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A finite element model for the ocean circulation driven by wind and atmospheric heat flux

Carbonel H,Carlos A. A.; Galeão,Augusto C. N. R.
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2010 Português
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A finite element model for solving ocean circulation forced by winds and atmospheric heat fluxes is presented. It is vertically integrated 1 1/2 layer model which solves the motion and continuity hydrodynamic equations coupled with the advection-diffusion transport equation for temperature. A space-time Petrov-Galerkin formulation is used to minimize the undesirable numerical spurious oscillation effects of unresolved boundary layers solution of classical Galerkin method. The model is employed to simulate the circulation of the eastern South Pacific Ocean represented by a mesh covering the area between the equator and 30ºS and between the 70ºW to 100ºW. Monthly climatological data are used to determine the wind and heat fluxes forcing functions of the model. The model simulates the main features of observed sea surface temperature (SST) pattern during the summer months showing the upwelling along the coastal boundary with currents oriented northwestward and the presence of southward flows and warm water intrusion in offshore side. The calculated SST fields are compared with the mean observed SST showing that the coastal processes and the interaction with the equatorial band are physically better resolved.

Timing of the Departure of Ocean Biogeochemical Cycles from the Preindustrial State

Christian, James R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 11/11/2014 Português
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Changes in ocean chemistry and climate induced by anthropogenic CO2 affect a broad range of ocean biological and biogeochemical processes; these changes are already well underway. Direct effects of CO2 (e.g. on pH) are prominent among these, but climate model simulations with historical greenhouse gas forcing suggest that physical and biological processes only indirectly forced by CO2 (via the effect of atmospheric CO2 on climate) begin to show anthropogenically-induced trends as early as the 1920s. Dates of emergence of a number of representative ocean fields from the envelope of natural variability are calculated for global means and for spatial ‘fingerprints’ over a number of geographic regions. Emergence dates are consistent among these methods and insensitive to the exact choice of regions, but are generally earlier with more spatial information included. Emergence dates calculated for individual sampling stations are more variable and generally later, but means across stations are generally consistent with global emergence dates. The last sign reversal of linear trends calculated for periods of 20 or 30 years also functions as a diagnostic of emergence, and is generally consistent with other measures. The last sign reversal among 20 year trends is found to be a conservative measure (biased towards later emergence)...

Evaluating the Use of Ocean Models of Different Complexity in Climate Change Studies

Sokolov, Andrei P.; Dutkiewicz, Stephanie.; Stone, Peter H.; Scott, Jeffery.
Fonte: MIT Joint Program on the Science and Policy of Global Change Publicador: MIT Joint Program on the Science and Policy of Global Change
Tipo: Relatório Formato: 950520 bytes; application/pdf
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The study of the uncertainties in future climate projections requires large ensembles of simulations with different values of model characteristics that define its response to external forcing. These characteristic include climate sensitivity, strength of aerosol forcing and the rate of ocean heat uptake. The latter can be easily varied over a wide range in an anomaly diffusing ocean model (ADOM). The rate of heat uptake in a three-dimensional ocean general circulation model (OGCM) is, however, defined by large number of factors and is far more difficult to vary. Necessity to obtain a realistic ocean circulation places additional constraints, making it impossible to cover the range of values suggested by observations. As a result, a simpler model like an ADOM needs to be used in uncertainty studies. To evaluate the performance of the ADOM on different time scales we compare results of simulations with two versions of the MIT Integrated Global System Model (IGSM): one with a ADOM and the second with a full three-dimensional OCGM. Our results show that through the 20th and 21st century, the version of the IGSM with ADOM is able to reproduce important aspects of the climate response simulated by the version with the OCGM. However, the inability of the ADOM to depict feedbacks associated with the changes in the ocean circulation significantly affects its performance on the longer timescales. In particular...

