Professor Jim Shuttleworth sadly passed away on Sunday 20 December, surrounded by his family. Jim was a pioneer in the field of hydrometeorology and best known for his innovative contributions to our understanding of evaporation.

After finishing a PhD in high energy nuclear physics at the University of Manchester in 1971 Jim joined the Institute of Hydrology in Wallingford (now the UK Centre for Ecology and Hydrology) at a time when the Institute was expanding rapidly in process  hydrological research under the leadership of Jim McCulloch. He first wrote a series of papers in Boundary-Layer Meteorology that remain fundamental in our understanding of evaporation. One of his further insights was that equations for potential evaporation such as the Priestley Taylor equation could not be used directly for estimating forest evaporation, as the difference between transpiration and evaporation from a wet canopy (interception) called for a separately description. An important spin-off from this early work was the development of the sparse crop evaporation model that included the effects of an interacting bare soil with the environment surrounding the leaves of the plants.

He led the group at IH to develop one the first integrated eddy correlation devices, exploiting concurrent developments in microelectronics (the name eddy covariance came later) that was ahead of its time, and now superseded by the off-the-shelf technology that many of us use in FLUXNET. The design of the Hydra, as the instrument was called, was unique in that it measured the temperature, humidity and windspeed fluctuations all in the same path. It was also battery-powered and could work in remote locations. In 1983 it was used in the Ducke Reserve near Manaus providing the first direct measurements ever of evaporation from Amazonian rainforest. In doing these measurements Jim not only initiated a whole area of Amazonian environmental research but also  collaborated with and, importantly, trained a group of young Brazilian scientists that would later form the core of the international ABRACOS and LBA experiments and would later leave their mark on Amazonian science.

Jim also realized that the Global Climate Models that were starting to be used to predict the effects of Amazonian deforestation on climate were poor in their representation of the interaction between the land surface and the atmosphere. He wrote seminal papers on the emergence of Macrohydrology and started working together with scientists from the Meteorological Office in the UK (part of which would later form the Hadley Centre for Climate Prediction and Research) to improve these models. At that time he spent a year with Pier Sellers at NASA to explore the use of eddy covariance data in calibrating land surface models. It was here that he started liking the scientific environment in the US.

Probably as a result, in the early nineties Jim moved to the University of Arizona where he started to study the impact of heterogeneity on evaporation and wrote the influential chapter on evaporation in the Handbook of Hydrology, which aimed to bridge the gap between engineering hydrology solutions to estimate evaporation and more process-based ones. He started to teach a new generation of hydrometeorologists and wrote the only existing textbook on the subject. His research interest in heterogeneity and averaged measurements led him to propose a network of cosmic ray neutron absorption instruments to estimate soil moisture – neatly bringing him back to nuclear physics.

Jim was member of several national and international committees (IGBP-BACH, GEWEX) and received numerous honors and awards, amongst others the 2006 International Hydrology Prize of the IAHS), and the Robert E. Horton medal of the AGU (2014). Jim leaves a vast legacy of important experimental insights and theoretical developments in the field of land surface atmosphere interaction. He contributed to philosophical perspectives in hydrology, as well as hydrologic understanding and prediction based on careful integration of observations and theory. He leaves a wife, three sons and a daughter. He will be sadly missed by all of us who knew and worked with him.

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