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1

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Probabilistic seasonal forecasts of droughts with a simplified coupled hydrologic-atmospheric model for water resources planning (2000)

Anderson, M. L. ; Mierzwa, M. D. ; Kavvas, M. L.

Springer

Stochastic environmental research and risk assessment 14 (2000), S. 263-274

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ISSN: 1436-3259

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract. Because of the nonlinear processes and interactions of the hydroclimatic system, a given hydroclimatic event has an associated probability distribution of possible hydrologic response that changes in space and time. An initial approach in quantifying these evolving probability distributions for use in water resources planning utilizes a simplified climate model. The simplified climate model incorporates the salient physics of the hydroclimatic system for the midlatitudes of the Northern Hemisphere. Using a Monte Carlo format with random initial conditions for the model state variables, hydrologic system response associated with a selected hydroclimatic event is quantified. A case study is presented that utilizes results from the simplified climate model to provide probabilistic seasonal forecasts for water resources planning.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004770000049

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2

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Analytical extensions on a stochastic description of Cyclonic precipitation fields in time and space (1988)

Kavvas, M. L. ; Puri, P. S. ; Saquib, M. N.

Springer

Stochastic environmental research and risk assessment 2 (1988), S. 263-279

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ISSN: 1436-3259

Keywords: Cyclonic rain fields ; cyclone center behavior ; stochastic model

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract Earlier the authors have developed a stochastic geometric model for extratropical cyclonic precipitation fields at synoptic and meso scales as they are typically observed by weather radars over the mainland U S A (see Kavvas and Puri 1983; Kavvas et al. 1987). Here the earlier mathematical development of the model is further extended by incorporating the stochastic description of cyclone center births and their evolutions over U S A into the model.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01544040

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3

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Simulation of the time-space evolution of an extratropical cyclonic precipitation field over USA (1988)

Saquib, M. N. ; Kavvas, M. L. ; Puri, P. S.

Springer

Stochastic environmental research and risk assessment 2 (1988), S. 281-294

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ISSN: 1436-3259

Keywords: precipitation field ; stochastic time-space evolution ; simulation

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract The time-space evolution of an extratropical cyclonic precipitation field over U S A is simulated in a stochastic setting as outlined in Kavvas et al. (1988). The birth of a cyclonic storm is characterized by the simultaneous birth of a cyclone center and births of subsynoptic precipitation areas (SPA) at preferred locations around the cyclone center. The precipitation cores and cells which are used as the fundamental building blocks of the SPAs are approximated by circular precipitation areas (CPA) of different sizes. The time space evolution of the precipitation field after the birth is governed by (1) the movement of the synoptic cyclone described by the cyclone center trajectory, (2) independent nonidentically distributed random velocities of the individual CPAs relative to the cyclone center, (3) the births of new CPAs in time and space relative to the cyclone center, (4) the independent evolution in time of the individual spatially uniform intensities of the existing CPAs, (5) the expansion and shrinkage of the existing CPAs in the course of movement and (6) the dissipation (death) of a random number of existing CPAs within the cyclonic system. The computer simulation, the results of which are presented in this paper, successfully reproduced the general mesoscale and synoptic scale features of the radar detected cyclonic rain fields as observed by Austin and Houze (1972), Houze et al. (1976), Hobbs (1978), Hobbs and Locatelli (1978), Houze (1981), Houze and Hobbs (1982) and others.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01544041

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4

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Stochastic overland flows (1991)

govindaraju, R. S. ; Kavvas, M. L.

Springer

Stochastic environmental research and risk assessment 5 (1991), S. 105-124

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ISSN: 1436-3259

Keywords: Stochastic differential equations ; overland flows ; Monte-Carlo simulations

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract The theory developed in Part I of this paper is now applied to study the probabilistic behavior of the depth at the outlet of an impermeable overland flow section under the diffusion and kinematic wave approximations. This process is excited by stochastic rainfields which are conceptualized from radar observations. The depth at the outflow section is of prime importance and the solution methodology concentrates on obtaining the evolutionary probability distribution function for this physical quantity. This theoretical distribution is then compared with the empirical distribution function obtained from a thousand Monte-Carlo simulations. The simplified theory leading to the Fokker-Planck equation is also investigated. It is observed that the ‘time window’ used for simulation purposes can affect the results. The theoretical methodology performs satisfactorily when compared to simulation results. Some of the notable features of the proposed methodology are presented and further suggestions for improvement and extension of this work are discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01543053

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5

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On a stochastic description of the time-space behaviour of extratropical cyclonic precipitation fields (1987)

Kavvas, M. L. ; Saquib, M. N. ; Puri, P. S.

