Science Publications

The impact and quality of Saildrone’s data has been featured in numerous scientific papers. Saildrone has demonstrated the highest possible levels of data quality, which has established scientific confidence in our measurements and sampling protocols. You can review some of the science publications below.

Uncrewed Ocean Gliders and Saildrones Support Hurricane Forecasting and Research

In the United States alone, hurricanes have been responsible for thousands of deaths and over US$1 trillion in damages since 1980 (https://www.ncdc.noaa.gov/billions/). These impacts are significantly greater globally, particularly in regions with limited hurricane early warning systems and where large portions of the population live at or near sea level. The high socioeconomic impacts of tropical cyclones will increase with a changing climate, rising sea level, and increasing coastal populations. To mitigate these impacts, efforts are underway to improve hurricane track and intensity forecasts, which drive storm surge models and evacuation orders and guide coastal preparations. Hurricane track forecasts have improved steadily over past decades, while intensity forecasts have lagged until recently (Cangialosi et al., 2020). Hurricane intensity changes are influenced by a combination of large-scale atmospheric circulation, internal storm dynamics, and air-sea interactions (Wadler et al., 2021, and references therein). Components of the sustained ocean observing system (e.g., profiling floats, expendable bathythermographs, drifters, moorings) are useful for understanding the role of the ocean in hurricane intensity changes. However, gaps in the ocean observing system, particularly collection of data near the air-sea interface and in coastal regions, boundary currents (e.g., the Gulf Stream, Kuroshio, among others), and areas with complex currents and seafloor topography (e.g., the Caribbean Sea), have led to difficulties in accurately representing upper ocean features and processes in numerical ocean models. Employment of uncrewed ocean observing platforms has begun to fill these gaps by offering rapid relocation and adaptive sampling of regions and ocean features of interest. These platforms include autonomous underwater gliders (Figure 1; Testor et al., 2019) and surface vehicles (Meinig et al., 2019). Uncrewed surface vehicles (USVs), such as saildrones and wave gliders, are systems designed for data collection in hazardous conditions. Data collected by these platforms have improved our understanding of upper ocean temperature and salinity stratification and mixing processes and are becoming critical in improving operational ocean and coupled air-sea hurricane forecast models (Domingues et al., 2021). This paper provides a broad overview of the ongoing US hurricane glider project and details of a new effort with the Saildrone USV during the 2021 hurricane season. While this article focuses on the US East Coast, Gulf of Mexico, and Caribbean Sea, similar efforts are underway in Korea, the Philippines, Japan, and China, among other countries.

Miles, T.N., D. Zhang, G.R. Foltz, J. Zhang, C. Meinig, F. Bringas, J. Triñanes, M. Le Hénaff, M.F. Aristizabal Vargas, S. Coakley, C.R. Edwards, D. Gong, R.E. Todd, M.J. Oliver, W.D. Wilson, K. Whilden, B. Kirkpatrick, P. Chardon-Maldonado, J.M. Morell, D. Hernandez, G. Kuska, C.D. Stienbarger, K. Bailey, C. Zhang, S.M. Glenn, and G.J. Goni. 2021. Uncrewed ocean gliders and saildrones support hurricane forecasting and research. Pp. 78–81 in Frontiers in Ocean Observing: Documenting Ecosystems, Understanding Environmental Changes, Forecasting Hazards. E.S. Kappel, S.K. Juniper, S. Seeyave, E. Smith, and M. Visbeck, eds, A Supplement to Oceanography 34(4), https://doi.org/10.5670/oceanog.2021.supplement.02-28.

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Uncrewed surface vehicle (USV) survey of walleye pollock, Gadus chalcogrammus, in response to the cancellation of ship-based surveys

In 2020, the developing COVID-19 pandemic disrupted fisheries surveys to an unprecedented extent. Many surveys were cancelled, including those for walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea (EBS), the largest fishery in the United States. To partially mitigate the loss of survey information, we deployed three uncrewed surface vehicles (USVs) equipped with echosounders to extend the ship-based acoustic-trawl time series of pollock abundance. Trawling was not possible from USVs, so an empirical relationship between pollock backscatter and biomass established from previous surveys was developed to convert USV backscatter observations into pollock abundance. The EBS is well suited for this approach since pollock dominate midwater fishes in the survey area. Acoustic data from the USVs were combined with historical surveys to provide a consistent fishery-independent index in 2020. This application demonstrates the unique capabilities of USVs and how they could be rapidly deployed to collect information on pollock abundance and distribution when a ship-based survey was not feasible. We note the limitations of this approach (e.g. higher uncertainty relative to previous ship-based surveys), but found the USV survey to be useful in informing the stock assessment in a situation where ship-based surveys were not possible.

