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Lifting solutions of quasilinear convection-dominated problems

Ferreira, J. A.; Mouro, A. P.; Oliveira, P.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.82%
In certain cases, quasilinear convection-diffusion-reaction equations range from parabolic to almost hyperbolic, depending on the ratio between convection and diffusion coefficients. From a numerical point of view, two main difficulties can arise related to the existence of layers and/or the non-smoothness of the coefficients of such equations. In this paper we study the steady-state solution of a convection-dominated problem. We present a new numerical method based on the idea of solving an associated modified problem, whose solution corresponds to a lifting of the solution of the initial problem. The method introduced here avoids an a priori knowledge of the layer(s) location and allows an efficient handling of the lack of smoothness of the coefficients. Numerical simulations that show the effectiveness of our approach are included.; http://dx.doi.org/10.1080/00207160802385800

A coupled convection-diffusion level set model for tracking epithelial cells in colonic crypts

Figueiredo, Isabel N.; Leal, Carlos; Leonori, Tommaso; Romanazzi, Giuseppe; Figueiredo, Pedro N.; Donato, M. Manuel
Fonte: Centro de Matemática da Universidade de Coimbra Publicador: Centro de Matemática da Universidade de Coimbra
Tipo: Pré-impressão
ENG
Relevância na Pesquisa
36.82%
Colorectal cancer is initiated in colonic crypts as a consequence of alterations leading to the disruption of the normal colonic cellular process. We propose a new model, which couples a convection-di usion type equation with a level set equation, for tracking the time evolution of an epithelial cell set, inside a colonic crypt, until it reaches the top of the crypt. The convection-di usion equation describes the evolution of the density of the cells in the epithelial cell set. The parameters of this equation regulate the geometric and temporal cellular mechanism, and di erent parameter choices lead to distinct cell behavior. The level set equation tracks the location and shape of the epithelial cell set, inside the crypt, as well as its interface, separating the cell set from the others cells, which reside within the crypt. The interfacial velocity of the epithelial cell set is obtained from the convection-di usion type equation. Some in silico experiments are described. They are performed in a relative small time, with respect to the real biological evolution.

Three-dimensional natural convection in rooms connected to the outside through large openings

Ramos, João António Esteves; Martinho, N. A. G.; Pitarma, Rui A.; Carvalho, Maria da Graça
Fonte: Instituto Politécnico de Leiria Publicador: Instituto Politécnico de Leiria
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2002 ENG
Relevância na Pesquisa
36.82%
The growing interest in the study of natural convection in geometrically complex enclosures with restricted communication has been stimulated by applications involving energy-efficient passive-solar buildings, natural convection cooling of electronic equipment and room heating and ventilation. Airflow through doorways, windows and other large openings are significant ways in which air, pollutants and thermal energy are transferred from one zone of a building to another or to outside. The present paper describes a numerical method for analysing three-dimensional natural convection in rooms connected to the outside through large openings. The calculations made use of a Computational Fluid Dynamics (CDF) procedure taking into account the effects of buoyancy, heat sources, thermal radiation heat transfer and air flow turbulence. The CDF predictions agree with the experimentally observed features of the flow field, including the vertical air temperature stratification, with a reasonable degree of accuracy.

Desenvolvimento de uma técnica não intrusiva de medição do coeficiente de convecção: solução do problema térmico inverso; Development of a non-intrusive technique for measuring of the convection coefficient: solution of the inverse thermal problem

