Scatterometers and radiometers on several polar-orbiting satellites routinely produce oceanic surface wind field data. For this study, we merged the NASA scatterometer (NSCAT) data with scatterometer data from the European Remote Sensing (ERS) satellite 2, and the wind speeds from two of the Special Sensor Microwave/Imagers (SSM/I) and produced daily 1° latitude by 1° longitude gridded wind fields over the global ocean for September 1996 through June 1997. This time period coincides with the lifetime of the NSCAT aboard ADEOS-1. We created these wind fields by utilizing the Kriging technique with its associated variograms, which consider both space and time wind vector structures. The resulting daily wind fields, when compared with moored-buoy wind speed and direction measurements, resulted in a root-mean-square (rms) difference of less than 1.5 m/s. No significant difference was found between statistical parameters estimated over the equatorial zone and middle latitudes. To investigate the global patterns of these new satellite wind fields, comparisons with the National Environmental Prediction Center's (NCEP) re-analysis products have been carried out. The satellite data and the NCEP products have a similar statistical error structure, but the merged wind fields provide complete coverage at much higher spatial resolution. Accurate surface wind speed estimates are an important factor in determining the velocity and magnitude of air-sea gas exchange.

Surface fluxes of momentum, freshwater, and energy across the air-sea interface determine oceanic circulation and its variability at all timescales. The goal of this paper is to estimate and examine some ocean surface flux variables using satellite measurements. The remotely sensed data come from the European Remote Sensing (ERS) satellite scatterometer on ERS-2, NASA scatterometer (NSCAT), and several Defense Meteorological Satellite Program (DMSP) radiometers [Special Sensor Microwave Imager (SSM/I)] on board the satellites F10-F14. The sea surface temperature comes from daily analysis calculated from Advanced Very High Resolution Radiometer (AVHRR) measurements. This study focuses on the 9-month period (October 1996-June 1997) of the NSCAT mission. To ensure high quality of the merged surface parameter fields, comparisons between different satellite estimates for the same variable have been performed, and bias corrections have been applied so that they are compatible with each other. The satellite flux fields are compared to in situ observations from buoys and ships globally and in different regions of the ocean. It is found that the root-mean-square (rms) difference with weekly averaged wind speeds is less than 2.5 m s(-1) and the correlation coefficient is higher than 0.8. For weekly latent heat flux, the rms difference between satellite and buoys does not exceed 30 W m(-2). The comparisons with weekly ship latent heat flux estimates gives an rms difference approaching 40 W m(-2). Comparisons are also made between satellite fields and atmospheric analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) and reanalyses from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR). The wind speeds and latent heat fluxes from these atmospheric analyses compare reasonably well with the satellite estimates. The main discrepancies are found in regions and seasons of large air-sea temperature difference and high wind speed, such as the Gulf Stream during the winter season.

Satellite-derived estimates of weekly latent heat flux for the tropical and subtropical Atlantic Ocean (40°S to 40°N) were calculated for a one-year period from September 30, 1996 to September 28, 1997 (52 weeks). The oceanic variables required to estimate evaporation (sea surface temperature, surface wind speed, and surface air humidity) were obtained from sensors on several polar-orbiting satellites including the European Remote Sensing satellite 2 (ERS-2), the NASA scatterometer (NSCAT), and the Special Sensor Microwave/Imager (SSM/I). During this period, high values of the weekly satellite estimates of wind speed and latent heat flux were found over the northeast and southeast trade wind regions. In these regions, the 52-week average fields showed wind speeds greater than about 7 m s1 and associated evaporation rates greater than 120 W m2. The annual cycle dominates the temporal evolution of sea surface temperature but is hardly noticeable in wind speed and latent heat flux, which are dominated by large 3-4 week fluctuations. The most significant event during our period of study was a strong northeast trade wind burst that originated near the northwest African coast in early February 1997. It persisted for five weeks as it crossed the North Atlantic Ocean and finally dissipated in the Caribbean Sea in early March 1997. In the southeast trade region, a similar but less intense period of higher flux was observed during July 1997. These large-scale wind bursts illustrate the strong role that the Atlantic trade winds play in enhancing evaporation.

Far from land and surface ship observations, most tropical depressions are identified by examining images from geostationary satellites for the presence of rotation of the convective cloud masses. During the 1999 hurricane season, surface wind vectors obtained by the SeaWinds scatterometer on the QuikSCAT satellite for the tropical Atlantic and Caribbean Sea were examined to test the hypothesis that developing tropical depressions (TDs) could be observed with this satellite sensor, before identification by the traditional means. QuikSCAT was able to detect the presence of closed circulation in the surface winds before the systems were designated as depressions. The satellite's unprecedented large swath width of 1800 km allows twice a day observation of most of the tropical oceans. SeaWinds data can, therefore, provide valuable guidance that are an important addition to the tools available to the tropical cyclone forecasting community.

