We use the software program ClimateNA (Wang et al. 2016) to produce a suite of 31 annual 30-year normal (i.e., the average value of the prior 30 years) bioclimatic variables from 1984 to present based on a 250m resolution digital elevation model (ESA Copernicus). ClimateNA statistically downscales PRISM gridded historical and projected future climate data (Daly et al. 2008) based on local lapse rates that govern the relationships between climate variables and elevation.

We also used ClimateNA to project those same annual 30-year normal variables to future years (2040, 2070, and 2100) under the CMIP6 SSP2-4.5 scenario using 5 different Global Climate Models (ACCESS-ESM1-5, CNRM-ESM2-1, MIROC6, IPSL-CM6A-LR and an ensemble of 8 GCMs). We then used a harmonic regression implemented in Google Earth Engine to interpolate projections between historical years and to create decadal predictions for each GCM from 2020 to 2100.

The historical and projected future 30-year normal annual variables include:

  • mean annual temperature (°C)

  • mean temperature of the warmest month (°C)

  • mean temperature of the coldest month (°C)

  • difference between mean coldest and mean warmest month temperature (°C)

  • winter (December to February) mean temperature (°C)

  • spring (March to May) mean temperature (°C)

  • summer (June to August) mean temperature (°C)

  • autumn (September to November) mean temperature (°C)

  • mean annual precipitation (mm)

  • mean summer (May to Sep) precipitation (mm)

  • winter (December to February) precipitation (mm)

  • spring (March to May) precipitation (mm)

  • summer (June to August) precipitation (mm)

  • autumn (September to November) precipitation (mm)

  • annual heat moisture index

  • summer heat moisture index

  • degree-days below 0°C (freezing degree days)

  • degree-days above 5°C (growing degree days)

  • the number of frost-free days

  • frost-free period

  • the julian date on which the frost-free period begins

  • the julian date on which the frost-free period ends

  • precipitation as snow (mm)

  • extreme minimum temperature over 30 years

  • extreme maximum temperature over 30 years

  • Hargreave's reference evaporation

  • Hargreave's climatic moisture index

  • mean annual solar radiation (MJ m-2 d-1)

  • mean annual relative humidity (%)

  • Hogg’s climate moisture index (mm)

  • degree-days above 10°C and below 40°C

Last updated