Questions tagged [numerical-modelling]

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18
votes
2answers
4k views

What are the applications of hydrostatic solvers vs non-hydrostatic solvers in numerical weather prediction?

In the atmospheric dynamics research community, many colleagues of mine happen to use atmospheric models that have non-hydrostatic equation solvers, e.g. the UK MetOffice model, and WRF-ARW: The ...
17
votes
1answer
8k views

What are the differences between an LES-SGS model and a RANS based turbulence model?

I'm kind of new to the Large Eddy Simulation (LES) modeling world and I wondered what is the difference between an LES subgrid scale model like the Smagorinsky–Lilly model and a one-equation Reynolds-...
14
votes
2answers
659 views

How important is understanding linear algebra in groundwater modeling?

I am considering taking a course in linear algebra and wanted to get a survey to see how important it is. My goal is not just to understand how to push the buttons in some software (e.g. GW Vistas, ...
14
votes
1answer
667 views

What is the force imposed by underwater currents?

I would like to calculate the force of an underwater current on a meter by meter plate (or any other unit that you may use to represent it) that is standing in front of the current. How do I calculate ...
12
votes
4answers
5k views

How to get cell indices from latitude and longitude in WRF model grids?

I am using Weather Research and Forecasting model WRF and the WRF Preprocessing System WPS and could not get a satisfying answer from wrfhelp. Can anyone guide me in transforming latitude and ...
12
votes
3answers
5k views

What are the differences between implicit and explicit methods when applied to modelling Earth systems?

I am struggling to understand the difference between implicit methods and explicit methods in numerical modelling of Earth processes, particularly when applied to modelling Earth systems in 2 or more ...
11
votes
2answers
383 views

Are there any general-purpose climate-model coupling projects?

In climate modelling, there are three major model types that form the basis of a fully coupled Atmosphere-Ocean General Circulation Model (AOGCM): Atmosphere circulation models Ocean circulation ...
10
votes
3answers
4k views

Meaning of Coupling in Modelling

The Community Earth System Model (CESM) is described as a fully-coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate ...
10
votes
1answer
219 views

Stability correction factor in the Wavewatch III wave model

I'm studying the Wavewatch III wave model (http://polar.ncep.noaa.gov/waves/index2.shtml). I'm confused by the stability correction factor, named ASF in the code. What is its purpose? Is it related to ...
10
votes
1answer
646 views

Resources for learning the technical parts of atmospheric modeling

I'm a computer/atmospheric science undergrad and I'm trying to get into atmospheric modeling. Any recommendations for resources to get going or to learn about approaches? I can handle fairly technical ...
10
votes
1answer
398 views

Optimal vertical coordinate for complex topography

There are plenty of choices in models in so far as choice of vertical coordinate is concerned for meteorological models. Five that I know of: The sigma coordinate system - Hybrid coordinate system(...
10
votes
1answer
88 views

How to estimate dispersion in stratified flows

Consider a 2-dimensional domain with the typical x-z coordinates. Given an arbitrarily stratified flow, how can we estimate the depth varying horizontal dispersion of passive particles induced by the ...
10
votes
2answers
335 views

The origin of spurious high frequency waves in numerical weather prediction

I am currently reading this paper on digital filters and their relevance to meteorological models Digital Filter Initialization . My question relates to this following text - "The requirement to ...
9
votes
4answers
210 views

Confusion about grid registration concepts and their relevance in modelling

I'm trying to make use of the ETOPO1 dataset as the bathymetry input of a wave model. I came upon this discussion of grid registration: Registration of Structured Square-Cell Grids. I read this ...
9
votes
1answer
148 views

Why should dynamical downscaling of meteorological data be made incrementally?

When downscaling meteorological data by using limited area models, many support forums recommended you to downscale incrementally in small steps. For example let's assume that your input data is on a ...
8
votes
3answers
496 views

What exactly is a model grid?