Overflows and upper ocean interactions : a mechanism for the Azores current

Kida, Shinichiro
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 162 p.
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The oceanic response to overflows is explored using a two-layer isopycnal model. Overflows are a major source of the dense water of the global deep ocean, originating from only a few marginal seas. They enter the open ocean as dense gravity currents down a continental slope and play a crucial role in the deep ocean circulation. To understand the dynamics of these overflows, previous studies simplified their dynamics by treating the overlying ocean as inactive. This simplification may be a first approximation for the overflow but not for the overlying ocean. The Mediterranean overflow, for example, entrains about 2 Sv of overlying Atlantic water when it enters the Atlantic through Gibraltar Strait. The upper ocean must balance the mass loss and vortex stretching associated with entrainment. Thus for the upper ocean, overflows represent a localized region of intense mass and PV forcing. The simulations in this study show that in the upper layer, entrainment forces a cyclonic circulation along bathymetric contours. This is a topographic [beta]-plume and its transport depends on the entrainment region size and the topographic slope.; (cont.) Baroclinic instability also develops and creates eddy thickness flux to the in-shore direction...

Variability of zooplankton and sea surface temperature in the Southern Ocean

Verdy, Ariane
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 74 p.
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Interactions between physical and biological processes in the Southern Ocean have significant impacts on local ecosystems as well as on global climate. In this thesis, I present evidence that the Southern Ocean circulation affects the variability of zooplankton and sea surface temperature, both of which are involved in air-sea exchanges of carbon dioxide. First, I examine the formation of spatial patterns in the distribution of Antarctic krill (Euphausia superba) resulting from social behavior. Turbulence of the flow is found to provide favorable conditions for the evolution social behavior in an idealized biological-physical model. Second, I analyze observations of sea surface temperature variability in the region of the Antarctic circumpolar current. Results suggest that propagating anomalies can be explained as a linear response to local atmospheric forcing by the Southern Annular Mode and remote forcing by El-Nifio southern oscillation, in the presence of advection by a mean flow.; by Ariane Verdy.; Thesis (S.M.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006.; Includes bibliographical references (p. 69-74).

Toward quantifying the impact of atmospheric forcing on Arctic sea ice variability using the NPS 1/12 degree pan-Arctic coupled ice-ocean model

Tseng, Hsien-Liang R.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
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The rapid Arctic sea ice decline since the 1970s has propelled the United States into a state of urgency for updating its defense plan as Arctic and non-Arctic nations alike are taking an interest in the newfound natural resources of an ice-declining Arctic. In line with the National Security Presidential Directive-66, we quantify the amount of anomalous sea ice variability (aSIV) that anomalous atmospheric forcing parameters explain using partial covariance analysis. A one-system approach where the NPS Model sea ice parameters are the direct output of the atmospheric forcing parameters input is employed. Atmospheric forcing fields of 2-m temperature, downward shortwave and longwave fluxes, 10-m zonal and meridional winds and stresses, are from the European Centre for Medium-Range Weather Forecasts Reanalysis-15 and Operational Products. Locations of interest are the Central Arctic seas, and locations along the Northwest Passage (NWP) and the Northern Sea Route (NSR). Results show that the atmospheric parameter having the largest influence on aSIV is anomalous surface air temperature. This occurs during the cooling months and averages 4-39% of aSAT contribution to aSIV in the Central Arctic, 9-16% along the NWP, and 11-25% along the NSR. Results also suggest that atmospheric forcing alone does not explain all of aSIV.

The role of strong atmospheric forcing events in the modification of the upper ocean thermal structure during the cooling season.

Camp, Norman Thomas
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
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49.5765%
The role of strong atmospheric forcing events in determining the evolution of the upper ocean during the fall and early winter cooling season was investigated. The historical series of surface and near-surface marine observations at three mid-latitude ocean weather ships (PAPA (OWS P), NOVEMBER (OWS N), and VICTOR (OWS V)) support the hypothesis that the integrated effects of these events dominate this evolution. For example, periods when the mechanical forcing was greater than the long-term mean accounted for approximately 35% of the time in the record examined at the three stations. However 85%/68%/57% of the sea-surface temperature change at OWS N/OWS P/OWS V occurred during these periods. Forty-nine data sets were examined and modeled during periods of intense fall and winter forcing. The significant thermal structure modifications observed during these strong events were simulated successfully using three modifications of the Kraus and Turner (1967) one- dimensional model. Evidence is presented which demonstrates that the amount of mechanically-generated turbulent kinetic energy available for entrainment decreases as the mixed-layer depth increases. Furthermore, in agreement with Gill and Turner (1976), these case studies suggest that only a small percentage of the convectively-generated turbulent kinetic energy is available for increasing the potential energy of the ocean by entrainment. (Author)