Brandi, Analice Costacurta
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 13/08/2010 PT
Relevância na Pesquisa
36.88%
A tomografia por sensoriamento térmico é muito utilizada em diferentes aplicações industriais, tais como a determinação de propriedades térmicas de novos materiais, o controle da produção de calor e a temperatura no processo de manufatura. Entretanto, o emprego de técnicas tomográficas em processos industriais envolvendo transferência de calor ainda carece de métodos robustos e computacionalmente eficientes. Nesse contexto, o principal objetivo deste trabalho é contribuir para o desenvolvimento de uma técnica não intrusiva de medição do coeficiente de convecção a partir de medidas externas de temperatura e fluxo de calor baseada na solução do problema térmico inverso. Para tanto é necessário resolver um problema de condução acoplado a um problema de convecção de calor. Este acoplamento ocorre através do coeficiente de convecção no interior do domínio do problema, cuja determinação pode ser feita através da aplicação de um fluxo de calor e medição das temperaturas resultantes na superfície externa. A tomografia térmica é tratada como um problema de minimização global, cuja função objetivo é um funcional de erro que quantifica a diferença entre as medidas externas não intrusivas (temperatura real) e as medidas calculadas no modelo numérico (temperatura aproximada). A natureza mal condicionada do problema assim formulado se manifesta na superfície de minimização por produzir topologias problemáticas tais como múltiplos mínimos locais...

Thermally developing forced convection of non-Newtonian fluids inside elliptical ducts

Maia, Cassio Roberto Macedo; Aparecido, João Batista; Milanez, Luiz Fernando
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 13-22
ENG
Relevância na Pesquisa
36.88%
Laminar-forced convection inside tubes of various cross-section shapes is of interest in the design of a low Reynolds number heat exchanger apparatus. Heat transfer to thermally developing, hydrodynamically developed forced convection inside tubes of simple geometries such as a circular tube, parallel plate, or annular duct has been well studied in the literature and documented in various books, but for elliptical duct there are not much work done. The main assumptions used in this work are a non-Newtonian fluid, laminar flow, constant physical properties, and negligible axial heat diffusion (high Peclet number). Most of the previous research in elliptical ducts deal mainly with aspects of fully developed laminar flow forced convection, such as velocity profile, maximum velocity, pressure drop, and heat transfer quantities. In this work, we examine heat transfer in a hydrodynamically developed, thermally developing laminar forced convection flow of fluid inside an elliptical tube under a second kind of a boundary condition. To solve the thermally developing problem, we use the generalized integral transform technique (GITT), also known as Sturm-Liouville transform. Actually, such an integral transform is a generalization of the finite Fourier transform...

A study of the effect of overshooting deep convection on the water content of the TTL and lower stratosphere from Cloud Resolving Model simulations

Grosvenor, D. P.; Choularton, T. W.; Coe, H.; Held, G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 4977-5002
ENG
Relevância na Pesquisa
36.93%
Simulations of overshooting, tropical deep convection using a Cloud Resolving Model with bulk microphysics are presented in order to examine the effect on the water content of the TTL (Tropical Tropopause Layer) and lower stratosphere. This case study is a subproject of the HIBISCUS (Impact of tropical convection on the upper troposphere and lower stratosphere at global scale) campaign, which took place in Bauru, Brazil (22° S, 49° W), from the end of January to early March 2004. Comparisons between 2-D and 3-D simulations suggest that the use of 3-D dynamics is vital in order to capture the mixing between the overshoot and the stratospheric air, which caused evaporation of ice and resulted in an overall moistening of the lower stratosphere. In contrast, a dehydrating effect was predicted by the 2-D simulation due to the extra time, allowed by the lack of mixing, for the ice transported to the region to precipitate out of the overshoot air. Three different strengths of convection are simulated in 3-D by applying successively lower heating rates (used to initiate the convection) in the boundary layer. Moistening is produced in all cases, indicating that convective vigour is not a factor in whether moistening or dehydration is produced by clouds that penetrate the tropopause...

