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Author: Suneil Iyer Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Air-sea interactions are a critical component of the global climate system. Despite this, uncertainty remains in our understanding of air-sea interaction across spatial scales, particularly on small scales, which are not observable by remote sensing and often not explicitly represented in models due to computational limitations. This dissertation provides insight into the key processes that drive air-sea interaction in two tropical regions that are important for modulating synoptic to global-scale weather and climate: the inter-tropical convergence zone and the trade winds. The first chapter uses a series of model experiments based on observations from the rainy eastern tropical Pacific to evaluate the influence of preexisting ocean stratification and tropical rain modes on the upper ocean salinity response to rainfall, a process that modulates how freshwater is incorporated into the ocean structure. Differences in the timing of convective and stratiform components of rain events can modify the duration which surface salinity anomalies persist following rain for over two hours, while strong preexisting stratification can allow near-surface salinity anomalies produced by rain to persist for over seven hours longer compared to when rain falls on a well-mixed ocean. Similar differences in salinity structure can exist at deeper depths of up to 20 meters in the mixed layer. This work provides insight into the limitations of using low-resolution satellite rain observations in the context of physical oceanographic studies and examines a critical component of the global water cycle. The second and third chapters use observations from surface drifters and autonomous vehicles that measure the atmosphere and near-surface ocean in the tropical Atlantic trade wind region to evaluate the spatial variability of ocean surface waves and bulk air-sea fluxes. While previous research has mostly been limited to areas having particularly strong submesoscale activity, this work provides insight into the spatial variability present in a less energetic region representative of larger areas of the global ocean. Surface current variability in the trade winds influence wave slope and air-sea momentum flux due to changes in the relative wind speed and wave-current interactions. Wave-current interactions specifically modify momentum flux by as much as 10%. Across scales of tens of kilometers, air-sea sensible heat, latent heat, and upward buoyancy fluxes vary by 10, 50, and 10 watts per square meter. Sensible heat and upward buoyancy fluxes are significantly influenced by spatial sea surface temperature variability, while latent heat flux variability is primarily driven by changes in the atmosphere. The findings from this work could ultimately be used to guide the development of fully coupled atmosphere-wave-ocean models or quantify the limitations of using lower-resolution remote observations or models. Collectively, the following work serves to elucidate the physics of the dominant small-scale air-sea processes in two regions of the tropical ocean, quantify the influence of these processes on air-sea interaction and upper-ocean mixing, and suggest hypotheses on the implications of neglecting small-scale processes in regional or global studies of the coupled air-sea system.
Author: Suneil Iyer Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Air-sea interactions are a critical component of the global climate system. Despite this, uncertainty remains in our understanding of air-sea interaction across spatial scales, particularly on small scales, which are not observable by remote sensing and often not explicitly represented in models due to computational limitations. This dissertation provides insight into the key processes that drive air-sea interaction in two tropical regions that are important for modulating synoptic to global-scale weather and climate: the inter-tropical convergence zone and the trade winds. The first chapter uses a series of model experiments based on observations from the rainy eastern tropical Pacific to evaluate the influence of preexisting ocean stratification and tropical rain modes on the upper ocean salinity response to rainfall, a process that modulates how freshwater is incorporated into the ocean structure. Differences in the timing of convective and stratiform components of rain events can modify the duration which surface salinity anomalies persist following rain for over two hours, while strong preexisting stratification can allow near-surface salinity anomalies produced by rain to persist for over seven hours longer compared to when rain falls on a well-mixed ocean. Similar differences in salinity structure can exist at deeper depths of up to 20 meters in the mixed layer. This work provides insight into the limitations of using low-resolution satellite rain observations in the context of physical oceanographic studies and examines a critical component of the global water cycle. The second and third chapters use observations from surface drifters and autonomous vehicles that measure the atmosphere and near-surface ocean in the tropical Atlantic trade wind region to evaluate the spatial variability of ocean surface waves and bulk air-sea fluxes. While previous research has mostly been limited to areas having particularly strong submesoscale activity, this work provides insight into the spatial variability present in a less energetic region representative of larger areas of the global ocean. Surface current variability in the trade winds influence wave slope and air-sea momentum flux due to changes in the relative wind speed and wave-current interactions. Wave-current interactions specifically modify momentum flux by as much as 10%. Across scales of tens of kilometers, air-sea sensible heat, latent heat, and upward buoyancy fluxes vary by 10, 50, and 10 watts per square meter. Sensible heat and upward buoyancy fluxes are significantly influenced by spatial sea surface temperature variability, while latent heat flux variability is primarily driven by changes in the atmosphere. The findings from this work could ultimately be used to guide the development of fully coupled atmosphere-wave-ocean models or quantify the limitations of using lower-resolution remote observations or models. Collectively, the following work serves to elucidate the physics of the dominant small-scale air-sea processes in two regions of the tropical ocean, quantify the influence of these processes on air-sea interaction and upper-ocean mixing, and suggest hypotheses on the implications of neglecting small-scale processes in regional or global studies of the coupled air-sea system.
