Wind speed climatology and trends for Australia, 1975–2006: Capturing the stilling phenomenon and comparison with near‐surface reanalysis output

Abstract

Near‐surface wind speeds ( u ) measured by terrestrial anemometers show declines (a ‘stilling’) at a range of mid‐latitude sites, but two gridded u datasets (a NCEP/NCAR reanalysis output and a surface‐pressure‐based u model) have not reproduced the stilling observed at Australian stations. We developed Australia‐wide 0.01° resolution daily u grids by interpolating measurements from an expanded anemometer network for 1975–2006. These new grids represented the magnitude and spatial‐variability of observed u trends, whereas grids from reanalysis systems (NCEP/NCAR, NCEP/DOE and ERA40) essentially did not, even when minimising the sea‐breeze impact. For these new grids, the Australian‐averaged u trend for 1975–2006 was −0.009 m s −1 a −1 (agreeing with earlier site‐based studies) with stilling over 88% of the land‐surface. This new dataset can be used in numerous environmental applications, including benchmarking general circulation models to improve the representation of key parameters that govern u estimation. The methodology implemented here can be applied globally.