Interactions between the land surface and rainfall at convective scales PDF Download

Author: D B. Clark
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: D B. Clark
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Oluseun Samuel Idowu
Publisher:
ISBN:
Category : Convection (Meteorology)
Languages : en
Pages : 105

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This dissertation investigates the modulating effects of land-atmosphere and aerosol interactions on meso-scale convective systems across the sub-Saharan West Africa region, and aims at providing a value-added contribution towards better understanding of the controlling mechanisms for these interactions, in order to improve predictability of the highly frequent, high-impact meso-scale convective systems. It is very well known that aerosols alter the surface energy budget resulting into complex and multi-scale interactions between the land-atmosphere and mesoscale convective systems, which are yet to be fully understood. In this study, we used a highly proven successful cognitive recognition artificial neural network intelligence problem solving tool -- Self-Organizing Maps (SOM) in investigating the modulating effects of aerosol-land-atmosphere interactions for enhancing the predictability of meso-scale convective systems. The SOM method is not yet commonly used by climate scientists for solving climate research problems. For the first time in this research -- at least to the best of our knowledge -- we used the SOM method to solve climate research problems over Africa. Our results show very strong seasonal influence in determining the dominant controlling variable (e.g. soil moisture, aerosols) on the interactions between atmospheric aerosols, meso-scale convective systems and land-surface properties across the study region. It was also found that these controlling variables are generally very significant in modulating atmospheric interactions across the region during the monsoon (wet) seasons than during the nonmonsoon (dry) seasons. Furthermore, results showed that even though there is noticeable control by aerosols on the interactions between land-atmosphere and meso-scale convective systems, available surface soil moisture exerts the most dominant control across the region especially during the active convective period (monsoon season) of the year. Results further showed that soil moisture has the potential to control the convective available potential energy (CAPE) up to about 79% during the monsoon season and up to about 67% during the non-monsoon seasons, while aerosols can control CAPE up to about 67% during monsoon and up to about 23% during the non-monsoon season.

Author: William K.-M. Lau
Publisher: Springer Science & Business Media
ISBN: 354027250X
Category : Science
Languages : en
Pages : 477

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This is the first comprehensive review of intra-seasonal variability (ISV); the contents are balanced between observation, theory and modeling. Starting with an overview of ISV and historical observations, the book addresses the coupling between ocean and atmosphere, and the worldwide role of ISV in monsoon variability. Also considered are the connections between oscillations like the Madden, Julian and El Nino/Southern and short-term climate.

Author: David A. Randall
Publisher: Springer
ISBN: 9811333963
Category : Science
Languages : en
Pages : 372

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This book focuses on the development of physical parameterization over the last 2 to 3 decades and provides a roadmap for its future development. It covers important physical processes: convection, clouds, radiation, land-surface, and the orographic effect. The improvement of numerical models for predicting weather and climate at a variety of places and times has progressed globally. However, there are still several challenging areas, which need to be addressed with a better understanding of physical processes based on observations, and to subsequently be taken into account by means of improved parameterization. And this is all the more important since models are increasingly being used at higher horizontal and vertical resolutions. Encouraging debate on the cloud-resolving approach or the hybrid approach with parameterized convection and grid-scale cloud microphysics and its impact on models’ intrinsic predictability, the book offers a motivating reference guide for all researchers whose work involves physical parameterization problems and numerical models.

Author: Deborah Kay-Morton Nykanen
Publisher:
ISBN:
Category :
Languages : en
Pages : 384

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Author: Tiantian Xiang
Publisher:
ISBN:
Category : Boundary layer (Meteorology)
Languages : en
Pages : 194

