Download or read book Sensitivities of Deep ocean Heat Uptake and Heat Content to Surface Fluxes and Subgrid scale Parameters in an Ocean GCM with Idealized Geometry written by Boyin Huang and published by . This book was released on 2002 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sensitivities of the net heat flux into the deep-ocean (Qnet) and of the deep-ocean heat content (DOC) below 700 m are studied using an ocean general circulation model and its adjoint. Both are found to have very similar sensitivities. The sensitivity to the surface freshwater flux (E-P-R) is positive in the Atlantic, but negative in the Pacific and Southern Ocean. A positive sensitivity to the downward net surface heat flux is found only in the North Atlantic north of 40ʻN and the Southern Ocean. The diapycnal diffusivity of temperature affects Qnet and DOC positively in a large area of the tropics and subtropics in both the Pacific and Atlantic Ocean. The isopycnal diffusivity contributes to Qnet and DOC mainly in the Southern Ocean. Detailed analysis indicates that the surface freshwater flux affects Qnet and DOC by changing vertical velocity, temperature stratification, and overturning circulation. The downward net surface heat flux appears to increase Qnet and DOC by strengthening vertical advection and isopycnal mixing. The contribution of isopycnal diffusivity to Qnet and DOC is largely associated with the vertical heat flux due to isopycnal mixing. Similarly, the diapycnal diffusivity of temperature modulates Qnet and DOC through the downward heat flux due to diapycnal diffusion. The uncertainties of Qnet and DOC are estimated based on the sensitivities and error bars of observed surface forcing and oceanic diffusivities. For DOC, they are about 0.7°K (1°K = 3 x 1024 J) for the isopycnal diffusivity, 0.4°K for the diapycnal diffusivity of temperature, 0.3°K for the surface freshwater flux, and 0.1°K for the net surface heat flux and zonal wind stress. Our results suggest that the heat uptake by ocean GCMs in climate experiments is sensitive to the isopycnal diffusivity as well to the diapycnal thermal diffusivity.

Download or read book Sensitivities of Deep ocean Heat Uptake and Heat Content in an OGM with Idealized Geometry written by Boyin Huang and published by . This book was released on 2003 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) The uncertainties of Qnet and DOC are estimated based on the sensitivities and error bars of observed surface forcing and oceanic diffusivities. For DOC, they are about 0.7°K (1°K = 3 x 1024J) for the isopycnal diffusivity, 0.4°K for the diapycnal diffusivity of temperature, 0.3°K for the surface freshwater flux, and 0.1°K for the net surface heat flux and zonal wind stress. Our results suggest that the heat uptake by ocean GCMs in climate experiments is sensitive to the isopycnal diffusivity as well to the diapycnal thermal diffusivity.

Download or read book The Deep ocean Heat Uptake in Transient Climate Change written by Boyin Huang and published by . This book was released on 2002 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The deep-ocean heat uptake (DOHU) in transient climate changes is studied using an ocean general circulation model (OGCM) and its adjoint. The model configuration consists of idealized Pacific and Atlantic basins. The model is forced with the anomalies of surface heat and freshwater fluxes from a global warming scenario with a coupled model using the same ocean configuration. In the scenario CO2 concentration increases 1% per year. The heat uptake calculated from the coupled model and from the adjoint are virtually identical, showing that the heat uptake by the OGCM is a linear process. After 70 years the ocean heat uptake is almost evenly distributed within the layers above 200 m, between 200 and 700 m, and below 700 m (about 20 x 1022 J in each). The effect of anomalous surface fresh water flux on the DOHU is negligible. Analysis of CMIP-2 data for the same global warming scenario shows that qualitatively similar results apply to coupled atmosphere-ocean GCMs. The penetration of surface heat flux to the deep ocean in our OGCM occurs mainly in the North Atlantic and the Southern Ocean, since both the sensitivity of DOHU to the surface heat flux and the magnitude of anomalous surface heat flux are large in these two regions. The DOHU relies on the reduction of convection and Gent-McWilliams-Redi mixing in the North Atlantic, and the reduction of Gent-McWilliams- Redi mixing in the Southern Ocean.

Download or read book Ocean Heat Uptake in Transient Climate Change written by Boyin Huang and published by . This book was released on 2003 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) Experiments are carried out with values of the diffusivity of 500, 1000, and 2000 m2/sec. The total OHU is insensitive to these changes. The insensitivity is mainly due to the changes in the vertical heat flux by GMR mixing being compensated by changes in the other vertical heat flux components. In the Atlantic when the diffusivity is reduced from 1000 to 500 m2/sec, the surface warming can penetrate deeper. Therefore, the warming decreases by about 0.158C above 2000 m but increases by about 0.158C below 2500 m. Similarly, when the diffusivity is increased from 1000 to 2000 m2 s21, the surface warming becomes shallower; the warming increases by about 0.28C above 1000 m but decreases by about 0.28C below 1000 m. These changes in the vertical distribution of the OHU also contribute to the insensitivity of the total OHU to changes in the GMR mixing ...

