MT3DMS: Model Use, Calibration, and Validation

Chen, Kewei; Hill, Mary C.; Cao, Guoliang; Ma, Ruiqiu

doi:10.13031/2013.42263

Cited by 62 publications

(37 citation statements)

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“…Thus, we set q = 0 in the interaction Hamiltonian H I . Here, we have excluded the possibility of an inhomogeneous superfluid phase (i.e., q = 0), which may exist in the presence of an in-plane Zeemanfield [37]. This is consistent with the two-body calculation [13,27,38] that the ground state of two particles in our Hamiltonian always has zero center-of-mass momentum.…”

Section: Mean Field Theorysupporting

confidence: 84%

Validity of a single-channel model for a spin-orbit-coupled atomic Fermi gas near Feshbach resonances

et al. 2012

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We theoretically investigate a Rashba spin-orbit coupled Fermi gas near Feshbach resonances, by using mean-field theory and a two-channel model that takes into account explicitly Feshbach molecules in the close channel. In the absence of spin-orbit coupling, when the channel coupling g between the closed and open channels is strong, it is widely accepted that the two-channel model is equivalent to a single-channel model that excludes Feshbach molecules. This is the so-called broad resonance limit, which is well-satisfied by ultracold atomic Fermi gases of 6 Li atoms and 40 K atoms in current experiments. Here, with Rashba spin-orbit coupling we find that the condition for equivalence becomes much more stringent. As a result, the single-channel model may already be insufficient to describe properly an atomic Fermi gas of 40 K atoms at a moderate spin-orbit coupling. We determine a characteristic channel coupling strength gc as a function of the spin-orbit coupling strength, above which the single-channel and two-channel models are approximately equivalent. We also find that for narrow resonance with small channel coupling, the pairing gap and molecular fraction is strongly suppressed by SO coupling. Our results can be readily tested in 40 K atoms by using optical molecular spectroscopy.

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Section: Mean Field Theorysupporting

confidence: 84%

Validity of a single-channel model for a spin-orbit-coupled atomic Fermi gas near Feshbach resonances

et al. 2012

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“…The loss function in the model is trying to minimize the fraction of variance unexplained, or the residual sum of squares divided by the total sum of squares (equation (8)). The loss function is also a part of Nash-Sutcliffe efficiency (NSE; equation (9)), which is a widely used performance evaluation method for hydrological modeling (Arnold et al, 2012;Krause et al, 2005). It is also the main evaluation method used in this study.…”

Section: Model Settingsmentioning

confidence: 99%

“…where Y i is the observation at time i, b Y i is the model result at time i,Ȳ is the mean of all observations, and n is the total number of observations. NSE ranges from −∞ to 1, and the closer its value is to 1, the better the model performs (Arnold et al, 2012). Other performance statistics including Pearson's correlation coefficient (r), percent bias (BIAS), and normalized root-mean-square error (NRMSE) are used for model evaluation (equations (10)-(12)).…”

