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Author: Jiangfeng Wei
Publisher:
ISBN:
Category : Plant-atmosphere relationships
Languages : en
Pages :
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Book Description
Land-atmosphere interaction includes complex feedbacks among radiative, hydrological, and ecological processes, and the understanding of it is hindered by many factors such as the heterogeneity of land surface properties, the chaotic nature of the atmosphere, and the lack of observational data. In this study, several different methods are used to investigate the land-atmosphere interaction processes and their relationship with climate variability. Firstly, a simple one-dimensional model is developed to simulate the dominant soil-vegetation-atmosphere interaction processes in the warm climate. Although the physical processes are described coarsely, the model can be more easily used to find some relationships which may be drown out or distorted by noise. The influence of land on climate variability mainly lies in it memory, which is greatly related with the atmospheric forcing, so this model is used to investigate the influence of different forcing strengths on land-atmosphere interaction and its difference at different land covers. The findings from the simple model can provide guidance for other studies. The second part of the study compares a lagged soil moisture-precipitation (S-P) correlation (soil moisture in current day and precipitation in future 30 days) in three atmospheric reanalysis products (ERA-40, NCEP/DOE reanalysis-2, and North American Regional Reanalysis (NARR)), Global Soil Wetness Project Phase 2 (GSWP-2) data, and NCAR CAM3 simulations. Different datasets and model simulations come to a similar negative-dominant S-P correlation pattern. This is different from the traditional view that the soil moisture should have positive influence on future precipitation. Further analysis shows that this correlation pattern is not caused by the soil moisture feedback but due to the combined effect of the precipitation oscillation and the memory of soil moisture. Theoretical analysis confirms the above results and finds that the precipitation time series with the strongest oscillation at 32-60 day period is most likely to induce a significantly negative S-P correlation, and regions with longer soil water retention time are more likely to have a significantly negative S-P correlation. This study illustrates that a lagged correlation does not always indicate a causal relation.
Author: Jiangfeng Wei
Publisher:
ISBN:
Category : Plant-atmosphere relationships
Languages : en
Pages :
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Book Description
Land-atmosphere interaction includes complex feedbacks among radiative, hydrological, and ecological processes, and the understanding of it is hindered by many factors such as the heterogeneity of land surface properties, the chaotic nature of the atmosphere, and the lack of observational data. In this study, several different methods are used to investigate the land-atmosphere interaction processes and their relationship with climate variability. Firstly, a simple one-dimensional model is developed to simulate the dominant soil-vegetation-atmosphere interaction processes in the warm climate. Although the physical processes are described coarsely, the model can be more easily used to find some relationships which may be drown out or distorted by noise. The influence of land on climate variability mainly lies in it memory, which is greatly related with the atmospheric forcing, so this model is used to investigate the influence of different forcing strengths on land-atmosphere interaction and its difference at different land covers. The findings from the simple model can provide guidance for other studies. The second part of the study compares a lagged soil moisture-precipitation (S-P) correlation (soil moisture in current day and precipitation in future 30 days) in three atmospheric reanalysis products (ERA-40, NCEP/DOE reanalysis-2, and North American Regional Reanalysis (NARR)), Global Soil Wetness Project Phase 2 (GSWP-2) data, and NCAR CAM3 simulations. Different datasets and model simulations come to a similar negative-dominant S-P correlation pattern. This is different from the traditional view that the soil moisture should have positive influence on future precipitation. Further analysis shows that this correlation pattern is not caused by the soil moisture feedback but due to the combined effect of the precipitation oscillation and the memory of soil moisture. Theoretical analysis confirms the above results and finds that the precipitation time series with the strongest oscillation at 32-60 day period is most likely to induce a significantly negative S-P correlation, and regions with longer soil water retention time are more likely to have a significantly negative S-P correlation. This study illustrates that a lagged correlation does not always indicate a causal relation.