Impact of different internal convection control strategies in a non-evacuated CPC collector performance

Horta, Pedro; Henriques, J.C.C.; Pereira, M. Collares
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
Relevância na Pesquisa
36.82%
Over the last decade the technological advances observed in solar collector materials, namely better spectrally selective absorber coatings and ultra clear glass covers, contribute to performance improvements and translate into higher operational temperature ranges with higher efficiency values. While the use of Evacuated Tube Collectors (ETCs) is becoming widespread in the thermal conversion of solar energy, non-evacuated solar collectors still hold advantages at manufacturing, reliability and/or cost levels, making them interesting and competitive for a large range of applications, in particularly, in temperature ranges up to 80 °C. However, these advantages have not prevented the major drawback of these collectors when compared to ETCs: thermal losses due to internal convection which prevent their general use in the range of operating temperatures up to 150 °C.Insulation, double glazing or selective coatings can be used in non-evacuated collectors to reduce heat losses. To prevent internal convection losses in these solar collectors, different control strategies have been studied, such as the adoption of different inert gases within the collector cavity, physical barriers reducing air flow velocities over the absorber or cover surfaces or the use of concentration. In the present article...

A sensitivity study using two different convection schemes over south america

Pezzi,Luciano Ponzi; Cavalcanti,Iracema F. A.; Mendonça,Antônio M.
Fonte: Sociedade Brasileira de Meteorologia Publicador: Sociedade Brasileira de Meteorologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2008 EN
Relevância na Pesquisa
36.96%
The sensitivity of cumulus convection parameterizations is investigated using the CPTEC/COLA Atmospheric General Circulation Model (AGCM) with T62L28 resolution. This model has been used at CPTEC/INPE since 1995 with the Kuo convective scheme for weather and seasonal climate forecasts. In this study, two sets of integrations are performed using climatological Sea Surface Temperature (SST) of the Southern Hemisphere summer season (December, January and February) as bottom boundary conditions. Five integrations with different initial conditions are applied for each ensemble. The study was divided in two groups, one using the adjusted Relaxed Arakawa-Schubert convection scheme considering modifications in the convection physics (ARAS) and the other one using the Kuo convection scheme (KUO). The atmospheric circulation and precipitation model results are compared with NCEP/NCAR reanalysis data and CMAP precipitation data. The results are analyzed mainly over South America and also for the Southern Hemisphere to verify the model response compared to observed data when different convection scheme is applied. The adjusted scheme for RAS suggested in this study, reduced errors in several areas of South America, when comparing with the previous version. Over most of South America areas KUO gives smaller errors than ARAS. Over tropical Pacific Ocean...

Integral transform solution of natural convection in a square cavity with volumetric heat generation

An,C.; Vieira,C. B.; Su,J.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
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The generalized integral transform technique (GITT) is employed to obtain a hybrid numerical-analytical solution of natural convection in a cavity with volumetric heat generation. The hybrid nature of this approach allows for the establishment of benchmark results in the solution of non-linear partial differential equation systems, including the coupled set of heat and fluid flow equations that govern the steady natural convection problem under consideration. Through performing the GITT, the resulting transformed ODE system is then numerically solved by making use of the subroutine DBVPFD from the IMSL Library. Therefore, numerical results under user prescribed accuracy are obtained for different values of Rayleigh numbers, and the convergence behavior of the proposed eigenfunction expansions is illustrated. Critical comparisons against solutions produced by ANSYS CFX 12.0 are then conducted, which demonstrate excellent agreement. Several sets of reference results for natural convection with volumetric heat generation in a bi-dimensional square cavity are also provided for future verification of numerical results obtained by other researchers.

On the relative role of convection, chemistry, and transport over the South Pacific Convergence Zone during PEM-Tropics B: A case study

