WorldCat Identities

Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics

Works: 159 works in 187 publications in 1 language and 1,609 library holdings
Genres: Academic theses  Periodicals 
Roles: isb
Classifications: TC171.M41, 621.2
Publication Timeline
Most widely held works about Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics
Most widely held works by Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics
An analytical and experimental investigation of surface discharges of heated water by Keith D Stolzenbach( Book )

2 editions published in 1971 in English and held by 121 WorldCat member libraries worldwide

Density induced mixing in confined aquifers by Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics( Book )

4 editions published in 1972 in English and held by 119 WorldCat member libraries worldwide

Temperature prediction in stratified water : mathematical model-user's manual (supplement to report 16130DJH01/71) by Patrick J Ryan( Book )

2 editions published in 1971 in English and held by 104 WorldCat member libraries worldwide

Predictions of the complex annual cycle of temperature changes in a lake or reservoir are necessary if proper water quality control is to be achieved. Many lakes and reservoirs exhibit horizontal homogeneity and thus a time-dependent, one-dimensional model describing the temperature variation in the vertical direction is adequate. A discretized mathematical model was developed based on the absorption and transmission of solar radiation, convection due to surface cooling and advection due to inflows and outflows. The model contains provision for simultaneous or intermittent withdrawal from multi-level outlets and time of travel for inflows within the reservoir
Mathematical modeling of near coastal circulation by John D Wang( Book )

3 editions published in 1975 in English and held by 28 WorldCat member libraries worldwide

Stochastic modeling of groundwater systems by L. W Gelhar( Book )

1 edition published in 1974 in English and held by 26 WorldCat member libraries worldwide

This research developed important new results on the use of spectral analysis techniques to evaluate groundwater resources. The linear theory of aquifer spectral response in the frequency domain is developed, including effects of aquifer slope, vertical flow, variable transmissivity and other features. Numerical simulations of the nonlinear effects in the spectral domain are developed and show that the nonlinear effects are typically quite small, thus making the simple linear theory applicable for most field situations. Some additional features which are explored are the effects of spatial variability of hydraulic conductivity and the influence of transient flow in the partially saturated zone above the water table. Through spectral analysis in the wave number domain, an error criterion is established for a simple observation network which is used to measure groundwater flow. The effects of storage in the partially saturated zone on the frequency spectrum of groundwater fluctuations are estimated and found to be negligible in most cases. The theoretical results are applied to evaluate, through spectral analysis, time series of groundwater levels, precipitation and stream stage for a site in Kansas. From these data, using a procedure based on the linear spectral theory, estimates of aquifer transmissivity and storativity are developed. The procedure yields parameter estimates which are in agreement with those obtained from pumping tests. The results of the study should be applicable under specified conditions to the estimation of aquifer parameters from natural fluctuations of groundwater level
Sediment transport in the coastal environment by Ole Secher Madsen( Book )

1 edition published in 1976 in English and held by 25 WorldCat member libraries worldwide

