Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and prod... more Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and production, is typically not considered in studies of the deep sea. Our observations and models demonstrate an unexpected influence of surface-generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern East Pacific Rise. Transport by these deep-reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat flux into the deep-ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities. Because the eddies interacting with the East Pacific Rise are formed seasonally and are sensitive to phenomena such as El Niño, they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea.
TOPEX/Poseidon and ERS-2 satellite altimeter observations and the 1/16° Naval Research Laboratory... more TOPEX/Poseidon and ERS-2 satellite altimeter observations and the 1/16° Naval Research Laboratory (NRL) Layered Ocean Model (NLOM) show the existence of anticyclonic eddies in the Cabo Corrientes - María Islands region off the Mexican West Coast. Analysis of the results demonstrates that: (1) The Cabo Corrientes - María Islands region is characterized by mean poleward coastal currents, driven by local wind forcing. (2) The local currents are intensified by the arrival of baroclinic downwelling coastally trapped waves (CTWs), generated in the equatorial Pacific. (3) Anticyclonic eddies are generated as the intensified local currents pass cape-like features in the coastline or shelf-break geometry. (4) From 1979 to 2001 the CTWs generated an average of 2.35 (2.5) Cabo Corrientes (María Islands) anticyclonic eddies per year. (5) The formation of eddies varies interannually, increasing (decreasing) during El Niño (La Niña) years. Comparison of a variety of numerical simulations, which include different dynamics and/or different wind forcing and/or different topographic effects, suggests that bottom topography, local wind, and baroclinic instabilities are not essential for the eddy generation. It is (a) the capes at Cabo Corrientes and the María Islands and (b) the strong transient events associated with the CTWs that are essential to the formation of these newly recognized eddies.
The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in ... more The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in various parts of the world ocean (the Gulf of Mexico, the northern Gulf of Mexico, the Persian Gulf, the Gulf of California, and the Hawaii region). The horizontal resolution varies between them, but the coarsest is ~3.5 km. Vertical resolution varies from 20 to 32 layers. Lateral boundary forcing is supplied by global or basin- scale versions of HYCOM, and surface wind and heat flux forcing from the Navy Operational Global Atmospheric Prediction System (NOGAPS). The lateral boundary conditions use a "buffer area" for the baroclinic mode where the fine-grid solution is relaxed towards the outer coarse grid solution. The method of Characteristics is used for the barotropic mode. Most of the models assimilate ocean observations via the Navy Coupled Ocean Data Assimilation (NCODA) system. The primary observations include satellite-derived sea surface height and temperature as well as Argo profile data. The NCODA configuration used here is based on multi-variant optimal interpolation and uses the Cooper-Haines (1983) technique for downward projection of surface observations. The forecast length varies but is typically between 3-7 days. The value-added of downscaling to higher resolution is demonstrated through various model-data comparisons, particularly data that was withheld from the data assimilation system. In the Gulf of Mexico, Loop Current Rings and (some) cyclonic rings compare favorably to independently derived thermal fronts measured with multi-channel SST's (MCSST). The northern Gulf of Mexico domain, which represents a triple- nested system, is used to generate ensembles to examine the variance associated with errors in the initial state, surface wind forcing, etc. Near-surface current patterns in the Persian Gulf are compared to drouged drifters. Several of the circulation features in the Hawaii area are compared to observations collected during a recent Navy exercise. The sea level height in the Gulf of California agrees very well with the height measured by coastal tide guage stations. This domain was also used to exhaustively investigate the sensitivity of the lateral boundary condition parameters. The general circulation features in these regions are discussed, as well as technical aspects of the assimilation and validation.
The variability of the Eastern Pacific Warm Pool (EPWP) is studied analyzing observations from th... more The variability of the Eastern Pacific Warm Pool (EPWP) is studied analyzing observations from the Modular Ocean Data Assimilation System, results from the HYbrid Coordinate Ocean Model (HYCOM), and sea surface height anomaly data. Results indicate that the EPWP strengthens and weakens, but remains throughout the year. The monthly variability of the EPWP is primarily forced by the surface heat
The interaction of cyclonic eddies with the Loop Current (LC) evolution is studied using the Navy... more The interaction of cyclonic eddies with the Loop Current (LC) evolution is studied using the Navy Coastal Ocean Model, the Navy Layer Ocean Model, Topex/Poseidon altimetry, and AVHRR images. It is shown that the longest period registered between eddy shedding, from February 1998 to August 1999, is associated with the presence of a large cyclone that remains north of the
Analysis of observations of the Loop Current (LC) northward penetration and LC area, from satelli... more Analysis of observations of the Loop Current (LC) northward penetration and LC area, from satellite sea surface temperature, Topex/Poseidon (TP) sea surface height anomaly, and results from numerical simulations shows that when a relatively large cyclone remains north of the LC, the shedding period between two consecutive eddies may increase. It is shown,that the interaction between the LC and
Operational Oceanography in the 21st Century, 2011
... Harley E. Hurlburt1, E. Joseph Metzger1, James G. Richman1, Eric P. Chassignet2, Yann Drillet... more ... Harley E. Hurlburt1, E. Joseph Metzger1, James G. Richman1, Eric P. Chassignet2, Yann Drillet3, Matthew W. Hecht4, Olivier Le ... for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway ...
