The WCRP-FPA2 Polar Challenge: expanding the capabilities of current Autonomous Underwater Vehicles Walter Meier (NASA Goddard Space Flight Center) and Michel Rixen (World Meteorological Organization) The cryosphere is a major indicator of global climate change and plays a fundamental role in the climate system. But despite advances in numerical modelling, the reliability of long-term climate change predictions in the Arctic and Antarctic is severely limited by the lack of systematic in situ observations of and beneath the sea-ice. The World Climate Research Programme (WCRP) and the Prince Albert II of Monaco Foundation (FPA2) are sponsoring a Polar Challenge (www.wcrp-climate.org/polarchallenge) that will reward the first team to complete a 2 000 km mission with an Autonomous Underwater Vehicle (AUV) under the Arctic or Antarctic sea-ice. Bonus awards will go to the team that can demonstrate that they have taken regular measurements of sea-ice thickness or draft and to those who successfully transmit their under-ice position and environmental data to operational networks. In situ ocean observations in polar regions are inherently expensive, risky and sparse, even more so under the sea-ice. A new paradigm is required to complement remotely sensed Earth observations. WCRP and the Foundation identified AUV technology as the answer due to its potential scalability, limited risks and cost-effectiveness. The challenges of under-ice observations Different types of AUVs are already operating in ice-free zones around the world, surfacing regularly to obtain a GPS (Global Positioning System) fix and to transmit near real-time environmental data. They are able to collect high-quality oceanographic observations – temperature, salinity, chlorophyll concentration, pH levels and more – at much lower cost compared to conventional observing systems, such as ship-based measurements.. Operating range, positioning and data transmission represent major challenges for AUVs under sea-ice but the integration of some recent innovations – for example in power systems, navigation and communication techniques – could expand the range of their application. WCRP and FPA2 aim to promote technological innovation towards a future cost-effective, autonomous and scalable observing network for sea-ice covered regions based on a fleet of AUVs. The ultimate goal is to achieve what ARGO (www.argo.ucsd.edu/) has accomplished for the open ocean. The competition The Polar Challenge competition, including registration, is scheduled to open around Jan 2016, when more details on the prize and rules will be provided. Competitors are responsible for mobilizing their own resources for attempting the Challenge. The prize amount is expected to represent a significant incentive for teams with adequate capabilities to attempt the Challenge missions, taking

into account the costs of engineering developments, operations and the AUV itself. Detailed rules of the Challenge are currently being developed. Subject to further refinements, however, they are as follows: - Main mission (mandatory):

• A continuous 2 000 km AUV mission under the sea-ice; • Defined deployment and recovery areas via accurate way points; • Autonomous navigation; and • Regular observations of temperature and salinity from the near-

surface to a depth of at least 700 metres. - Bonus demonstration 1 (optional):

• Regular observations of sea ice thickness or draft. - Bonus demonstration 2 (optional):

• Successful under-ice transmission of position and environmental data onto operational networks such as WIS/GTS.

The long-term benefit This initiative is co-sponsored by the European Space Agency (ESA), the Group on Earth Observation (GEO), the Intergovernmental Oceanographic Commission (IOC) of UNESCO, the Scientific Committee on Oceanic Research (SCOR) and the Global Climate Observing System (GCOS). It is aligned with WCRP research priorities, in particular the Grand Challenge on Melting Ice and Global Consequences, and the Grand Challenge on Regional Sea Level Rise. It contributes to WMO polar initiatives, such as the Global Cryosphere Watch (GCW) and the Global Integrated Polar Prediction System (GIPPS), as well as the Global Framework for Climate Services (GFCS). If successful, the initial proof of concept could be scaled up into a game-changing ocean monitoring network for the poles with wide-ranging benefits for climate research and services as well as for other sectors such as environmental protection, weather forecast, tourism, safety, security, transport, energy, biodiversity, fisheries and insurance. Ultimately, this initiative can have a tremendous impact in shaping future climate research in the polar regions. New collocated multidisciplinary data sets of sea-ice and under-ice properties at unprecedented temporal and spatial resolution far into unexplored territories could revolutionize our knowledge of climate change in those regions, for example, in the areas of heat fluxes and storage, fresh water exchanges, carbon sequestration and ocean acidification.

Financial contributions from the public and private sectors are most welcome to support this effort and complement the Prize money award. For more information, please visit www.wcrp-climate.org/polarchallenge) or contact us at polarchallenge@wcrp-climate.org.