We present the evolution of oceanographic conditions off the western coast of South America between 1996 and 1999, including the cold periods of 1996 and 1998–1999 and the 1997–1998 El Niño, using satellite observations of sea level, winds, sea surface temperature (SST), and chlorophyll concentration. Following a period of cold...
We present a modeling study of the upwelling ocean circulation off central Chile (34°–40°S). Using a primitive equation model, we make a numerical simulation of the ocean circulation for summer of 1993, a year characterized by moderate but persistent equatorward winds. The results indicate the formation of an eastern boundary...
Continuous records of upper water column (0–150 m) temperature profiles, spectral distribution of downwelling irradiance, and phytoplankton solar-induced fluorescence at 25 m depth were obtained during the inaugural deployment of the Hawaii Air-sea Logging Experiment, A Long-term Oligotrophic Habitat Assessment (HALE ALOHA) mooring, near the Hawaii Ocean Time-series (HOT) Station...
Satellite-derived pigment concentrations from the west coast time series (WCTS) are averaged into monthly mean fields over the California Current system (CCS) for the period July 1979 to June 1986. Errors caused by the scattering algorithm used in the WCTS are reduced by an empirical correction function, although winter values...
Satellite data from the Geosat altimeter and the Advanced Very High Resolution Radiometer (AVHRR) are used to show the large-scale structure of the surface circulation of the California Current System in summer. These data show the connection between an equatorward jet and temperature front off Oregon that lies within 100...
Data from Geosat and TOPEX altimeters are used to infer the structure of the Peru-Chile Countercurrent, a jet that flows from at least as far north as 10ºS (historical data suggests 7ºS) to 35º–40ºS, maintaining its position between approximately 100–300 km offshore. Although the annual mean current cannot be determined...
Concurrent satellite-measured chlorophyll (CHL), sea surface temperature (SST), sea level anomaly (SLA) and model-derived wind vectors from the 13+ year SeaWiFS period September 1997 – December 2010 quantify time and space patterns of phytoplankton variability and its links to physical forcing in the Pacific Ocean. The CHL fields are a...
On Oregon coastal rocky shores, filter‐feeders were relatively abundant and macrophytes were relatively scarce at Strawberry Hill, whereas opposite abundance patterns occurred at Boiler Bay. To determine whether nearshore oceanographic differences were associated with these patterns, we made shore‐based measurements of nutrient and Chl a concentrations. We used a three‐level...
We examine large-scale atmospheric behavior around the time of the spring and fall transitions in the coastal ocean off the west coast of North America. Records of adjusted sea level (ASL), coastal wind stress, sea level atmospheric pressure (SLP), and 500-mbar heights for the years 1971-1975 and 1980-1983 are analyzed....
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
Altimeter sea surface height (SSH) fields are analyzed to define and discuss the seasonal circulation
over the wide continental shelf in the SW Atlantic Ocean (27°–43°S) during 2001–2012. Seasonal variability
is low south of the Rio de la Plata (RdlP), where winds and currents remain equatorward for most of
the...
Altimeter sea surface height (SSH) fields are analyzed to define and discuss the seasonal circulation
over the wide continental shelf in the SW Atlantic Ocean (27°–43°S) during 2001–2012. Seasonal variability
is low south of the Rio de la Plata (RdlP), where winds and currents remain equatorward for most of
the...
The Kenyan-Tanzanian coastal region in the western Indian Ocean faces several environmental challenges including coral reef conservation, fisheries management, coastal erosion, and nearshore pollution. The region lacks hydrodynamic records and oceanographic studies at adequate spatial and temporal scales to provide information relevant to the local environmental issues. We have developed...
The Kenyan-Tanzanian coastal region in the western Indian Ocean faces several environmental challenges including coral reef conservation, fisheries management, coastal erosion, and nearshore pollution. The region lacks hydrodynamic records and oceanographic studies at adequate spatial and temporal scales to provide information relevant to the local environmental issues. We have developed...
Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the
shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these
exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined
seasonal pattern of SSS during...
Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the
shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these
exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined
seasonal pattern of SSS during...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
The Kenyan-Tanzanian coastal region in the western Indian Ocean faces several environmental challenges including coral reef conservation, fisheries management, coastal erosion, and nearshore pollution. The region lacks hydrodynamic records and oceanographic studies at adequate spatial and temporal scales to provide information relevant to the local environmental issues. We have developed...
