ClimateChange Assessment Guide.pdf - University of Waterloo

Appendix E E-27Subwatershed 19 Case Study• NCEP data is the daily reanalysis data for 1961 to 2003 required to calibrate the SDSM model to currentconditions;• CGCM3A2 data for 2001 to 2100 contains the daily predictor files for the future with the A2 scenarioconditions; and• CGCM3A1B data for 2001 to 2100 contains the daily predictor files for the future with the A1B scenarioconditions.The datasets can be downloaded once the user is a registered with DAI. The data for coordinates 42.68 N and-281.25 or 281.25 W is selected as the closest grid point to the study area. There are 25 predictors available inseparate *.dat files for each dataset.The change field information for scenarios CGCM3-A1B and CGCM3-A2 were also acquired for two reasons. Firstly,so that future solar radiation and wind speed can be altered in a consistent manner with the temperature andprecipitation portion of the scenario and secondly, so that through comparison between the change field climateoutcomes and the SDSM climate outcomes, the variability in the SDSM climates can be determined. The two GCMscenarios selected for downscaling method are shown in Figure 4-1 with grey triangles. Application of the weather generator, LARS-WG, requires the use of GCM scenario change fields to calibrate aweather generator model and as a way to adjust average conditions for the generated weather representing futurescenarios. The model also requires daily predictand output for the parameters of interest from the future timehorizons. This information is used to characterize the wet-dry day condition and the variance of parameters with thefuture scenarios.The data was acquired through the CCCSN website by downloading the necessary change field data. The processfollowed was to select Download Data - GCM - Get GCM Temporal-Averages. The desired coordinates,assessment AR4 (2007), GCM model CGCM3T47-Run 4, emission experiment SR-A1B and SR-A2, and the followingparameters were selected:• Air Temperature – Mean Max (2m);• Air Temperature – Mean Min (2 m);• Precipitation – Total; and• Wind Speed – Mean (10 m).The time period 2050s was selected. By selecting Get Data, files for each parameter with monthly, seasonal andannual average conditions for the 2041 to 2070 time period selected were obtained for the two GCM scenarios.The daily data is acquired from the DAI site as instructed in Section 6.5.4 of the Guide. In this case study, theCGCM3.1- A2 scenario data was downloaded for the full available time period (i.e., 1961 to 2100). Only minimumand maximum daily temperatures and precipitation are required. Text format was specified. Daily Time Series wasselected. Data was provided for each scenario in a single file with all parameters.