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Author: Ajiao Chen Publisher: ISBN: Category : Languages : en Pages :
Book Description
Land-atmosphere interactions encompass complex surface processes that exchange energy and matter between land and the atmosphere, which play important roles in modulating variations in climate. Prediction on future climate change calls for more precise prediction models. Improving the representation of physical processes of land-atmosphere interactions and the availability of key variables for characterizing those processes could help reduce uncertainties in the prediction models, and consequently make contribution to extreme weather forecasting and natural disasters prevention. -- Terrestrial water storage (TWS, includes surface water, soil moisture, groundwater, snow, and ice) constitutes a significant memory component within the climate system. However, in Australia, the driest inhabitant continent, there is still a lack of investigation on the long-term TWS variation pattern. In addition, soil moisture as the most variable component of TWS has strong interactions with vegetation and near-surface temperature, but investigations on those interactions have been impeded by the scarcity of soil moisture observations. -- The long-term wetting/drying pattern in Australia was investigated in this thesis by applying the Gravity Recovery and Climate Experiment (GRACE) satellite derived TWS anomaly and extended datasets. A seesaw pattern of TWS variation between eastern and western Australia was revealed: eastern Australia gaining water, while western Australia is losing water, and vice versa. This phenomenon is resulted from a combination of effects from large-scale climate mode and dynamic vegetation and soil moisture interactions. It highlighted the bidirectional effects between surface vegetation and land water conditions, but such knowledge of Australia remained poorly understood. Results of this thesis for the first time indicated that non-linear interactions between vegetation and TWS occurred in 58% of the area of Australia. Those new findings partly improved our understanding of physical processes in Australia's land-atmosphere interactions. -- On the other hand, this thesis proposes the first use of wavelet decomposed GRACE TWS as a proxy of soil moisture to investigate its relationship with air temperature anomaly/hot extremes at the global scale. Compared to raw TWS, decomposed TWS showed improved skill in explaining temperature variability. It is because that the decomposed components could reflect different roles of moisture at different soil depths in the soil moisture-temperature coupling. The wavelet decomposed TWS also performed better than other commonly used soil moisture proxies (i.e., precipitation relevant index, products derived from land surface model and microwave remote sensing technology). Besides, by using the decomposed TWS to represent local moisture deficit, it played a more important role in influencing hot extreme occurrences in regions with a total area 1.6 times as large as the area strongly influenced by global temperature change during the study period 1985-2015. The results suggested that local land management is essential for combating hot extreme expansion in regions with strong land-atmosphere coupling, and global measures for reducing emissions are required in the face of increasing greenhouse gas forcing. -- In summary, this thesis improved the knowledge of land-atmosphere interactions at continental and global scales through further investigation on TWS variation pattern and its relationships with vegetation and temperature. This thesis also suggested a useful soil moisture proxy, i.e., the wavelet decomposed GRACE TWS, that can be applied to examine other processes in land-atmosphere interactions and to evaluate the performance of land surface models.
Author: Ajiao Chen Publisher: ISBN: Category : Languages : en Pages :
Book Description
Land-atmosphere interactions encompass complex surface processes that exchange energy and matter between land and the atmosphere, which play important roles in modulating variations in climate. Prediction on future climate change calls for more precise prediction models. Improving the representation of physical processes of land-atmosphere interactions and the availability of key variables for characterizing those processes could help reduce uncertainties in the prediction models, and consequently make contribution to extreme weather forecasting and natural disasters prevention. -- Terrestrial water storage (TWS, includes surface water, soil moisture, groundwater, snow, and ice) constitutes a significant memory component within the climate system. However, in Australia, the driest inhabitant continent, there is still a lack of investigation on the long-term TWS variation pattern. In addition, soil moisture as the most variable component of TWS has strong interactions with vegetation and near-surface temperature, but investigations on those interactions have been impeded by the scarcity of soil moisture observations. -- The long-term wetting/drying pattern in Australia was investigated in this thesis by applying the Gravity Recovery and Climate Experiment (GRACE) satellite derived TWS anomaly and extended datasets. A seesaw pattern of TWS variation between eastern and western Australia was revealed: eastern Australia gaining water, while western Australia is losing water, and vice versa. This phenomenon is resulted from a combination of effects from large-scale climate mode and dynamic vegetation and soil moisture interactions. It highlighted the bidirectional effects between surface vegetation and land water conditions, but such knowledge of Australia remained poorly understood. Results of this thesis for the first time indicated that non-linear interactions between vegetation and TWS occurred in 58% of the area of Australia. Those new findings partly improved our understanding of physical processes in Australia's land-atmosphere interactions. -- On the other hand, this thesis proposes the first use of wavelet decomposed GRACE TWS as a proxy of soil moisture to investigate its relationship with air temperature anomaly/hot extremes at the global scale. Compared to raw TWS, decomposed TWS showed improved skill in explaining temperature variability. It is because that the decomposed components could reflect different roles of moisture at different soil depths in the soil moisture-temperature coupling. The wavelet decomposed TWS also performed better than other commonly used soil moisture proxies (i.e., precipitation relevant index, products derived from land surface model and microwave remote sensing technology). Besides, by using the decomposed TWS to represent local moisture deficit, it played a more important role in influencing hot extreme occurrences in regions with a total area 1.6 times as large as the area strongly influenced by global temperature change during the study period 1985-2015. The results suggested that local land management is essential for combating hot extreme expansion in regions with strong land-atmosphere coupling, and global measures for reducing emissions are required in the face of increasing greenhouse gas forcing. -- In summary, this thesis improved the knowledge of land-atmosphere interactions at continental and global scales through further investigation on TWS variation pattern and its relationships with vegetation and temperature. This thesis also suggested a useful soil moisture proxy, i.e., the wavelet decomposed GRACE TWS, that can be applied to examine other processes in land-atmosphere interactions and to evaluate the performance of land surface models.
