Author: Chu-Hui ChenPublisher:
ISBN:
Category :
Languages : en
Pages : 242
Book Description
A Model for the Diurnal Variation of Simultaneous Heat and Water Transport in a Soil Profile with an Evaporating Bare Surface and Hysteresis
Author: Chu-Hui ChenEncyclopedia of Agrophysics
Author: Jan GlińskiPublisher: Springer Science & Business Media
ISBN: 9048135842
Category : Technology & Engineering
Languages : en
Pages : 1075
Book Description
This Encyclopedia of Agrophysics will provide up-to-date information on the physical properties and processes affecting the quality of the environment and plant production. It will be a "first-up" volume which will nicely complement the recently published Encyclopedia of Soil Science, (November 2007) which was published in the same series. In a single authoritative volume a collection of about 250 informative articles and ca 400 glossary terms covering all aspects of agrophysics will be presented. The authors will be renowned specialists in various aspects in agrophysics from a wide variety of countries. Agrophysics is important both for research and practical use not only in agriculture, but also in areas like environmental science, land reclamation, food processing etc. Agrophysics is a relatively new interdisciplinary field closely related to Agrochemistry, Agrobiology, Agroclimatology and Agroecology. Nowadays it has been fully accepted as an agricultural and environmental discipline. As such this Encyclopedia volume will be an indispensable working tool for scientists and practitioners from different disciplines, like agriculture, soil science, geosciences, environmental science, geography, and engineering.
An Analytical Soil Thermodynamic Model for the Diurnal Variation of Ground Surface Temperature
Author: Samuel Y. K. YeePublisher:
ISBN:
Category : Earth temperature
Languages : en
Pages : 32
Book Description
An analytical expression is given for time variations of temperature within a model soil slab that is subjected to idealized heating at the supper surface and maintained at constant temperature at the lower surface. Applied at the upper surface, the model temperature may be considered to be the ground surface temperature of the earth. An important feature of this model is that phase-shifted on-linear responses to the forcing are allowed at the upper boundary. The analytical nature of the solution enables us to easily study the relative importance of various physical processes in the model surface energy budget equation. For example, evaporational cooling is found to be an important feedback process under model summer conditions, accounting for a change of about 6K in the daily mean surface temperature; under winter conditions, the change attributable to evaporation is only about 1K. The perturbation method used in our approach to linearize the model upper boundary condition is shown to be applicable to more complicated and more realistic upper boundary conditions.
American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 896
Book Description
Heat and Water Transfer in Bare Topsoil and the Lower Atmosphere
Author: Hein F. M. ten BergePublisher:
ISBN:
Category : Evaporation (Meteorology)
Languages : en
Pages : 224
Book Description
This book describes an analysis of processes and factors that affect the energy balance of bare soil, and the associated exchange of heat and moisture at the surface. After a brief treatment of basic transport theory, the processes of soil-atmosphere interaction are expressed in a simulation algorithm. This algorithm provides an instrument to study the 'conditioning' effect of soil on the lower atmosphere, and vice versa. Examples of sensitivity analysis are presented, with emphasis on the behaviour of surface temperature. In remote sensing practice, surface temperature is estimated from thermal imagery; simulation algorithms can assist in its interpretation. Field data of fluxes, state variables and soil properties are extensively discussed and are used to validate appropriate sections of the model.
An Analytical Soil Thermodynamic Model for the Diurnal Variation of Ground Surface Temperature
Author: Samuel Y. K. YeePublisher:
ISBN:
Category : Earth temperature
Languages : en
Pages : 0
Book Description
An analytical expression is given for time variations of temperature within a model soil slab that is subjected to idealized heating at the supper surface and maintained at constant temperature at the lower surface. Applied at the upper surface, the model temperature may be considered to be the ground surface temperature of the earth. An important feature of this model is that phase-shifted on-linear responses to the forcing are allowed at the upper boundary. The analytical nature of the solution enables us to easily study the relative importance of various physical processes in the model surface energy budget equation. For example, evaporational cooling is found to be an important feedback process under model summer conditions, accounting for a change of about 6K in the daily mean surface temperature; under winter conditions, the change attributable to evaporation is only about 1K. The perturbation method used in our approach to linearize the model upper boundary condition is shown to be applicable to more complicated and more realistic upper boundary conditions.
