Model Hierarchy for Mountainous Hydrological Observatories (MH2O)

2021 ◽  
Author(s):  
William Collins
Keyword(s):  
Model Hierarchy

scholarly journals Can one use Earth’s magnetic axial dipole field intensity to predict reversals?

2020 ◽  
Author(s):  
K Gwirtz ◽  
M Morzfeld ◽  
A Fournier ◽  
G Hulot
Keyword(s):  
Magnetic Field ◽  
Numerical Models ◽  
Dipole Field ◽  
Axial Dipole ◽  
Intensity Threshold ◽  
Magnetic Dipole Field ◽  
Model Hierarchy ◽  
Definition Of ◽  
Virtual Axial Dipole Moment ◽  
Prediction Strategy

Summary We study predictions of reversals of Earth’s axial magnetic dipole field that are based solely on the dipole’s intensity. The prediction strategy is, roughly, that once the dipole intensity drops below a threshold, then the field will continue to decrease and a reversal (or a major excursion) will occur. We first present a rigorous definition of an intensity threshold-based prediction strategy and then describe a mathematical and numerical framework to investigate its validity and robustness in view of the data being limited. We apply threshold-based predictions to a hierarchy of numerical models, ranging from simple scalar models to 3D geodynamos. We find that the skill of threshold-based predictions varies across the model hierarchy. The differences in skill can be explained by differences in how reversals occur: if the field decreases towards a reversal slowly (in a sense made precise in this paper), the skill is high, and if the field decreases quickly, the skill is low. Such a property could be used as an additional criterion to identify which models qualify as Earth-like. Applying threshold-based predictions to Virtual Axial Dipole Moment (VADM) paleomagnetic reconstructions (PADM2M and Sint-2000) covering the last two million years, reveals a moderate skill of threshold-based predictions for Earth’s dynamo. Besides all of their limitations, threshold-based predictions suggests that no reversal is to be expected within the next 10 kyr. Most importantly, however, we show that considering an intensity threshold for identifying upcoming reversals is intrinsically limited by the dynamic behavior of Earth’s magnetic field.

scholarly journals Extending the Modular Earth Submodel System (MESSy v2.54) model hierarchy: the ECHAM/MESSy IdeaLized (EMIL) model setup

2020 ◽  
Vol 13 (11) ◽  
pp. 5229-5257
Author(s):  
Hella Garny ◽  
Roland Walz ◽  
Matthias Nützel ◽  
Thomas Birner
Keyword(s):  
Climate Model ◽  
Polar Vortex ◽  
Equilibrium Temperature ◽  
Earth System ◽  
Tracer Transport ◽  
Dynamical Core ◽  
Vortex Strength ◽  
Model Hierarchy ◽  
Model Setup ◽  
The Impact

Abstract. As models of the Earth system grow in complexity, a need emerges to connect them with simplified systems through model hierarchies in order to improve process understanding. The Modular Earth Submodel System (MESSy) was developed to incorporate chemical processes into an Earth System model. It provides an environment to allow for model configurations and setups of varying complexity, and as of now the hierarchy ranges from a chemical box model to a fully coupled chemistry–climate model. Here, we present a newly implemented dry dynamical core model setup within the MESSy framework, denoted as ECHAM/MESSy IdeaLized (EMIL) model setup. EMIL is developed with the aim to provide an easily accessible idealized model setup that is consistently integrated in the MESSy model hierarchy. The implementation in MESSy further enables the utilization of diagnostic chemical tracers. The setup is achieved by the implementation of a new submodel for relaxation of temperature and horizontal winds to given background values, which replaces all other “physics” submodels in the EMIL setup. The submodel incorporates options to set the needed parameters (e.g., equilibrium temperature, relaxation time and damping coefficient) to functions used frequently in the past. This study consists of three parts. In the first part, test simulations with the EMIL model setup are shown to reproduce benchmarks provided by earlier dry dynamical core studies. In the second part, the sensitivity of the coupled troposphere–stratosphere dynamics to various modifications of the setup is studied. We find a non-linear response of the polar vortex strength to the prescribed meridional temperature gradient in the extratropical stratosphere that is indicative of a regime transition. In agreement with earlier studies, we find that the tropospheric jet moves poleward in response to the increase in the polar vortex strength but at a rate that strongly depends on the specifics of the setup. When replacing the idealized topography to generate planetary waves by mid-tropospheric wave-like heating, the response of the tropospheric jet to changes in the polar vortex is strongly damped in the free troposphere. However, near the surface, the jet shifts poleward at a higher rate than in the topographically forced simulations. Those results indicate that the wave-like heating might have to be used with care when studying troposphere–stratosphere coupling. In the third part, examples for possible applications of the model system are presented. The first example involves simulations with simplified chemistry to study the impact of dynamical variability and idealized changes on tracer transport, and the second example involves simulations of idealized monsoon circulations forced by localized heating. The ability to incorporate passive and chemically active tracers in the EMIL setup demonstrates the potential for future studies of tracer transport in the idealized dynamical model.

