastructure that provides improved remote sensing observations and support for the nation and the globe. A partnership between the private, government, and education sectors will enhance remote sensing support and product development for critical coastal and deep-water regions based on infrared, ocean color, and microwave satellite sensors. These partnerships need to include international research, government, and industry sectors in order to facilitate open data access, understanding of calibration and algorithm strategies, and fill gaps in covera- e. Such partnerships will define the types of observations required to sustain vibrant coastal economies and to improve the health of our marine and coastal ecosystems. They are required to plan, fund, launch and operate the types of satellite sensors needed in the very near future to maintain continuity of observations.