I have just begun reading some notes about modelling and can't seem to understand what a 1°x1° grid or a 2.5° grid or 1/4° grid is. I know it is something related to the resolution of the area over ...
8
votes
3answers
1k views

Effect of urbanization on weather events

At what stage is the studies on effect of urbanization on weather events (eg: Rainfall, Temperature, UHI) are now? There has been a number of observational and modelling studies around the world and ...
8
votes
1answer
141 views

Unrealistic solution for advection-diffusion-reaction PDE with heterogeneous porous media

About the code: I have a code which simulates concentration from advection-diffusion-reaction PDE in 2D space (X,Y) with time. The solution is obtained using fully implicit finite-difference method ...
8
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0answers
200 views

Modeling swirling storms

I'm looking to demonstrate the rotational behaviour of swirling storms with a numerical simulation. So far it includes pressure-gradient, Coriolis acceleration, frictional forces and the acceleration ...
7
votes
1answer
486 views

Computing Isentropic Potential Vorticity from Hybrid Sigma Pressure levels

My task is to compute isentropic potential vorticity on a grid. All data (ECMWF ens) are given on a hybrid sigma pressure grid. Since I really cannot find reference, I assume (!) that relative ...
7
votes
1answer
337 views

What's the prospect of air quality forecasting based on machine learning?

Air quality forecasting models which are useful for atmospheric scientist and government can be built based on numerical theory or statistic theory. The first approach outline the basic physics ...
6
votes
2answers
80 views

Does hydroxyl radical chemistry in air quality models create numerical stability problems?

Atmospheric mixing ratios of the hydroxyl radical have relatively short lifespans (on the order of microseconds). When modeling air quality or the weather, the time step is usually much larger than ...
5
votes
1answer
247 views

How do spectral methods work in the context of numerical weather prediction models?

I am broadly familiar with the concept of numerical weather prediction models using various finite methods to solve the primitive equations used in these models, but how do spectral methods work, ...
5
votes
2answers
172 views

correct way to calculate transport through a section in an ocean numerical model

Suppose that I want to calculate the transport across a certain transect (green line) from the outputs of an ocean numerical model. The model has the $u$ values at the center of the grids (crosses) ...
5
votes
1answer
65 views

Calculate the number of model grid cells covering a specific country

What is the best method of calculating the number of model grid cells (e.g. of climate models) covering a specific country? For example, if I wanted to know how many 2 degree grid cells are in the ...
5
votes
1answer
355 views

What is “focus point” in WRF-plots grid box? (python code)

has anyone used the python code from here (written by Geir Arne Waagbo) to plot skewT plot from WRF output? I've got a question regarding some of the functions used in the code found in ...
4
votes
1answer
99 views

Simple and realistic data for glacier modeling

I'm programming the nonlinear Stokes problem (with a finite element method), $$\operatorname{div}(\mu(u)\nabla u+pI)=f$$ where $\mu(u)$ is the Glen's power flow law (typical for glaciers). I want to ...
4
votes
0answers
68 views

What is the equivalent of CFL criterion when using spectral models?

I would like to know what the equivalent of the CFL criterion is for atmospheric models based of spectral grids. In other words, how do you find the necessary horizontal resolution in meters for ...
3
votes
0answers
18 views

Statistical dependence of mean annual soil evaporation and mean annual precipitation globally

I am studying a simple dynamical system that represents a plant and water system, similar to Klausmeier. In Klausmeier model the mean annual precipitation and the soil evaporation are introduced as ...
3
votes
0answers
54 views

Determining rotation of a bending detachment fault system

I would like to obtain the angle of rotation (𝛿θ) of a detachment fault (or oceanic core complex) after X meters of rock displaced during spreading at a mid-ocean ridge. I have a differential ...
3
votes
0answers
73 views

Unwanted oscillations in Synthetic seismogram

I have generated a synthetic seismogram using FDTD elastic velocity-stress formulation on a staggered grid. I can't understand origin of oscillations modulating on seismogram. Is it a result of ...
2
votes
2answers
100 views

Temperature Advection using finite differences with gridded data

Advection of a scalar quantity, such as temperature (T), by the horizontal wind, is defined as follows: $-\textbf{U}\cdot\nabla T$ where $\textbf{U}$ is the horizontal wind vector, $\textbf{U}=(u,v)$...
2
votes
1answer
118 views

Difference between model parameter and observable parameter

In Inverse problem theory, what is meant by "results of the measurements of observable parameter"?
2
votes
1answer
1k views

How to set up a domain from namelist in WRF?