We form a new data set of fields of sea level anomalies by combining gridded daily fields derived from altimeter data with coastal tide gauge data. Within approximately 50-80 km of the coast, the altimeter data are discarded and replaced by a linear interpolation between the tide gauge and remaining...
Altimeter sea surface height (SSH) fields are analyzed to define and discuss the seasonal circulation over the wide continental shelf in the SW Atlantic Ocean (27°–43°S) during 2001–2012. Seasonal variability is low south of the Rio de la Plata (RdlP), where winds and currents remain equatorward for most of the...
Satellite‐derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf‐open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well‐defined seasonal pattern of SSS during...
The goal of the Pacific Ocean Boundary Ecosystem and Climate Study
(POBEX) was to diagnose the large-scale climate controls on regional transport
dynamics and lower trophic marine ecosystem variability in Pacific Ocean boundary
systems. An international team of collaborators shared observational and eddy-resolving
modeling data sets collected in the Northeast...
Using satellite sea surface height (SSH) and chlorophyll (CHL), the year 2000 is analyzed to characterize the effects of mesoscale circulation patterns on phytoplankton spatial variability in the California Current (CC) off Baja California. Satellite data are combined with and compared to in situ field measurements (chlorophyll-a and hydrographic variables)...
We evaluate the method of estimating sea surface velocities from sequences of AVHRR and CZCS images using the maximum cross-correlation (MCC) technique. A set of synthetic images is created by advecting an AVHRR-SST field with a QG model velocity field. The MCC method of determining the sea surface velocities is...
The four components of the long-term annual mean net surface heating of the tropical Pacific Ocean between 30°N and 40°S are calculated and portrayed. These flux elements were derived by using the bulk formulas and about 5 million marine weather reports for the years 1957–76. In addition to illustrating the...
An inversion method is presented that determines mesoscale sea surface currents using satellite altimeter data. The method directly uses geostrophic cross-track velocity components, expands the unknown velocity components with spline functions, and includes weighted constraints for divergence and kinetic energy. The success of this method is measured by the misfit...
Insight into the dependence of benthic communities on biological and physical processes in nearshore pelagic environments, long considered a ``black box,'' has eluded ecologists. In rocky intertidal communities at Oregon coastal sites 80 km apart, differences in abundance of sessile invertebrates, herbivores, carnivores, and macrophytes in the low zone were...
Previously published physical and biological data document a zonally oriented frontal region within the California Current system separating colder and more eutrophic water north of ≈33°N from warmer; more stratified, and oligotrophic water farther to the south. Satellite images of phytoplankton pigment from the coastal zone color scanner from 1979-1983...
A 5-year time series of coastal zone color scanner imagery (1980-1983, 1986) is used to examine
changes in the large-scale pattern of chlorophyll pigment concentration coincident with the spring
transition in winds and currents along the west coast of North America. The data show strong
interannual variability in the timing...
Seasonal cycles of coastal wind stress, adjusted sea level (ASL), shelf currents, and water
temperatures off the west coast of North America (35°N to 48°N) are estimated by fitting annual and
semiannual harmonics to data from 1981-1983. Longer records (9-34 years) of monthly ASL indicate
that these two harmonics adequately...
Past measurements off the coast of central Oregon and Washington have shown that the rapid change
from northward monthly mean winter winds to southward summer winds forces a "spring transition" of
the coastal ocean: sea levels and temperatures drop, and mean surface currents shift from northward to
southward. Current and...
A numerical model has been used to investigate the wind-driven circulation in a stratified basin of
moderate size, Lake Tahoe, California-Nevada. Two types of circulation are identified: "direct" circulations,
in which the current directions remain relatively constant and the mean circulation formed over
several days resembles the instantaneous circulation, and...
Two methods of estimating surface velocity vectors from advanced very high resolution radiometer (AVHRR) data were applied to the same set of images and the results were compared with in situ and altimeter measurements. The first method used and automated feature –tracking algorithm and the second method used an inversion...
Satellite-derived data provide the temporal means and seasonal and nonseasonal
variability of four physical and biological parameters off Oregon and Washington
(41°–48.5°N). Eight years of data (1998–2005) are available for surface chlorophyll
concentrations, sea surface temperature (SST), and sea surface height, while six years of
data (2000–2005) are available for...