Mari, Céline; Saüt, Carine; Jacob, Daniel James; Staudt, Amanda; Avery, Melody A.; Brune, William H.; Faloona, Ian; Heikes, Brian G.; Sachse, Glen W.; Sandholm, Scott T.; Singh, Hanwant B.; Tan, David
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.96%
A mesoscale 3D model (Meso-NH) is used to assess the relative importance of convection (transport and scavenging), chemistry, and advection in the vertical redistribution of HOx and their precursors in the upper tropical troposphere. The study is focused on marine deep convection over the South Pacific Convergence Zone (SPCZ) during the PEM-Tropics B Flight 10 aircraft mission. The model reproduces well the HOx mixing ratios. Vertical variations and the contrast between north and south of the SPCZ for O3 are captured. Convection uplifted O3-poor air at higher altitude, creating a minimum in the 9–12 km region, in both modeled and observed profiles. The model captured 60% of the observed HCHO variance but fails to reproduce a peak of HCHO mixing ratio at 300 hPa sampled during the northern spirals. Simulated HCHO mixing ratios underestimate observations in the marine boundary layer. In the model, convection is not an efficient process to increase upper tropospheric HCHO, and HCHO is unlikely to serve as a primary source of HOx. Convection plays an important role in the vertical distribution of CH3OOH with efficient vertical transport from the boundary layer to the 10–15 km region where it can act as a primary source of HOx. The SPCZ region acts as a barrier to mixing of tropical and subtropical air at the surface and at high altitudes (above 250 hPa). The 400–270 hPa region over the convergence zone was more permeable...

Reconstruction des structures magnéto-convectives solaires sous une région active, par l’utilisation conjointe d’un modèle de convection anélastique et d’une méthode d’assimilation de données.

Pirot, Dorian
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.93%
L’utilisation d’une méthode d’assimilation de données, associée à un modèle de convection anélastique, nous permet la reconstruction des structures physiques d’une partie de la zone convective située en dessous d’une région solaire active. Les résultats obtenus nous informent sur les processus d’émergence des tubes de champ magnétique au travers de la zone convective ainsi que sur les mécanismes de formation des régions actives. Les données solaires utilisées proviennent de l’instrument MDI à bord de l’observatoire spatial SOHO et concernent principalement la région active AR9077 lors de l’ ́évènement du “jour de la Bastille”, le 14 juillet 2000. Cet évènement a conduit à l’avènement d’une éruption solaire, suivie par une importante éjection de masse coronale. Les données assimilées (magnétogrammes, cartes de températures et de vitesses verticales) couvrent une surface de 175 méga-mètres de coté acquises au niveau photosphérique. La méthode d’assimilation de données employée est le “coup de coude direct et rétrograde”, une méthode de relaxation Newtonienne similaire à la méthode “quasi-linéaire inverse 3D”. Elle présente l’originalité de ne pas nécessiter le calcul des équations adjointes au modèle physique. Aussi...

Mixed thermal convection: fundamental issues and analysis of the planar case

PADET,JACQUES; COTTA,RENATO M.; MLADIN,EMILIA C.; PADET,COLETTE
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2015 EN
Relevância na Pesquisa
36.88%
This paper aims to renew interest on mixed thermal convection research and to emphasize three issues that arise from the present analysis: (i) a clear definition of the reference temperature in the Boussinesq approximation; (ii) a practical delimitation of the three convective modes, which are the forced convection (FC), mixed convection (MC) and natural (or free) convection (NC); (iii) and, finally, a uniform description of the set FC/MC/NC in the similarity framework. The planar case, for which analytical solutions are available, allows a detailed illustration of the answers here advanced to the above issues.

Modeling the Plasma Convection in Saturn's Inner Magnetosphere

Liu, Xin
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: application/pdf
ENG
Relevância na Pesquisa
36.93%
Saturn's magnetosphere is unique in the solar system. The rotation-driven convection consists of alternating channels of cool plasma from an interior source moving outward and hot plasma from outside moving inward, making Saturn’s inner magnetosphere a dynamical region. This thesis describes work on developing numerical models to simulate the plasma convection pattern in Saturn's inner magnetosphere. Chapter 2 introduces the numerical Rice Convection Model (RCM), a multi-fluid model that was originally developed for Earth’s magnetosphere. We adapt it for Saturn’s conditions in this thesis. In Chapter 3, we show results of initial RCM simulation runs, in which only cool plasma from the interior source is considered. We also include the Coriolis force and the pickup effect. Because the cool plasma is much denser than the hot plasma and always dominant in determining the convection pattern, it is important and necessary to investigate it first. Chapter 4 compares several cool plasma source models and determines the one that produces the best simulation results when compared to Cassini spacecraft observations. In Chapter 5, we add the finite temperature and associated plasma pressure of the cool plasma. The effect of ionospheric Pedersen conductance is also investigated. Finally in Chapter 6...