One-dimensional model preditions of ocean temperature anomalies during Fall 1976

Elsberry, Russell L; Gallacher, Patrick Charles; Garwood, Roland W
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
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This report is based on research reported at the NORPAX Co-Principal Investigators Meeting held at Lake Arrowhead, Calif., on *»-8 June 1979; The hypothesis that upper ocean temperature anomalies that developed over the North Pacific Ocean during the fall-winter of 1976-77 were primarily generated by vertical mixing processes was tested using the Garwood (1977) mixed layer model. A series of points along 175 W and along 38 N were chosen for use in this preliminary study. Atmospheric forcing for the one-dimensional ocean model was derived from the surface heat budget calculations in the Fleet Numerical Weather Central (FNWC) atmospheric prediction model. The suitability of the FNWC heat flux calculations was evaluated through comparison with the upper ocean heat content changes derived from the TRANSPAC analyses. The comparisons showed better agreement along 175 W than along 38 N. A series of ocean thermal structure predictions from 15 September to 31 December 1976 were made using the time series of the atmospheric forcing and the initial profile from the September TRANSPAC analysis. In the central region near 38 N, 165 W the predicted thermal structure agreed very well with the TRANSPAC analysis for December 1976. Near the southern and western ends of the domain...

On oceanic forcing of Arctic climate change

Maslowski, W.; Clement, J.; Jakacki, J.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
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Recent dramatic climate change in the Arctic is most manifested by the reduction of multiyear sea ice pack. It has been commonly associated with anomalies of surface air temperature and atmospheric circulation, which in turn have been linked to the Arctic Oscillation (AO). A typical assessment of such hypotheses is the assumption of the dominant role of external atmospheric forcing and the neglect of effects of processes internal to the Arctic Ocean. Especially the oceanic thermodynamic control of sea ice through the under-ice ablation and lateral melt along marginal ice zones tends to be overlooked. However, those ice-ocean interactions may act to de-correlate AO forcing, which helps to explain some of the timing issues between AO/atmospheric forcing and recent sea ice variability.

Evaluation of data sets used to force sea ice models in the Arctic Ocean

Curry, J. A.; Schramm, J. L.; Alam, A.; Reeder, R.; Arbetter, T. E.; Guest, P.
Fonte: American Geophysical Union Publicador: American Geophysical Union
Tipo: Artigo de Revista Científica Formato: 11 p.
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Approved for public release; distribution is unlimited; The article of record as published may be found at http://dx.doi.org/10.1029/2000JC000466; Basin-scale sea ice models are often run uncoupled to either an atmosphere or ocean model to evaluate the sea ice model, to compare different models, and to test changes in physical parameterizations. Such simulations require that the boundary forcing be specified. The specification of atmospheric forcing associated with the surface heat and freshwater fluxes has been done in various sea ice simulation using climatology, numerical weather prediction analyses, or and satellite data. However, the errors in the boundary forcing may be so large that it is difficult to determine whether discrepancies between simulated and observed properties of sea ice should be attributed to deficiencies in the sea ice model or to the boundary forcing. To assess the errors in boundary forcing, we use data from the Surface Heat Budget of the Arctic Ocean (SHEBA) to evaluate various data sets that have been used to provide boundary forcing for sea ice models that as associated with the surface heat and freshwater fluxes. The impact of errors in these data sets on a sea ice model is assessed by using a single-column ice thickness distribution mode...

