# Questions tagged [models]

A tag for questions about conceptual, analytical or numerical models used in Earth science disciplines.

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### A good book or source for climate science and meteorology basics?

I have a mainly a hydro-geological and geo-statistical background, I would like to have a basic introduction to meteorological, climatic processes and modelling techniques related to these fields. Any ...
172 views

### What modelling approaches are used to predict the aurora?

Are there any resources (books/links) that discuss the mathematical tools and methods used to forecast the aurora borealis activity in a particular location? I see many websites that claim to predict ...
136 views

### How to model bed load transport in channels of non-rectangular cross sections

All the formulas presented in the relevant technical literature refer to channels of rectangular cross section — the formulas assume a constant depth of flow right across the channel section. I need ...
541 views

### What is a Geophysical Model Function (GMF)?

I have heard the term mentioned many times in seminars, and in papers on remote sensing. What does it mean? References would be helpful if available.
329 views

### Understanding the Mercator Projection

To illustrate my problem, let's say I have lattitude and longitude coordinates, such as 38.871105, -77.056042. I want to be able to calculate the new lattitude and longitude if, say, I moved 300m ...
1k views

### Help interpreting a wind rose diagram

Can someone comment on technical explanation of the wind rose attached? I can understand the wind is blowing between WNW & SSW with speed of 7-11 km/h. For frequency of 11-16 km/h its blowing ...
1k views

### How to calculate w-wind?

My model (AGCM) does not compute w-wind (the vertical component of the wind velocity). However, I do have the following available variables from AGCM output: ...
781 views

### Long-term Wind Speed Forecasting: reality or wishful thinking?

I have been studying/working with Wind Energy for a while and, one of my main responsabilities right now is to search for adequate long-term wind speed forecasting models. However, 2 things strike me ...
771 views

### What is “qflux” and why is it important for climate models?

Evaluation of the Ocean Q Flux is an example of qflux used in the CESM model. Why is it important?
201 views

### Debunking weather conspiracy with statistics - why does temperature rise then fall for last weekend in June in recent years

I have a conspiracy-prone friend who believes that people are controlling the weather to ensure good weather for a large, annual festival (last weekend in June in San Francisco). As a scientist, (not ...
669 views

### WRF output grid is smaller than input definition

I am running some test forecasts using WRF 3.6.1. and am having some problems with my grids. Specifically, I am specifying a parent and nest domain each with 25 points for longitude and latitude (so ...
601 views

### Units of wave spectrum

In ocean spectra such as the Pierson Moskowitz or the JONSWAP models, the units of $S(\omega)$ are $m^2/(rad/s)$ (or whatever unit of measurement you are working in). Where does the $m^2$ come from ...
133 views

### What determines the spatial resolution of a study?

This might sound like a silly question to many of you, but I am addressing the comments of a referee regarding a study I'm trying to publish and I remained a little puzzled about this issue. Let's ...
426 views

### Monitoring air pollution with Landsat satellite data

I'm trying to build an air pollution model. So far I have built one for point sources. Now I'm looking at monitoring air pollution with satellite images, based on the idea that every basic pollutant ...
102 views

### Kalman - Data assimilation with external model

I'm working with a distributed snow model which simulates Snow Depth and Snow Cover area. It takes in input some atmospherics variables : Temperature / Precipitation / Wind speed ... I want to ...
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### What is the difference between GFS analysis and GFS forecast data?

gfsanl_3_20151201_0000_006 means that the analysis was made at 0000 UTC and is valid at 0600 UTC, doesn't it? But for how long, 3 hours? And what is the difference ...
274 views

### Methods and Software for Interpolating/Modelling of Stratigraphic Well Data in 2D/3D

I have some geologic well data. The lithologies have been interpreted, and stratigraphic columns have been drawn. The columns have been adjusted for elevation, and correlation has been done between ...
117 views

### How to derive the (dry) deposition velocity for particles in the atmosphere

In atmospheric dispersion modelling the deposition velocity of particulate matter is often described by: $$v_d = \frac{1}{r_A+r_B+r_A r_B v_g}+v_g \hspace{10mm}(1)$$ where $r_A$ is the aerodynamic ...
2k views

### Compute direction of gravity vector

As I understand to compute vector of gravity not saficient to compute normal to elipsoid, but we need to computer normal to geoid (by definition geoid is a surface to which the force of gravity is ...
234 views

### Seismic migration concepts

In Dr Hua-Wei Zhou's book Practical Seismic Data Analysis (2014), he includes and explains figures from previous classic works (i.e. Schneider, 1971) in order to describe migration from a fundamental ...
93 views

### Does a table summarizing basic details of significant operational weather models exist?

With all the questions we've had through the years that have tied into weather models, plus all the sites around the web providing weather model data, it got me wondering: is there any table that ...
721 views

### Why is WRF-Chem not reading my emissions data?

I've been trying to run WRF-Chem with my emissions but they are not being read by WRF-Chem. RADM2. I have emissions for the whole week, so io_style_emissions = 2 ...
2k views

### What are the domains of Earth Science?

Increasingly confused by all the "spheres" and agreed relationships between them. As a result, I am looking for a singular answer that clearly states at the very least what the top-level and secondary ...
4k views

### Meaning of Hindcast

Let $t_0$ be the time instant of interest, $t_{-1}$ be some time before $t_0$, and $t_1$ be some instant in time after $t_0$. Now there is no confusion with forecast - if the present time is $t_0$, a ...
2k views

