GO-SHIP A20 2021 Hydrographic Program

Cruise Scientific Objectives

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.

Programs and Principal Investigators

Program	Affiliation	Principal Investigator	Email
CTDO Data, Salinity, Nutrients, Dissolved O2	UCSD, SIO	Susan Becker, Jim Swift	sbecker@ucsd.edu, jswift@ucsd.edu
Total CO2 (DIC)	AOML, PMEL, NOAA	Richard Feely, Rik Wanninkhof	richard.a.feely@noaa.gov, Rik.Wanninkhof@noaa.gov
Underway Temperature, Salinity, and pCO2	PMEL, NOAA	Simone Alin	simone.r.alin@noaa.gov
Total Alkalinity, pH	SIO, RSMAS	Andrew Dickson, Frank Millero	adickson@ucsd.edu, fmillero@rsmas.miami.edu
Discrete pCO2	PMEL, NOAA	Rik Wanninkhof	Rik.Wanninkhof@noaa.gov
SADCP	UH	Eric Firing	efiring@soest.hawaii.edu
LADCP	LDEO	Andreas Thurnherr	ant@ldeo.columbia.edu
CFCs, SF6, N2O	UW	Mark Warner	warner@u.washington.edu
DOC, TDN	RSMAS	Dennis Hansell	dhansell@rsmas.miami.edu
Microgels	RSMAS	Dennis Hansell	dhansell@rsmas.miami.edu
C13 & C14	UW, WHOI	Rolf Sonnerup, Roberta Hansman	rolf@uw.edu, rhansman@whoi.edu
Transmissometry	TAMU	Wilf Gardner	wgardner@ocean.tamu.edu
Chipod	OSU	Jonathan Nash	nash@coas.oregonstate.edu
Argo Floats	WHOI	Susan Wijffels, Steven Jayne, Pelle Robbins	swijffels@whoi.edu, sjayne@whoi.edu, probbins@whoi.edu.
BGC Floats	MBARI, UW, Princeton, SIO, WHOI	Kenneth Johnson, Steven Riser, Jorge Sarmiento, Lynne Talley, Susan Wijffels	johnson@mbari.org, riser@uw.edu, jls@princeton.edu, ltalley@ucsd.edu, swijffels@whoi.edu
Nitrate isotopes	Princeton	Daniel Sigman	sigman@princeton.edu
Spotter drifters	Sofar Ocean	Cameron Dunning	cameron@sofarocean.com
Sargassum	WHOI	Dennis McGillicuddy	dmcgillicuddy@whoi.edu

Science Team and Responsibilities

Duty	Name	Affiliation	Email Address
Chief Scientist	Ryan Woosley	MIT	rwoosley@mit.edu
Co-Chief Scientist, LADCP	Andreas Thurnherr	LDEO	ant@ldeo.columbia.edu
CTD Watchstander	Elena Perez	WHOI	eperez@whoi.edu
CTD Watchstander	Cassondra Defoor	UNR	cdefoor@nevada.unr.edu
CTD Watchstander	Paige Hoel	UCLA	paigehoel@atmos.ucla.edu
CTD Watchstander	Francesca Alatorre	UCSC	falatorr@ucsc.edu
Nutrients, ODF supervisor	Susan Becker	UCSD ODF	sbecker@ucsd.edu
Nutrients	Alexandra Fine	NOAA	alexandra.fine@noaa.gov
CTDO Processing	Michael Kovatch	UCSD ODF	mkovatch@ucsd.edu
Salts, ET, CTD/Rosette Maintenance	John Calderwood	UCSD SEG	jcalderwood@ucsd.edu
Salts, CTD/Rosette Maintenance	Patrick A’Hearn	TAMU	pnahearn@gmail.com
Dissolved O2, Database Management	Andrew Barna	UCSD ODF	abarna@ucsd.edu
Dissolved O2	Robert Freiberger	UCSD	rfreiberger@ucsd.edu
DIC, underway pCO2	Andrew Collins	UW	andrew.collins@noaa.gov
DIC	Charles Featherstone	NOAA	charles.featherstone@noaa.gov
Discrete pCO2	Patrick Mears	U Miami	patrick.mears@noaa.gov
CFCs, SF6	Mark Warner	UW	warner@u.washington.edu
CFCs, SF6	Rolf Sonnerup	UW	rolf@uw.edu
CFCs, SF6 student	Carla Mejías-Rivera	U Puerto Rico	clmejiasrivera@gmail.com
pH, Total Alkalinity	Manuel Belmonte	UCSD	mbelmont@ucsd.edu
pH, Total Alkalinity	Daniela Nestory	UCSD	dnestory@ucsd.edu
pH, Total Alkalinity	Carmen Rodriguez	U Miami	crodriguez@rsmas.miami.edu
pH, Total Alkalinity	Albert Ortiz	U Miami	albert.ortiz@rsmas.miami.edu
DOC, TDN	Abigail Tinari	U Miami	abigail.tinari@rsmas.miami.edu
Indep/Nurse	Lauren Elium	Other	n/a
Marine Technician	Stephen Jalickee	UW	jalickee@uw.edu
Marine Technician	Elizabeth Ricci	UW	ericci@uw.edu