The subject of sediment transport in the coastal zone is investigated and the answers to some of the basic questions of sediment transport in unsteady, oscillatory flow are presented. By adopting Jonsson's (1966) results for the bottom shear stress associated with a simple wave motion, it is shown that Shield's criterion for the initiation of sediment movement on a flat bed holds in unsteady as well as steady flow. A simplified analysis as well as experimental data show the side effects associated with the experimental procedure in which a tray containing sediment is oscillated in still water is generally insignificant and is, therefore, a valid procedure for studying certain aspects of wave sediment interaction. Also, Shields Parameter is identified as the physically important parameter quantifying the fluid sediment interaction. An empirical relationship between a non-dimensional average sediment transport rate and Shields Parameter is found by reanalyzing the experimental data on the rate of sediment transport in oscillatory flow obtained by Einstein and co-workers at Berkeley. This relationship is similar to the Einstein-Brown sediment transport relationship in unidirectional, steady flow. By generalizing Jonsson's expression for the bottom shear stress associated with a sinusoidal wave motion, it is shown that the empirical sediment transport relationship may be derived from a quasi steady application of the Einstein-Brown sediment transport relationship. Also, it is demonstrated that the empirical relationship obtained using a friction factor based on grain roughness is capable of predicting sediment transport rates observed in experiments where bed forms were present. The general application of the derived sediment transport relationship for predicting net rates of sediment transport in the presence of second order effects such as bottom slope, wave asymmetry, mass transport currents and coastal currents is discussed. This discussion serves also to identify needed areas for future research. It is concluded that only the case of a small amplitude wave and a steady current seems to be understood to the extent that it is reasonable to evaluate the resulting sediment transport with any degree of confidence. Fortunately, this is a rather important situation in most offshore regions. A general numerical model is developed for the sediment transport and topographical changes resulting from spatially varying wave and current conditions. A simple numerical example of the evaluation of the topographical changes in the vicinity of the tip of a long straight breakwater is presented for periodic waves normally incident on the breakwater and a current parallel to the breakwater. This numerical example is chosen to resemble rather severe conditions for the Atlantic Generating Station (AGS) site with a maximum orbital wave velocity of 3.2 ft/sec (1 m/sec) and a current velocity 0.5 ft/sec (.15 m/sec). The results are.presented in a topographical relief map showing areas of scour and accretion of the order 0.78 inches/day (2 cm/day) at a maximum. Although the results of the example are somewhat more qualitative than-quantitative, it is felt that they provide a representative picture of the expected bottom changes in the vicinity of the AGS
Water balance studies of the Bahr El Ghazal swamp by Siu-On Chan( Book )

1 edition published in 1980 in English and held by 22 WorldCat member libraries worldwide

Future increases in Egyptian and Sudanese water resources may come from reduction of the large water losses of the Upper White Nile's swampy regions, particularly from the Bahr el Ghazal swamp. In this work, new methods of water balance estimation which incorporate the dynamic interaction of climate, soil and vegetation are applied to the Bahr el Ghazal basin in order to study its contribution to the flow of the White Nile, and to estimate the potential water recovery through drainage of this swamp
The methodology of Bayesian inference and decision making applied to extreme hydrologic events by Eric F Wood( Book )

1 edition published in 1974 in English and held by 20 WorldCat member libraries worldwide

This study presents the methodology of Bayesian inference and decision making applied to extreme hydrologic events. Inference procedures must consider both the natural or 'modelled' uncertainty of the hydrologic process and the statistical uncertainty due to a lack of information. Two types of statistical uncertainty were considered in this study. The first type is the uncertainty in modelling the hydrologic process, and the second type is the uncertainty in the values of the model parameters. The uncertainty is reduced by considering prior sources of information (regional regression, theoretical flood frequency analysis or subjective assessment) and historical flood data. A 'Bayesian distribution' of flood discharges is developed that fully accounts for parameter uncertainty. In an analogous manner, model uncertainty is analyzed, which leads to a 'composite Bayesian distribution'. The uncertainty in flood frequency curves from rainfall-runoff models is also analyzed, due to the uncertainty in the parameters of the models. The Bayesian inference model is then applied to a Bayesian decision model, where the decision rule is the maximization of expected net monetary benefits. A case study of determining the optimal size of local flood protection for Woonsocket, Rhode Island, was considered, using realistic flood damage and cost functions. The results indicate that Bayesian inference procedures can be used to fully account for statistical uncertainty and that Bayesian decision procedures provide a rational approach for making decisions under uncertainty
Estimation of stationary and non-stationary random fields : kriging in the analysis of orographic precipitation by Siong-Huat Chua( Book )

1 edition published in 1980 in English and held by 20 WorldCat member libraries worldwide

