Step 4: Collect Observed Climate Data
Growing conditions are highly localised, so we need high-resolution climate surfaces of the average climate that account for factors such as elevation (higher ground is cooler than sea level). We just need the recent average conditions, we don’t need time series or information about extreme events. We can get high-resolution climate surfaces for each month at www.worldclim.org.
Understanding the dataset:
WorldClim version 2 gives climate averages for the 1970–2000 period, the high-resolution version has ~1 km2 resolution. The dataset uses weather station data and satellite data as input, and fills the gaps between data points by using statistical techniques (thin-plate splines and covariates using elevation).
All temperature datasets rely heavily on high-quality weather stations with good coverage. Parts of PNG are not well covered by stations, so the accuracy of the temperature data will not be as high as in some other places. See Fick and Hijmans (2017) for more information.
Fick SE and Hijmans RJ. 2017. WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas. International Journal of Climatology, doi:10.1002/joc.5086