17
votes
Accepted
Why is WRF most often configured at 3:1 nesting ratio?
To understand why the nesting ratio of 3 is preferred to the nesting ratio of 2, it is important to understand the following two features of WRF:
1) Grids are Arakawa C-staggered: mass points are at ...
- 4,925
16
votes
Accepted
How to get cell indices from latitude and longitude in WRF model grids?
I've been a WRF user for almost 5 years now, and contributed code to a recent public release. I am not aware that WPS (WRF Preprocessing System) has such a tool that takes in the grid and point ...
- 4,925
10
votes
How to get cell indices from latitude and longitude in WRF model grids?
This question might be better suited for GIS stack exchange... but I'll take a shot:
dx and dy are the distance per grid cell in the projected grid units, which is part of your grid definition. ...
- 12.7k
9
votes
How to get cell indices from latitude and longitude in WRF model grids?
I am posting my code that calculates i_parent_start and j_parent_start. It is in Java and as people are aware Java does not have ...
- 6,208
9
votes
Does finer input data lead to a better model accuracy?
My experience with the WRF is in tropical cyclone simulation, but here are some things to consider:
Smaller scale information might already be resolved in your higher resolution initial conditions, ...
- 315
8
votes
Accepted
Why does computation cost increase 24 times when the spatial resolution doubles?
I can't answer why there's a 24x increase, according to the textbook - but it may well be the case for a specific model. In general,
If you double the resolution of a 3D model in each dimension, you ...
- 5,805
7
votes
Does finer input data lead to a better model accuracy?
Yes, of course finer input data can lead to better model accuracy, but only if the model's conceptualization is close to the mark. Of the many problems of climatic model misinterpretation, I would ...
- 14.1k
7
votes
How to get cell indices from latitude and longitude in WRF model grids?
Try NCL. It has a package for WRF-related functions, including the bidirectional grid-coordinates conversion routine.
To convert coordinate pairs to grid indices, follow the documentation here:
...
- 181
7
votes
Accepted
Calculate precipitation from WRF model output
Use (1) Precipitation, as it is the sum of convective and non-convective precipitation, integrate it over one day, voilà.
converting [$kg/(m^2 s)$] (precip):
$$ precip [kg/(m^2 s)] \cdot dt [s] \cdot ...
- 438
6
votes
Accepted
What denotes a parameterization in a model? (semantics )
As defined in the AMS glossary, a parameterization is a simplification of one or several processes in a model. I add that a parameterization commonly adds an error and increases the uncertainty in the ...
- 2,641
6
votes
Accepted
WRF output grid is smaller than input definition
Your model grid is an Arakawa C grid:
Image from Skamarock et al. A description of the Advanced Research WRF Version 3
It appears the geogrid grid generation uses the 25x25 as the furthest extents ...
- 13.9k
6
votes
regeride netcdf file to template netcdf file resoulution
Disclaimer: I have not looked at your particular files.
You can regrid the data in Python using the NetCDF-4 module. If you want to interpolate vertically, you can use the WRF module. And for ...
- 8,307
5
votes
Accepted
The climatological variance of albedo, soil moisture in weather models
WRF model development is done in such a way that users can run the model independently before you start adding more complex options to ingest observations. There is even an "ideal" mode that new ...
- 12.7k
5
votes
WRF vertical integrated moisture flux using NCL
I am going to explain my answer based on how the authors from this paper calculate this Vertically integrated moisture flux convergence as a predictor of thunderstorms. This is the equation that is ...
- 6,208
5
votes
Accepted
Running WRF with ECMWF GRIB2 model levels
I finally solved this problem with the following steps:
Download the ECMWF data separately for model level variables (Q,T,U,V and geopotential) and surface variables. In this way, you will get 'pure' ...
- 201
4
votes
ECMWF data as WRF input
For any of the basic forecast runs (10 day, ensembles, monthly/seasonal forecasts), I do not believe ECMWF data access is general controlled to ECMWF.INT. Generally most data, including anywhere near ...
- 7,660
4
votes
Why is WRF-Chem not reading my emissions data?
I could run model, i just had to change a bit the namelist. I added three parameters:io_form_auxinput5 = 2,auxinput5_inname = 'wrfchemi_d$<domain>$_$<date>$' and frames_per_auxinput5 ...
- 412
4
votes
Longitudes and latitudes are not regular in WRF-out files
I am not sure about your R code or your snippet of data. However, you could do an ncdump on the file and direct the output to text to get it "from the horses mouth" so to speak.
In general, the lat/...
- 12.7k
3
votes
Accepted
How to install WRF on a Mac?
The WRF Forum here describes some testing using a Mac, and they report success with 2 setups:
Mac 64-bit running OSX, with Intel chips, g95 gcc version 4.0.3 (g95 0.92!)
Mac 64-bit running OSX, with ...
- 12.7k
3
votes
Accepted
Can the dew point temperature be more than drybulb temperature?
Dew point gives an indication of the moisture content of air; it is the temperature at which air can no longer hold water vapour.
The following graph shows the relations of dew point to air ...
- 20.3k
3
votes
The climatological variance of albedo, soil moisture in weather models
For soil mosture you can initialize the model with a dataset that provides that information. If you are doing historical retrospective you are likely going to initialize from a reanalysis dataset and ...
- 13.9k
3
votes
Does WRF simulation use sigma or eta vertical coordinate system?
WRF is using the sigma (terrain-following) vertical coordinate. However, as @gansub has already referred, in WRF V3.9 you can now select a hybrid sigma-pressure vertical coordinate. The advantage of ...
- 391
2
votes
Accepted
Technique to delete spin-up frames from WRF
There is an feature of the -d option that makes the call of ncks redundant. However, it is available since NCO version 4.2.1 (...
- 2,641
2
votes
Technique to delete spin-up frames from WRF
Here is my present approach.
All wrfout-files are located in the same path.
Using pynco in python loop to split the spin-up dataframe
...
- 2,439
2
votes
What is "focus point" in WRF-plots grid box? (python code)
A Skew-T/Log-p plot is a vertical profile from a point, and it appears in that code that the point you are plotting the skew-T for is 60.2 latitude, 11.08 longitude. The snippet of code:
...
- 13.9k
2
votes
How to set up a domain from namelist in WRF?
There is a WRF domain Wizard offered by ESRL. You can download it here. Also, don't make the same mistake I made using Lambert Conformal- keep stand_lon the same as your ref_lon.
- 8,307
2
votes
How to properly setup a domain in NWP model (WRF) according to meteorological input data
A good rule of thumb for down-scaling with WRF is not to interpolate down more than 3 or 4 times; with 3 being the standard recommendation. So while 18 km is probably overkill for an outer domain (...
2
votes
How to map emission inventory from lat&lon corrdinate to WRF model grid
I would suggest using cdo for your purpose. At least for variables, which values are independent of the grid cell size, one can use cdo.
cdo
cdo (Climate Data Operators) is a command line program to ...
- 2,641
2
votes
Accepted
WRF/Chem: Editing NetCDF (wrfchemi files) for own emissions
You can try the R package eixport, with wrf_put
...
- 412
2
votes
Accepted
Spatial allocation of road emissions and unit conversion
You have got your emissions over a square kilometer. To get to square meters you divide by 1000000 since $1km^2=10^6m^2$.
- 994
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