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The Science Ice Exercise (SCICEX) program is a collaboration between the U.S. Navy and the marine research community to utilize nuclear-powered submarines for the study of the Arctic Ocean. Unlike surface ships, submarines have the unique and valuable ability to operate and take measurements regardless of sea ice cover and weather conditions. The goal of the program is to acquire comprehensive data about Arctic sea ice, water properties, and bathymetry.

SCICEX was officially founded in 1994 after a successful feasibility test that took place in 1993 where civilian scientists joined naval personnel on the submarine to acquire scientific data. SCICEX data provide an extraordinary volume of ice draft measurements from upward-looking sonar and depth soundings from side-scan and other sonar. These measurements constitute one of the most complete mappings available of ice thickness in the central Arctic Basin and provide orders of magnitudes more bathymetry data of the region than previously acquired.

SCICEX is important because it adds critical pieces to the overall information needed to analyze sea ice and ocean dynamics — ice thickness and bathymetry data in particular but also chemical, biological, and physical oceanographic data. With the success of the initial project in 1993, the U.S. Navy and the National Science Foundation (NSF) signed a Memorandum of Agreement (MOA) in 1994 that called for five more dedicated SCICEX missions. The dedicated SCICEX cruises occurred in 1995, 1996, 1997, 1998, and 1999.

Data from SCICEX cruises are central to improving scientific understanding of the complex Arctic Ocean environment and to defining the scope of recent changes. These data also contribute to the safety, stability, and success of Arctic military and civilian marine operations.

• Sea Ice Thinning. Profiles of sea ice draft obtained from the upward-looking sonars of submarines transiting the Arctic Ocean have provided the bulk of our current knowledge of ice thickness, and how it varies over the Arctic basin. By comparing ice draft data collected by SCICEX with previously published data, scientists established that sea ice has thinned significantly within the Data Release Area between 1950–1970 and the 1990s.

• Bathymetry. SCICEX data contributed to the new International Bathymetric Chart of the Arctic Ocean, which led to first-order changes in the mapped positions and depths of major bathymetric features. Knowledge of seafloor topographic features is important for studies of Arctic Ocean circulation, seafloor volcanism, and hydrothermal circulation, and has informed a scientific ocean drilling expedition dedicated to understanding Arctic climate over the past 65 million years

Warming of Atlantic Waters. Hydrographic data provide definitive, synoptic evidence of upper ocean circulation pathways, and evidence of warming and penetration of Atlantic water as it propagates along basin peripheries and ridges. As the SCICEX data archive has grown, it has played a greater role in climate and modeling studies to validate model results of temperature and salinity distributions. • O cean Acidification. Chemistry data show that the rate of CO2 uptake by the Arctic Ocean is twice the average for the global ocean, leading to acidification of the Arctic Ocean. 

• Biological Response to Reduced Summer Ice. Sensor estimates of chlorophyll and oxygen reflect the response of Arctic productivity to decreased sea ice extent during summer. Measurements of organic material help to define transport pathways of carbon from shelves to basins. Current biological approaches can characterize the microbial communities that impact the ecological dynamics and biogeochemical fluxes of the Arctic.