A physically-based variability model is developed to explain threshold voltage (V T ) and drain i... more A physically-based variability model is developed to explain threshold voltage (V T ) and drain induced barrier lowering (DIBL) variations, and their correlations. Inputs to the model rely on forward (F) and reverse (R) data of measured transistor pair mismatch. Positionally asymmetric and symmetric random dopant fluctuation components of V T and DIBL variability are identified for SRAMs and analog devices from a 32nm HKMG technology and their correlations explained.
ESSCIRC 2007 - 33rd European Solid-State Circuits Conference, 2007
Logic performance is improved by creating more stress in the channel in advanced CMOS technologie... more Logic performance is improved by creating more stress in the channel in advanced CMOS technologies. Impact of stress on different circuit blocks in a microprocessor chip has not been studied in detail. This paper presents a comprehensive study on the effects of stress and ...
The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in ... more The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in various parts of the world ocean (the Gulf of Mexico, the northern Gulf of Mexico, the Persian Gulf, the Gulf of California, and the Hawaii region). The horizontal resolution varies between them, but the coarsest is ~3.5 km. Vertical resolution varies from 20 to 32 layers.
A great loss of life of marine fauna in the North Region of the Gulf of California (RNGC) in the ... more A great loss of life of marine fauna in the North Region of the Gulf of California (RNGC) in the winter of 1994-1995 is attributed initially to an intentional spill of a chemistry on the part of narcotics traffickers; such asseveration is refuted by an analysis of data of temperature and circulation taken in the same dates in an intense
Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and prod... more Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and production, is typically not considered in studies of the deep sea. Our observations and models demonstrate an unexpected influence of surface-generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern East Pacific Rise. Transport by these deep-reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat flux into the deep-ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities. Because the eddies interacting with the East Pacific Rise are formed seasonally and are sensitive to phenomena such as El Niño, they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea.
Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and prod... more Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and production, is typically not considered in studies of the deep sea. Our observations and models demonstrate an unexpected influence of surface-generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern East Pacific Rise. Transport by these deep-reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat flux into the deep-ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities. Because the eddies interacting with the East Pacific Rise are formed seasonally and are sensitive to phenomena such as El Niño, they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea.
TOPEX/Poseidon and ERS-2 satellite altimeter observations and the 1/16° Naval Research Laboratory... more TOPEX/Poseidon and ERS-2 satellite altimeter observations and the 1/16° Naval Research Laboratory (NRL) Layered Ocean Model (NLOM) show the existence of anticyclonic eddies in the Cabo Corrientes - María Islands region off the Mexican West Coast. Analysis of the results demonstrates that: (1) The Cabo Corrientes - María Islands region is characterized by mean poleward coastal currents, driven by local wind forcing. (2) The local currents are intensified by the arrival of baroclinic downwelling coastally trapped waves (CTWs), generated in the equatorial Pacific. (3) Anticyclonic eddies are generated as the intensified local currents pass cape-like features in the coastline or shelf-break geometry. (4) From 1979 to 2001 the CTWs generated an average of 2.35 (2.5) Cabo Corrientes (María Islands) anticyclonic eddies per year. (5) The formation of eddies varies interannually, increasing (decreasing) during El Niño (La Niña) years. Comparison of a variety of numerical simulations, which include different dynamics and/or different wind forcing and/or different topographic effects, suggests that bottom topography, local wind, and baroclinic instabilities are not essential for the eddy generation. It is (a) the capes at Cabo Corrientes and the María Islands and (b) the strong transient events associated with the CTWs that are essential to the formation of these newly recognized eddies.
