Trends in evaporative demand in Great Britain using high-resolution meteorological data

Observations of climate are often available on very different spatial scales from observations of the natural environments and resources that are affected by climate change. In order to help bridge the gap between these scales using modelling, a new dataset of daily meteorological variables was created at 1 km resolution over Great Britain for the years 1961--2012, by interpolating coarser resolution climate data and including the effect of local topography. These variables were used to calculate evaporative demand at the same spatial and temporal resolution, both excluding (PET) and including (PETI) the effect of water intercepted by the canopy. Temporal trends in evaporative demand were calculated, with PET found to increase in all regions and PETI found to increase in England. The trends were found to vary by season, with spring evaporative demand increasing by 14 % (11 % when the interception correction is included) in Great Britain over the dataset, while there is no statistically significant trend in other seasons. The trends in PET were attributed analytically to trends in the climate variables, with the spring trend in evaporative demand being driven by radiation trends, particularly by increasing solar radiation.