Download or read book Open Ocean Convection and the Uptake of Heat by the Deep Ocean written by Sarah Marcil and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Understanding how the ocean takes up heat is crucial to improve prediction of the future global surface temperature increase. While many previous studies have evaluated the spatial distribution of heat content change across the global ocean, a complete explanation of the mechanisms responsible for this distribution remains largely unknown, and hence, we lack a measureable indicator of model performance that could help constrain future prediction. We examine a large ensemble of climate models to understand what creates the large inter-model variability in heat content change under global warming. Based on earlier studies on ocean vertical heat transfer, we hypothesize that open water deep convection is an important mechanism for the transfer of heat from the deep ocean to the atmosphere. Therefore, the cessation of convection, as predicted in future climate change scenario, would contribute to the increase of deep ocean heat content. We compare the convective volume and ocean heat content anomalies in 34 climate models of the IPCC Assessment Report 5. Most of models show signs of open water deep convection in the North Atlantic and in the Southern Ocean, and the variability in convective volume is linked to ocean heat content anomalies in individual models. In order to identify the most realistic climate models in term of these parameters, we compare the model convection against observations. While convection in some models is a robust predictor of deep ocean heat uptake, the models suggest a diversity of processes plays a role in the transfer of heat to the deep ocean." --

Download or read book Natural Climate Variability on Decade to Century Time Scales written by National Research Council and published by National Academies Press. This book was released on 1996-08-30 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reflects the current state of scientific knowledge about natural climate variability on decade-to-century time scales. It covers a wide range of relevant subjects, including the characteristics of the atmosphere and ocean environments as well as the methods used to describe and analyze them, such as proxy data and numerical models. They clearly demonstrate the range, persistence, and magnitude of climate variability as represented by many different indicators. Not only do natural climate variations have important socioeconomic effects, but they must be better understood before possible anthropogenic effects (from greenhouse gas emissions, for instance) can be evaluated. A topical essay introduces each of the disciplines represented, providing the nonscientist with a perspective on the field and linking the papers to the larger issues in climate research. In its conclusions section, the book evaluates progress in the different areas and makes recommendations for the direction and conduct of future climate research. This book, while consisting of technical papers, is also accessible to the interested layperson.

Download or read book Sensitivity of the Ocean s Climate to Diapycnal Diffusivity in an EMIC written by Fabio Dalan and published by . This book was released on 2005 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: (cont.) Surface warming, induced by enhanced CO2 in the atmosphere, leads to a reduction of the isopycnal slope which translates into a reduction of the above fluxes. The amount of reduction is directly related to the magnitude of the isopycnal diffusive flux and GM advective flux at equilibrium. These latter fluxes depend on the thickness of the thermocline at equilibrium, hence on the diapycnal diffusion. Thus, the increase of deep-ocean heat uptake with diapycnal diffusivity is an indirect effect that the latter parameter has on the isopycnal diffusion and GM advection.

Download or read book Comparing Oceanic Heat Uptake in Atmosphere ocean General Circulation Model Transient Climate Change Experiments written by Andrei P. Sokolov and published by . This book was released on 2003 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transient response of both surface air temperature and deep ocean temperature to an increasing external forcing strongly depends on climate sensitivity and the rate of the heat mixing into the deep ocean, estimates for both of which have large uncertainty. In this paper a method for estimating rates of oceanic heat uptake for coupled atmosphere-ocean general circulation models from results of transient climate change simulations is described. For models considered in this study, the estimates vary by a factor of 2 1/2. Nevertheless, values of oceanic heat uptake for all models fall in the range implied by the climate record for the last century. It is worth noting that the range of the model values is narrower than that consistent with observations and thus does not provide a full measure of the uncertainty in the rate of oceanic heat uptake.

Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.

Download or read book A New Approach for Coupled GCM Sensitivity Studies written by and published by . This book was released on 2003 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Subgrid parameterization of surface heat and momentum fluxes over polar oceans written by T. VIHMA and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tracking Ocean Heat Uptake During the Surface Warming Hiatus written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean heat uptake is observed to penetrate deep during the recent hiatus1,2,3 of global warming in the Atlantic and Southern Ocean. This has been suggested to indicate that the two regions are the driver of the surface warming hiatus4. We show that the deep heat penetration in the Atlantic and Southern Ocean is not unique to the hiatus but common to the past four decades including the 1970s-90s epoch of accelerated surface warming. Our analyses of a large ensemble simulation5 confirm the deep heat penetration in the Atlantic and Southern Ocean in ensemble members with or without surface warming hiatus in the early 21th century. During the past four decades, the global ocean heat content (OHC) of upper 1500m is dominated by a warming trend, and the depth of anthropogenic heat penetration merely reflects the depth of the mean meridional overturning circulation in the basin. Furthermore, the heat penetration depth is not a valid basis to infer the hiatus mechanism.