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Land surface fluxes of energy and mass developed over heterogeneous mountain landscapes are fundamental to atmospheric processes. However, due to their high complexity and the lack of spatial observations, land surface processes and land-atmosphere interactions are not fully understood in mountain regions. This thesis investigates land surface processes and their impact on convective precipitation by conducting numerical modeling experiments at multiple scales over the North American Monsoon (NAM) region. Specifically, the following scientific questions are addressed: (1) how do land surface conditions evolve during the monsoon season, and what are their main controls?, (2) how do the diurnal cycles of surface energy fluxes vary during the monsoon season for the major ecosystems?, and (3) what are the impacts of surface soil moisture and vegetation condition on convective precipitation? Hydrologic simulation using the TIN-based Real-time Integrated Basin Simulator (tRIBS) is firstly carried out to examine the seasonal evolution of land surface conditions. Results reveal that the spatial heterogeneity of land surface temperature and soil moisture increases dramatically with the onset of monsoon, which is related to seasonal changes in topographic and vegetation controls. Similar results are found at regional basin scale using the uncoupled WRF-Hydro model. Meanwhile, the diurnal cycles of surface energy fluxes show large variation between the major ecosystems. Differences in both the peak magnitude and peak timing of plant transpiration induce mesoscale heterogeneity in land surface conditions. Lastly, this dissertation examines the upscale effect of land surface heterogeneity on atmospheric condition through fully-coupled WRF-Hydro simulations. A series of process-based experiments were conducted to identify the pathways of soil moisture-rainfall feedback mechanism over the NAM region. While modeling experiments confirm the existence of positive soil moisture/vegetation-rainfall feedback, their exact pathways are slightly different. Interactions between soil moisture, vegetation cover, and rainfall through a series of land surface and atmospheric boundary layer processes highlight the strong land-atmosphere coupling in the NAM region, and have important implications on convective rainfall prediction. Overall, this dissertation advances the study of complex land surface processes over the NAM region, and made important contributions in linking complex hydrologic, ecologic and atmospheric processes through numerical modeling.

Author: Robert S Plant
Publisher: World Scientific
ISBN: 1783266929
Category : Technology & Engineering
Languages : en
Pages : 1169

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Book Description
Precipitating atmospheric convection is fundamental to the Earth's weather and climate. It plays a leading role in the heat, moisture and momentum budgets. Appropriate modelling of convection is thus a prerequisite for reliable numerical weather prediction and climate modelling. The current standard approach is to represent it by subgrid-scale convection parameterization.Parameterization of Atmospheric Convection provides, for the first time, a comprehensive presentation of this important topic. The two-volume set equips readers with a firm grasp of the wide range of important issues, and thorough coverage is given of both the theoretical and practical aspects. This makes the parameterization problem accessible to a wider range of scientists than before. At the same time, by providing a solid bottom-up presentation of convection parameterization, this set is the definitive reference point for atmospheric scientists and modellers working on such problems.Volume 1 of this two-volume set focuses on the basic principles: introductions to atmospheric convection and tropical dynamics, explanations and discussions of key parameterization concepts, and a thorough and critical exploration of the mass-flux parameterization framework, which underlies the methods currently used in almost all operational models and at major climate modelling centres. Volume 2 focuses on the practice, which also leads to some more advanced fundamental issues. It includes: perspectives on operational implementations and model performance, tailored verification approaches, the role and representation of cloud microphysics, alternative parameterization approaches, stochasticity, criticality, and symmetry constraints.

Author: R.K. Smith
Publisher: Springer Science & Business Media
ISBN: 9401588287
Category : Science
Languages : en
Pages : 499

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An up-to-date summary of our understanding of the dynamics and thermodynamics of moist atmospheric convection, with a strong focus on recent developments in the field. The book also reviews ways in which moist convection may be parameterised in large-scale numerical models - a field in which there is still some controversy - and discusses the implications of convection for large-scale flow. Audience: The book is aimed at the graduate level and research meteorologists as well as scientists in other disciplines who need to know more about moist convection and its representation in numerical models.

Author: Shouting Gao
Publisher: Springer Science & Business Media
ISBN: 1402082762
Category : Science
Languages : en
Pages : 213

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Book Description
Clouds and cloud systems and their interactions with larger scales of motion, radiation, and the Earth’s surface are extremely important parts of weather and climate systems. Their treatment in weather forecast and climate models is a significant source of errors and uncertainty. As computer power increases, it is beginning to be possible to explicitly resolve cloud and precipitation processes in these models, presenting opportunities for improving precipitation forecasts and larger-scale phenomena such as tropical cyclones which depend critically on cloud and precipitation physics. This book by Professor Shouting Gao of the Institute of Atmospheric Physics in Beijing and Xiaofan Li of NOAA’s National Environmental Satellite Data and Information Services (NESDIS) presents an update and review of results of high-resolution, mostly two-dimensional models of clouds and precipitation and their interactions with larger scales of motion and the Earth’s surface. It provides a thorough description of cloud and precipitation physics, including basic governing equations and related physics, such as phase changes of water, radiation and mixing. Model results are compared with observations from the 1992-93 Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE) experiment. The importance of the ocean to tropical convective systems is clearly shown here in the numerical results of simulations with their air-sea coupled modeling system. While the focus is on tropical convection, the methodology and applicability can be extended to cloud and precipitation processes elsewhere. The results described in this well-written book form a solid foundation for future high-resolution model weather forecasts and climate simulations that resolve clouds explicitly in three dimensions—a future that has great promise for the understanding and prediction of weather and climate for the great benefit of society.