Water-column surveys by combined nephelometer/CTD (NCTD) tows contributed to the 1985 discovery of the first black smokers on the Mid-Atlantic Ridge. Subsequent regional water-column mapping has helped define the extent, mass and interactions of the suspended particulate matter phase (SPM) of the hydrothermal plumes emanating from the known and other nearby sources. The results of 29 NCTD cast/tows, covering 25–30 km2 of ridge segment, indicate the presence of as many as two additional sources based on SPM concentration gradients and plume-top doming over source areas. Plume doming, documented here for the first time from field observations, conforms strikingly with laboratory experiments and can serve as a marker for source field location. A comparison of the plumes' SPM with potential temperature and salinity distributions indicates close correlation in water-column anomaly patterns for each, confirming modification of the regional potential temperature and salinity structure by hydrothermal plumes, which is expressed by wide separation and sloping of isotherms and isohalines.

The continental slope gradient in the study area averages 7–8°. Many valleys, canyons and occasionally large sediment slumped masses occur. Moderate to steep slopes (19–27°) as well as very steep to precipitous slopes (> 27°) are abundant and occupy about 7% of the investigated area.

Evidence from over 200 sediment cores, numerous submersible dives, and bottom photographs prove that bioturbation and bioerosion are ongoing processes affecting northeastern U.S. continental slope and rise sedimentation. Evidence of biological activity was found in greater than 95% of the cores examined. Submersible dive observations reveal that the results of biological activity often dominate sea-floor microtopography. Bioturbation can disturb sediments several centimeters deep in a matter of seconds and is in some areas the primary sediment transport mechanism. Many cores with sandy intervals were profoundly disturbed by bioturbation. Biologically camouflaged sand-rich intervals can easily be missed by visual observation.

A sediment study suggests that Washington and Norfolk canyons off the Mid-Atlantic States are not inactive, but have served periodically since the Late Pleistocene as conduits of sediment originating on the adjacent shelf and upper slope. Large quantities of sand occur in the canyon heads as thin beds and laminae, and on the continental slope as mixtures of sand (to >40%), silt and clay that are extensively reworked by burrowing organisms. Sandy turbidites occur in the canyons on the rise. Basinward dispersal, from the outer shelf and uppermost slope, is recorded by heavy mineral suites and bioclastic components, primarily foraminifera of shallow marine origin, in the lower slope and upper continental rise canyon cores. The down-axis movement of material, presumably episodic, in the Holocene to recent results from offshelf spillover into canyon heads, failure on the steep walls bordering canyons on the slope, and resuspension by bottom currents.

Investigations of Veatch, Washington, and Norfolk Submarine Canyons, on the eastern continental margin of the United States, resulted in a detailed assessment of their past and present geologic processes. Norfolk and Washington Canyons share such characteristics as similar levee geometry, stratigraphy, and mineralogy; Veatch Canyon differs from Norfolk and Washington Canyons in these respects. Seismic reflection profiles of all three submarine canyon heads indicate an erosional origin. Seismic profiles of Veatch Canyon's lower continental slope indicate a formation by depositional processes; in contrast, the continental-slope profiles of Washington and Norfolk Canyons reveal a history of alternating episodes of deposition and erosion. Cored sediments from Washington and Norfolk Canyons disclose recent, intermittent, down-canyon transport of sand to the continental rise. Bathymetric and seismic profiles suggest Veatch, Washington, and Norfolk Canyons have all been subjected to a minimum of two periods of development. Similar axial trends of Washington and Norfolk Canyons imply a common structural influence.

Sedimentary properties and processes of a 7,500-km2 corridor seaward of the Baltimore Canyon Trough off New Jersey were studied in detail using over 100 bottom samples consisting of grab samples and box, hydroplastic, and piston cores. The sediments in both canyon and intercanyon areas are primarily bioturbated, olive-gray, sandy silts with local features indicative of gravity-induced mass sediment movements (i.e., graded sequences and load structures). C14-based sediment accumulation rates vary by a factor of three in cores separated by as little as 6 km. These variations seem to be a function of shelf-edge spillover rates. Detailed analyses of the sand grain-size distribution throughout the corridor reveal that the sand component of the slope and rise sediments contains a high percentage of material currently present on the adjacent shelf. The relatively large percentage of sandy sediment in the upper parts of cores from Spencer Canyon suggests its recent role in transporting shelf sediments seaward. Sandy intervals in other slope cores are commonly obscured by intense bioturbation. Cores from the continental rise show an upward decrease in the number of sand layers and lenses. Active transport of sediment to the slope and rise occurred during the late Pleistocene and, although the intensity has declined, the slope is presently the site of deposition for both fine and coarse sediment. End_of_Article - Last_Page 1662------------