Author: Eric Benjamin Jäger
Publisher:
ISBN:
Category :
Languages : en
Pages : 162
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Book Description
Author: Nafiseh Haghtalab
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 146
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Book Description
The Amazon basin, which contains about 60% of tropical rainforests in the world, plays vital roles in regulating climate patterns, sustaining ecosystem services, contributing to global biodiversity, and cycling nutrients. These services, however, have been disrupted by human activities within the region due to infrastructure development and resource extraction. These land-use changes have impacts from local to global scales, particularly on climate and hydrologic cycles, but the extent to which is unclear. Therefore, it is essential to examine precipitation variability and look for drivers of changes at multiple spatio-temporal scales. Analysis of hot spots of land-atmosphere interactions highlights the areas where changes in land surface characteristics influence the atmosphere behavior the most. This dissertation focuses on climate variability and land-atmosphere coupling across the Amazon basin. Research questions are addressed in three self-contained chapters. Chapter 2 examines the changes in precipitation amount and intensity using a high-resolution (0.05℗ʻ spatial resolution) gridded data set (CHIRPS) from 1982 to 2018. Several precipitation indices are developed to analyze trends using the Mann-Kendall test. Our results show landscape-scale changes in the timing and intensity of rainfall events. Specifically, wet areas of the western basin have become significantly wetter since 1982, with an increase of 182 mm of rainfall per year. In the eastern and southern regions, where deforestation is widespread, a significant drying trend is evident. In chapter 3, we aim to examine the impacts of potential tropical reforestation on surface energy and moisture budgets, including precipitation. We simulated changes in heat and moisture fluxes due to tropical reforestation using WRF.V3.9 (Weather Research and Forecast model) to analyze the sensitivity and magnitude of changes to the surface fluxes due to reforestation in the Amazon Basin. We found that the effects of reforestation on the atmosphere were more evident during the dry season; spatial patterns of the changes in atmospheric behavior due to reforestation were consistent with the pattern of land cover change, and the cooling effect of reforestation was evident at seasonal time scale. In chapter 4, following the results of chapter 3 on the effects of land surface characteristics on atmosphere behavior, we aim to find hot spots of strong land-atmosphere (L-A) coupling across the basin at regional scales. Strong land-atmosphere coupling is critical to understanding precipitation dynamics. Therefore, we applied two commonly used coupling approaches at the regional spatial scale and monthly temporal scale. Ultimately, we recommend a new metric considering more physical relationships, interactions, and lag times between variables. We found that the spatial pattern of hot spots is highly dependent on the temporal and spatial scales of analysis. Also, the interactions among variables within the boundary layer play a more important role in determining the hot spots of strong L-A coupling. Overall, the evidence provided here suggests that (1) precipitation distribution has changed over time (1982-2018) with wet areas getting wetter and dry areas getting drier across the Amazon basin; (2) reforestation of deforested regions across the basin moderates atmospheric patterns and behavior; (3) hot spots of strong L-A coupling are highly dependent on temporal and spatial scales of analysis as well as parameters interactions within the boundary layer.
Author: E.F. Wood
Publisher: Springer Science & Business Media
ISBN: 9400921551
Category : Science
Languages : en
Pages : 302
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Book Description
It is well known that the interactions between land surfaces and the atmosphere, and the resulting exchanges in water and energy have a tremendous affect on climate. The inadequate representation of land-atmosphere interactions is a major weakness in current climate models, and is providing the motivation for the HAPEX and ISLSCP experiments as well as the proposed Global Energy and Water Experiment (GEWEX) and the Earth Observing System (EOS) mission. The inadequate representation reflects the recognition that the well-known phys ical relationships, which are well described at small scales, result in different relationships when represented at the scales used in climate models. Understanding this transition in the mathematical relationships with increased space-time scales appears to be very difficult, and has led to different approaches; at one extreme, the famous "bucket" model where the land-surface is a simple one layer storage without vegetation; the other extreme may be Seller's Simple Biosphere Model (Sib) where one big leaf covers the climate model grid. Given the heterogeneous nature of landforms, soils and vegetation within a climate model grid, the development of new land surface parameterizations, and their verification through large scale experiments is perceived to be a challenging area of research for the hydrology and meteorology communities. This book evolved from a workshop held at Princeton University to explore the status of land surface parameterizations within climate models, and how observa tional data can be used to assess these parameterizations and improve models.
Author: Laszlo Nagy
Publisher: Springer
ISBN: 3662499029
Category : Science
Languages : en
Pages : 470
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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: Ram Babu Singh
Publisher:
ISBN:
Category : Business & Economics
Languages : en
Pages : 320
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Book Description
This text aims to promote a better understanding of land use and land-cover change in the assessment and management of global environmental resources, and to develop a comparative framework for assessing these changes.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309060982
Category : Science
Languages : en
Pages : 161
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Book Description
Society today may be more vulnerable to global-scale, long-term, climate change than ever before. Even without any human influence, past records show that climate can be expected to continue to undergo considerable change over decades to centuries. Measures for adaption and mitigation will call for policy decisions based on a sound scientific foundation. Better understanding and prediction of climate variations can be achieved most efficiently through a nationally recognized "dec-cen" science plan. This book articulates the scientific issues that must be addressed to advance us efficiently toward that understanding and outlines the data collection and modeling needed.