Author: Carlos R. Mechoso Publisher: Cambridge University Press ISBN: 1108492703 Category : Science Languages : en Pages : 359
Book Description
A comprehensive review of interactions between the climates of different ocean basins and their key contributions to global climate variability and change. Providing essential theory and discussing outstanding examples as well as impacts on monsoons, it a useful resource for graduate students and researchers in the atmospheric and ocean sciences.
Author: Jacques C. J. Nihoul Publisher: Elsevier Publishing Company ISBN: Category : Electronic books Languages : en Pages : 800
Book Description
The exchange of momentum, heat, moisture, gases (such as CO 2 and O 2 ) and salt between the atmosphere and the ocean is a phenomenon of paramount importance for the dynamics of the atmosphere and the ocean. With the pressing need for reliable climate forecast (e.g. to deal with severe food and energy problems) interactive ocean-atmosphere models have become one of the main objectives of geophysical fluid dynamics. This volume provides the first state-of-the-art review of interactive ocean-atmosphere modelling and its application to climates. The papers are by active and eminent scientists from different countries and different disciplines. They provide a up-to-date survey of major recent discoveries and valuable recommendations for future research."
Author: Chunzai Wang Publisher: American Geophysical Union ISBN: Category : Nature Languages : en Pages : 426
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 147. It is more than 30 years since the publication of Jacob Bjerknes' groundbreaking ideas made clear the importance of ocean-atmosphere interaction in the tropics. It is now more than 20 years since the arrival of a massive El Niño in the fall of 1982 set off a cascade of observational and theoretical studies. During the following decades, the climate research community has made exceptional progress in refining our capacity to observe earth's climate and theorize about it, including new satellite-based and in situ monitoring systems and coupled ocean-atmosphere predictive numerical models. Of equal importance. is the expanding scope ofresearch, which now reaches far beyond the Pacific El Niño and includes climate phenomena in other ocean basins. In order to cover the now global context of ocean-atmosphere interaction we have organized this monograph around five principal themes, each introduced by one or more broad overview papers. Theme I covers interaction and climate variability in the Pacific sector, with extensive discussion of El Niño-Southern Oscillation, and with the possible causes and consequences of variability on both shorter and longer timescales. Theme II is devoted to interaction in the Atlantic sector. This basin exhibits complex behavior, reflecting its geographic location between two major zones of convection as well as neighboring the tropical Pacific. Theme III reviews the recent, exciting progress in our understanding of climate variability in the Indian sector. Theme IV addresses the interaction between the tropics and the extratropics, which are linked through the presence of shallow meridional overturning cells in the ocean. Finally, Theme V discusses overarching issues of cross-basin interaction.
Author: Jackie Crystal May Publisher: ISBN: Category : Meteorology Languages : en Pages : 0
Book Description
The atmosphere and the ocean interact through air-sea heat and momentum fluxes. Thesefluxes are critical in ocean, atmosphere, and coupled modeling across a broad range of spatial and temporal scales, from large-scale global modeling to very high-resolution regional studies and from climate studies to operational forecasting. It is important to minimize the air-sea flux errors in order to obtain accurate and realistic model results. This study investigates two sources of air-sea flux errors within the Gulf Stream region during winter months: the horizontal model resolution of the atmosphere and the ocean, and the dynamical coupling and current feedback between the ocean surface currents and the wind stress. Four different atmospheric and ocean coupled model simulations are completed with various combinations of 2 km (submesoscale resolving) and 6 km (submesoscale permitting) grid spacing. Four additional model simulations are completed using the same model resolutions defined in the first four experiments, but the coupling and feedback between the surface currents and the wind stress is included. The dynamical coupling and the current feedback lead to large changes in the surfacestress and stress curl patterns. This leads to a reduction in the ocean's mean and eddy kinetic energy, which largely controls the Gulf Stream path. The dynamical coupling is also found to control the physical gradient related to the atmospheric horizontal momentum advection. The stress gradient largely explains the variability in the horizontal advection when the dynamical coupling is not included, while the current gradient across current direction largely explains the variability in the horizontal advection when the dynamical coupling is included. Additionally, the dynamical coupling and current feedback is found to be important in regulating the mixed layer depth and SST throughout the warm water to the right of the Gulf Stream path due to the horizontal heat advection in the mixed layer. A high-resolution ocean model is found to also be important in influencing the Gulf Stream path, as well as constraining the submesoscale vertical heat fluxes to the ocean's mixed layer. The atmospheric model resolution is found to impact the magnitude of the stress, wind work, sea surface height, and surface currents, in addition to the strength of the horizontal and vertical winds throughout the atmospheric column. The dynamical coupling and current feedback, as well as having a high-resolution atmosphere and ocean, is further found to be important in the vertical extent of the state parameter fields, as well as in the atmospheric circulation patterns.
Author: National Academies of Sciences, Engineering, and Medicine Publisher: National Academies Press ISBN: 0309388805 Category : Science Languages : en Pages : 351
Book Description
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.
Author: Suneil Iyer
Author: Suneil Iyer
Author: Carlos R. Mechoso
Author: 
Author: Jacques C. J. Nihoul
Author: 
Author: Chunzai Wang
Author: Jackie Crystal May
Author: Jane F. Gillooly
Author: National Academies of Sciences, Engineering, and Medicine
Author: D. Neelin