Individual and joint variations of extreme temperature and precipitation are assessed across Canada using the large ensemble of Canadian Regional Climate Model simulations (CanRCM4-LE) and two corresponding multivariate bias-corrected datasets (Canadian Large Ensembles Adjusted Datasets, CanLEAD-E & S). The overall performance of the three 50-member ensembles is evaluated against the NRCANmet gridded observation for 1951–2000. A hierarchical Bayesian framework is then applied to analyze the biases of each ensemble member, characterize the ensemble uncertainties associated with internal climate variability, and assess the trends and the joint distributions of temperature and precipitation. Further, projected changes of extreme climate indices are assessed across the three ensembles in the historical period and four future scenarios corresponding to +1.5 °C to +4.0 °C warming above the pre-industrial level of 1850–1900. Results show that the CanLEAD products have lower warm and wet biases compared to CanRCM4-LE over most regions and in all seasons except in winter. CanLEAD-S significantly reduces precipitation biases and represents the behaviour of extreme climate indices better than the other two ensembles. All ensembles consistently project strong warming and wetting trends over most parts of southern Canada excluding the Canadian Prairies in summer, which shows a drying trend towards the end of the 21st century. The ensembles show increases in hot extremes in central and southeastern Canada and increases in wet extremes in western coastal regions. The results of the study suggest that CanLEAD-E&S can be used as reliable products for climate change impact assessments at regional scales particularly for the analysis of nonstationary compound events.

使用加拿大区域气候模型模拟的大型集合 (CanRCM4-LE) 和两个相应的多变量偏差校正数据集（加拿大大型集合调整数据集，CanLEAD-E & S）评估加拿大各地极端温度和降水的个体和联合变化。根据 1951-2000 年的 NRCANmet 网格观测，评估了三个 50 成员集合的整体性能。然后应用分层贝叶斯框架来分析每个集合成员的偏差，表征与内部气候变率相关的集合不确定性，并评估温度和降水的趋势和联合分布。更远，在历史时期的三个集合和四个未来情景中评估极端气候指数的预测变化，对应于 1850-1900 年工业化前水平以上 +1.5°C 至 +4.0°C 变暖。结果表明，与 CanRCM4-LE 相比，CanLEAD 产品在大多数地区和除冬季外的所有季节都具有较低的暖湿偏差。CanLEAD-S 显着减少了降水偏差，并且比其他两个集合更好地代表了极端气候指数的行为。除加拿大大草原外，所有集合都一致预测加拿大南部大部分地区在夏季出现强烈的变暖和湿润趋势，这显示出到 21 世纪末的干燥趋势。集合显示加拿大中部和东南部极端高温增加，西部沿海地区极端潮湿增加。研究结果表明，CanLEAD-E&S 可用作区域尺度气候变化影响评估的可靠产品，特别是用于分析非平稳复合事件。