The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in ... more The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in various parts of the world ocean (the Gulf of Mexico, the northern Gulf of Mexico, the Persian Gulf, the Gulf of California, and the Hawaii region). The horizontal resolution varies between them, but the coarsest is ~3.5 km. Vertical resolution varies from 20 to 32 layers. Lateral boundary forcing is supplied by global or basin- scale versions of HYCOM, and surface wind and heat flux forcing from the Navy Operational Global Atmospheric Prediction System (NOGAPS). The lateral boundary conditions use a "buffer area" for the baroclinic mode where the fine-grid solution is relaxed towards the outer coarse grid solution. The method of Characteristics is used for the barotropic mode. Most of the models assimilate ocean observations via the Navy Coupled Ocean Data Assimilation (NCODA) system. The primary observations include satellite-derived sea surface height and temperature as well as Argo profile data. The NCODA configuration used here is based on multi-variant optimal interpolation and uses the Cooper-Haines (1983) technique for downward projection of surface observations. The forecast length varies but is typically between 3-7 days. The value-added of downscaling to higher resolution is demonstrated through various model-data comparisons, particularly data that was withheld from the data assimilation system. In the Gulf of Mexico, Loop Current Rings and (some) cyclonic rings compare favorably to independently derived thermal fronts measured with multi-channel SST's (MCSST). The northern Gulf of Mexico domain, which represents a triple- nested system, is used to generate ensembles to examine the variance associated with errors in the initial state, surface wind forcing, etc. Near-surface current patterns in the Persian Gulf are compared to drouged drifters. Several of the circulation features in the Hawaii area are compared to observations collected during a recent Navy exercise. The sea level height in the Gulf of California agrees very well with the height measured by coastal tide guage stations. This domain was also used to exhaustively investigate the sensitivity of the lateral boundary condition parameters. The general circulation features in these regions are discussed, as well as technical aspects of the assimilation and validation.
The variability of the Eastern Pacific Warm Pool (EPWP) is studied analyzing observations from th... more The variability of the Eastern Pacific Warm Pool (EPWP) is studied analyzing observations from the Modular Ocean Data Assimilation System, results from the HYbrid Coordinate Ocean Model (HYCOM), and sea surface height anomaly data. Results indicate that the EPWP strengthens and weakens, but remains throughout the year. The monthly variability of the EPWP is primarily forced by the surface heat
The interaction of cyclonic eddies with the Loop Current (LC) evolution is studied using the Navy... more The interaction of cyclonic eddies with the Loop Current (LC) evolution is studied using the Navy Coastal Ocean Model, the Navy Layer Ocean Model, Topex/Poseidon altimetry, and AVHRR images. It is shown that the longest period registered between eddy shedding, from February 1998 to August 1999, is associated with the presence of a large cyclone that remains north of the
Analysis of observations of the Loop Current (LC) northward penetration and LC area, from satelli... more Analysis of observations of the Loop Current (LC) northward penetration and LC area, from satellite sea surface temperature, Topex/Poseidon (TP) sea surface height anomaly, and results from numerical simulations shows that when a relatively large cyclone remains north of the LC, the shedding period between two consecutive eddies may increase. It is shown,that the interaction between the LC and
Operational Oceanography in the 21st Century, 2011
... Harley E. Hurlburt1, E. Joseph Metzger1, James G. Richman1, Eric P. Chassignet2, Yann Drillet... more ... Harley E. Hurlburt1, E. Joseph Metzger1, James G. Richman1, Eric P. Chassignet2, Yann Drillet3, Matthew W. Hecht4, Olivier Le ... for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway ...
A physically-based variability model is developed to explain threshold voltage (V T ) and drain i... more A physically-based variability model is developed to explain threshold voltage (V T ) and drain induced barrier lowering (DIBL) variations, and their correlations. Inputs to the model rely on forward (F) and reverse (R) data of measured transistor pair mismatch. Positionally asymmetric and symmetric random dopant fluctuation components of V T and DIBL variability are identified for SRAMs and analog devices from a 32nm HKMG technology and their correlations explained.
ESSCIRC 2007 - 33rd European Solid-State Circuits Conference, 2007
Logic performance is improved by creating more stress in the channel in advanced CMOS technologie... more Logic performance is improved by creating more stress in the channel in advanced CMOS technologies. Impact of stress on different circuit blocks in a microprocessor chip has not been studied in detail. This paper presents a comprehensive study on the effects of stress and ...
The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in ... more The Hybrid Coordinate Ocean Model (HYCOM) is used to forecast the three-dimensional structure in various parts of the world ocean (the Gulf of Mexico, the northern Gulf of Mexico, the Persian Gulf, the Gulf of California, and the Hawaii region). The horizontal resolution varies between them, but the coarsest is ~3.5 km. Vertical resolution varies from 20 to 32 layers.
A great loss of life of marine fauna in the North Region of the Gulf of California (RNGC) in the ... more A great loss of life of marine fauna in the North Region of the Gulf of California (RNGC) in the winter of 1994-1995 is attributed initially to an intentional spill of a chemistry on the part of narcotics traffickers; such asseveration is refuted by an analysis of data of temperature and circulation taken in the same dates in an intense
Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and prod... more Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and production, is typically not considered in studies of the deep sea. Our observations and models demonstrate an unexpected influence of surface-generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern East Pacific Rise. Transport by these deep-reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat flux into the deep-ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities. Because the eddies interacting with the East Pacific Rise are formed seasonally and are sensitive to phenomena such as El Niño, they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea.
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Papers by Luis Zamudio