It’s Raining Buckets: Simple Tools and Climate Monitoring

In a small corner of the historic Charles W. Morgan, a black rubber bucket sits on the deck. This tool would be perhaps more appropriate transporting horse feed across a barnyard; only the rope attached to its metal handle hints to its true purpose on the ship. In fact, this simple bucket alone will be used to simultaneously provide at least four different types of scientific data during the 38th Voyage.

In addition to the observations recorded in the scientific logbook, the 38th voyagers will take water samples as the Morgan sails. At the next sampling period, the bucket will be lowered over the side of the ship between New London and Newport. While it will later be used for both nutrient and chlorophyll-a analysis, this water sample can immediately provide insight into the currents on this stretch of the voyage through a very simple measurement: temperature.

Sea surface temperature measurements were gathered throughout the voyage and later plotted on a map of New England waters. Warmer temperatures are depicted in orange and red, while blue and green indicate cooler areas. Source: Lisa Gilbert

Knowledge of ocean currents is critical for predicting the presence of wildlife—a fact well-known to nineteenth-century whalers as they sought out their prey. Throughout their journey, the Morgan crew observed a broad range of temperature in just the New England region. Water samples varied from 12.7 degrees Celsius (54.9° F) to approximately 28° C (82.4° F) over the course of only 10 days between Boston and Provincetown. This broad range helps account for the types of fauna observed on these days, as many aquatic organisms are sensitive to high or low temperatures, depending on their physiology.

One of Mike Whitney’s GPS-tracked surface drifters, which he released on the voyage from Provincetown to Stellwagen Bank. The drifters flow along with the currents that connect coastal and open ocean waters, reporting their position every two hours. Source: Mystic Seaport

Early whalers understood that whale movements were driven by a food source that was concentrated in certain places during specific periods of time, and they used observations of currents to find these areas. Furthermore, the link between temperature and current also impacted navigation. In 1724, Benjamin Franklin discovered the significant rise in temperature that separated the fast-moving Gulf Stream from the surrounding ocean. As a result, more ship captains began to take temperature measurements to find the current, which would transport them quickly east but impede any attempt to travel west. With the development of new technology (including voyager Mike Whitney’s GPS-tracked surface drifters) came the ability to more thoroughly map global currents through temperature measurements, and fishermen and sailors alike now have access to charts created by real-time data.

While these applications certainly have a role in the modern age, the information from the logbook of the 38th voyage will be incorporated into a larger database for a critical new purpose. The ocean is a huge reservoir for heat, and as currents move tremendous amounts of water over vast distances, they transport this heat—a major driver of the earth’s climate—with them. As anthropogenic causes such as pollution and greenhouse gas emission contribute to global warming, changes in sea surface temperature (SST) are perhaps the single most important indicator of climate change. Because of this, SST is now constantly monitored worldwide. Such long-term data, used for both providing current weather forecasts and developing climate models, may indicate the state of our planet in the future.