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Questions tagged [atmosphere-modelling]

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21
votes
1answer
651 views

Significant difference between averaged wind speeds and averaged wind power density, for wind generation modelling?

Climate models outputs, particularly the reanalysis datasets, output wind speeds as zonal and meridional averages for the modelled time period (typically 1, 3 or 6 hours). So we get a 2-dimensional ...
16
votes
2answers
3k views

Why is aerodynamic resistance defined inversely?

When I think of wind resistance, I always think of the friction co-efficient, in $\mathrm{ms^{-1}}$, because that's always the way that it was presented in highschool and undergraduate physics. But ...
13
votes
1answer
2k views

What is the formula used for atmospheric visibility?

I am working on NCEP GFS data to plot various maps. One such plot I would like to have is visibility. I have seen some of the sites showing visibility charts and the source of the data was shown as ...
13
votes
1answer
191 views

How do Kelvin waves determine surface temperature variations?

Kelvin waves are basically waves that balance out the Coriolis force against topographic boundaries like coastlines and mountains. It seems very important in the oceans, for example. My question is ...
12
votes
1answer
2k views

Why is WRF most often configured at 3:1 nesting ratio?

In WRF application, nested domain has always been used for weather/air quality modeling for the place of interest in a better resolution. The figure below illustrates this: I have noticed that the ...
12
votes
2answers
232 views

What atmospheric radiative effects, if any, do contrails cause?

First of all, this question is not about the conspiracy theory based chemtrails as in the linked question, from the answers there and from the question Equation for predicting contrail formation I ...
12
votes
1answer
1k views

Numerical weather forecasting - resources for a programmer?

There is a community wiki question over at A good book or source for climate science and meteorology basics? that talks about meteorology basics. Building on that, but with a slightly different focus,...
11
votes
3answers
298 views

Does finer input data lead to a better model accuracy?

Climate and chemical transport models all need input files including meteorology data, emission inventory, surface data (e.g. land use type) to initialize the simulation field. Take the case of WRF ...
10
votes
2answers
695 views

Technique to delete spin-up frames from WRF

I'm a user of WRF V3.5 aiming at meteorological simulation. Sometimes, I'll run the model for a long period. My attempt I split the long period(e.g 1 year) into serval short ones. For ...
10
votes
1answer
237 views

What principles do we consider when selecting an air pollution monitor location?

I'm working on a project aiming at finding some potential point as a new air pollutant monitor site for a city to measure $SO_2$, $NO_2$, $PM_{2.5}$, etc. After modeling the surface concentration of ...
9
votes
2answers
1k views

How to compute du/dx and dv/dy in moisture flux convergence?

I have $u$-wind, $v$-wind and specific humidity. I would like to compute moisture flux convergence at a grid point. So I need to compute the value of $q(\frac{du}{dx} + \frac{dv}{dy})$ My question is ...
9
votes
1answer
156 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
548 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
2answers
3k views

On the light difference between morning and afternoon

It is long time that I am looking for what physical reason(s) explains this observation: the sun ambient light between sunrise and midday is crispy, somehow whiter than that of the afternoon hours. ...
8
votes
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
3answers
476 views

Correlation and causation

Linear correlation (Pearson's) is vastly applied in meteorology/climatology to assess the relationship between two variables, say precipitation and SST, for example. However, we know that correlation ...
7
votes
2answers
277 views

The climatological variance of albedo, soil moisture in weather models

Looking at WRF currently but I am sure this applies to most weather models there is a file (specifically LANDUSE.TBL) that specifies USGS derived albedo, soil ...
7
votes
1answer
121 views

What causes the semi-annual mesospheric meteoric potassium variability?

In a recent study presented in the article First global observations of the mesospheric potassium layer (Dawkins et al. 2014), space-borne resonance fluorescence observations confirmed previous LIDAR ...
7
votes
1answer
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 ...
7
votes
1answer
403 views

How will global warming affect climate systems like the ENSO or the MJO?

How will global warming influence climate systems such as the Madden–Julian Oscillation (MJO) or the El Niño Southern Oscillation (ENSO)?
7
votes
0answers
116 views

Shallow water height as vertical coordinate

In atmospheric physics we use often a variety of vertical coordinates, $z$ the height above some reference surface, or $r$ as distance from the planetary center. However sometimes it simplifies the ...
6
votes
2answers
504 views

How bad is geo-engineering?

It is just curiosity that forced me to ask this question. At some point in time, if we can't control global $\sf{CO_2}$ emissions, temperature will increase until a tipping point and it will be a ...
6
votes
3answers
1k views

Why are inversion layers so important in meteorology?

I keep hearing the term "inversion layer" when reading about pollution and meteorology. I know it vaguely amounts to "some place where the gradient of temperature is inverted". But why are inversion ...
6
votes
2answers
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 ...
6
votes
2answers
623 views

Take all the CO2 in the atmosphere and put it into a layer on the surface of earth, how thick would the layer be?

I teach a Middle School (year 8) Geometry course and have a student attempting to answer this question. My assumptions: earth's radius is $3959 \text{ mi}$ earth is a sphere There is approximately $3 ...
6
votes
1answer
163 views

How does temperature impact the elevation distribution of orographic precipitation?

Consider the case of two weather systems of different temperatures hitting the Andes Mountains from the west: After traveling a long distance over the Pacific ocean I would expect the air in both ...
6
votes
1answer
1k views

How to calculate humidity using outside temperature and outside relative humidity?

