Stockholm Environment Institute 1 GMET in Bolivia: building gridded climate datasets for water resource studies Highlights: • A common challenge in water resource studies is finding continuous spatial coverage of precipitation data, due to the sparse and often uneven distribution of meteorological stations. • The Gridded Meteorological Ensemble Tool (GMET) uses station data to create a continuous, gridded product – and unlike other tools, it incorporates data and prediction errors into its analysis. • SEI worked with Bolivian scientists and the National Center for Atmospheric Research (NCAR) to apply GMET to a country outside of the US for the first time. • The project provided a window into how GMET works in data-sparse regions, revealing both strengths and weaknesses. • The resulting tool is open-source and is now accessible to a broader community. 1 • This project included a technology transfer, with SEI working with government partners to train local experts on how to use and update the tool. Hydrologic applications for water planning and water balances require datasets for climate parameters, such as precipitation and temperature, that cover a territory on a continuous basis. However, meteorological stations are often unevenly distributed. Water managers thus use a variety of methods to generate the necessary continuous dataset from station observations. These methods typically do not recognize the gaps and errors in local observations, leading to uncertainty. This is a more acute problem in mountainous areas and other regions where meteorological stations are sparse and where the topography is complex. The Gridded Meteorological Ensemble Tool (GMET) enables water managers to use station data to generate historic climate grids for an area, along with statistical information that can provide an estimate of the level of uncertainty. Over the past few years, the National Center for Atmospheric Research (NCAR) developed GMET in collaboration with researchers from the US Army Corps of Engineers and the University of Washington. 2 An early application used 12,000 stations to generate a daily climate grid for the continental United States, which was applied in hydrologic modelling studies, climate forecasts and other applications. This brief describes SEI’s efort to use GMET in Bolivia, as a key input for the country’s water balance study. The study consisted of a comprehensive model of water availability in its rivers, lakes and streams. This marked the first time the tool has been applied outside of the United States. 1 http://gmet.sei-us.org/ 2 The scientific foundation of GMET is described in a paper by the main authors of the tool, Andrew Newman et. al. (2015). Building on the work of Clark and Slater (2006) they developed a station-based, ensemble dataset of precipitation and temperature for the contiguous United States. The current project is the first application of the tool outside of the United States. SEI brief February 2019 Bart (A.J.) Wickel Marisa Escobar Photo (above): © BART (A.J.) WICKEL / SEI