Hot answers tagged

18 votes
Accepted

Great Pacific Garbage Patch Equilibrium Points

Yes, you're right, there should be (at least one) saddle point in the middle of the loop. And indeed, if you search for illustrations of Pacific ocean circulation, you can see the saddle point in ...
Ilmari Karonen's user avatar
18 votes

Great Pacific Garbage Patch Equilibrium Points

Theoretically, I agree that there should be one instable equilibrium point between the two stable equilibrium points when we have a 2D current field. However, there are some additional components of ...
daniel.heydebreck's user avatar
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 ...
milancurcic's user avatar
  • 4,983
13 votes
Accepted

Why can't wave models model storm surge?

Yes. Spectral wave models cannot model storm surge because the wave energy balance equation that they integrate does not describe the physical processes associated with storm surge. Wave models solve ...
milancurcic's user avatar
  • 4,983
12 votes
Accepted

Predicting rainfall with governing equations

The Barotropic vorticity equation is insufficient to model rain. Part of this is due to the word 'Barotropic,' which indicates a lack of thermal gradient. The other reason is that while vorticity is a ...
BarocliniCplusplus's user avatar
11 votes

What exactly is a model grid?

A model is a simplified representation of a system. Rather than try to model everything down to the microscopic level, or as vectors, we often aggregate phenomena across geographic areas, to simplify ...
410 gone's user avatar
  • 4,090
11 votes
Accepted

Converting grid resolution from degrees to kilometers

Assuming spherical shape, Earth's circumference is about $40,000\mathrm{km}$. These are split into $360^\circ$, so one degree is a bit more than $100\mathrm{km}$. This is true for latitudes. For ...
Christoph's user avatar
  • 994
10 votes
Accepted

How to calculate w-wind?

Omega, ω is closely related to w in meteorology. It can be moved towards w using the chain (this reminder from Watkins at SJSU helped)... ...
JeopardyTempest's user avatar
10 votes

What is the difference between GFS analysis and GFS forecast data?

I'm no expert at this, I've just been working with a variety of gfs gribs for a while now. The only thing I know about them is what I've read and I'll cite them here. I don't know where you got ...
user6972's user avatar
  • 301
9 votes
Accepted

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

Warning: "long-term wind-speed forecasting for generation" has (at least) two very different meanings. One refers to forecasting a distribution of wind speeds; the other refers to hour-by-hour (or ...
410 gone's user avatar
  • 4,090
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, ...
jgadoury's user avatar
  • 315
9 votes
Accepted

How to run earth system, land surface and climate models?

As alluded to in some of the comments, all of the CMIP5 models will have been run on supercomputers, and it takes a lot of effort to get one of them running on a new platform, even for a team who know ...
Deditos's user avatar
  • 3,920
8 votes

Help interpreting a wind rose diagram

No, you've misunderstood it. There's lots of information you're missing. Every data point is information, and you've listed a tiny proportion of them. Furthermore, 4-7 km/h and 11-16 km/h aren't ...
410 gone's user avatar
  • 4,090
8 votes
Accepted

Kalman - Data assimilation with external model

$M$ is the forward model you are using. It is the dynamical model used to solve whatever discrete equation evolves the field ($d?/dt=$). The best way to start with data assimilation and understand ...
arkaia's user avatar
  • 15.4k
8 votes

Predicting rainfall with governing equations

TL;DR: Global NWP models such as NCEP's GFS (free access) and ECMWF's IFS (restricted access) provide forecasts at a horizontal scale of a few tens of kilometers every few hours. Starting from global ...
Nerevar's user avatar
  • 81
8 votes
Accepted

Why doesn't Wolfram Alpha show low gravitational acceleration for the Hudson Bay?

Wolfram Alpha reports values between 9.78 and 9.88 m/s2 depending on the location, which is odd because it should stay within the range 9.76 - 9.83 all over the world. It also seems to be using the ...
FSimardGIS's user avatar
8 votes
Accepted

Do tectonic plates "float" over the mantle and "collide" like icebergs?

you are missing a big factor, the plates are not moving due to the momentum of an initial impulse. They are being actively moved by the push and pull of mantle convection. Much like how icebergs are ...
John's user avatar
  • 6,803
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 ...
Gordon Stanger's user avatar
7 votes

Correct phrase for a 'forgetful' natural system?

How would you call a system that displays such 'forgetfulness'? In one word, dissipative. In multiple words, a system whose autocorrelation function tends to zero as time tends to infinity. Note ...
David Hammen's user avatar
7 votes

Are we now and/or have we been in the RCP8.5 scenario?

In short, I would say that it is too soon to say. But, if I were forced to guess: I would indeed incline to say that we live in a RCP 8.5-ish scenario. I'm not an expert at all on climate models or ...
Camilo Rada's user avatar
  • 17.6k
7 votes

How to run earth system, land surface and climate models?

We are moving all of CESM to open source - in particular here is the latest version of the Community Terrestrial Systems Model (CTSM) https://github.com/ESCOMP/ctsm Formerly known as CLM, CTSM ...
Jim Edwards's user avatar
7 votes
Accepted

How/where is randomness/stochasticity used in weather prediction

Probability is used in weather forecasting. I will only highlight some examples due to my lack of knowledge in some areas. Before initializing a forecast model the data needs to be assimilated. That ...
Joscha Fregin's user avatar
7 votes
Accepted

Why is it that "With higher CO2, the dry gets drier and the wet gets wetter"?

To my best knowledge, the paper by Held & Soden (2006) is the first paper that discussed the concept of the rich get richer. They used the climate change experiments generated for the Fourth ...
ahmathelte's user avatar
6 votes

Climate change review for a scientist

EnergyNumbers suggestion is good, but you can only go so far in reading about it second hand. I suggest that you pick a grid cell of interest, then go to the World Bank's climate change knowledge ...
Gordon Stanger's user avatar
6 votes

Correct phrase for a 'forgetful' natural system?

From physics standpoint I would say that such system is stable. For example think of a ball on a surface. If the ball is initially on the top of a hill a push would move the ball into the slope that ...
Communisty's user avatar
  • 1,064
6 votes

Waves in very thin layer

The problem with the cancelling you suggested is that it is imposed globally for the PDE and not locally (just on the thin layer). Usually when we talk about vertically layered media we use a plane ...
dvoytan's user avatar
  • 121
6 votes
Accepted

Milancovich analysis

The most common period to use is 30-years, which comes from the idea of climate normals used in NWP. Using only 10 years even global mean temperature will see the influence of a single large El Nino ...
Deditos's user avatar
  • 3,920
5 votes

What exactly is a model grid?

To add a bit more mathematical conception to the idea of a grid: think about a 2-D grid(X,Y) as a matrix: this matrix represents a solution to the system of equations you are trying to solve at grid ...
Neo's user avatar
  • 6,446
5 votes
Accepted

What modelling approaches are used to predict the aurora?

One model is the OVATION auroral precipitation model. OVATION stands for Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting. The NOAA Space Weather Prediction Center uses ...
Matt Hall's user avatar
  • 11k
5 votes

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

There are several approaches to answer this question. One is simple, but not that accurate. This approach would be to to discretize points along the perimeter and calculate a per point boundary shear ...
MaxC's user avatar
  • 111

Only top scored, non community-wiki answers of a minimum length are eligible