The theory of kriging, an optimal linear estimation technique for spatial stochastic processes, is presented and applied to the estimation of mean areal precipitation under stationary and non-stationary mean assumptions. In the stationary mean cases, the alternate use of semivariograms and covariances was investigated in conjunction with the adoption of a single realization versus a multirealization approach to defining the ensemble of events. Results favor the multirealization approach. The issue of the choice of covariogram model and optimization procedure appears questionable for the stationary mean case since traditional subjective areal averaging methods do as well as kriging. For non-stationary mean cases, assumed for storms in regions under orographic influence, kriging results with generalized covariances, identified under the necessary assumptions for intrinsic random functions of order k, were compared with a "detrending" procedure postulating a deterministic drift linearly related to ground elevation. The latter procedure gave more accurate kriging estimates but did not perform as well in representing the kriging estimation error variance. Generally, results point to the feasibility and attractiveness of kriging methods for MAP estimation, especially for non-stationary mean storms. The present work shows the need for further investigation in covariogram model inference and the effect of model errors on kriging results, particularly on the kriging estimation error variance
The coupled transport of water and heat in a vertical soil column under atmospheric excitation by P. C. D Milly( Book )

1 edition published in 1980 in English and held by 19 WorldCat member libraries worldwide

The purpose of this work is to develop a detailed, physically-based model of the response of the land surface to atmospheric forcing. The coupled, nonlinear partial differential equations governing mass and heat transport in the soil are derived. The theory of Philip and de Vries is re-cast in terms of the soil water matric potential, accounting for soil inhomogeneities and hysteresis of the moisture retention process. An existing model of hysteresis is modified to incorporate the effect of temperature and to facilitate numerical analysis. The Galerkin finite element method is applied in the development of a numerical algorithm for the solution of the governing equations. The numerical procedure is coded in FORTRAN for computer solution and several examples are run in order to test the method. The various modes of mass and heat transport are simulated accurately. A proposed procedure for the evaluation of non-linear storage coefficients in the numerical scheme yields excellent mass and energy balances
Geochemistry of municipal waste in coastal waters by François Morel( Book )

1 edition published in 1980 in English and held by 19 WorldCat member libraries worldwide

Introduction: As we mine primary ores at an increasing rate, as we synthesize more exotic compounds in greater quantities, as we produce expanding heaps of waste, as we reroute rivers through our faucets, we are becoming an important and sometimes a dominant agent of the global geochemical cycle. Disposal of municipal wastes is a key process in this anthropic part of the elemental fluxes, for a municipal sewage system is a giant funnel which brings in one place at each instant the end products of much of the dispersed consumptive activities of a whole community. In addition to its net contribution to the flux of natural elements and to the exotic nature of some of its constituents, it is this increasingly prevalent concentration process that gives human waste its unique position in the elemental economy of the planet. Lest we should be too conceited, even in our ability to pollute, the laws of nature must have their way. Ultimately all elements in the sea must be controlled by the biogeochemical processes that govern their oceanic cycles. The question posed by the practice of municipal waste disposal into the ocean is then principally one of rates: are natural biogeochemical processes in the oceans fast enough to "assimilate" human waste? Are the dispersive and degradative mechanisms suitably rapid to maintain the concentration of all potential toxicants at acceptably low concentrations? Are the ecological processes sufficiently dynamic to buffer the impact of concentrated elemental loads, to adapt to the presence of new chemical constituents? These questions can be asked on various geographical scales, from local to global, and on various time scales from hours to centuries. On the whole we are still quite ignorant of the functioning of oceanic systems; we do not comprehend sufficiently many of the processes that govern the fate of waste constituents; we cannot answer some of our basic questions. Yet, we are in the process of learning a great deal. This chapter is an attempt at organizing some of the key known facts on the biogeochemistry of waste in coastal waters, at developing a conceptual framework for research and decision making. There are on the order of ten thousand chemical constituents in wastewaters, only about a hundred of which we know anything about. It appears that our sole hope is to develop general principles to provide, in the long run, some of the necessary answers. Municipal wastewaters are a varied lot. Although domestic sewage has a fairly uniform composition throughout the country, the industrial wastes that are often added to it do not. Metal finishing plants contribute high concentrations of some metallic compounds; chemical manufacturing processes release highly specific sets of organic constituents. In cities with combined sewers, urban storm water runoff, with its own characteristic composition, is included in the municipal sewer system. Also varied are the levels of treatment and the methods of disposal. A few cities still dispose of their raw sewage while others have added tertiary treatment to their systems. Efficient outfalls with diffusers are used in some places to carry the effluents far offshore and dilute it effectively; in many others, wastewaters are released close to shore with inefficient mixing. Barge dumping of sludge is prevalent in many areas. Just as diverse are the hydrodynamic and hydrological characteristics of the receiving waters: confined bays, harbors and estuaries in some places, open coastline in others; rapidly increasing water depth offshore on one coast, extended continental margins on the other. Current and tidal regimes which vary with time and location result in widely different waste dilution and transport processes. All this variability in effluent composition, in initial mixing, and in short and long term transport processes affects to a large degree the fate of the waste constituents. At this point, it would be a hopeless task to attempt to cover all combinations of these, to consider the problem of disposal of all types of municipal wastes in all types of receiving waters. By a fortune of sorts, one is quite limited by the available information. We have made no attempt in this chapter to be exhaustive; rather we have concentrated on these systems for which extensive data were available. In this way it is hoped that a self coherent picture will be obtained from which one may draw information to be applied to other situations. However, major caveats are clearly in order: i) the available information concerns almost exclusively the major urban centers; in some instances it may be of little relevance to small or medium size communities; ii) the Southern California Bight--which is by no means typical--has been the locus of the most intensive and extensive research efforts on the geochemistry of waste. As such it provided the data for much of this chapter. (For convenient reference on names and locations, a map of the major Southern California outfalls is provided in Fig. 0-1). One should keep in mind these demographic and geographical biases
An analytical and experimental study of transient cooling pond behavior by P. J Ryan( Book )