### Running WRF with ECMWF GRIB2 model levels

ECMWF model data comes in a hybrid GRIB format, that is, model level output is stored in GRIB2 messages, whereas surface data still uses GRIB1 format. Ungrib is unable to understand this hybrid GRIB ...
160 views

### Is there a simple temperature prediction model?

I'm working on piecing together a game that involve sea trading, loosely based on historical conditions. As a part of making the game, I'm creating a map. From that map, I'm trying to determine what ...
119 views

### What's the difference between these most basic, first-order models for estimating runoff?

There are a lot of variations of basic, first-order hydrology models to estimate runoff from rainfall with a few other parameters. From what I can tell, most very basic rainfall-runoff models use one ...
79 views

### Nonlinear Stokes equations for glacier modeling

What is the difference between $$\operatorname{div}(-\mu(u)\nabla u+pI)=f\tag{1}$$ and $$\operatorname{div}(-\mu(u)(\nabla u\color{red}{+(\nabla u)^\mathsf{T}})+pI)=f\tag{2}$$ from the physical ...
211 views

### Timeline of atmospheric model resolution

I'm looking for a graph of improvements in spatial resolution for any atmospheric model (such as the UK Met Office Unified Model or ECMWF IFS). Ideally it would include a range of historical model ...
78 views

### How to create a model to predict the salmon run

Are there any publicly available models that show you how to accurately predict the salmon run in both the Pacific and Atlantic oceans? This has been such a long interest of mine, I often see the ...
155 views

### Comparing Pros and Cons of SWAT and HSPF

To model hydrology in a watershed, two of the most famous and widely used distributed models are SWAT and HSPF. I have some good understanding of HPSF, but I don't know when and why should one prefer ...
303 views

### In hydrology, what's the difference between specific and total catchment area?

I am getting stuck on the concepts of Total Catchment Area (TCA) and Specific Catchment Area (SCA) as I try to learn more about TOPMODEL and hydrology modeling. What do these metrics mean in hydrology?...
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 ...
74 views

### snow modelling using raster data with different resolution

I am trying model to some snow processes for the whole US. I do have daily climate forcing time series for a 1 x 1 km raster in a Lambert Conformal Conic Projection (netCdf format). The MODIS snow ...
250 views

### What is the difference between the freezing level and 0C isotherm in NOAA's GFS?

I'm playing around with NOAA's GFS forecast data and I see that it contains both a "0C isotherm level" and a "Highest tropospheric freezing level". Could someone tell me the difference between these ...
580 views

### Why did the GFS switch to hourly forecasts through hour 120?

About a month ago, the GFS was upgraded. Among other things (like making parallel GFS data available), the upgrade notice said: Include hourly forecasts out to 120 hr Now, this seemed ...
124 views

### References for moving and nested grids in models

Would anyone know of references that give detailed explanations on concepts such as moving grids and nested grids in models?
185 views

### Coupling recharge with 1D groundwater flow model

Suppose we are modeling 1D groundwater flow in an aquifer of extent $x$ from $A(x=0)$ to $C$. Lets say for unsteady state conditions, the input is at $A(x=0)$, we can model piezometeric response at \$B ...
198 views

### Global Gridded Daily Temperature (at 2m): difference between GEFS Reforcast and NCEP Reanalysis

I am looking for gridded/raster estimates of daily mean temperature (ideally ambient/at 2 meter) for a public health analysis. Specifically, I want to correlate daily mortality counts with daily mean ...
1k views

### Negative values of relative humidity in CFSR

I recently started using the Climate Forecast System Reanalysis (CFSR) 6-hourly products (http://rda.ucar.edu/datasets/ds093.0/), and I noticed many values of relative humidity are negative. Is this ...
253 views

### What is the difference between the Hydraulic diffusion equation and the Richards equation in groundwater dynamics?

What is the difference between the Hydraulic diffusion equation and the Richards equation in groundwater dynamics? I want also to understand the difference between the different storage coefficients (...
40 views

### Dealing with uncertainty in source apportionment

I have a dataset of dissolved load (major and trace elements), the associated error is specified as <10% for all the cases, in the same way I have rock analysis (major and trace) with the same ...
952 views

### Predicting rainfall with governing equations

Which model is a good starting point for predicting precipitation (rain) for 24 hours in advance? I looked at Kalnay's Atmospheric modeling, data assimilation and predictability, and Holton's An ...
95 views

### Do tectonic plates “float” over the mantle and “collide” like icebergs?

I'm always hearing about tectonic plates as large chunks of crust floating on the mantle just like boats. In timescales of millions of years they move and even collide. But I'm starting to think this ...
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### What is the difference between Precipitable Water (PW or PWAT) and Quantitive Precipitation Forecast (QPF) in terms of computer weather model data?

When I take a look at weather models, there is an option to take a look at PWAT or QPF. What's the difference?
58 views

### Is it possible to have an AR(0) for streamflow?

Autoregressive models (AR) are extensively used to understand the behavior of streamflow. The literature abounds with examples of AR models from different families applied "everywhere" to fully ...
145 views

### Meaning of “Objectively analyzed”

I've found that there may possibly be many meanings of "objectively analyzed" and "objective analysis" in modeling and data assimilation. What are some of the accepted meanings?
1k views

### How to install WRF on a Mac?

I would like to install the WRF model on my Mac computer. Where can I find up to date and step-by-step instructions on how to install it?