The 2018 Fridtjof Nansen Medal is awarded to Rainer Feistel for creating the rigorous conceptual foundation of ocean thermodynamics through forming a Gibbs function for seawater.
Oceanography is a young discipline compared with physics and chemistry. Consequently, only twenty years ago, seawater thermodynamics was an area with poor foundations. But Rainer Feistel’s intellect, energy, productivity, and leadership have since placed ocean thermodynamics firmly within the pantheon of rigorous physics and chemistry. His work has pushed back the boundaries of thermodynamics of water and seawater across all the science and engineering disciplines where H2O is relevant. It is no exaggeration to say that Feistel is the pre-eminent oceanographer in the area of seawater thermodynamics.
Feistel realised that the properties of seawater, as defined by the 1980 international standard EOS-80, were thermodynamically inconsistent. In a series of papers published in 1993, 1995, 1999, and 2008 he formed a Gibbs function for seawater, from which all of the thermodynamic properties of seawater can be derived by simple mathematical operations such as differentiation. His foresight and his innovative science extended to his Gibbs function for ice, and then, through a larger collaborative effort, to the thermodynamic description for humid air. None of these substances, seawater, ice or humid air, had previously been described by a thermodynamic potential. Despite this, Feistel completed the full thermodynamic description of all the fluid and ice components of the Earth’s climate system, from the upper atmosphere to the ocean depths.
Feistel’s Gibbs function (2008) has now become the internationally accepted definition of the thermodynamic properties of seawater. To this end, Feistel built contacts with meteorologists (to put our measurements on a firm meteorological foundation), with standards-developing organisations (to make sure we could develop standards worthy of their name), with atmospheric scientists (to solve thermodynamic issues related to air/water mixtures), and chemists. Feistel was twenty years ahead of the rest of the oceanographic community. He realised the need, did all the original thinking, the detailed numerical work to develop this very accurate description of seawater, and only then did the world come knocking on his door with a view to adopting his work as a new global standard.
Feistel’s work has changed how we think about ocean thermodynamics, how we make use of the foundational theory, and how we communicate these ideas within our discipline and across to other disciplines. The impacts of Feistel’s work penetrate every corner of the ocean and climate community. It is very important to have firm theoretical foundations for all aspects of oceanography. Feistel has performed a heroic task in bringing these foundations for seawater thermodynamics well into the 21st century.