The importance of perivitelline fluid convection to oxygen uptake of Pseudophryne bibronii eggs

Mueller, C.; Seymour, R.
Fonte: Univ Chicago Press Publicador: Univ Chicago Press
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
36.99%
The ciliated epithelium of amphibian embryos produces a current within the perivitelline fluid of the egg that is important in the convective transfer of oxygen to the embryo's surface. The effects of convection on oxygen uptake and the immediate oxygen environment of the embryo were investigated in Pseudophryne bibronii. Gelatin was injected into the eggs, setting the perivitelline fluid and preventing convective flow. Oxygen consumption rate (M(.)o₂) and the oxygen partial pressure (Po₂) of the perivitelline fluid were measured in eggs with and without this treatment. M(.)o₂ decreased in eggs without convection at Gosner stages 17-19 under normoxia. The lack of convection also shifted embryos from regulators to conformers as environmental Po₂ decreased. A strong Po₂ gradient formed within the eggs when convection was absent, demonstrating that the loss of convection is equivalent to decreasing the inner radius of the capsule, an important factor in gas exchange, by 25%. M(.)o₂ also declined in stage 26-27 embryos without cilia-driven convection, although not to the extent of younger stages, because of muscular movements and a greater skin surface area in direct contact with the inner capsule wall. This study demonstrates the importance of convective flow within the perivitelline fluid to gas exchange. Convection is especially important in the middle of embryonic development...

Pattern formation in solutal convection: vermiculated rolls and isolated cells

Cartwright, Julyan H. E.; Piro, Oreste; Villacampa, Ana I.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 2373 bytes; 1175297 bytes; text/plain; application/pdf
ENG
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36.93%
8 pages, 3 figures.-- PACS nrs.: 47.27.Te; 47.54.+r; 89.75.Kd.-- Printed version published Nov 1, 2002.; Observations of the peculiar behaviour of a drink of liqueur topped with cream led us to perform experiments showing that the instability is a convection phenomenon that arises through destabilizing surface-tension forces. The convection is solutal: driven by gradients of concentration of a solute, rather than by heat gradients as in the more commonly studied thermal convection. The convective patterns, vermiculated rolls and isolated cells, are quite unlike the usual planforms. They are associated with an elastic surface film, and the Marangoni number is high, characteristic of solutal convection. We have conducted further experiments that reproduce these patterns in simpler working fluids.; JHEC acknowledges the financial support of the Spanish CSIC, Plan Nacional del Espacio contract ESP98-1347. OP acknowledges the Spanish Ministerio de Ciencia y Tecnologia, Proyecto CONOCE, contract BFM2000-1108. AIV acknowledges the financial support of the Spanish MEC, and the hospitality of the Physics Department of the UIB during summer 1997, when this work was begun.; Peer reviewed

Use of a fictitious Marangoni number for natural convection simulation

Arias, Francisco J.; Parks, Geoffrey T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; accepted version
EN
Relevância na Pesquisa
36.96%
This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.04.089; In this paper, a method based on the use of a fictitious Marangoni number is proposed for the simulation of natural thermocapillary convection as an alternative to the traditional effective diffusivity approach. The fundamental difference between these two methods is that the new method adopts convective mass flows in simulating natural convection. Heat transfer in the natural convection simulation is calculated through the mass transport. Therefore, empirical Nusselt numbers correlations required in the effective diffusivity method are eliminated. This represents a clear advantage in the context of design studies where flexibility in varying the geometry unconstrained by the availability of appropriate correlations is highly desirable. The new method is demonstrated using a simple geometrical model. An analytical expression of the fictitious Marangoni number associated with convection between vertical plates is derived and a computational fluid dynamics (CFD) simulation is performed to study the efficacy of the proposed method. The results show that the new method can approximate real natural convection quite accurately and can be used to simulate the convective flow in complex...

