Hourly near-surface vapour pressure deficit grids for Australia 

This collection provides hourly near-surface (1.5 m) vapour pressure deficit grids for Australia with a spatial resolution of 1 km. These data are derived from hourly air temperature and vapour pressure grids that 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 vapour pressure deficit beginning on 01/Jan/2015, and (iii) an animation of the 30-year climatology from (i).

Further details are provided in the README file.
 

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.


 

These data were developed to support numerous scientific applications.
 

Vapour pressure deficit is derived from hourly air temperature and vapour pressure grids. 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 air temperature and 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 deficit climatologies (every 5th DOY, 1991-2020)
2.      Hourly vapour pressure deficit (every hour, 01/Jan/2015 onwards)

Each are derived from the corresponding hourly air temperature and vapour pressure grids. First, saturation vapour pressure (eₛ) is calculated from air temperature (T) following Tetens (1930):

eₛ = 6.108 exp (17.27T / T+237.3)

The vapour pressure deficit (VPD) is then calculated as:

VPD = max(0, eₛ - eₐ)

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 for both air temperature and vapour pressure. The product version has been set to v3 for consistency with the air temperature product.

References:

Tetens O. 1930. Über einige meteorologische Begriffe (On some meteorological terms). Z. Geophys., 6, 297–309.