I'm fairly inexperienced with WRF and was wondering if anyone could point me in the direction of any helpful resources for it. The task I have is to make a simple 9 km domain, but I'm having trouble ...
2
votes
1answer
27 views

Discrete distribution of daily rainfall

How can I estimate the rainfall rate every ten minutes during a day having the total amount of rainfall during that day ?
2
votes
1answer
64 views

Computation of geostrophic wind

I am attempting to calculate the zonal and meridional components of geostrophic wind using the equations below: $u_g = -\frac{g_0}{f} \cdot \frac{1}{r} \cdot \frac{\partial \Phi }{\partial \phi}$ $...
2
votes
0answers
139 views

python generate 3d unstructured grid

I would like to create a 3d unstructured grid based on data points with xyz and property. Can Python do this and what tools? My question is quite generic but i can provide more details: the data has ...
2
votes
0answers
46 views

Reasons for choosing LES in stead of RANS models?

In oceanography, is there any particular reason why choosing large eddy simulations in stead of RANS (regardless of the type of flow)? In both cases, 2d simulations would be used (shallow water model)....
2
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0answers
43 views

Visually Realistic Supercell Modeling

Are there any published descriptions of simple equations governing the formation, evolution, and decay of severe storms? Specifically, I am interested in equations that are able to produce tornadoes ...
2
votes
2answers
53 views

Which equations describe complete (or near complete) behaviour of magma moving through rocks?

Yes this is a bit broader question but I want to know which processes play their role in movement of magma. If one wants to model magma movement through rocks, which processes should one not miss at ...
2
votes
0answers
58 views

Formula for numerical model for sustained warming in marine sediment?

I have been reading this paper and found simple numerical formulations to model the time duration, affected depth and amount of warming of marine sediments. The author uses a rudimentary estimate of ...
2
votes
0answers
92 views

Numerical methods for solving shallow-water equations with a source

What are the numerical methods used for solving shallow water equations (PDEs) with a mass source, at the synoptic scales of the atmosphere, if I have a finite east-west boundary (may be periodic wave ...
2
votes
0answers
272 views

What is difference between Riverbed conductance term and streambed leakance/retardation coefficient?

In literature some times to account for semi-pervious sediments at bottom of stream, streambed leakance also called retardation coefficient ($L$) is used. This is equal to the ratio of conductivity of ...
2
votes
0answers
132 views

Problem running the WAM wave model [closed]

In the WAM Cycle 4 wave model, why doesn't the model work for the year 1999? When I tried to run for the year 1999 the model does not produce any results.
1
vote
1answer
67 views

Why RBF is gridless and kriging is not?

I read about it somewhere in a paper. Why is kriging not gridless if I can krig points in space? Whats is the big difference from RBF?
1
vote
0answers
15 views

How to determine the orientation of coastline from NetCDF file

I have a NetCDF file (gridded data) with a landsea mask. I would like to determine, for the coastal grid-cells, what the orientation of the coastline is. I need to do this in order to calculate the ...
1
vote
0answers
22 views

How to control output precision when running WRF?

I am very new in this area and wondering if anyone can answer my following questions: I am running WRF (4.0.3, ideal) to study rounding and truncation. I use the NCL (6.5.0) print command to access ...
1
vote
0answers
66 views

WRF: minimal list of variables required by coupling a land surface model to the whole system

We are trying to couple our land surface model into WRF. As a first step, we'd like to know what is the minimal list of variables required by such coupling?
0
votes
0answers
13 views

Do snow and ice have different temperatures at their interface?

tl;dr: For snow on top of ice, is the temperature at the base of the snowpack always (practically) the same as the temperature at the top of the ice? I was trying to understand how the thermodynamics ...