Sensitivity of tropical deep convection in global models: effects of horizontal resolution, surface constraints and 3D atmospheric nudging

Chemel, Charles; Russo, Maria; Hosking, Scott; Telford, Paul; Pyle, John
Fonte: Wiley Publicador: Wiley
Tipo: Article; accepted version
Relevância na Pesquisa
36.88%
This is the accepted version of the following article: 'Sensitivity of tropical deep convection in global models: effects of horizontal resolution, surface constraints and 3D atmospheric nudging', which will be published in Atmospheric Science Letters. This record will be updated with citation and DOI after publication.; This Author Accepted Manuscript version will be embargoed until 12 months after publication date to meet the publisher requirements. However the Gold Open Access version will be made available on publication.; We investigate the ability of global models to capture the spatial patterns of tropical deep convection. Their sensitivity is assessed through changing horizontal resolution, surface flux constraints, and constraining background atmospheric conditions. We assess two models at typical climate and weather forecast resolutions. Comparison with observations indicates that increasing resolution generally improves the pattern of tropical convection. When the models are constrained with realistic surface fluxes and atmospheric structure, the location of convection improves dramatically and is very similar irrespective of resolution and parameterisations used in the models.; RCUK, Other

Role of Surface Evapotranspiration on Moist Convection along the Eastern Flanks of the Andes

Sun, Xiaoming
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014
Relevância na Pesquisa
36.93%

The contribution of surface evapotranspiration (ET) to moist convection, cloudiness and precipitation along the eastern flanks of the Andes (EADS) was investigated using the Weather Research and Forecasting (ARW-WRF3.4.1) model with nested simulations of selected weather conditions down to 1.2 km grid spacing. To isolate the role of surface ET, numerical experiments were conducted using a quasi-idealized approach whereby at every time step the surface sensible heat effects are exactly the same as in the reference simulations, whereas the surface latent heat fluxes are prevented from entering the atmosphere.

Energy balance analysis indicates that local surface ET along the EADS influences moist convection primarily through its impact on conditional instability, because it acts as an important source of moist entropy in this region. The energy available for convection decreases by up to ~60% when the ET contribution is withdrawn. In contrast, when convective motion is not thermally driven, or under conditionally stable conditions, latent heating from the land surface becomes secondary. At the scale of the Andes proper, removal of surface ET weakens upslope flows by increasing static stability of the lower troposphere, as the vertical gradient of water vapor mixing ratio tends to be less negative. Consequently...

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
Relevância na Pesquisa
37.01%
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...

Sensitivity of simulated convection to soil moisture in a region in central Amazon

Mendina,M.; Terra,R.
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 01/07/2012 EN
Relevância na Pesquisa
36.88%
We study the sensitivity of convective precipitation to soil moisture in a continental region in Central Amazon based on Atmospheric General Circulation Model (AGCM) simulations and further analyze the physical processes involved, in particular those related to the diurnal cycle. The region was selected based on the analysis of perpetual January simulations with the University of California at Los Angeles AGCM. It shows a uniform and differentiated behavior in the diurnal cycle of convection, which is strongly associated to surface forcing and in opposite phase to large scale ascending motion. Sensitivity to ground wetness was explored based on a control parameter (which varies between 0 and 1) that multiplies evaporation. Results show that the largest sensitivity appears for relatively dry conditions, confirming previous studies. Although evaporation decreases monotonically as the control parameter is reduced, a slight increase in moisture convergence maintains precipitation almost unchanged up to a value of 0.3 of the parameter. The daily maxima in moisture convergence (excluding the extreme case with no evaporation within the region), convective precipitation, and large scale ascending motion at 500 mb are reached in the simulation with a value of 0.4 of the control parameter. Soil and surface temperature increase with decreasing sensitivity parameter...