Download or read book Improving Our Understanding of the Relationship Between Ocean Heat Uptake and Climate Sensitivity written by Michael Cameron Rencurrel and published by . This book was released on 2020 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Surface Heat Flux Uncertainties and Their Impacts on the Study of Ocean Mixed Layer Temperature Variability written by Jason Brent Roberts and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: A major theme of recent research is the investigation of the nature of climate variability and the current capability to measure, model, and predict it. This is a formidable task that involves understanding complex interactions and exchanges of energy between the major elements of the Earth system. With their ability to store and release vast quantities of heat, the oceans are an integral element of climate variability. Accurately modeling coupled atmosphere-ocean variability relies upon a proper characterization of the exchanges of heat and momentum across the air-sea interface. The exchange of heat takes place through net shortwave and terrestrial radiative fluxes and turbulent exchanges of heat and moisture. Estimating these interactions with sufficient accuracy is a difficult challenge. These processes contain inherent errors due to insufficient knowledge of physics, observational uncertainty, and parameterization deficiencies. Uncertainties arising from the estimation of the surface turbulent and radiative processes generate limitations to the understanding of the primary mechanisms governing oceanic variability. This work elucidates the impact of uncertainties in the estimation of turbulent and radiative heat fluxes on the analysis of the mixed layer temperature balance, an effect that has not been properly quantified although recognized in most previous analyses. In particular, this work focuses on variability at seasonal and intraseasonal time scales. The analyses of this work include- i) an updated characterization of uncertainties in current state-of-the-art estimates of the turbulent and radiative heat fluxes, ii) an examination of the closure of the mixed layer temperature balance on seasonal and intraseasonal time scales, iii) an evaluation of the sensitivity of the mixed layer temperature balance to differences between surface heat flux estimates, iv) the development of a flexible approach by which to determine required accuracies of the net surface heat flux, and v) an exploration of the role of mixed layer depth variability on the mixed layer temperature balance. Taken together, the results of these analyses provide a framework to understand the impact of surface heat flux uncertainties within the context of upper ocean mixed layer variability. The analyses performed in this study have exploited a set of eight turbulent and six radiative heat flux estimates. An intercomparison of these products has revealed that the typical spread between products has been reduced relative to previous generations of estimates. Differences between radiative and turbulent heat flux estimates are typically within 15-20% of one another on regional and seasonal scales although larger uncertainties remain in traditionally problematic regions (e.g., cloud-topped boundary layers, western boundary currents). On both intraseasonal and seasonal time scales, the ocean mixed layer is controlled most strongly by the net shortwave and turbulent latent heat fluxes over the world oceans with the exception of the deep tropics wherein oceanic processes are also important. The current ensemble mean estimates of the net surface heat fluxes and oceanic process are capable of resolving the upper ocean mixed layer temperature seasonal cycle quite well in many locations; areas of strong net heat flux warming are somewhat problematic. On intraseasonal time scales, small signal to noise ratios and large residual imbalances leave little room to make definitive conclusions on the role of individual elements of mixed layer forcing. However, general features of the relative importance of surface heat flux variability versus oceanic variability are supported from previous studies. The mixed layer temperature balance is found to be most sensitive to uncertainties in the latent and net shortwave heat fluxes. The timing of the shoaling of the mixed layer depth is also important to the sensitivity of the mixed layer temperature balance. Taking into account mixed layer depth variability is found to be important to understanding the role of the net surface heat fluxes in generating mixed layer temperature warming and cooling. Current estimates of the net heat flux uncertainty are outside of the traditional 10 W m &minus 2 goal on seasonal time scales and spatial scales on the order of 1000 km. The approach designed within this investigation suggests that a 10 W m &minus 2 limit is somewhat too restricting if the aim is to resolve the seasonal mixed layer temperature evolution. In short, the use of the ocean mixed layer temperature balance has provided a unique framework for translating uncertainties in the surface heat flux estimates into a practical context. It is hoped that a better appreciation of these uncertainties will lead to an improved ability to model and understand the mechanisms by which the oceans contribute to variability of Earth's climate.

Download or read book Atmospheric and Oceanic Fluid Dynamics written by Geoffrey K. Vallis and published by Cambridge University Press. This book was released on 2006-11-06 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid dynamics is fundamental to our understanding of the atmosphere and oceans. Although many of the same principles of fluid dynamics apply to both the atmosphere and oceans, textbooks tend to concentrate on the atmosphere, the ocean, or the theory of geophysical fluid dynamics (GFD). This textbook provides a comprehensive unified treatment of atmospheric and oceanic fluid dynamics. The book introduces the fundamentals of geophysical fluid dynamics, including rotation and stratification, vorticity and potential vorticity, and scaling and approximations. It discusses baroclinic and barotropic instabilities, wave-mean flow interactions and turbulence, and the general circulation of the atmosphere and ocean. Student problems and exercises are included at the end of each chapter. Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-Scale Circulation will be an invaluable graduate textbook on advanced courses in GFD, meteorology, atmospheric science and oceanography, and an excellent review volume for researchers. Additional resources are available at www.cambridge.org/9780521849692.

Download or read book The Importance of Open boundary Estimation for an Indian Ocean GCM data Synthesis written by Qian Zhang and published by . This book was released on 1998 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Next Generation Earth System Prediction written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-08-22 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the nation's economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices. Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation's S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.