Oceanographic research relies on a variety of platforms to gather data and understand complex ocean processes. These platforms vary significantly in size, capabilities, and deployment strategies. From stationary moored buoys to large research vessels and innovative unmanned surface vehicles like saildrones, each platform offers unique advantages for ocean observation. Understanding the size and scale of these vehicles is crucial to appreciating their respective roles in the Global Ocean Observing System (GOOS). This article compares the sizes and functionalities of saildrones, moored buoys, and research vessels, highlighting the unique contributions of each to oceanographic research.
Saildrone Unmanned Surface Vehicles (USVs): Compact and Versatile
Saildrone USVs represent a significant advancement in ocean observing technology. These wind and solar-powered vehicles are designed for long-duration missions, capable of traversing thousands of kilometers while collecting high-quality oceanographic and atmospheric data. While not explicitly detailed in terms of exact dimensions in the original article, we can infer that saildrones are relatively compact vehicles. They are designed to be launched from shore and navigate autonomously, suggesting a size that is manageable for deployment and recovery without requiring large port infrastructure.
Figure 1 provides a diagram of a saildrone, showcasing its sensor suite. Visually, the diagram and accompanying images suggest a vehicle that is considerably smaller than a research vessel but potentially larger than some types of smaller, simpler buoys. The key size-related feature of a saildrone is its wing or sail. This prominent vertical structure, essential for wind propulsion, gives the saildrone a significant height profile, allowing sensors to be mounted at 3–6 meters above the ocean surface, as mentioned in the original article. This elevated sensor placement is a key advantage for air-sea interaction measurements, positioning them above the wave boundary layer.
Compared to larger platforms, the compact size of saildrones offers several benefits. Their smaller footprint translates to lower operational costs compared to research vessels, making long-term and widespread ocean monitoring more feasible. The maneuverability afforded by their size also allows for adaptive sampling strategies and access to remote ocean regions, as demonstrated in the Tropical Pacific Observing System (TPOS)-2020 mission described in the original article.
Moored Buoys: Stationary Sentinels of the Ocean
Moored buoys, such as the Tropical Atmosphere Ocean (TAO) buoys and the WHOI buoy mentioned in the article, serve as stationary platforms for continuous, long-term ocean observations at specific locations. While the article doesn’t explicitly compare the physical size of buoys to saildrones, it positions them as established and reliable platforms against which saildrone measurements are validated. Figure 4 and 5 display comparisons of data collected by saildrones and the WHOI buoy.
Buoys come in various sizes, but those equipped with comprehensive sensor suites for air-sea interaction measurements, like the ASIMET system on the WHOI buoy, are substantial structures. They are designed to withstand harsh marine conditions and house a range of instruments, power supplies, and data telemetry systems. While stationary, their size is dictated by the need for stability in the ocean and the capacity to support long-term, unattended operation.
In terms of size comparison to saildrones, buoys and saildrones likely have comparable horizontal footprints when considering the buoy body and the saildrone hull. However, the saildrone’s prominent wing gives it a greater vertical dimension. Buoys, in contrast, may have a lower profile above the water but a significant underwater component for mooring and stability. The key difference in “size” is not just physical dimensions but operational scale: buoys are site-specific and provide intensive, continuous data at a fixed point, while saildrones offer spatial coverage and mobility over vast ocean areas.
Research Vessels: Large and Multifunctional Oceanographic Platforms
Research vessels, exemplified by the R/V Revelle in the article, represent the largest and most comprehensive platforms for oceanographic research. Figure 6 illustrates the R/V Revelle alongside saildrones and a buoy, implicitly showcasing the significant size difference. Research vessels are essentially floating laboratories, capable of carrying large scientific teams, deploying and recovering a wide array of instruments, and conducting diverse research activities.
The size of research vessels is driven by their need to accommodate crew, scientists, extensive laboratory spaces, and heavy equipment. They are designed for long voyages and can operate in virtually any ocean condition. Their large size allows for the deployment of complex instruments and the execution of multidisciplinary research projects that go beyond the capabilities of smaller, unmanned platforms.
While research vessels offer unmatched capabilities, their operation is significantly more expensive than deploying saildrones or maintaining buoys. Ship time is a valuable and limited resource. Saildrones, as highlighted in the conclusion of the original article, offer a cost-effective alternative for many ocean observing tasks, particularly for long-term monitoring and deployments in remote regions where the logistical challenges and costs of research vessel operation become prohibitive.
Conclusion: Matching Vehicle Size to Research Needs
Comparing the “sizes” of ocean observing vehicles is not just about physical dimensions but also about operational scale, capabilities, and cost-effectiveness. Research vessels are the largest and most versatile, offering the broadest range of research capabilities but at a high operational cost. Moored buoys are stationary and provide intensive, long-term data at specific locations, representing a medium-scale, fixed-point observation strategy. Saildrones, with their compact size and autonomous operation, bridge the gap by offering mobile, long-endurance ocean observation at a significantly lower cost than research vessels.
The choice of platform depends on the specific research objectives. For broad spatial surveys, long-term monitoring in remote areas, and validation of sensor technology, saildrones offer a compelling solution. For in-depth, multidisciplinary research requiring extensive laboratory facilities and large scientific teams, research vessels remain essential. Moored buoys continue to be crucial for continuous, high-resolution time-series measurements at key ocean locations. The optimal ocean observing system often involves a combination of these platforms, leveraging the unique strengths of each vehicle size to achieve comprehensive and cost-effective ocean monitoring.
