Arthur C. Clarke, inarguably one of the most brilliant minds of modern times, said, “How inappropriate to call this planet Earth when it is quite clearly Ocean.” Two-thirds of our home planet are covered by seas and oceans, both deep and shallow. According to the United Nations, 40% of the world’s population lives within 100 km of a coast.
The vastness of oceanic mapping, both historically and technologically, makes this a challenging story to cover in just one article. However, I’ll offer some hopefully fascinating stories about this ongoing and epic effort to map the enormous world ocean.
One World, One Ocean … or Is It?
As I mentioned in a previous article, our planet makes cartography relatively easy, since we have the equipotential surface of the sea from which to measure elevation, unlike other planets which have no known surface water. Looking at a world map, we can see that aside from a few landlocked seas, such as the Caspian and Aral, the world is one ocean. From pole to pole, from the Caribbean to Gulf of Aden, the ocean is an equipotential surface, and all the waters are one. (That was, also, one of the lines in our wedding vows, but that’s another story.)
However, in reality, that isn’t always true. The seas and oceans of our world are separated by both physiographic and political divisions. The nuances of maritime climatology and geopolitics are incredibly complex, so being neither a physical scientist nor a political scientist, I can offer only broad strokes. That being said, as a generalist, I can say that the two factors are inextricably intertwined.
As the vast continent of Asia warms during the summer, it creates a low-pressure system that draws in moisture from the Indian Ocean. In a fascinating book with exceptional maps, “Monsoon: The Indian Ocean and the Future of American Power,” Robert D. Kaplan explains how the monsoon patterns of the Indian Ocean have shaped the geopolitics of that region for centuries. From Portugal to China, sailors have used the usually predictable winds and weather patterns to make epic voyages in time with the seasons.
Several years ago, a professor at Oregon State University launched a research project in the Indian Ocean using Doppler lidar to detect how the diurnal warming of the ocean affected atmospheric turbulence. Similar research has been conducted by NASA’s Global Precipitation Measurement mission.
Both of these studies illustrate the interaction of natural weather patterns and their effects on the human environment. Summer monsoons bring massive amounts of rain to the region, which nurture the crops that feed the densely populated sub-continent of India, Pakistan, Bangladesh and other countries. (Bangladesh hosts a population half the size of the entire U.S. in an area the size of Iowa.) However, these rains that bring prosperity also bring tragedy. According to NASA, “… the amount of rainfall [in 2020] has been so excessive that it has resulted in widespread flooding, hundreds of fatalities, thousands of properties damaged and millions affected.”’
"What if We Could Make 60 Equators?"
As much as I dislike its gross distortion of area, the Mercator projection has become ubiquitous in everything from classroom maps to web apps. Also, it does have its benefits. All projections must distort something: area, distance, direction or shape, or a combination thereof. Designed for transatlantic travel from Europe to the Americas, it didn’t matter that Greenland was the size of Africa. What mattered is that the mid-latitudes had orthometric lines and accurate distances, perfect for navigation.
Nearly all of us who have worked in the field have used the USGS 7.5-minute topographic maps, which are based on the UTM projection, formally called Universal Transverse Mercator. Despite its distortions, the Mercator projection is almost perfect at the equator. So, cartographers flipped the projection (transverse) and created 60 zones, each stretching from pole to pole and 10 degrees of latitude wide. This is yet another example of how antique, analog cartographic techniques have contributed to modern mapping and geospatial technologies.
Marine Geospatial Technologies in the Classroom and Beyond
What I love about teaching geospatial technologies is how much I learn from students. Teaching a spatial analysis course at the University of Washington, one of my students did his capstone project on marine traffic, mining a HUGE dataset over the course of a year. I don’t recall the specific database he used, but a similar one is available here.
With over a million records, it was a challenge. We tried to parse it down to a monthly level, experimented with daily and weekly structures, and vessel types, but it was still unreadable. Being a dedicated student, he created a map that told a snapshot of just a single day’s global traffic on the seas.
Which is Smarter: Latitude or Longitude?
That’s a classic geography joke, the one you hold for those awkward few minutes when you’re changing speakers and thumb drives at a conference. The answer of course is longitude … it has more degrees! As I have mentioned in several previous articles, humans have been reading the stars for millennia, and we learned to measure the Earth’s size, and how to measure latitude from pole to pole. Longitude proved far more challenging.
It wasn’t until the invention of a clock that could withstand rolling seas that longitude could be measured, as described in Dava Sorbel’s epic and very readable book “Longitude.” It describes the 40-year effort of a humble clockmaker to make such a device, which was completed in the 18th century.
The concept was simple: one clock set to Greenwich mean time (on the prime meridian), the other set to ship-board time, with noon measured by a sextant. The difference between the two would indicate how many nautical miles were traveled. It was the mechanics of the clock that proved the greatest challenge.
This same concept applies to modern GNSS, like GPS and GLONASS. Distance = velocity * time. So, 60 mph * 6 hours = 360 miles. With atomic clocks on the satellites calibrated to milliseconds, and signals moving at the known speed of light (299,792,458 meters per second), it is easy to calculate distance from a single satellite. Then, with at least three satellites, we have triangulation of a single point on Earth. Obviously, the more satellites, the better the accuracy, but, as in the case of measuring longitude, it’s all about the clock!
From the Sky and From the Surface
Along with GNSS, there is an incredible array of satellites mapping the ocean. One of the literal hotspots is the Arctic Ocean. There are both environmental and geopolitical factors at stake, deeply intertwined. For centuries, mariners sought a northwest passage from Europe to Asia, hoping to find a way to bypass the long and dangerous voyages around the Straits of Magellan at the southern tip of South America, and Cape Horn at the southern tip of Africa. Before the Suez and Panama canals were built, these were the only possible routes.
Early voyages by European sailors were disastrously unsuccessful. Yet, the Northwest Passage may no longer be a dream but a reality. As has been empirically determined, the Arctic is warming much faster than lower latitudes in recent years. In 2015, several vessels were able to make the long-sought passage for the first time. NOAA’s Joint Polar Satellite System is monitoring the ice pack in the area, especially above Canada, and providing navigational aids to commercial vessels.
The geopolitics of the passage are far beyond the scope of this article, but as discussed in an article by the Arctic Institute, the primary Arctic nations — U.S., Canada and Russia—will have to shift to a new paradigm regarding international relations in this previously impassible region. Hopefully, geospatial technologies can offer a means to a peaceful resolution.
A Planet Still of Mystery … and Endless Potential
At the global scale, we have mapped the Mid-Atlantic rift and the Marianas Trench. At the local scale, there are maps of coastal areas, but there is still much more to be discovered and mapped. We know more about Mars and Venus than we know about the Ocean.
The oceanic pole of inaccessibility is the point in the ocean that is farthest away from land, at 48°52.6′S 123°23.6′W deep in the South Pacific Ocean. It is more than 1,000 miles from any land, and these are only remote islands, themselves nearly inaccessible except for Easter Island.
In an odd coincidence (… or is it?), H.P. Lovecraft’s 1926 horror story “The Call of Cthulhu” describes a location almost identical to the pole of inaccessibility, but it was written almost 50 years before a computer model found this place. (Maybe I should have included this in my article on mapping the unknown.)
My former professor and chief scientist at Esri, Dr. Dawn Wright (aka Deepsea Dawn), has an amazing site with links to data, blogs and much more, illustrating how much there is to be known. Even a landlubber like me can explore the oceans!