Monthly composite images from the global coastal zone color scanner
(CZCS) data set are used to provide an initial illustration and comparison of seasonal
and interannual variability of phytoplankton pigment concentration along the western
coasts of South and North America in the Peru Current system (PCS) and California
Current system...
Time series of satellite measurements are used to describe patterns of surface
temperature and chlorophyll associated with the 1996 cold La Nina phase and the 1997-1998
warm El Nino phase of the El Nino - Southern Oscillation cycle in the upwelling region off
northern Chile. Surface temperature data are available...
Over 30 years of hydrographic data from the northern Chile (18°S-24°S) upwelling
region are used to calculate the surface and subsurface seasonal climatology extending 400 km
offshore. The data are interpolated to a grid with sufficient spatial resolution to preserve crossshelf
gradients and then presented as means within four seasons:...
The evolution of oceanographic conditions in the upwelling region off northern Chile
(18°–24°S) between 1996 and 1998 (including the 1997–1998 El Niño) is presented using
hydrographic measurements acquired on quarterly cruises of the Chilean Fisheries Institute, with
sea surface temperature (SST), sea level, and wind speeds from Arica (18.5°S), Iquique...
Mean fields, seasonal cycles, and interannual variability are examined for fields of
satellite-derived chlorophyll pigment concentrations (CHL), sea surface height (SSH), and
sea surface temperature (SST) during 1997–2002. The analyses help to identify three
dynamic regions: an upwelling zone next to the coast, the Ensenada Front in the north,
and...
In this article we analyze the momentum and vorticity balances of a numerical
simulation of the upwelling circulation off central Chile (34° –40°S) and its response to
interannual local wind changes. Our analysis indicates that the path of the upwelling jet is
strongly controlled by the bottom topography. This topographic...
We used wavelet analyses of sea surface height (SSH) from >13 years of satellite
altimeter data to characterize the variability in mesoscale circulation in the northern
California Current (35°N–49°N) and explore the mechanisms of variability. We defined
‘‘mesoscale’’ circulation as features, such as eddies and filaments, which have 50- to...
In this paper, we evaluate the temporal and horizontal resolution of geostrophic
surface velocities calculated from TOPEX satellite altimeter heights. Moored velocities
(from vector-averaging current meters and an acoustic Doppler current profiler) at depths
below the Ekman layer are used to estimate the temporal evolution and accuracy of
altimeter geostrophic...
Present methods used to retrieve altimeter data do not provide reliable estimates of
sea surface height (SSH) in the nearshore region, resulting in a measurement gap of
25–50 km next to the coast. In the present work, gridded SSH fields produced by
Archiving, Validation, and Interpretation of Satellite Oceanographic data...
The objective of this article is to present evidence for
the existence of seasonal variability in sea surface height
(SSH) anomaly in the Agulhas Retroflection region.
TOPEX/POSEIDON altimeter data are used to estimate
seasonal changes in the mesoscale SSH variability.
There is a seasonal oscillation of SSH variability characterized
by...
Data from the Coastal Transition Zone (CTZ) experiment are used to describe the velocity fields and water properties associate with cold filaments in the California Current. Combined with previous field surveys and satellite imagery, these show seasonal variability with maximum dynamic height ranges and velocities in summer and minimum values...
Physical and biological fields in the coastal transition zone off northern California were measured during February, March, May and June 1987 in an extended alongshore region between 60 km and 150 km offshore. The spring transition, as seen in coastal sea level and winds, occurred in mid-March. Surface variability during...
Five years (1997–2002) of northern California Current SeaWiFS ocean color data put cold, low salinity hydrographic anomalies observed in summer 2002 into a spatial/temporal context and present their biological ramifications. Monthly mean chlorophyll concentrations were >1.0 mg m–3 larger than the previous 3 year average over the entire shelf from...
Surface transports into the California Current are calculated from TOPEX/POSEIDON altimeter surface height slopes during the 9.5 year period from October 1992–May 2002. These quantify the anomalous onshore and southward displacements of the water column during the 2000–2002 period, which had been hypothesized by others based on anomalous water properties...
The first three years of SeaWiFS data (1997-2000) provide the most complete quantification to date of chlorophyll seasonal variability along the full latitudinal extent of the four major eastern boundary currents (EBCs). Comparisons to previously published chlorophyll seasonal climatologies deduced from the relatively sparse coverage provided by the Coastal Zone...