1. Observing Wave Patterns off Spain’s coast utilizing in-situ measurements Danielle Holden, Melissa Grimm
Intro: As RU27 moved closer to its destination of Spain, waves began to play a more important role in the mission. Waves are a huge factor in our ability to recover the glider and bring it safely to Spain. Our purpose was to attempt to predict the wave heights just outside of Spain as accurately as possible.
Methods: To do this, we analyzed archived and real time wave, wind, and weather data from the Puertos del Estado website. We specifically looked at the measurements from one deep water buoy, located off the coast of Cabo Silleiro, 323 meters deep, at 42°7.2’ North, 9°24.0’ West. We also looked at wave prediction charts, for the same buoy, that predicted waves up to 72 hours in advance. However, this buoy was not working properly because it was transmitting incorrect data. When it came time to make our final predictions as to what the waves were going to be like for the recovery of RU27, we used the buoy off the coast of Estaca de Bares, 382 meters deep, at 44°3.6’ North, 7°37.2’ West.
Results: Looking through archived wave and wind data reports from 2000 to 2007, it is worth noting that there is a correlation between wind and wave measurements. In November 2006 for example, winds were 15 m/s in the v direction and when waves were seven meters high on November 27.
The real-time wind and wave data (from Estaca de Bares) and wave prediction maps are from November 30, 2009 and were used to determine how high the waves would be during RU27’s recovery. The real time data indicated no change in measurements--though the measurements were staggered there was no indication of an upward trend. The prediction map, however, suggested there will be an increase of wave heights to 6 meters
Top Right Corner:
Below left: real-time data for mean wave period, wind speed and significant wave height from November 25, 2009 to November 30, 2009
Below Right: One of the wave prediction maps used for RU27’s recovery. This map is predicting 60 hours in advance from November 30, 2009
Bottom Left Corner:
Left Figure: Daily wind measurements from November 2006
Right Figure: Daily wave height measurements from November 2006: average wave heights are indicated with black line, maximum wave heights are indicated with gray line.
Conclusion: As RU27 approached the coast, we realized that the waves were becoming difficult to predict, even with wind and weather measurements. There is a definite correlation between waves and winds; whenever winds are at high velocities, energy is transferred into the water and pressure gradients form as a result. Therefore, there are bigger wave heights with faster wind speeds. However, as RU27 approached the end of its journey it was becoming difficult to predict waves and winds because measurements taken by our deep water buoy, Cabo Silleiro, were becoming random. These measurements were so random that we would not be able to predict the intensity of the waves and winds without looking at wave prediction maps. Looking strictly at real time data, we could not predict when the wind speeds and wave heights will be large because a pattern did not exist.