In our previous posts we mentioned the major storm our Wave Gliders went through, and we just recently found out that we weren’t alone out there! We learned that there was a Canadian family that was rescued by a container ship in the same vicinity (~600 Miles away) as our Wave Gliders.
We’re not sure if our Wave Glider data could have helped them in this instance. Maybe we could have helped steer them in the right direction, or have told them to maintain a holding pattern until the storm passed. But what is important to note is the lack of data available when you’re in the open ocean, you’re on your own as far as knowing what conditions to expect. Currently the only sources of data are buoy’s which are few and far between, and satellite instruments (which can be seen via the S.T.A.R. website). Unfortunately there is no single place where all of this data is aggregated and easily available to the public.
Up to now the Wave Gliders have not seen any horrible weather, conditions have been ideal. Starting in early February, the vehicles encountered their first significant storm. In the images below you can see wind gusts between 40 and 100 knots starting on February 5th. This is coincidental with the barometric pressure dropping below 1000 mb for Papa Mau and approaching 980 for Piccard Maru. A pressure that low is comparable to pressures at the center of a hurricane! The wave heights associated with this storm were near 8 meters!
polarjacksw asked: When computing the solar position corresponding to "Benjamin venturing west Sunday morning, January 29, 2012 at 16:18z", it seems that the sun is under the horizon (Zenith Distance: 93.18°, Azimuth: 114.56°). Is it really the correct time of the picture ?
What latitude and longitude did you use in your calculation? You stated the azimuth but what was the resulting altitude of the sun?
michaelkoopmans asked: When a wave spectra is calculated, isn't a response amplitude operator utilized? Where does the Datawell sensor get this information? Or has Liquid Robotics estimated this statistic using a combination of wave tank testing and computer simulations?
The filter response of the instrument is determined ahead of time. In addition, there is of course the hydrodynamic response of the glider with its length and width in relation to the wave length. This was examined when the glider travelled a square trajectory, The resulting spectra showed only little differences due to slowly changing wave conditions, rather than hydrodynamic response issues.
LB
tritonimaginginc asked: Hi - just started looking at this so forgive me if this has been asked before. There is now a considerable spread in positions between the 4 vehicles of 200+ miles. Any thoughts on why?
If we consider the 4 wave gliders as physically identical, the only explanation for the current spread in position is local oceanographic and meteorological conditions.
LB
michaelkoopmans asked: After analyzing Waveglider Ben's significant wave height estimations vs. the Half Moon Bay buoy no. 46012 during 11/17 18:00 - 11/19 22:30, I found a data set ~3 weeks old was much worse than one I downloaded yesterday. What kind of modifications were made to the data set this long after recording and why?
The datasets for that time period haven’t changed (I hope!) The did get regenerated a few times, but the conversion code for those instruments is the same. During the time that the craft were in Monterey Bay, the manufacturers of the Datawell sensor sent us new firmware that fixed a calibration problem affecting wave direction only. That was installed on December 7th. Does this sound like what you’re seeing?
regexguy asked: Can the robots be used to measure bathymetry (depth)? It would be useful for storm surge modelling if they could give us good data for depths of 10m or less along the coast.
No, there are no depth sensors on the PacX vehicles, but for folks who are using other gliders, bathymetry sensors are an option.