Alex De Robertis, Mike Levine, Nathan Lauffenburger, Taina Honkalehto, James Ianelli, Cole C Monnahan, Rick Towler, Darin Jones, Sarah Stienessen, Denise McKelvey, Uncrewed surface vehicle (USV) survey of walleye pollock, Gadus chalcogrammus, in response to the cancellation of ship-based surveys, ICES Journal of Marine Science, 2021. https://doi.org/10.1093/icesjms/fsab155

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Spatiotemporal Dynamics in the Acoustic Backscatter of Plankton and Lesser Sandeel (Ammodytes marinus) in the North Sea Measured Using a Saildrone

With accelerating global warming and human activities, the North Sea is one of the marine ecosystems undergoing rapid change. The need for spatially-temporally extendable survey platforms for assisting well-established vessel-based surveys are increasing. In this thesis, short-term variation in spatial structure of plankton and lesser sandeel (Ammodytes marinus) were investigated in the North Sea by using unmanned surface vehicle (USVs) Saildrones equipped with dual-frequency (38, 200 kHz) echo sounder. The data was collected in two areas, a part of the standard Aberdeen-Hanstholm transect and English Klondyke, an important sandeel fishing ground. These areas were repeatedly covered by two Saildrones in May-June 2019. Repeated surveys witnessed high plankton density in the western part of the Aberdeen-Hanstholm transect constantly during the survey period. Salinity seemed to be one possible factor explaining the heterogeneity of plankton density in both vertical and horizontal structure. Sandeel appeared diurnally at various depths from 2 m to near the sea bottom. There was only a weak tendency that the schools were distributed deeper around midday. However, their diverse vertical distribution indicated underlying drivers of their behavior other than light. Despite the existing uncertainty of species identification due to lack of ground-truthing and limited frequency availability, this saildrone survey conveyed little but purposeful information of the dynamics in spatial utilization of plankton and sandeel over a short period of time.

Komiyama, Sakura. "Spatiotemporal Dynamics in the Acoustic Backscatter of Plankton and Lesser Sandeel (Ammodytes marinus) in the North Sea Measured Using a Saildrone." Master's thesis, University of Bergen, 2021. Bergen Open Research Archive, https://hdl.handle.net/11250/2759844

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Exploring the Pacific Arctic Seasonal Ice Zone With Saildrone USVs

More high-quality, in situ observations of essential marine variables are needed over the seasonal ice zone to better understand Arctic (or Antarctic) weather, climate, and ecosystems. To better assess the potential for arrays of uncrewed surface vehicles (USVs) to provide such observations, five wind-driven and solar-powered saildrones were sailed into the Chukchi and Beaufort Seas following the 2019 seasonal retreat of sea ice. They were equipped to observe the surface oceanic and atmospheric variables required to estimate air-sea fluxes of heat, momentum and carbon dioxide. Some of these variables were made available to weather forecast centers in real time. Our objective here is to analyze the effectiveness of existing remote ice navigation products and highlight the challenges and opportunities for improving remote ice navigation strategies with USVs. We examine the sources of navigational sea-ice distribution information based on post-mission tabulation of the sea-ice conditions encountered by the vehicles. The satellite-based ice-concentration analyses consulted during the mission exhibited large disagreements when the sea ice was retreating fastest (e.g., the 10% concentration contours differed between analyses by up to ∼175 km). Attempts to use saildrone observations to detect the ice edge revealed that in situ temperature and salinity measurements varied sufficiently in ice bands and open water that it is difficult to use these variables alone as a reliable ice-edge indicator. Devising robust strategies for remote ice zone navigation may depend on developing the capability to recognize sea ice and initiate navigational maneuvers with cameras and processing capability onboard the vehicles.

Chiodi Andrew M., Zhang Chidong, Cokelet Edward D., Yang Qiong, Mordy Calvin W., Gentemann Chelle L., Cross Jessica N., Lawrence-Slavas Noah, Meinig Christian, Steele Michael, Harrison Don E., Stabeno Phyllis J., Tabisola Heather M., Zhang Dongxiao, Burger Eugene F., O’Brien Kevin M., Wang Muyin, "Exploring the Pacific Arctic Seasonal Ice Zone With Saildrone USVs," Front. Mar. Sci., May 3, 2021. https://doi.org/10.3389/fmars.2021.640697

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Cold Pools Observed by Uncrewed Surface Vehicles in the Central and Eastern Tropical Pacific

New in situ observations collected by Saildrones, a novel uncrewed surface vehicle (USV), are used to investigate atmospheric cold pools during three 6-month missions to the central and eastern (∼140°W–125°W) tropical Pacific. Cold pool fronts in the atmospheric boundary layer are identified by a −1.5°C air temperature drop occurring in 10 min or less. While cold pool events were observed in the central Pacific as far north as 30°N and within the equatorial band, the majority of observed cold pools occurred within the convective, low-wind shear environment of the Intertropical Convergence Zone. Composite time series analysis of measurements during the 382 cold pool events reveals new insights on high-frequency variations in air temperature, wind speed, humidity, pressure, and sea surface temperature and salinity associated with cold pool fronts. The results highlight the unique capabilities of Saildrone USVs to resolve small spatial and temporal scales of variability over observationally sparse ocean regions.

Wills, S. M., Cronin, M. F., & Zhang, D. (2021). Cold pools observed by uncrewed surface vehicles in the central and eastern tropical Pacific. Geophysical Research Letters, 48, e2021GL093373. https://doi.org/10.1029/2021GL093373

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