Two types of climate data were used data used in this study, observed and interpolated climate data.
Observed Climate Data
Observed climate data used in the study was generated from historical climate data available online from the Adjusted Historical Canadian Climate Data-AHCCD. This data is available as monthly mean, maximum and minimum temperature and monthly precipitation for various weather stations across the region. Observed data was available from 98 weather stations for temperature variables and precipitation from 184 stations (a total of 224 weather stations-some stations had both temperature and precipitaion data). Location of weather stations is shown in the map below.
Annual (mean annual temperture-MAT and mean annual precipitation-MAP) and seasonal variables, that is; mean warmest month (july) temperature-MWMT, mean coldest month (January) temperatute-MCMT, temperature difference (MWMT-MCMT) -TD and mean summer (may-September) precipitation)-MSP were computed from the obtained monthly values of temperature and precipitation. In addition, deviations of all the 1901 - 2002 annual climate values from the 1961-990 climate normals were computed.
Interpolated Climate data
Interpolated Climate data was generated using a technique developed Drs. Andreas Hamann and Togli Wang at Center for Forest Gene Conservation, University of British Columbia. The technique is available online as a stand-alone Microsoft Windows application -Climate BC-PP.
The ClimateBC-PP technique generates data for up to 18 biologically important climate variables for any location in western Canada given its latitude, longitude and elevation. Data can be for the past or future. Future climate is based on several global circulation models and IPCC’s SRES emission scenarios.
In order to generate interpolated climate data for the study area, the north American digital elevation model was used to get a digital elvelation model for the the study area. This involved importing and joining the western and eastern north America digital elevation models available from the United States Geological Service -USGS website in ArcMap. Latitude and longitude values were then added. Files for generating climate data at approximately 15 km x 15 km resolution and at 1x1km resolution were made. Due to the large size of the file, the 1x1km resolution was subsampled taking every fourth grid to get a coverage that is roughly 4x4km. To be able to generate climate data values for each ecozone, interoplated climate data was overlaid on the ecozones layer in ArcMap and the two files joined using the spatial join tool. From this, average values for each cimate variable were genarated using pivot tables in excel.
Interpolated climate data was generated for each year from 1901 to 2002 for the entire region as well as for individual weather station locations. Climate data was also generated for the future period (2011-2040, 2041-2070 and 2071-2100), based onthe Canadian Climate Model -CGCM2 and SRES emission scenario A2.
|
