Recent research focused upon whether the tidal patterns are changing. This is an important question because tides effect more things than we realize. In fact, the 18.6 year cycle in lunar tides effects climate in South America.
Use the graph above and take a few minutes to explore five years of NOAA high tide predictions. It is easy to adjust the area you are foucsed upon by adjusting the sliding scale below the larger graph. I created this chart using the awesome d3 visualization library. This graph confirms what we already know to be true. Remember that in 2012 Seattle saw the largest tide in over 113 years. If you zoom into December of 2012, you can clearly see this local high was even predicted by NOAA to exceed 12 feet.
Will these rising tides change the shape of the landscape surrounding world cities? Will the tidal surge engulf areas currently inhabited by people? Will the coastal and inter-coastal climates changes as the tides increasingly vary? These are important questions to consider. Perhaps the future landscape will look much different than it does currently. Here is a picture I (my wife) took a while back of a beach whose tides already expand and contract by hundreds of yards each day:
Splendid in its beauty, this image illustrates what the world of the future might look like if tidal surges get larger in coastal regions. But why did the tide get so large on December 13th, 2012? What is the typical tidal pattern and what was the pattern like on the day of the increase? A great way to explore longitudinal data and to learn more about cyclical patterns is to explore the increasing or decreasing nature of such patterns. This technique is used in a lot of disciplines, especially for mining insights from text and social data . Advanced algorithms aside, what visual patterns stand out at a high level?
These graphs show the daily NOAA predicted high (top) and low (bottom) tide levels. I also created these charts using the d3 library. If the current day's tide is higher than the previous day, the difference between these two tides is shown in green. Otherwise, the deficit is shown in red. Both graphs encompass the period of the local 113 year high tide.
Notice that there streaks of several days where tides are increasing or decreasing. Also, you probably noticed that in every case high tides are increasing and that low tides are decreasing at the same time. These two attributes are perfectly out of sync with each other. The 113 year high tide coincides with the peak of one such cyclical pattern.
How has the relationship between high and low tides changed over time? Are similar phenomenon occurring in other places in the US? Some of these questions will require more in-depth analysis. All of these questions will require a lot more data. I'll dig into these issues in more in the future.