Author: Majeti Narasimha Var Prasad
Publisher: Elsevier
ISBN: 0128180331
Category : Science
Languages : en
Pages : 840
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Book Description
Climate Change and Soil Interactions examines soil system interactions and conservation strategies regarding the effects of climate change. It presents cutting-edge research in soil carbonization, soil biodiversity, and vegetation. As a resource for strategies in maintaining various interactions for eco-sustainability, topical chapters address microbial response and soil health in relation to climate change, as well as soil improvement practices. Understanding soil systems, including their various physical, chemical, and biological interactions, is imperative for regaining the vitality of soil system under changing climatic conditions. This book will address the impact of changing climatic conditions on various beneficial interactions operational in soil systems and recommend suitable strategies for maintaining such interactions. Climate Change and Soil Interactions enables agricultural, ecological, and environmental researchers to obtain up-to-date, state-of-the-art, and authoritative information regarding the impact of changing climatic conditions on various soil interactions and presents information vital to understanding the growing fields of biodiversity, sustainability, and climate change. Addresses several sustainable development goals proposed by the UN as part of the 2030 agenda for sustainable development Presents a wide variety of relevant information in a unique style corroborated with factual cases, colour images, and case studies from across the globe Recommends suitable strategies for maintaining soil system interactions under changing climatic conditions
Author: Song Yang
Publisher: Springer Nature
ISBN: 9811582254
Category : Science
Languages : en
Pages : 420
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Book Description
This book is mainly focused on the climate change in Southeast Asia and its adjacent regions. It summarizes results from recent scientific research based on observational analysis, data diagnosis, theoretical analysis, and model simulations. The book covers the following research areas: (1) characteristics and mechanisms of spring–summer atmospheric circulation systems, (2) ocean-atmosphere-land interaction and climate variability, (3) climate effect of the Tibetan Plateau, (4) attribution of regional climate change and feedback/impact of regional climate on the global climate, and (5) seasonal-to-subseasonal climate prediction. It is anticipated that the book provides useful information for enhancing our understanding of the change in climate over Southeast Asia and the adjacent regions.
Author: Amir Erfanian Javadian Entezar Yazd
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
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Book Description
Land, atmosphere, and oceans interact with each other through energy, mass, and momentum exchanges. These interactions regulate climate variability and influence climate changes at the regional scale. One notable example of highly influential land-atmosphere-ocean interactions on regional climates is monsoonal systems that influence a substantial portion of the world’s population. In this dissertation, the present and future climates of West Africa (WA) and South America (SA), two important monsoon regions, were studied utilizing Regional and Global Climate Models (RCMs and GCMs), mathematical techniques and data mining tools, and observational data (in-situ, remote-sensing, and reanalysis). The objective is to advance our understanding on the role of land-atmosphere-ocean feedbacks, especially vegetation-climate interactions, in the climate variability, change, and extremes over these regions. Special attention was given to the improvement of climate simulations and reliability of future climate projections by quantifying and/or reducing uncertainties from multiple sources. As part of this dissertation, two new approaches concerning regional climate modeling and projection were developed, each pertaining to one of the geographic domains. One is the Ensemble-based Reconstructed Forcings (ERF) method that faithfully reproduces the Multi-Model Ensemble (MME) mean but requires only a fraction of the computational cost of the conventional MME approach, which is critical for reducing the high uncertainties in the outlook of future precipitation change over WA. The other newly developed approach tackle the nesting practice, a major source of RCM bias that causes (large-scale) circulation in SA to drift away from that of the driving GCMs. To this end, a new paradigm of regional climate modeling was proposed that includes the influential oceans within the RCM domain to better resolve the large-scale circulation of the SA climate. Results from a fully coupled regional climate model, with and without dynamic vegetation, revealed significant influence of vegetation-climate interactions on the mean and variability of the surface hydroclimate of the two regions of focus. Precipitation, surface temperature, evapotranspiration, and soil moisture were all strongly influenced. In particular, results from both numerical experiments and observational data analysis indicated that tropical oceanic variability plays a dominant role in precipitation variability over SA, including the unprecedented extreme drought of 2016; in addition, greenhouse gas warming was found to significantly contribute to the amplification of the 2016 drought, especially during the pre-monsoon season. Natural vegetation dynamics improves the model performance in capturing the anomalies of surface water storage but has a negligible impact on precipitation anomalies of this extreme drought. Results of this research help advance our understanding and improve our capability to quantify and predict climate variability, change, and extremes over WA and SA.