2 editions published in 1973 in English and held by 19 WorldCat member libraries worldwide

Cooling ponds offer many advantages as a means of closed cycle heat dissipation. These are simplicity, low maintenance.and power requirements, aesthetic and possible recreational values, and high thermal inertia. A cooling pond is also subject to minimal environmental problems, since fogging tends to be localized, blowdown water can be stored for long periods, and make-up water requirements are intermittent and often lower than for other closed systems. In s~pite of the above advantages it is presently estimated that less than one third of the closed cycle power stations. built in the next 30 years, will utilize cooling ponds. One reason for this is lack of land, but another reason is the lack of confidence in the ability of existing models to predict cooling pond performance under transient heat loads and meteorological conditions. The use of simple steady state models and various commonly used assumptions as to surface heat loss and circulation patterns can lead to differences of at least 100% in the predicted required land area. Physical models have severe limitations, and this uncertainty in design often results in the rejection of the cooling pond alternative, which may be a mistake from economic, aesthetic and environmental considerations. An analytical and experimental investigation of cooling ponds is conducted. The guiding principle of this investigation is that a cooling pond can be designed on a rational basis only if the desired pond behavior is first clearly defined and the important mechanisms of heat transfer both within the pond itself, and at the water surface, are isolated and quantified. An efficient pond has been defined in terms of maximum surface heat transfer and maximum response time; this leads to the requirement that a pond be capable of sustaining a vertical temperature stratification, that entrance mixing be a minimum, and that a skimmer wall intake be used. The various components of heat transfer at a water surface are discussed, and existing empirical formulae are reviewed. Existing formulae for predicting evaporative flux from an artificially heated water surface are found to be unsatisfactory. Field data indicates that commonly used formulae may predict evaporative losses that are too low by as much as 50% for a heavily loaded water surface. A new formulae is proposed which explicitly accounts for mass transfer due to free convection. This can be very significant at low wind speeds. The proposed formula for evaporative flux performs well both in the laboratory and the field. The effect of entrance mixing and density currents on both the steady state and transient behavior of a cooling pond is examined in the laboratory,,and where possible laboratory results are supported by field observations. It is concluded that the reduction of entrance mixing is a very significant factor in improving the pond performance. In a stratified pond density currents can be of paramount importance in distributing the heat to backwater areas, thus making the pond performance essentially independent of shape. Steady state analytical models and a numerical transient model for the prediction of cooling pond performance are developed. The steady state models demonstrate the effect of entrance mixing and different circulation patterns. The major components of the transient model are a relatively thin surface region with horizontal temperature gradients overlying a deeper subsurface region with vertical temperature gradients. The entrance mixing is determined using the Stolzenbach- Harleman surface jet model, and the M.I.T. reservoir model is used to simulate the subsurface behavior. Output is given in terms of transient surface temperature distribution (area under isotherms), transient vertical temperature distribution, and transient intake temperatures. The transient model has been tested in the laboratory, and against five years of field data on two ponds with completely different characteristics, with very satisfactory results. The input data required by the transient model are that which are available before the pond is built, i.e. the model is predictive. The transient mathematical model is relatively simple and inexpensive, with an execution time of less than 1 minute per simulated year on an IBM 370/155. Thus the model can be used as a design tool, or as a component of a management model which compares different heat disposal alternatives. Design considerations, such as design of outlet and intake, the use of internal diking, and the use of physical models are briefly discussed, and a design approach is recommended
Groundwater pollution : technology, economics, and management by John L Wilson( Book )