Springer

Stochastic environmental research and risk assessment 1 (1987), S. 37-52

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ISSN: 1436-3259

Keywords: Cyclonic precipitation ; mathematical modeling ; simulation

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract A stochastic description is developed for extratropical cyclonic precipitation fields at synoptic and meso scales as they are typically observed by radars over the Earth. This description attempts to account I) for the synoptic scale behavior of a cyclonic storm (its birth, its synoptic scale motion trajectory, and its dissipation) II) for the synoptic-scale organizational structure of subsynoptic precipitation areas (rainbands, precipitation cores and raincells) within a cyclonic storm; and III) for the behavior of subsynoptic precipitation areas, in terms of their births, their spatial configuration evolutions, their motions, and their deaths (dissipation). The precipitation cores and the raincells are taken as the building blocks of the subsynoptic precipitation, areas within a cyclonic rainfield.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01543908

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6

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A radar-based stochastic model for the time-space arrivals of the rain fields onto a geographical region (1989)

Kavvas, M. L. ; Chen, Z.

Springer

Stochastic environmental research and risk assessment 3 (1989), S. 261-280

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ISSN: 1436-3259

Keywords: Rain fields ; time-space arrivals ; stochastic model

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract Rainfall in time at any ground location can be described by the rain intensity distribution over the subtrajectories which are drawn by the ground location point on the radar-detected incremental rain fields (IRFs) that pass over this location. Based on this conceptualization, this study develops a stochastic description of the arrivals of IRF subtrajectories (SIRFs) onto any given set of ground locations over a geographical region. The arrivals of SIRFs is described by a multivariate doubly stochastic Poisson process, excited by the time-space arrival process of IRFs onto the designated geographical region. The arrival process of IRFs is described by a 3-level time-space nonhomogeneous Poisson cluster model. At the primary level of this model are the arrivals of synoptic cyclonic systems; at the secondary level are the arrivals of large mesoscale rain areas (LMSAs) and at the tertiary level are the arrivals of IRFs onto the designated geographical region, all detected by the weather radar. The models are substantiated both by the graphical analysis of rain fields, as detected on a radar scope, and by the statistical analysis of the arrivals data at all of the four levels at three different ground locations over a rectangular geographical region in Northern Kentucky. It is pointed out that a doubly stochastic Poisson process is basically a Poisson cluster process. Hence, the final process of SIRF arrivals onto any ground location may be interpreted as a 4-level Poisson cluster process. Finally, heavy tails in the sample covariance density functions of the IRF and SIRF arrivals are detected. This study shows that the appropriate incorporation of clustering at all observable distinct scales of the rain fields models the heavy tail behavior of the covariance density adequately.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01543460

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7

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Stochastic overland flows (1991)

Kavvas, M. L. ; Govindaraju, R. S.

Springer

Stochastic environmental research and risk assessment 5 (1991), S. 89-104

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ISSN: 1436-3259

Keywords: Overland flows ; nonlinear SPDE ; evolutionary probability distributions

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract A theoretical solution framework to the nonlinear stochastic partial differential equations (SPDE) of the kinematic wave and diffusion wave models of overland flows under stochastic inflows/outflows, stochastic surface roughness field and stochastic state of flows was obtained. This development was realized by means of an eigenfunction representation of the time-space overland flow depths, and by transforming the problem into the phase space. By using Van Kampen's lemma and the cumulant expansion theory of Kubo-Van Kampen-Fox, the deterministic partial differential equation (PDE) for the evolutionary probability density function (pdf) of overland flow depths was finally obtained. Once this deterministic PDE is solved for the time-varying pdf of overland flow depths, then the time-space varying pdf of overland flow depths can be obtained by a transformation given in the text. In this solution framework it is possible to incorporate the stochastic dynamic behavior of the parameters and of the forcing functions of the overland flow process. For example, not only the individual rainfall duration and fluctuating rain intensity characteristics but also the sequential behavior of rainfall patterns is incorporated into the evolutionary probability density function of overland flow depths.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01543052

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