Author: J. Grace Publisher: CABI ISBN: 9780851998695 Category : Nature Languages : en Pages : 310
Book Description
Annotation. Forest ecosystems exist at the interface between the land and the atmosphere. Understanding the properties of this planetary boundary layer is very important for a number of related disciplines. This book presents an overview of topics that are of significance at this interface, starting at the scale of intra-leaf organelles, ranging to higher levels of organisation such as communities and ecosystems. It covers topics such as stomatal functioning, large scale processes, radiation modelling, forest meteorology and carbon sequestration. Based on proceedings of a conference to mark the retirement of Professor Paul Jarvis from the University of Edinburgh, the book contains contributions from leading international scientists. It will be of significant interest to researchers in forestry, ecology, environmental sciences and natural resources.
Author: Laszlo Nagy Publisher: Springer ISBN: 3662499029 Category : Science Languages : en Pages : 470
Book Description
This book offers a panorama of recent scientific achievements produced through the framework of the Large-Scale Biosphere-Atmosphere programme (LBA) and other research programmes in the Brazilian Amazon. The content is highly interdisciplinary, with an overarching aim to contribute to the understanding of the dynamic biophysical and societal/socio-economic structure and functioning of Amazonia as a regional entity and its regional and global climatic teleconnections. The target readership includes advanced undergraduate and post-graduate students and researchers seeking to untangle the gamut of interactions that the Amazon’s complex biophysical and social system represent.
Author: Timothy Wallace Cronin Publisher: ISBN: Category : Languages : en Pages : 171
Book Description
I present work on several topics related to land-atmosphere interaction and radiative-convective equilibrium: the first two research chapters invoke ideas related to land-atmosphere interaction to better understand radiative-convective equilibrium; the last two research chapters use the framework of radiative-convective equilibrium to better understand land-atmosphere interaction. First, I calculate how averaging the incident solar radiation can lead to biases in idealized climate models. I derive an expression for the absorption-weighted solar zenith angle, which minimizes the bias in mean absorbed shortwave radiation, and I find that it is closely matched by the insolation-weighted zenith angle. Common use of daytime-weighted zenith angle likely leads to high biases in albedo by ~3%. Second, I explore the time scales of approach to radiative-convective equilibrium with both a simple linearized two-variable model, and a single-column model with full physics. I show that there is a long time scale of approach to radiative-convective equilibrium that is order hundreds of days even when the surface heat capacity vanishes. The impact of water vapor on the effective atmospheric heat capacity can more than double this time scale for warm temperatures and low surface heat capacities. Third, I develop an analytic theory for the sensitivity of near-surface temperature to properties of the land surface. I show that the theory compares well against a simple numerical model of the coupled boundary layer-surface system, as well as a more complex two-column model, and discuss application of the theory to questions of how changes in land use or ecosystem function may affect climate change. Finally, I find that the diurnal cycle of convection is important for the spatial distribution of rainfall in idealized simulations of radiative-convective equilibrium with a cloud-resolving model. In a region that is partly an island and mostly ocean, precipitation over the island falls primarily in a regular, strong, afternoon thunderstorm, with a time-mean rainfall rate more than double the domain average. I explore mechanisms for this island rainfall enhancement, investigate the importance of island size for my results, and find that the upper troposphere warms with the inclusion of an island, which may have implications for the large-scale tropical circulation.