1 edition published in 1976 in English and held by 18 WorldCat member libraries worldwide

A review of the technical, economic and management aspects of groundwater pollution is presented. The groundwater pollution problem is described and several of its important characteristics are pointed out. A description of the physical, chemical and biological aspects of groundwater pollution is given. The technology of groundwater pollution detection and observation is reviewed, including elements in the design and operation of a groundwater quality monitoring system. The concept of pollution is related to the economic concept of externalities, and the interrelationships of technology, institutions and economics in groundwater pollution management are presented. Technical, institutional, legal and economic measures to induce pollution control in groundwater systems are reviewed. The financial aspects, and the costs and benefits of groundwater pollution control are discussed. The causes, types and extent of groundwater pollution are described. These include agricultural, industrial, domestic and urban, radiological, and natural or induced sources of pollution. Methods of control for each are given. Methods of analysis as applied to groundwater pollution management are described within the context of total resource management and long range planning. Criteria for choosing among alternative plans, systems analysis, and optimization and simulation techniques are discussed. A case study of integrated groundwater-surface water management with specific groundwater quality considerations is described and discussed
The design of rainfall networks in time and space by Ignacio Rodríguez-Iturbe( Book )

1 edition published in 1973 in English and held by 18 WorldCat member libraries worldwide

A methodology for the design of precipitation networks is formulated. The network problem is discussed in its general conception and then focus is made in networks to provide background information for the design of more specific gaging systems. The rainfall process is described in terms of its correlation structure in time and space. A general framework is developed to estimate the variance of the sample long-term mean areal precipitation and mean areal rainfall of a storm event. The variance is expressed as a function of correlation in time, correlation in space, length of operation of the network and geometry of the gaging array. The trade of time-vs-space is quantitatively developed and realistic examples are worked out showing the influence of the network design scheme in the variance of the estimated values
Mass transport in water waves by Chiang C Mei( Book )

1 edition published in 1972 in English and held by 18 WorldCat member libraries worldwide