Mesoscale forcing on ocean waves during Gulf Stream North Wall events

Okon, John A.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: x, 103 p. : col. ill. ;
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Approved for public release; distribution is unlimited; Under meteorological conditions associated with extreme cold air outbreaks (CAO) off the U.S. East Coast, large ocean waves sometimes develop along the North Wall of the Gulf Stream. These wave events produce wave heights above those expected given the short fetch and moderate winds. The highest waves are often very localized, which suggests localized forcing by the atmosphere. In this study, results from four cases are examined to characterize the role of high resolution, mesoscale wind forcing in generating localized regions of large ocean waves during events with large air-sea temperature differences. A known "true" atmosphere is simulated through the use of the Navy's Coupled Oceanographic and Atmospheric Mesoscale Prediction System (COAMPS). Model surface wind output from COAMPS is used to generate a wave field using Wavewatch Three (WW3), which is then compared to buoy observations and ship reports. Results of these cases show the mesoscale wind forcing of ocean waves during CAO and the importance of mesoscale atmospheric modeling in localized generation of ocean wind waves. Additionally, empirical wave forecast techniques are compared to WW3 model output for these cases to further reinforce the mesoscale atmospheric forcing during rapid growth of wind wave events in fetch limited environments.; Lieutenant Commander...

Air-sea interactions and deep convection in the Labrador Sea

Bramson, Laura S.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: ix, 76 p.;28 cm.
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Approved for public release; distribution is unlimited; Deep convection in the oceans, particularly at high latitudes, plays an important role in the climate systems of the world's oceans and atmosphere. This study was conducted to examine atmospheric forcing effects on deep convection in the Labrador Sea. The Naval Postgraduate School one dimensional ocean mixed layer model was applied to the Labrador Sea from February 12 to March 10, 1997. The model was initialized and forced with oceanographic and atmospheric data collected onboard the R/V Knorr during the first field program of the Labrador Sea Deep Convection Experiment. An ocean mixed layer depth close to 1300m was predicted and verified using the observed data. A sensitivity study was conducted using deviations from observations as input to determine how variations in atmospheric forcing could lead to the observed and even deepened ocean mixed layer. Observed Conductivity, temperature and depth (CTD) data were used to verify the model's spatial and temporal predictions of mixed layer temperature, salinity and depth. Model predicted mixed layer depths were usually slightly deeper than those observed. The final model output predicted temperature rather accurately, but model predicted salinity values were consistently low. A variety of sensitivity studies gave new insight to the individual influences of surface fluxes...

Evaluation of COAMPS performance forecasting along coast wind events during a frontal passage; Evaluation of COAMPS forecasting performance of along coast wind events during frontal passages

James, Carl S.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 63 p.
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Approved for public release, distribution is unlimited; Performance of high resolution mesoscale models has been in a continuous state of refinement since their inception. Mesoscale models have become quite skillful in forecasting synoptic scale events such as mid-latitude cyclones. However, atmospheric forcing becomes a much more complicated process when faced with the challenge of forecasting near topography along the coastline. Phenomena such as gap flows, blocked flow winds and low level stratification become important to predictability at these scales. The problem is further complicated by the dynamics of a frontal passage event. The skill of mesoscale models in predicting these winds is not as well developed. This study examines several forecasts by the Coupled Ocean Atmospheric Mesoscale Prediction System (COAMPS) during frontal passage events for the Winter of 2003-2004. An attempt is made to characterize the predictability of the wind speed and direction both before and after frontal passage along the California coast. Synoptic forcing during this time is strong due to the effects of the mid-latitude cyclones propagate across the Pacific. The study's results indicate that the wind field predictability is subject to several consistent errors associated with the passage of fronts over topography. These errors arise due to difficulty in the model capturing weak thermal advection events and topographic wind funneling. The deficiencies in model representation of topography contributes to these errors.; Lieutenant...

