One of hydrology’s most eminent trail-blazing scientists, William James (Jim) Shuttleworth, an incredibly warm, kind and compassionate person, sadly passed away on 20th December 2020 at the age of 75. 

Jim arrived at the UK Institute of Hydrology in 1972: with a nuclear physics background,  he looked at hydrology with fresh eyes.  

He was recruited to work on a project making Bowen ratio measurements of forest evaporation. Faced with the difficulty of measuring the very small temperature and humidity gradients found above forest, Jim rapidly concluded that there must be an easier way. The strongest candidate was the eddy-correlation method and Jim’s vision saw a minimalist battery-powered instrument that could operate continuously in remote places. 

The successful development of this instrument transformed our ability to measure evaporation. The over 300 Fluxnet stations now using this approach have a provenance traceable back to Jim’s original device. 

When an opportunity arose to exploit the new instruments measuring Amazonian evaporation, Jim grabbed it. Others saw the project in terms of understanding the water balance of the rainforest, but Jim recognized it as an opportunity to pioneer a new field of global hydrology,  combining hydrological measurements with new global models.

In the early 1980s, with Global Circulation Models, in their infancy, only a handful of visionaries believed in their potential to predict future climate. An early application was to predict the climatic consequences of deforesting the Amazon basin. Yet the representation and parameterization of the forest in these models was basic — often just guesswork. By linking directly to scientists at NASA and the UK Met Office Jim ensured that the Amazonian demonstration of how micrometeorological land surface flux measurements could anchor models to the real world, was rapidly incorporated into the new GCMs, thus kick-starting many other international experiments.

Jim joined the Department of Hydrology and Water Resources at The University of Arizona in 1993, ultimately becoming Regents Professor. He created their first degree programme in hydrometeorology, writing the definitive textbook on the subject, and instigating their Hydrology and Atmospheric Sciences (HAS) programme. 

Jim maintained his theoretical ability throughout and among his 200 scientific publications - "Evaporation From Sparse Crops - An Energy Combination Theory" has been cited over 2000 times.  

Among his many international recognitions are the International Hydrology Prize in 2006, and the AGU Robert E. Horton Medal in 2014 for “outstanding contributions to hydrology.” (https://profiles.arizona.edu/person/shuttle)

Jim is survived by his beloved wife Hazel, three of his four sons and one daughter, fifteen grandchildren, and three great-grandchildren. And, of course, by those of us lucky enough to have had him as one of our dearest friends, who will all miss him very deeply.
 

Colin Lloyd, Jim Wallace and John Gash

Figure caption: Jim Shuttleworth on the Les Landes forest tower during HAPEX-MOBILHY, in 1986.