# Tag Info

13

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 the wave energy balance equation: $$\dfrac{\partial E}{\partial t} + \dfrac{\partial (c_gE)}{\partial x} + \dfrac{\partial (\dot{k}E)}{\partial k} + \dfrac{... 12 The stability correction factor ASF is related to the effects of atmospheric stability (function of buoyancy and shear) on wave growth, and has been implemented in Wavewatch3 in the Tolman and Chalikov 1996 input source term. The code where the correction happens can be found in w3updtmd.ftn: ! 5. Stability correction ( !/STAB2 ) ! Original settings : !... 11 The linked paper does numerical modelling of a hypothetical tsunami and predicts speeds between 60 m/s (at its point of origin) and 30 m/s (nearer to shore). We can try a back-of-an-envelope approximation to see if we get close, and to understand why the speed would be so much lower than on Earth. A tsunami behaves as a gravity wave with a very long ... 10 Whitecapping refers to the steepness-induced wave dissipation in deep water during which some air is entrained into the near-surface water, forming an emulsion of water and air bubbles (foam) that appears white. It occurs when the velocity of individual water particles near the wave crest exceed the phase speed of the wave, causing the front face of the wave ... 10 Yes, lithology interpretation/classification directly from seismic inversion products is something people do. I've seen it work very well in oil and gas exploration and development of fields. I personally think that there are two main challenges involved in predicting lithology from seismic inversion impedances. It would be a bit of a cop out to say that ... 10 I think the best option for sediment transport modeling is the Community Sediment Transport Modeling System (CSTMS) package that was developed for ROMS. CSTMS was created by a group of sediment transport modelers lead by the USGS. One of the many benefits is that it is open-source and, thus, free. The model was designed for realistic simulations of processes ... 9 Two-way time to depth calibration is a vertical problem. How you handle deviated wells probably depends a bit on how you are tying the wells. Here are two things to watch out for: You should be tying to true vertical depth (TVD) anyway — make sure you're not using measured depth somehow. I expect you are using TVD — so the deviated section will be ... 9 Yes, wave variance or energy spectrum, direcional or non-directional is positive-definite as @aretxabaleta said in the comment. In linear water-wave theory, the surface elevation is described as a linear superposition of sinusoids:$$ \eta(t) = \sum_{i-1}^{N}a_i \sin(f_i t + \phi_i)  where $a_i$, $f_i$ and $\phi_i$ are the amplitude, frequency and ...

7

Yes, the GFS model is a global model. The data is released in the public domain, so you can use it for free for any lawful purpose. See complete terms of use here. You can get the data here.

7

Large parts of Delft3D - including, I think, the sediment transport module - are available in an open source form. The GUI is not currently open source, but (a) Deltares have been offering licences for this for free for academic use; (b) if they are no longer doing this, it is entirely possible to use the software without the GUI. FVCOM also has a sediment ...

7

Seismic, but... There are lots of ways of estimating wavelets. None of them rely on well logs alone, because they don't contain any information about the wavelet. Some methods are purely statistical, some use the seismic data, and some of them use seismic and well logs. Background I recommend reading what you can about wavelet extraction. Especially these ...

6

My preferred way of doing this (I've been working in seismic data processing and analysis for over 20 years now) is: Start with theoretical (or notional) source wavelet. Shape the source wavelet to zero phase (or minimum phase, depending on your application). Design a cross-equalization filter that takes the input from step 1 as the source and step 2 as ...

5

You need to use the following line in your model setup: COORDINATES SPHERICAL Otherwise SWAN will try to calculate wave properties on a curvilinear grid with coordinates provided in meters. In your present case, the computational area is 0.47 m x 0.24 m instead of degrees longitude and latitude.

5

It depends.† Some factors to consider: The sample interval of your seismic data. there's not a lot of point in being smaller than that. For most legacy data it's 4 ms; these days it's often 2 ms. This is a lower bound; you can increase from here if your data have limited bandwidth; there's no point using less than 8 ms for data that's just noise past ...

5

It is a kind of spectral shaping, intended to increase the vertical resolution of seismic reflection data. The logic goes like this: Seismic data is band-limited and lacks high frequencies. This limits its vertical (travel time, and thus thickness) resolution. This is annoying because we often care about thin beds. The spectral peak of seismic data tends ...

4

The peak period is only one of multiple parameters that is used to describe the spectral shape of ocean waves. Most commonly used parameters are significant wave height, mean period, and dominant (peak) period. Significant wave height is proportional to the square-root of total wave energy and it tells us how much bulk wave energy is there at any given ...

4

One common issue is that sonic logs in deviated wells are affected by rock anisotropy (e.g. TVI in shales), and thus yield quite different velocities than are measured in vertical wells. This may affect your correlations as well as things mentioned above.

4

There are two physical processes at play here: Wind speed relative to the ocean surface Wave focusing and blocking in opposing current Wind speed relative to the ocean surface As you describe in your question, wind speed relative to the ocean surface varies depending on the current orientation and magnitude. The rate of wave growth is proportional to the ...

3

There are a few sea surface height datasets available on PO.DAAC (the Physical Oceanography Distributed Active Archive Center), but this one seems to be (near-)real-time and global: the SARAL Near-Real-Time Value-added Operational Geophysical Data Record Sea Surface Height Anomaly. It was launched in 2013 so there is just 3 years of data so far but it should ...

3

There is a good discussion of the anisotropy issue by Hornby, Howie and Ince, 2003, Anisotropy correction for deviated-well sonic logs: Application to seismic well tie, Geophysics, 68(2):464-471, doi 10.1190/1.1567212. If you have an estimate of the anisotropy parameters it is possible to correct your sonic logs for the anisotropic effect. Note that well ...

2

It depends on what your starting information about your seismic data is. For example, if you know that your data contains an impulsive (minimum phase) source wavelet (i.e. the acquisition source was dynamite or a big ol' hammer, or some other impulsive source, and has not been modified) then you can apply the workflow of txpaulm or use spiking deconvolution. ...

2

The peak period is also important in evaluating the interaction of waves and human-built structures such as drilling platforms. If the frequencies of resonance of a drilling platform coincide with the peak frequency of waves, you will get rather sea sick occupants or, more seriously, structural failure. All platforms are designed to tune their resonance ...

2

When searching for a place to publish Earth Science stuff, have a look at the two big continental scientific societies: the American Geophysical Union (AGU) and the European Geosciences Union (EGU). Both have a wide array of publications in the various fields of geosciences. AGU has JGR Oceans, while EGU has Ocean Science (open access). If you want to reach ...

1

There are different factors that make water a media for waves. For transversal waves the viscosity and cohesion of molecules are essential. Even if the water is assumed not to evaporate. Try to imagine pushing a boat forward in a liquid with low viscosity. The propeller will just easily skid without generating any wave or traction. However for P waves a ...

1

Higher amplitude waves, on water, are caused by larger disturbances and longer durations of energy input, in the form of wind, than smaller ones. Quite simply in order to build a big ocean wave you need to put in a lot of acceleration of surface waters over an extended period of time. So it's not just that the wave itself is travelling that much faster, the ...

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