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# Questions tagged [numerical-modelling]

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### 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 ...
9k 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-...
686 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, ...
720 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 ...
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 ...
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 ...
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 ...
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 ...
220 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 ...
673 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 ...
406 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(...
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 ...
342 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 ...
212 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 ...
155 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 ...
530 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 ...
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 ...
143 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 ...
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 ...
516 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 ...
343 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 ...
82 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 ...
291 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, ...
196 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) ...
68 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 ...
364 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 ...
102 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 ...
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 ...
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 ...
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 ...
74 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 ...
123 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, $\textbf{U}=(u,v)$...
145 views

### Difference between model parameter and observable parameter

In Inverse problem theory, what is meant by "results of the measurements of observable parameter"?
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 ...
37 views

### Discrete distribution of daily rainfall [closed]

How can I estimate the rainfall rate every ten minutes during a day having the total amount of rainfall during that day ?
86 views

133 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.
68 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?
9 views

### Model relating reservoir releases with downstream temperature

Are there any statistical/numerical models developed relating release from reservoirs with the downstream river temperatures? I know of complicated hydrodynamic models such as CE-QUAL-W2 etc. but I am ...
20 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 ...
28 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 ...