I would like to ask how to calculate the relative humidity that a heated indoor area would have using only outside temperature and outside relative humidity. I found the Relative Humidity Calculator ...
6
votes
1answer
670 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 ...
6
votes
1answer
814 views

Specific humidity range in tropical lowlands?

I am running a land biosphere model that uses meteorological data as drivers. The model has a threshold of 32g/kg for specific humidity. The data I am using taken from a reanalysis performed by J. ...
6
votes
1answer
83 views

Does thermal bubble initiated in WRF dissipate over time?

I am running idealised supercell simulation using WRF model. The supercell storm is initiated with a thermal bubble. I just wonder if the thermal bubble is only affecting the initial temperature. I ...
6
votes
0answers
78 views

Spatial variability in ocean surface winds

For the near-surface winds over the ocean, many model products and satellite footprints have spatial resolutions on the order of tens of kilometers. I'm interested in knowing how much the winds (both ...
5
votes
1answer
285 views

How does the tornado chaser locate the spot?

In my opinion, tornado is hard to forecast in three different aspects: The size of tornado is about 100 ~ 1000 m which can't be represented well in weather model or detected by limited weather ...
5
votes
2answers
542 views

What is the meaning of step in ERA reanalysis data?

The webpage to download ERA data includes an option called "time" which is intuitive, but also an option called "step". I can't find an explanation of the meaning of this. It can't be a time step ...
5
votes
1answer
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 ...
5
votes
1answer
81 views

What is the characteristical time of the loss of the Earth atmosphere, how can it be calculated?

Somewhere I've read it is in the order of some tens of billions of years, but unfortunately I can't find any reference with it in Google. I suspect, the losses are coming mainly from analyzing the ...
5
votes
1answer
139 views

Why are “ground level” air quality monitors really on rooftops?

There are many papers that talk about the air quality at ground-level in cities, observed by air quality monitors. Some monitors are located above the building(not actually on the ground). For ...
5
votes
2answers
132 views

Change in vertical wind intensity in atmospheric modeling

I am a beginner to atmospheric modeling. I want to know about the change in vertical wind intensity in modeling studies. In general, if I initiate a simulation,I will get the real vertical wind ...
5
votes
1answer
529 views

What is the height above ground of NCEP/NCAR Reanalysis 1 variables?

I am confused regarding the height above ground of this data set. http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html I have to reprocess this data set and need to know this piece of ...
5
votes
2answers
274 views

How to map emission inventory from lat&lon corrdinate to WRF model grid

Here, I have a regional emission inventory, which mainly contains the varibales of lat,lon,...
5
votes
0answers
143 views

Is there a reconstruction of paleoclimate sea level air pressure?

In paleoclimateology graphs of both temperature and atmospheric composition versus time are common. Where can I find a reconstruction of sea surface pressure versus time? I have found one paper that ...
5
votes
0answers
96 views

Dig in the rationality of model evaluation of WRF with land-based station data

I use WRF (Weather research and forecasting) model for in regional scale meteorology simulation. And then, the WRF output files will be deemed as criterial input data applying for chemical transport ...
5
votes
0answers
123 views

Forced shallow-water equation with diabatic heating as the source term

How to obtain the divergence of velocity field $\left(\nabla.\mathbf{u}\right)$ with ${Q}$ (something proportional to the diabatic heating rate) as the source term from the thermodynamic equation? ...
5
votes
0answers
188 views

Bulk and dynamic viscosity in the atmosphere

I'm studying the physics of the atmosphere but I'm struggling with the matter of viscosity (Navier-Stokes equation) for gravito-acoustic waves. From Landau-Lifschitz : $$ (T)_{ij} = -p\delta_{ij} + \...
4
votes
2answers
3k views

Interpolate Gaussian grids to regular fixed grids using bilinear interpolation?

I want to regrid GCM data available on Gaussian grids to regular grids, say at 1 deg X 1 deg. How to do this using CDO or Python ...
4
votes
2answers
210 views

Why does computation cost increase 24 times when the spatial resolution doubles?

In a Chinese book, I read about the relationship between the numerical model spatial resolution and the computation cost. It states: when the spatial resolution of model is finer, the result ...
4
votes
2answers
1k views

Historical NWS GFS forecast data

The National Weather Service (NWS) makes the results from its Global Forecast System model (GFS) available for download as GRIB2 files. While accessing current (or recent) forecasts is straight-...
4
votes
1answer
2k views

How do I convert Relative Humidity into specific humidity [duplicate]

I am using NCEP_DOE reanalysis 2 data set. It include only relative humidity while I need specific humidity. How do I convert the relative humidity into specific humidity?
4
votes
1answer
508 views

How much do anthropogenic carbon aerosols (soot) affect the atmospheric radiation budget?

Anthropogenic carbon or black carbon (BC), particularly soot, is a product of many human activities, a major one being incomplete combustion of hydrocarbons. The occurrences of soot are mainly in ...
4
votes
0answers
227 views

How to transform the inventory data from degrees to kilometers

First all, my question was different from the question Converting grid resolution from degrees to kilometers. In chemical transport modeling, the pollutant source inventory was an essential input ...
4
votes
0answers
170 views

Pasquill-Gifford stability class data for one station

On my project, Stability classes is an useful tool to analysis the weather condition for one place. Using R Package Worldmet, I can get the hourly weather ...