DOI: 10.5194/hess-18-2521-2014
Scopus记录号: 2-s2.0-84903828635
论文题名: Kalman filters for assimilating near-surface observations into the Richards equation – Part 2: A dual filter approach for simultaneous retrieval of states and parameters
作者: Medina H ; , Romano N ; , Chirico G ; B
刊名: Hydrology and Earth System Sciences
ISSN: 10275606
出版年: 2014
卷: 18, 期: 7 起始页码: 2521
结束页码: 2541
语种: 英语
Scopus关键词: Kalman filters
; Nonlinear filtering
; Soil moisture
; Solute transport
; State space methods
; Time series
; Ensemble Kalman Filter
; Meteorological forcing
; Saturated hydraulic conductivity
; Soil hydraulic functions
; Soil hydraulic parameters
; Standard Kalman filters
; State space formulation
; Unscented Kalman Filter
; Parameter estimation
; correlation
; filter
; flow modeling
; hydraulic conductivity
; Kalman filter
; parameterization
; Richards equation
; soil aggregate
; soil water
; time series
英文摘要: This study presents a dual Kalman filter (DSUKF - dual standard-unscented Kalman filter) for retrieving states and parameters controlling the soil water dynamics in a homogeneous soil column, by assimilating near-surface state observations. The DSUKF couples a standard Kalman filter for retrieving the states of a linear solver of the Richards equation, and an unscented Kalman filter for retrieving the parameters of the soil hydraulic functions, which are defined according to the van Genuchten-Mualem closed-form model. The accuracy and the computational expense of the DSUKF are compared with those of the dual ensemble Kalman filter (DEnKF) implemented with a nonlinear solver of the Richards equation. Both the DSUKF and the DEnKF are applied with two alternative state-space formulations of the Richards equation, respectively differentiated by the type of variable employed for representing the states: either the soil water content (θ) or the soil water matric pressure head (h). The comparison analyses are conducted with reference to synthetic time series of the true states, noise corrupted observations, and synthetic time series of the meteorological forcing. The performance of the retrieval algorithms are examined accounting for the effects exerted on the output by the input parameters, the observation depth and assimilation frequency, as well as by the relationship between retrieved states and assimilated variables. The uncertainty of the states retrieved with DSUKF is considerably reduced, for any initial wrong parameterization, with similar accuracy but less computational effort than the DEnKF, when this is implemented with ensembles of 25 members. For ensemble sizes of the same order of those involved in the DSUKF, the DEnKF fails to provide reliable posterior estimates of states and parameters. The retrieval performance of the soil hydraulic parameters is strongly affected by several factors, such as the initial guess of the unknown parameters, the wet or dry range of the retrieved states, the boundary conditions, as well as the form (h-based or θ-based) of the state-space formulation. Several analyses are reported to show that the identifiability of the saturated hydraulic conductivity is hindered by the strong correlation with other parameters of the soil hydraulic functions defined according to the van Genuchten-Mualem closed-form model. © Author(s) 2014. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/78201
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Basic Sciences, Agrarian University of Havana, Havana, Cuba; Department of Agricultural Engineering, University of Naples Federico II, Naples, Italy
Recommended Citation:
Medina H,, Romano N,, Chirico G,et al. Kalman filters for assimilating near-surface observations into the Richards equation – Part 2: A dual filter approach for simultaneous retrieval of states and parameters[J]. Hydrology and Earth System Sciences,2014-01-01,18(7)