Author: Sam James Silva Publisher: ISBN: Category : Languages : en Pages : 191
Book Description
The interactions between the biosphere and the atmosphere are an important controlling factor for regional to global atmospheric chemistry and composition. This ultimately has wide impacts on issues like air quality and climate change. However, there are still substantial uncertainties in the biosphere-atmosphere interaction processes that drive the global abundance and variability of many critically important atmospheric constituents, including ozone, aerosol, and Volatile Organic Compounds (VOCs). This thesis aims to address these uncertainties through a multifaceted approach, combining theory and data-driven models with observations. The scope of the research completed herein is introduced and described in Chapter 1. Chapter 2 is a case study of biosphere atmosphere interactions where the air quality impact of large-scale agricultural deforestation in Southeast Asia is investigating using global models. Chapters 3 and 4 focus on research toward improving model estimates of dry deposition, a process by which vegetation functions as a sink for atmospheric aerosol and reactive gas species. Chapter 3 constrains theoretical estimates of global dry deposition through comparison to a large suite of observations, in order to provide a detailed assessment of current theory. Chapter 4 develops a data-driven model for this process using "deep learning", an artificial intelligence-based regression method. This data-driven approach is nearly an order of magnitude more accurate than current theoretically based models. Chapter 5 focuses on assessing simulated impacts of biosphere-atmosphere interactions on atmospheric chemistry. Satellite observations of formaldehyde and glyoxal were used to constrain the chemical transformations relevant for VOC chemistry globally. In the final project, in Chapter 6, an improved representation of plant canopy processes for use in atmospheric chemistry simulations is developed, and its performance is assessed. Finally, Chapter 7 summarizes the work completed in this thesis.
Author: Xiaoyan Jiang (doctor of geological sciences.) Publisher: ISBN: Category : Languages : en Pages : 368
Book Description
Land surface areas, which represent approximately 30% of the Earth's surface, contribute largely to the complexity of the climate system by exchanging water, energy, momentum, and chemical materials with the overlying atmosphere. Because of the highly heterogeneous nature of the land surface and its rapid transformation due to human activities, future climate projections are less certain on regional scales than for the globe as a whole. The work presented in this dissertation is focused on a better understanding of regional-scale land--atmosphere interactions and their impacts on climate and air quality. Specifically, I concentrate my research on three typical regions in the United States (U.S.): 1) the Central U.S. (representing transition zones between arid and wet climates); 2) the Houston metropolitan region (representing a major urban area); and 3) the eastern U.S. (representing temperate forested regions). These regions are also chosen owing to the consideration of data availability. The first study concerns the roles of vegetation phenology and groundwater dynamics in regulating evapotranspiration and precipitation over the transition zones in summer months. It is found that the warm-season precipitation in the Central U.S. is sensitive to latent heat fluxes controlled by vegetation dynamics. Groundwater enhances the persistence of soil moisture memory from rainy periods to dry periods by transferring water to upper soil layers through capillary forces. Enhancement in soil moisture facilitates vegetation persistence in dry periods, producing more evaporation to the atmosphere and resulting in enhanced precipitation, which then increases soil moisture. The second study compares the impacts of future urbanization and climate change on regional air quality. The results show that the effect of land use change on surface ozone (O3) is comparable to that of climate change, but the details differ across the domain. The third study deals with the formation and distributions of secondary organic aerosols (SOA) -- a largely overlooked but potentially important component in the climate system. Under future different climate scenarios, I found that biogenic emissions -- an important precursor of SOA -- are expected to increase everywhere over the U.S., with the largest increase found in the southeastern U.S. and the northwestern U.S., while changes in SOA do not necessarily follow those in biogenic emissions. Other factors such as partitioning coefficients, atmospheric oxidative capability, primary organic carbon, and anthropogenic emissions also play a role in SOA formation. Direct and indirect impacts from climate change complicate the future SOA formation.
Author: Ni-Bin Chang Publisher: CRC Press ISBN: 1000687279 Category : Technology & Engineering Languages : en Pages : 450
Book Description
Multiscale Hydrologic Remote Sensing: Perspectives and Applications integrates advances in hydrologic science and innovative remote sensing technologies. Raising the visibility of interdisciplinary research on water resources, it offers a suite of tools and platforms for investigating spatially and temporally continuous hydrological variables and p
Author: Ajiao Chen
Author: Ajiao Chen
Author: W J. Shuttleworth
Author: J. Grace
Author: Laszlo Nagy
Author: 
Author: Timothy Wallace Cronin
Author: Sam James Silva
Author: Xiaoyan Jiang (doctor of geological sciences.)
Author: Ni-Bin Chang
Author: Mikhail Ivanovich Budyko