Organization: National Science Foundation (NSF)

Research Title: Ridge Interdisciplinary Global Experiments (RIDGE)

Funding Level (millions of dollars):

FY94 4.1
FY95 4.0
FY96 3.7

Committee on Environment and Natural Resources (CENR) Component:
(a) Subcommittee: Global Change Subcommittee (100%) NSTC Committee on Fundamental Science
(b) Environmental Issue: Global Change (50%); Natural Variability (50%)
(c) Research Activity: System Structure and Function: Understand (100%)

Organizational Component:
Ocean Sciences Division
NSF OCE/NSF, Room 725
4201 Wilson Blvd.
Arlington, VA 22230

Point of Contact:
Philip Taylor
Phone: 703-306-1586

Research Goals:
The goal of the RIDGE program is to understand the physical, chemical, and biological causes and consequences of the energy transfer through time and space between the global mid-ocean ridge volcanic system and the ocean environment.

Program Interfaces:
The NSF RIDGE program is closely linked with the NOAA VENTS program. RIDGE is also linked with the USGS program of deformation studies on the Juan de Fuca Ridge, and ONR studies of "natural laboratories" on the East Pacific Rise and the Mid-Atlantic Ridge. The US programs are linked to international mid-ocean ridge research through InterRIDGE, which, at this time, is comprised France, Germany, Spain, UK, Iceland, Canada, and the US; together with several other associate countries. InterRIDGE has been designated a Working Group of the ICSU Scientific Committee on Oceanic Research (SCOR).

Program Milestones:
(1) Implementation and completion of field projects along the Juan de Fuca Ridge in the North Pacific, the East Pacific Rise, and the Mid-Atlantic Ridge and progressively between 1996 -1998 and (2) incorporation of heat and chemical flow variables into coupled ocean-climate models in stages from 1996 to 1999.

Research Description:
Within the Geosciences Directorate the RIDGE program is divided between the Global Change initiative and Disciplinary Geosciences. The shorter time scale processes, such as hydrothermal circulation, are relevant to global change, whereas, the longer time scale processes, such as mid-ocean ridge magmatic processes, are considered within Disciplinary Geosciences. Relative to global change, the primary objective of RIDGE is to understand the geological, chemical, biological, and physical oceanographic interactions between the oceans and hydrothermal circulation of seawater through the ocean crust. Most of the heat loss from the interior of the Earth occurs through the mid-ocean ridge system by means of this circulation. Hydrothermal venting at mid-ocean ridges produces a wide variety of important effects in the overlying water column, including the formation of turbulent, buoyant plumes, the introduction of chemicals and biota, and the modification of deep ocean circulation and mixing patterns. "Megaplumes" of hydrothermal discharge into the overlying layers of the ocean suggest that the effects of venting may not be confined to the deep ocean. While megaplumes are expected to be episodic, events on the Juan de Fuca Ridge (in the northeast Pacific) in 1986 and in 1993 suggest that the frequency of the events, and thus the accompanying effects, may be higher than expected. Major RIDGE projects aimed at understanding hydrothermal circulation will be conducted on the Juan de Fuca Ridge, the East Pacific Rise, and the Mid-Atlantic Ridge. The Juan de Fuca project is a multi-disciplinary, manned and unmanned submersible, surface-ship, and laboratory investigation of major vent fields. The East Pacific Rise and Mid-Atlantic Ridge projects will determine the distribution, relative intensity, and first-order chemical characteristics of hydrothermal venting and its relation to ridge morphology, geophysics, petrology, biology, and ecology.

Policy Payoffs:
The role of hydrothermal circulation on deep-ocean circulation, on the chemical mass balance of the oceans, and on the biological communities in the ocean basins are only beginning to be understood, and the role of the factors in effecting global climate is unknown, but cannot be ignored since they could potentially be substantial.