When a fluid is in periodic wave motion, a fluid particle is carried by a velocity field varying from place to place. At different instants the location of the particle differs and so does the velocity field in its immediate neighborhood. As a result the time-averaged velocity of a particle may be different from the local velocity field. In particular, a fluid particle may have a net mean drift even if the local velocity field has zero mean; this is indeed the case in irrotational gravity waves. In a viscous fluid, the wave-induced Reynolds stress imparts a steady momentum to the fluid; a steady shear is set up to balance it and hence a further mean velocity field results. The sum of these two steady currents provides the total drift by which a fluid particle migrates, and is termed the mass transport velocity. It is of importance to the study of sediment motion in coastal waters. The present report describes a coordinated inquiry into both theoretical and experimental aspects of mass transport by waves. In accordance with the division of effort, it is separated into two parts. However, nearly all ideas expressed and actions taken in both parts have been influenced by extensive mutual discussions. Part I (Theory) begins with a review of the basic assumptions underlying existing theories. General formulas of mass transport velocity components throughout the Stokes boundary layer near a solid body are then derived; details of two examples are calculated. The three-dimensional mass transport distribution throughout the cross section of a wave tank is worked out for progressive waves of very small amplitudes. The effects of finite width is studied with the assumption that vorticity is diffused by molecular viscosity throughout the entire cross section. For a wave obliquely incident and reflected from a vertical sea wall, the structure in the second boundary layer between the Stokes layer and the inviscid core is investigated. This is appropriate for amplitudes much greater than the Stokes layer thickness. Part II (Experiments), were intended in part to check and to evaluate the theoretical deductions in Part I. In particular, extensive measurements were made for the longitudinal mass transport velocity in a progressive wave in a long tank with a smooth bottom. For standing waves and partially standing waves, possible features of erosion and deposition were observed by spreading (1) a small amount of sand on a smooth bottom and (2) a thick layer of sand on the bottom. The relevance of mass transport very near the bottom to the bed load transport is discussed in the light of the real beach environment
Water balance estimates of the Machar Marshes by Ismail Ibrahim El-Hemry( Book )

1 edition published in 1980 in English and held by 17 WorldCat member libraries worldwide

Further increases of the River Nile discharge may come from reducing the water losses in the upstream swampy areas in the Nile basin. The Machar region is one of the main losers of water in this basin. In this work, the general water balance of the Machar region is studied using new models which incorporate the dynamic interaction of climate, soil and vegetation. Also, the random variability of the different hydrologic components are investigated. Probabilistic estimates of annual water yield of the Machar catchments are presented. These estimates show the amount of water that may be saved and they provide a guide to the Egyptian and Sudanese water resource planners in their design of a channelization system in the region
The practice of kriging by John C Kafritsas( Book )

1 edition published in 1981 in English and held by 17 WorldCat member libraries worldwide

The theory of intrinsic random functions of order k (IRF-K) and its use in optimal linear interpolation is presented using a simple deterministic formulation. Also outlined are the procedures for identification of generalized covariances corresponding to an IRF-K. Included is documentation, example and listing of a general purpose computer package for point and block kriging using IRF-K theory. The accessibility of such a tool should be welcomed by mining engineers, hydrologists and other geophysicists
A physically based channel network and catchment evolution model by Garry Willgoose( Book )

1 edition published in 1989 in English and held by 17 WorldCat member libraries worldwide

A catchment evolution and channel network growth model is presented. Elevations within the catchment are simulated by a sediment transport continuity equation applied over geologic time. Sediment transport may by modelled by both fluvial (e.g. Einstein-Brown) and mass movement (e.g. creep and landsliding) mechanisms. An explicit differentiation between the channel and the hillslope is made with different transport processes in each regime. The growth of the channel network is governed by a physically based threshold, which is nonlinearly dependent on discharge and slope and thus governed by hillslope form. Hillslopes and the growing channel network interact through the different sediment transport processes and the preferred drainage to the channels to produce the long term form of the catchment. General requirements for network formation in physically based models are examined by use of a previously reported leaf vein growth model. Elements of chaos were discovered that result in apparently random networks being generated. It was argued that this is also true for the catchment and connections with topologically random networks were provided. Synthetic catchments were simulated using a numerical implementation of the model and statistics for the catchments are analyzed. Drainage density and elevation characteristics are correlated with nondimensional numbers arising from a nondimensionalization of the governing equations. These nondimensional numbers parameterize rates of tectonic uplift, sediment transport, both in the channel and the hillslope, channel growth, and resistance to channelization. Runoff rate, erodability and flood frequencies arise explicitly in these numbers. A fundamental measure of catchment dissection based on one of the nondimensional numbers is proposed. It follows that drainage density and hillslope length are dependent, in a well defined way, on runoff rate, slopes and catchment erodability. Simulation results are compared with reported field data and small scale experimental catchment evolution studies and found to be consistent. A linear log-log relationship between channel slope and area, observed in the field, is also observed in the simulation data at dynamic equilibrium. An explanation based on model physics is proposed, a central feature being the balance between tectonic uplift and fluvial erosion at dynamic equilibrium. This explanation also accounts for observed deviations from the linear log-log relationship where slopes are reduced for small areas; these small areas are dominated by diffusive transport processes in the hillslope. The channelization threshold based on discharge and slope is compared with recently reported data of hillslope slopes and contributing areas at channel heads; the threshold is consistent with the field data. Observed differences between hypsometric curves, previously attributed to catchment age, are found to result from differences in the tectonic uplift regime. A scheme for landscape classification, based on the nondimensional numbers, is proposed which is more consistent with the governing physical processes than previous work. A one-dimensional advection-diffusion reformulation of the sediment transport equation is proposed that predicts rates of hillslope retreat and hillslope degradation, and provides a link to observed hillslope transport mechanisms
A statistical linearization approach to real time nonlinear flood routing by Konstantine P Georgakakos( Book )