Water Transfer from Soil to the Atmosphere as Related to Climate and Soil Properties
Author: C. W. WendtCoupled Heat and Water Transport in Bare Soils in Semi-arid and Arid Regions
Author: T. BerendsPublisher:
ISBN:
Category :
Languages : en
Pages : 88
Book Description
For more than 50 years coupled heat and water transport is an interesting topic in the field of vadose zone hydrology. One basis is the theory by Philip & de Vries (1957) which couples the mass balance for water, the Richards equation, with a heat conservation equation based on Fickian diffusion process. In this thesis the contribution of water vapour flow to the total water movement on a daily time scale is analysed. At first the literature is reviewed, starting from the theory of Philip and de Vries and the many papers which have continued on this theory. Next to the theory also the literature on experiments associated to coupled transport is reviewed, distinguishing field and laboratory experiments. Data were collected during field work in Trabadillo, Spain under semi-arid weather conditions. Soil water pressure, soil water content and soil temperature were measured for 149 days on an hourly interval during the dry period. The soil hydraulic and soil thermal parameters are calibrated on this data in Hydrus-1D by using an inverse parameter estimated method. In the calibrated Hydrus model Monte Carlo simulations are performed to include the uncertainty in the parameters. Instantaneous fluxes of liquid water, isothermal water vapour and thermal water vapour flow are examined at multiple moments in time. Selecting fluxes for inclusion on an daily time basis in the SWAP model, the Hydrus 1-D isothermal water vapour flow is zero during night and day and is therefore not included in the SWAP model. A significant daily pattern is identified for the thermal water vapour flux and this flux is implemented in SWAP in addition to the standard isothermal liquid water flux. The cumulative net flux is computed for four different models, a Hydrus and SWAP model with only liquid water transport and a Hydrus and SWAP model with both coupled heat and water transport. Intercomparison between the four model versions showed that the contribution of water vapour flow is insignificant compared to the total transport of water. As a sensitivity analysis in addition to the soil hydraulic parameters from the field situation, simulations are also performed for a European set of soils from the HYPRESS project Wosten et al. (1999). The Hydrus model did not converge to a satisfactory numerical solution with a maximum spatial discretisation of 1 cm, which is advised by Simunek et al. (2008). In SWAP the contribution of water vapour movement to the total water transport is insignificant on a daily time scale for all the soil types. Finally a laboratory experiment design is proposed with the focus on coupled heat and water transport. The plan for the laboratory experiment will be based on the experience from the fieldwork and the literature study. Important components for this plan are the type of measurement devices, the spatial set-up of those devices and the boundary conditions. A model study is executed to look for the optimal measurement set-up for a laboratory experiment to liquid water and water vapour transport. Inverse modelling is used to determine the soil hydraulic and soil heat parameters from a selection of data and direct modeling is performed with the determined parameters to compare the accuracy of these parameters and so the data selection. The optimal laboratory design according to the model study includes measurements of soil temperature, soil water content and soil water pressure at depths of 5, 25 and 50 cm beneath the soil surface.
Novel Techniques to Determine Soil Evaporation Rates
Author: Kashifa RumanaPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Soil water evaporation is a critical component of both the surface energy balance and the hydrologic cycle, coupling heat and water transfer between land and atmosphere. Bare-soil evaporation and plant-soil-atmospheric interactions are important components of the water balance, especially in semiarid and arid regions. Soil evaporation has been thoroughly studied during the past century, yielding many methods and models. However, none of the methods have adequately addressed the needs for in situ and real-time monitoring of soil evaporation. The objectives of this research project were to track soil water evaporation losses using two different methods: a heat pulse probe (HPP) array and a fully automated microlysimeter (FAML). The HPP consists of a heater needle and five thermistor needles; when rotated to an angle of 27.3℗ʻ from a vertical orientation, it yielded temperature measurements every 3 mm within the soil profile. On the application of heat input to a resistance wire in the heater needle, the remaining thermistor needles measured the temperature response at a fixed distance of 6.5 mm from the heater. Results from our study demonstrate application of the sensible heat balance approach that provided reasonable estimates of subsurface evaporation rates. Inconsistencies due to the inability of the HPP to estimate evaporation rates in the near-surface "undetectable zone" are also reported in comparison to actual stage-2 evaporation based on the mass balance method. Additionally, deviations from the prescribed installation angle introduced errors when calculating the temperature gradient; hence, a vertical spacing algorithm was developed to resolve spacing errors. In the third chapter, a fully automated design is discussed based on the microlysimeter concept with the enhancement of an 8- cm deep lysimeter that was mounted on a 10 kg load cell for real-time monitoring diurnal evaporation rates from bare soil. The comparison with HYDRUS-1D simulation validated the FAML measured instantaneous evaporation rates with slight disparity toward the end of the experiment. Overall, this study shows two feasible methods for estimating real time evaporation rates in situ over prolonged periods with the aid of the HPP or the FAML. These tools can assist researchers with improved assessment of soil evaporation while taking into account proper correction methods.
Principles of Environmental Physics
Author: John MonteithPublisher: Butterworth-Heinemann
ISBN: 9780713129311
Category : Nature
Languages : en
Pages : 308
Book Description
Thoroughly revised and up-dated edition of a highly successful textbook.