Section: Loss Functionmentioning

confidence: 99%

A Rainfall‐Runoff Model With LSTM‐Based Sequence‐to‐Sequence Learning

Xiang

Yan²,

Demir

2020

Water Resources Research

439

169

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Rainfall-runoff modeling is a complex nonlinear time series problem. While there is still room for improvement, researchers have been developing physical and machine learning models for decades to predict runoff using rainfall data sets. With the advancement of computational hardware resources and algorithms, deep learning methods such as the long short-term memory (LSTM) model and sequence-to-sequence (seq2seq) modeling have shown a good deal of promise in dealing with time series problems by considering long-term dependencies and multiple outputs. This study presents an application of a prediction model based on LSTM and the seq2seq structure to estimate hourly rainfall-runoff. Focusing on two Midwestern watersheds, namely, Clear Creek and Upper Wapsipinicon River in Iowa, these models were used to predict hourly runoff for a 24-hr period using rainfall observation, rainfall forecast, runoff observation, and empirical monthly evapotranspiration data from all stations in these two watersheds. The models were evaluated using the Nash-Sutcliffe efficiency coefficient, the correlation coefficient, statistical bias, and the normalized root-mean-square error. The results show that the LSTM-seq2seq model outperforms linear regression, Lasso regression, Ridge regression, support vector regression, Gaussian processes regression, and LSTM in all stations from these two watersheds. The LSTM-seq2seq model shows sufficient predictive power and could be used to improve forecast accuracy in short-term flood forecast applications. In addition, the seq2seq method was demonstrated to be an effective method for time series predictions in hydrology. Key Points:• An hourly runoff model was developed using the LSTM sequence-to-sequence learning method for 24-hr predictions on USGS stations • The proposed model shows better performance than traditional data-driven models and is applicable to different watersheds • The advantages and limitations of seq2seq models and how this model structure could work on the rainfall-runoff modeling is presented Supporting Information:• Supporting Information S1 Correspondence to: Z. Xiang, zhongrun-xiang@uiowa.edu Citation: Xiang, Z., Yan, J., & Demir, I. (2020). A rainfall-runoff model with LSTM-based sequence-to-sequence learning. Water Resources Research, 56, e2019WR025326. https://doi.

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“…The groundwater mean age, integrating the effects of dispersion, diffusion and mixing over the length of flow paths, may be a more sound approach to determine the spatial distribution of ages than the use of advective ages or point measurements of tracer-age, where the implicit assumption of piston flow is made (Cornaton and Perrochet, 2006;Newman et al, 2010). Groundwater age distribution controlled by advection and dispersion was simulated using the MT3DMS program (Zheng and Wang, 1999;Zheng et al, 2012) in a steady-state mode. The same code can be used to simulate the heat transfer when effects of buoyancy and changes in viscosity are small (Hecht-Méndez et al, 2010).…”

mentioning

confidence: 99%

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Cao

Han

Currell

et al. 2016

Journal of Asian Earth Sciences

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a b s t r a c tGroundwater flow in deep sedimentary basins results from complex evolution processes on geological timescales. Groundwater flow systems conceptualized according to topography and/or groundwater table configuration generally assume a near-equilibrium state with the modern landscape. However, the time to reach such a steady state, and more generally the timescales of groundwater flow system evolution are key considerations for large sedimentary basins. This is true in the North China Basin (NCB), which has been studied for many years due to its importance as a groundwater supply. Despite many years of study, there remain contradictions between the generally accepted conceptual model of regional flow, and environmental tracer data. We seek to reconcile these contractions by conducting simulations of groundwater flow, age and heat transport in a three dimensional model, using an alternative conceptual model, based on geological, thermal, isotope and historical data. We infer flow patterns under modern hydraulic conditions using this new model and present the theoretical maximum groundwater ages under such a flow regime. The model results show that in contrast to previously accepted conceptualizations, most groundwater is discharged in the vicinity of the break-in-slope of topography at the boundary between the piedmont and central plain. Groundwater discharge to the ocean is in contrast small, and in general there are low rates of active flow in the eastern parts of the basin below the central and coastal plain. This conceptualization is more compatible with geochemical and geothermal data than the previous model. Simulated maximum groundwater ages of $1 Myrs below the central and coastal plain indicate that residual groundwater may be retained in the deep parts of the basin since being recharged during the last glacial period or earlier. The groundwater flow system has therefore probably not reached a new equilibrium state with modern-day hydraulic conditions. The previous hypothesis that regional groundwater flow from the piedmont groundwater recharge zone predominantly discharges at the coastline may therefore be false. A more reliable alternative might be to conceptualize deep groundwater below the coastal plains a hydrodynamically stagnant zone, responding gradually to landscape and hydrological change on geologic timescales. This study brings a new and original understanding of the groundwater flow system in an important regional basin, in the context of its geometry and evolution over geological timescales. There are important implications for the sustainability of the ongoing high rates of groundwater extraction in the NCB.

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MT3DMS: Model Use, Calibration, and Validation

Cited by 62 publications

References 0 publications

Validity of a single-channel model for a spin-orbit-coupled atomic Fermi gas near Feshbach resonances

Validity of a single-channel model for a spin-orbit-coupled atomic Fermi gas near Feshbach resonances

A Rainfall‐Runoff Model With LSTM‐Based Sequence‐to‐Sequence Learning

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

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