1 edition published in 1980 in English and held by 16 WorldCat member libraries worldwide

Empirical temperature forecasting : extensions of the model output statistics method by David Eugene Langseth( Book )

1 edition published in 1980 in English and held by 16 WorldCat member libraries worldwide

Deterministic models of complex natural phenomena such as streamflow or weather events are usually either unknown or unwieldy and thus are often augmented or replaced by stochastic or empirical models. For example, the National Weather Service (NWS) uses a combination of deterministic and empirical models to predict several weather parameters. An approximate deterministic model of the atmosphere provides predictions of some meteorological parameters at the grid points used in the numerical solution of the model. Some of these deterministic predictions, along with recent measured data, are then used as input variables to an empirical prediction equation. The National Weather Service uses a stepwise least-squares regression algorithm to develop the empirical equations. The prediction of maximum surface air temperature is investigated in this work. The NWS currently uses 10 variable linear models to predict maximum temperatures. The 10 variable restriction is based on research and the linear restriction is based primarily on the prohibitive amount of time and effort required to develop non linear models. The potential model improvements from relaxing these two restrictions are examined in this work. Data from Huntsville, Alabama, supplied by the NWS, is used. Non linear models are created by applying a non linear model identification algorithm called the Group Method of Data Handling to the data. Two linear model identification algorithms are also used. The usefulness of the removal of harmonic components and the identification of principal components were investigated along with each of the model identification algorithms. It is shown that, for the site investigated, the linear restriction does not hurt model quality and that while 10 is a reasonable number of variables, models with fewer variables can also perform well. Also, modeling the mean trends separately from the more transient effects improves model quality
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Alternative Names

controlled identityMassachusetts Institute of Technology. Department of Civil Engineering. Water Resources and Environmental Engineering Division

controlled identityMassachusetts Institute of Technology. Hydrodynamics Laboratory

controlled identityParsons Laboratory for Environmental Science and Engineering (Massachusetts Institute of Technology)

Massachusetts Insitute of Technology. Dept. of Civil Engineering. Hydrodynamics Laboratory

Massachusetts Insitute of Technology Hydrodynamics Laboratory

Massachusetts Institute of Technology Cambridge, Mass Parsons Laboratory for Water Resources and Hydrodynamics

Massachusetts Institute of Technology Cambridge, Mass Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics

Massachusetts Institute of Technology Department of Civil Engineering Parsons Laboratory for Water Resources and Hydrodynamics

Massachusetts Institute of Technology Department of Civil Engineering Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics

Massachusetts Institute of Technology. Department of Civil Engineering. Water Resources and Environmental Engineering Division. Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics

Massachusetts Institute of Technology Parsons Laboratory for Water Resources and Hydrodynamics

Massachusetts Institute of Technology Ralph M. Parsons Laboratory for Water Resources and Hydrodynamics

Parsons Laboratory for Water Resources and Hydrodynamics

Parsons Laboratory for Water Resources and Hydrodynamics Cambridge, Mass

Ralph M. Parsons Laboratory

Ralph M. Parsons Laboratory Hydrology and Water Resource Systems

Raplh M. Parsons Laboratory

English (30)