First-generation numerical ocean prediction models : goal for the 1980's

Elsberry, Russell L; Garwood, Roland W
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
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This report is based on a talk presented at the Geophysical Fluid Dynamics Laboratory, Princeton, NJ during November 1979.; Using the experience of numerical weather prediction during the 1950's and 1960's as a model, a case is presented for development during the 1980's of an ocean prediction capability. Examples selected from recent research at the Naval Postgraduate School are used to illustrate some aspects of the theoretical background, representation of physical processes, observational-support systems and the justification for a first-generation ocean prediction system; Prepared for: Naval Ocean Research and Development Activity Office of Naval Research, Ocean Science and Technology; http://archive.org/details/firstgenerationn00elsb; NA

Self sustained thermohaline oscillations and their implications for biogeochemical cycles

Zhang, Rong, 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 156 p.; 9141423 bytes; 9141176 bytes; application/pdf; application/pdf
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An ocean general circulation model (OGCM) configured with a paleo ocean bathymetry such as late Permian shows that different modes of ocean circulation might exist in warm climate: a strong 'thermal mode' induced by cooling at high latitudes and a weak 'haline mode' induced by evaporation at subtropics. The 'haline mode', obtained with enhanced freshwater flux and reduced vertical diffusivity, is inherently unstable, flushed by thermally-driven polar convection every few thousand years. A 3-box model of the thermohaline circulation is developed to study the basic physical mechanism of thermohaline oscillations. By including convective adjustment and a parameterization of the localized nature of convection, the box model shows that haline mode is unstable over a certain freshwater forcing/vertical diffusivity range.; (cont.) Self-sustained oscillatory thermohaline circulations, with periods ranging from centuries to several millennia, are supported. When the amplitude of surface freshwater flux exceeds a certain threshold the haline mode stabilizes. The relationship between oscillation periods and the freshwater flux/vertical diffusivity is also studied. Biogeochemical modeling of the late Permian ocean shows that the strong 'thermal mode' leads to well oxygenated deep ocean...

High-latitude forcing of diatom productivity in the southern Agulhas Plateau during the past 350 kyr

Romero, O. E.; Kim, J. H.; Bárcena, M. A.; Hall, Ian R.; Zahn, Rainer; Schneider, R.
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2015 Português
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The hydrography of the Indian-Atlantic Ocean gateway has been connected to high-latitude climate dynamics by oceanic and atmospheric teleconnections on orbital and suborbital timescales. A wealth of sedimentary records aiming at reconstructing the late Pleistocene paleoceanography around the southern African continent has been devoted to understanding these linkages. Most of the records are, however, clustered close to the southern South African tip, with comparatively less attention devoted to areas under the direct influence of frontal zones of the Southern Ocean/South Atlantic. Here we present data of the composition and concentration of the diatom assemblage together with bulk biogenic content and the alkenone-based sea surface temperature (SST) variations for the past 350 kyr in the marine sediment core MD02-2588 (approximately 41°S, 26°E) recovered from the southern Agulhas Plateau. Variations in biosiliceous productivity show a varying degree of coupling with Southern Hemisphere paleoclimate records following a glacial-interglacial cyclicity. Ecologically well-constrained groups of diatoms record the glacial-interglacial changes in water masses dynamics, nutrient availability, and stratification of the upper ocean. The good match between the glacial maxima of total diatoms concentration...

Coupling of Wave and Circulation Models for Predicting Storm-Induced Waves, Surges, and Coastal Inundation

Chen, Yunfeng
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
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Shi, Fengyan; Kirby, James T.; The purpose of this study is to apply coupled systems for wave-current interaction for use in simulating and predicting storm-induced surges, waves and coastal inundation. Two coupled systems are used. One includes model components: ROMS (a three-dimensional ocean model) and SWAN (a third-generation numerical wave model). The other system is NearCoM (a nearshore community model) which couples SWAN and SHORECIRC (a quasi-3D nearshore circulation model). A coupled model system including ROMS and SWAN is based on MCT implementation. It is applied to Delaware Bay for wave and current simulation. The computational domain is a regional ocean scale domain covering the entire Delaware Bay and adjacent shelf region. Numerical results from the coupled system are compared with available wave and current data obtained from Delaware Bay Observing System (DBOS). Comparisons show good agreement between model results and observations. Strong tidal modulations of surface waves are identified in both model results and measured data. A nearshore community model system NearCoM couples SWAN and SHORECIRC models based on the Master Program implementation. The system is used in a series of numerical experiments that are carried out in an idealized...