scholarly journals A Model Hierarchy for Psychological Science

2019 ◽  
Author(s):  
David Kellen
Keyword(s):  
Scientific Practices ◽  
Comprehensive List ◽  
Psychological Science ◽  
Model Hierarchy

Lee et al. (2019) provided a comprehensive list of recommendations for modelers thataims at improving the robustness of their results. Drawing from the literature onphilosophy of science, the present commentary argues for a broader view of modeling that considers the different roles that they play in our scientific practices. Following Suppes (1966), I propose a model hierarchy and discuss the distinct issues that arise at each of its levels. The benefit of a hierarchy of this kind is that it can aid researchers in better understanding the different challenges that they face.

A MODEL HIERARCHY FOR IONOSPHERIC PLASMA MODELING

2004 ◽  
Vol 14 (03) ◽  
pp. 393-415 ◽  
Author(s):  
CHRISTOPHE BESSE ◽  
PIERRE DEGOND ◽  
FABRICE DELUZET ◽  
JEAN CLAUDEL ◽  
GÉRARD GALLICE ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Density ◽  
Maxwell Equations ◽  
Ionospheric Plasma ◽  
Practical Interest ◽  
Plasma Modeling ◽  
Model Hierarchy ◽  
Great Practical Interest ◽  
Two Fluid ◽  
Insight Into

This paper deals with the modeling of the ionospheric plasma. Starting from the two-fluid Euler–Maxwell equations, we present two hierarchies of models. The MHD hierarchy deals with large plasma density situations while the dynamo hierarchy is adapted to lower density situations. Most of the models encompassed by the dynamo hierarchy are classical ones, but we shall give a unified presentation of them which brings a new insight into their interrelations. By contrast, the MHD hierarchy involves a new (at least to the authors) model, the massless-MHD model. This is a diffusion system for the density and magnetic field which could be of great practical interest. Both hierarchies terminate with the "classical" Striation model, which we shall investigate in detail.

scholarly journals Model hierarchy of upper‐convected Maxwell models with regard to simulations of melt‐blowing processes

PAMM ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Manuel Wieland ◽  
Walter Arne ◽  
Nicole Marheineke ◽  
Raimund Wegener
Keyword(s):  
Melt Blowing ◽  
Model Hierarchy ◽  
Maxwell Models

scholarly journals Searches for Direct Pair Production of Third Generation Squarks with the ATLAS Detector

2018 ◽  
Vol 46 ◽  
pp. 1860057
Author(s):  
Federico Meloni
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Higgs Sector ◽  
Fine Tuning ◽  
Proton Collision ◽  
Third Generation ◽  
Proton Proton ◽  
Missing Transverse Momentum ◽  
Model Hierarchy ◽  
Generation Squarks

This document summarises recent ATLAS results for searches for third generation squarks using 36.1 [Formula: see text] of LHC proton-proton collision data collected at [Formula: see text] TeV. Despite the absence of experimental evidence, weak scale supersymmetry remains one of the best motivated and studied Standard Model extensions. Supersymmetry can naturally solve the Standard Model hierarchy problem by preventing a large fine-tuning in the Higgs sector: a typical natural SUSY spectrum contains light third generation squarks (stops and sbottoms). Both R-Parity conserving and R-Parity violating scenarios are considered. The searches involve final states including jets, missing transverse momentum, electrons or muons. Simplified models predicting pair production of third generation squarks have been excluded at 95% CL up to about one TeV in the most favourable scenarios.

Constructive Representation of Heterogeneous Objects

2001 ◽  
Vol 1 (3) ◽  
pp. 205-217 ◽  
Author(s):  
Ki-Hoon Shin ◽  
Debasish Dutta
Keyword(s):  
Data Structure ◽  
Material Composition ◽  
Binary Trees ◽  
Heterogeneous Objects ◽  
Computer Representation ◽  
Model Hierarchy ◽  
Representation Scheme

This paper proposes a constructive representation scheme for heterogeneous objects (or FGMs). In particular, this scheme focuses on the construction of complicated heterogeneous objects, guaranteeing desired material continuities at all the interfaces. In order to create various types of heterogeneous primitives, we first describe methods for specifying material composition functions such as geometry-independent, geometry-dependent functions, and multiple sets of these functions. Constructive Material Composition (CMC) and corresponding heterogeneous Boolean Operators (e.g., material union, difference, intersection, and partition) are then proposed to illustrate how material continuities are dealt with. Finally, we will describe the model hierarchy and data structure for computer representation. Even though the constructive representation alone is sufficient for modeling heterogeneous objects, the proposed scheme pursues a hybrid representation between decomposition and construction. That is because hybrid representation can avoid unnecessary growth of binary trees.

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