Ryan Woosley
Complex oceanic responses to climate change can only be characterized with regular repeat high-quality shipboard measurements of climate-relevant ocean properties. GO-SHIP repeat transoceanic surveys (www.goship.org) provide full water column hydrographic observations with temporal and spatial resolutions adequate to resolve decadal variability in oceanic storage of heat, freshwater, carbon, oxygen, nutrients and transient tracers. Repeat hydrographic physical-biogeochemical measurements nominally along 52° 20’N in the North Atlantic Ocean enables scientists to better tackle important unresolved aspects of the Atlantic Ocean’s response to decadal scale variability and increases in both heat and carbon dioxide as a result of anthropogenic activies. The U.S. GO-SHIP A20 2021 hydrographic section revisited this line for the fourth time, with prior transects occurring in 1997, 2003, and 2012. Temperature, salinity, and velocity measurements from A20 2021 reveal how the heat content of deep and bottom waters in the North Atlantic have changes over the last 24 years. A20 2021 measurements of oxygen, nutrients, transient tracers, and dissolved inorganic carbon allow quantifying the anthropogenic component in the total inventory changes of surface and deep waters. Combined carbon and current measurements from the repeat A20 line are used to determine rates of regional carbon accumulation and exchange with adjacent circulations. The overarching achievement of GO-SHIP A20 2021 measurements was the reoccupation of 90 full-depth CTD stations and the collection of water samples at different levels with 36 Niskin bottles. Measured temperature, salinity, pressure, oxygen, fluorometry, shear and micro-scale temperature,and the major nutrients, oxygen, salinity, CFC and carbon components (total dissolved inorganic carbon, total alkalinity, pH, and fugacity of CO2) were discretely analyzed on board. Measurements of dissolved organic carbon, nitrate isotopes, radiocarbon, and Sargassum seaweed samples were collected and will be measured in laboratories on shore. Core Argo and BGC-Argo floats along with SOFAR drifters were also deployed, generally after a CTD cast while leaving station.
Cruise track and station locations. The lack of cruise track between the last station and the end port of St. Thomas, USVI is due to the ship science data logger being turned off after the last station since the ship would enter Surinamese waters shortly after departing.
.. tabularcolumns:: |p{4.0cm}|p{3.0cm}|p{4.0cm}|p{4.5cm}|
.. tabularcolumns:: |p{4.0cm}|l|l|l|