Monitoring Changing Waters using the Gulf of Maine Atlantic Time Series (GNATS)

The Gulf of Maine North Atlantic Time Series (GNATS) is a transect time series across the widest part of the Gulf of Maine, between Portland, Maine and Yarmouth, Nova Scotia. It was started in 1998, funded by the Office of Biology and Biogeochemistry at NASA. It has two primary goals: (a) the calibration and validation of ocean color satellite remote sensing and (b) the development of a time series of physical, chemical, biological, biogeochemical and bio-optical variables with which to evaluate climate change.

As of 2021, the GNATS data set includes results from 215 cruises. This visualization shows a small subset of variables collected from the first 20 years of GNATS (1998-2018 inclusive; 204 cruises in total), showing the location and temperature across the GNATS transect (vertical drops of expendable bathythermographs plus Moving Vessel Profiler measurements), autonomous Slocum Electric Glider missions (beginning 2008) and surface phytoplankton primary productivity. Since 1998, GNATS has documented extreme drought years, some of the wettest years in the last century, extreme warming events and an overall average decreasing primary production (60% mean decline). All of these results show the Gulf of Maine coastal shelf sea in transition, during our current geological epoch known as the Anthropocene.

The visualization zooms into the Gulf of Maine region revealing sea surface temperatures (SST) that vary seasonally. Next GNATS transects of temperature data are shown over time as the data are collected. These data were collected from a mobile platform on a ferry. Next, data from a Slocum Electric Glider (an underwater vehicle) are shown. Once all of the Glider data are shown, all data are faded out except for "Henry Mission #4" data which were acquired between April 28 and May 21 of 2009. Then as a comparison, data from "Henry Mission #17" are shown which were acquired data between April 21 and May 12 of 2017. The change shows significantly more warm water in the deeper parts of the Gulf of Maine. These differences are similar to what the data show as a whole. The Gulf of Maine is warming. Finally, the visualization zooms out showing Sea Surface Temperature from a global perspective.

The GNATS data used in this study are available from NASA SEABASS; https://seabass.gsfc.nasa.gov/experiment/GNATS
doi: 10.5067/SeaBASS/GNATS/DATA001

See also: https://youtu.be/n6kX8liqDJU

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We gratefully acknowledge the captains, crews and staff of the various ships used in the GNATS program since 1998: M/S Scotia Prince, HSV The CAT, M/S Nova Star, HSV Alakai, R/V Connecticut, R/V Argo Maine, R/V Endeavor, F/V Ella and Sadie. We would also like to thank numerous former employees of Bigelow Laboratory who participated in the 204 GNATS cruises shown here: Danielle Alley, Amanda Ashe, Emily Booth, Rosaline Campbell, Susanne Dunford, Colin Fischer, Dr. Joaquim Goes, James Johnson, Laura Lubelczyk, Emily Lyczkowski, Elise Olson, Abby Onos, Carlton Rauschenberg, Dr. Bob Vaillancourt, Dr. Laura Windecker, Dr. Meredith White, Heather-Anne Wright and Amy Wyeth.

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