Monthly class A pan evaporation: ANUClimate 1.0, 0.01 degree, Australian Coverage, 1970-2014

Abstract

Monthly total class A pan evaporation for the Australian continent between 1970-2014. Class A pan evaporation is useful for estimating evaporation rates and water need and use. Modelled by expressing each monthly value as a normalised anomaly with respect to gridded 1976-2005 means and standard deviations for each month. The monthly anomalies have been interpolated by trivariate thin plate smoothing spline functions of longitude, latitude and vertically exaggerated elevation using ANUSPLIN Version 4.5. Station elevations were 0.05 degree local averages of grid values from the GEODATA 9 second DEM version 3 as provided by ANUClimate_v1-0_digital-elevation-model-05deg-average_terrain_0-01deg. Monthly data values were obtained from Bureau of Meterology data at stations where there were at least 25 daily observations in each month, with short records scaled up to the complete month. This gave an average of 249 data points per month between 1970 and 2014. Automated quality assessment rejected on average 0.5 data values per month with extreme studentised residuals. The mean absolute value of all individual cross validation residuals provided by the spline analysis is 15.3 mm (10% of the overall mean). A comprehensive assessment of the analysis and the factors contributing to the quality of the final interpolated monthly rainfall grids is in preparation.