A study of deep ocean convection and the sea level variability in the North Atlantic

Li, Feili
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
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59.792676%
Yan, Xiao-Hai; Aspects of convection in the Labrador Sea and the circulations from the mid- to high-latitude North Atlantic are investigated using a variety of in-situ, satellite, and atmospheric reanalysis data products. Deep ocean convection in the Labrador Sea has transitioned from a period of intensification during the early 1990s into current stage of weakening with, however, higher variability in strength. Changes in hydrographic properties were used to investigate the evolution of deep convection at the monthly to interannual timescales. The atmospheric forcing characterized by the North Atlantic Oscillation (NAO) index has an important role in setting deep convection variability. On one hand, enhanced atmospheric forcing favors the extremely strong convective activity in the Labrador Sea as happened in the winter of 2008. On the other hand, over longer timescales, the cumulative NAO index is significantly correlated to the interannual variations in the heat content and mixed layer depths in the central Labrador Sea. Moreover, although ongoing warming in the intermediate layers tends to impede rigorous convection down to 1500m depth by steadily adding buoyancy, shallow convection will most likely remain active in the near future. The linkages between the horizontal and the overturning circulations in the North Atlantic were investigated in terms of sea level changes based on altimeter observations. A dipole pattern...

Year-round pack ice in the Weddell Sea, Antarctica: Response and sensitivity to atmospheric and oceanic forcing

Geiger, Cathleen A.; Ackley, Stephen F.; Hibler, M. D.
Fonte: International Glaciology Society Publicador: International Glaciology Society
Tipo: Artigo de Revista Científica
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Final published version; Using a dynamic-thermodynamic numerical sea-ice model, external oceanic and atmospheric forcings on sea ice in the Weddell Sea are examined to identify physical processes associated with the seasonal cycle of pack ice, and to identify further the parameters that coupled models need to consider in predicting the response of the pack ice to climate and ocean-circulation changes. In agreement with earlier studies, the primary influence on the winter ice-edge maximum extent is air temperature. Ocean heat flux has more impact on the minimum ice-edge extent and in reducing pack-ice thickness, especially in the eastern Weddell Sea. Low relative humidity enhances ice growth in thin ice and open-water regions, producing a more realistic ice edge along the coastal areas of the western Weddell Sea where dry continental air has an impact. The modeled extent of the Weddell summer pack is equally sensitive to ocean heat flux and atmospheric relative humidity variations with the more dynamic responses being from the atmosphere. Since the atmospheric regime in the eastern Weddell is dominated by marine intrusions from lower latitudes, with high humidity already, it is unlikely that either the moisture transport could be further raised or that it could be significantly lowered because of its distance from the continent (the lower humidity source). Ocean heat-transport variability is shown to lead to overall ice thinning in the model response and is a known feature of the actual system...

The response of the Gulf of Mexico to wind and heat flux forcing: What has been learned in recent years?

ZAVALA-HIDALGO,JORGE; ROMERO-CENTENO,ROSARIO; MATEOS-JASSO,ADRIANA; MOREY,STEVEN L.; MARTÍNEZ-LÓPEZ,BENJAMÍN
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 Português
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The Loop Current and its shed eddies dominate the circulation and dynamics of the Gulf of Mexico (GoM) basin. Those eddies are strongly energetic and are the cause of intense currents that may penetrate several hundred meters deep. However, there are regions in the GoM and periods of time in which the local atmospheric forcing plays an important role in its dynamics and thermodynamics. The circulation on the shelves, and particularly on the inner shelf, is mainly wind-driven with seasonality, changing direction during the year with periods of favorable upwelling/downwelling conditions. The wind-driven circulation is associated with the transport of waters with different temperature and salinity characteristics from one region to another. The interannual variability of the circulation on the shelves is linked to the atmospheric variability. Intraseasonal variability of the wind patterns considerably affects the likelihood and magnitude of upwelling and downwelling. The geometry of the GoM is such that large-scale winds may drive opposing upcoast/ downcoast currents along different parts of the curving coast, resulting in convergence or divergence zones. The width of the shelves in the GoM is variable;while the West Florida Shelf, the Texas-Louisiana shelf and the Campeche Bank are more than 200 km wide...