This collection provides hourly near-surface (1.5 m) vapour pressure for Australia with a spatial resolution of 1 km. These data are spatially interpolated using quart-variate thin plate splines (full spline dependence on easting, northing, elevation, and time- and space-varying coastal distance index). This collection includes: (i) a 30-year climatology for every hour on every 5th day of the year (1991-2020), (ii) a time-series of hourly vapour pressure beginning on 01/Jan/2015, (iii) an animation of the 30-year climatology from (i), and (iv) supporting metadata and point-based climatologies for weather station locations to enable comparative statistical analyses.
Further details are provided in the README file.
Credit
We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. This work was funded by the Terrestrial Ecosystem Research Network (TERN), an Australian Government NCRIS enabled project, and is supported by the use of TERN infrastructure.
Purpose
These data were developed to support numerous scientific applications.
Lineage
Full details of the hourly interpolation methodology are provided in Stewart et al. (2024), including the Supplementary Material.
The original station data were supplied by the METAR data stream from BoM from January 1990 to March 2023 for 621 stations across Australia. A direct spatial interpolation approach (i.e., models are re-fitted for each time step using all available observations and model covariates) was applied to generate vapour pressure grids across all Australia using the ANUSPLIN v4.4. software (Hutchinson and Xu, 2013). Two key data products are included in this collection:
1. Hourly vapour pressure climatologies (every 5th DOY, 1991-2020)
Hourly vapour pressure climatologies were interpolated with quart-variate thin plate splines as a function of easting, northing, elevation, and a time- and space-varying coastal distance index. Elevation (m) was exaggerated by a factor of 100 to represent the differences in horizontal and vertical synoptic scales typical for spline-based climate interpolation (Hutchinson et al. 2009). The coastal distance index is calculated as a limiting transformation of the generalised distance to coast (Hutchinson et al. 2021), and corresponds to sea breeze dynamics, particularly during spring and summer in the afternoon and evening hours. Observations of the same hour within +/- 5 DOYs (i.e., 5 DOYs before and 5 DOYs after the target DOY for each hour) are included to increase the number of values available for calculating stable climatologies. A total of 482 stations were used for interpolating climatologies using the v3 methodology representing 1991 to 2020.
2. Hourly vapour pressure (every hour, 01/Jan/2015 onwards)
Hourly vapour pressure was directly interpolated with quart-variate thin plate splines as a function of easting, northing, elevation, and a time- and space-varying coastal distance index (i.e., following the same approach as the climatologies, but for every hour). A total of 525 stations were used for interpolating hourly vapour pressure using the v3 product methodology between 01/Jan/2015 and 23/Jan/2024.
Version history:
v3 – Initial publication using the time- and space-varying coastal distance index that optimises the covariate surface by day-of-year and local solar time. The product version has been set to v3 for consistency with the air temperature product.
