Observing the Inflow of Pacific Water to the Arctic


OCCI Project Funded: 2004

What are the primary questions you are trying to address with this research?
This project focuses on two questions. First, what is the nature of Pacific Water exchange with the Arctic? In particular, what is the typical composition of northward flowing Pacific Water in different seasons, and how much of it is transported into the Arctic Basin near Point Barrow, Alaska? Second, how can emerging robotic vehicle technology, presently adapted to open water conditions, be applied to the problem of making measurements under the Arctic ice cover in winter?

What is the significance of this research for others working in this field of inquiry and for the broader scientific community?
To better predict changes in the Arctic environment, there is a need for improved understanding of the processes by which Pacific Water flowing through the Bering Strait is modified in the shallow Chukchi Sea and then transported to the Arctic basin. This transformation sets up water column conditions that influence the thickness and extent of Arctic sea ice. While some aspects of the Pacific Water inflow are presently being monitored (e.g. transport through the Bering Strait), the transport of modified Pacific Water into the Arctic during winter has never been directly observed.

What is the significance of this research for society?
Scientists investigating the Arctic have collected significant new data in recent years and have noted a broad spectrum of environmental changes, including reduced sea ice cover (see the Study of Environmental ARctic CHange (SEARCH) web site). The overarching goal is to determine how the observed environmental changes relate to the Arctic's natural variability and whether these changes indicate the start of a major shift in Arctic conditions in response to global climate change. Understanding the inflow of Pacific Water is a critical aspect of these studies because it plays an important role in maintaining the Arctic ice cap.

When and where will this investigation be conducted?
The narrow passage between Point Barrow, Alaska, and the flank of Barrow Canyon is a critical “choke point” of the system, where Pacific Water becomes concentrated subsequent to modification by shelf processes, and prior to exchange with Arctic waters (see Figure 1).  We will obtain hydrographic transects across this choke point, from a location near the Alaskan coast out to the eastern flank of Barrow Canyon.

What are the key tools or instruments needed to conduct this research?
Hydrographic transects will be obtained with a free-swimming robotic vehicle called REMUS that has been developed at WHOI (see figure below).  The capabilities of the standard vehicle are well suited to the Pacific Water study, but additional sensors and significant improvements to the navigation system are required to obtain credible scientific results from the summer fieldwork and to prepare for follow-on work in winter under the sea ice. 

What are the greatest challenges physical or intellectual to conducting this investigation?
In order to understand Arctic Ocean variability in the context of global climate change, an effective and economical means is needed for repeated hydrographic surveys at key choke points, particularly in winter when the region is covered by sea ice. This project, to be conducted in summer when ice cover is not expected, seeks to demonstrate that autonomous robotic vehicles are capable of obtaining hydrographic surveys beneath the ice cover in winter. This will set the stage for follow-up work to observe winter conditions.