AR39-06: NAAMES 4

Ship

Cruise Party

Departure: Mar 17, 2018

Arrival: Apr 10, 2018

Operations Area

Science Objectives

The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) is an interdisciplinary investigation addressing two primary science goals: (1) Define environmental and ecological controls on plankton communities and (2) Define linkages between ocean ecosystem properties and biogenic aerosols. Within these two broad goals, the NAAMES investigation focuses on identifying environment-ecosystem-aerosol interdependencies in the climate-sensitive North Atlantic. This ocean region hosts the largest annual plankton bloom in the global ocean and its impact on Earth’s radiative balance is particularly sensitive to biogenic aerosol emissions. Specific baseline science objectives of NAAMES are to (1) Characterize plankton ecosystem properties during primary phases of the annual cycle in the North Atlantic and their dependence on environmental forcings, (2) Determine how primary phases of the North Atlantic annual plankton cycle interact to recreate each year the conditions for an annual bloom, and (3) Resolve how remote marine aerosols and boundary layer clouds are influenced by plankton ecosystems in the North Atlantic. These objectives are accomplished by coupling autonomous in situ and satellite measurements sustained throughout the NAAMES investigation with short-term, coordinated ship and airborne campaigns that target critical events in the annual plankton cycle and focus on detailed system characterization. These direct observations are integrated with climate-ecosystem modeling to create a process-based understanding that allows improved interpretation of historical data records and improved predictions of future change.

Science Activities

The NAAMES investigation has a duration of 5 years and involves 4 field campaigns.  Each field campaign will share a common observation profile.  Campaigns conducted to date occurred in November 2015, May 2016, and September 2017, all on the UNOLS R/V Atlantis.  For each campaign, ship-based measurements are accompanied by aircraft measurements.  The aircraft is a NASA C-130 stationed either from Saint John’s Bay, Canada, or the Lajes Field in the Azores. Global Class Research Vessels, such as the Atlantis, are required for each field campaign due to requirements for foreward deck space for full-sized aerosols vans, deck space for a radioisotope van, and the large scientific complement (34 berths).  A global class vessel is also advantageous for the NAAMES project on account of sea-worthiness during field studies that span the annual cycle.

Each field campaign involves a ~26-day, roughly triangular-shaped ship transect (see uploaded files on transect and stations). For the 2018 March campaign, the ship will leave San Juan and sail to ~40oN, 40oW and then continue along the 40oW line toward ~55oN before returning to Woods Hole. During all legs, underway sampling is conducted.  Regular overboard deployments will begin around 40oN, 40oW, but it may also be beneficial to make one or more stops during the outbound transect to conduct a ‘shake-down’ station of overboard operations.  The full complement of ship-based measurements begins around 40oN, 40oW and continues until the northern-most turning point (~55° N). During this primary latitudinal science leg, daily operations involve a sampling station that begins around midnight and then continues until the following day.  Station operations include multiple CTD/Rosette casts, the first of which are relatively shallow casts (~200 m), followed by a deep cast to ~2000 m.  Optical and other instruments mounted on the rosette for the shallow casts but with depth limits <2000 m will need to be removed before the deep cast.  Following the deep cast, an additional shallow cast will be conducted for final water sampling and underwater light measurements.  Also during station, measurements will be made of downwelling light properties and water leaving radiances.  In addition to daily station occupations, 2 stations will be chosen for long-term measurement series.  At all stations, surface lagrangian drifter may be deployed upon arrival at station and then measurements will be conducted over the following occupation while following the trajectory of the drifter.  This approach minimizes the impacts of advective processes on measured system changes over the long-term station. Once the primary science transect is complete and the northern-most turning point is reached, the return transect will commence, with continuous in-line measurements conducted until the day before port arrival, but no additional station occupations are anticipated.

In addition to water sampling and flow through seawater measurements, another key component of the NAAMES investigation is the measurement of aerosols.  For this aspect, key measurements will be conducted from the Aersosol Vans, located on the forward deck of the ship.  Aerosol measurements are conducted continuously while the wind is from the forward direction. These measurement have to be terminated when the wind is from the backward direction, due to contamination from the ship.  Thus, it is desired to keep the ship orientation favorable for aerosol samples for the greatest fraction of the time feasible (understanding that ship orientation during overboard castings is dictated by sea state and wire angle). 

Also during the field campaigns, deployments will be made of autonomous profiling floats and surface drifters.  Deployments will occur along the N-S primary latitudinal science transect, with exact location dependent on station location and real-time information on regional mesoscale eddies.  Surface drifter deployments will target mesoscale eddy centers and will provide water parcel tracking capabilities that inform flight patterns for the C-130.   

Airborne deployments accompanying the ship measurements will focus on the primary N-S latitudinal transect.  The airborne measurements include in situ aerosol sampling and remote sensing measurements with a hyperspectral ocean color sensor, a high resolution lidar, a polarimeter, and a downwelling irradiance sensor.  Aircraft measurements need to be highly coordinated with the ship, so regular communications between the two platforms is essential.  The NAAMES team gained considerable experience conducting successful ship-aircraft campaigns during the previous 3 campaigns.  Aircraft measurements begin shortly after takeoff, and continue during the transect to the ship.  Once arriving at the ship, a diversity of flight patterns are followed to characterize horizontal and vertical variability in ocean ecosystem and aerosol properties.  The aircraft transect will also include fly-overs of regions previously sampled by the ship, as tracked by the surface drifters.  These drifters essentially provide a ‘bread crumb trail’ that allows the aircraft to follow changes in system properties well after the ship has departed a given sampling station.  One the primary science measurements are complete along the ship transect, the aircraft returns to base.

Additional Info

Stations:

Supporting documentation:

Shipboard Equipment

Shipboard Communication

CTD/Water Sampling

Critical CTD Sensors

Hydrographic Analysis Equipment

MET Sensors

Sample Storage

Navigation

Navigation

Winches

Standard Oceanographic Cables

Portable Vans

Checklist

Checklist