ABSTRACT

This study performs a comprehensive analysis of the influence of low-frequency variability modes (LFVMs) on the average and extreme temperature and precipitation in the extended winter (November–February) over Northwestern North America (NWNA). Maximum covariance analysis is applied to quantify the covariability between LFVMs and regional climate variables, followed by composite analysis to assess the influence of each LFVM on extremes at local scales using high-resolution gridded observations. This study extends previous analyses by characterizing the spatial patterns of regional climate variations associated with a suite of LFVMs. This includes the associations between negative phases of North Atlantic Oscillation (NAO) and extreme precipitation over western NWNA and the central Columbia basin and the positive phase of the North Tropical Atlantic (NTA) with increases in the minimum and maximum temperature of NWNA except for the western Fraser basin. Overall, the analyses show that LFVM effects are more pronounced over the eastern and southcentral parts of NWNA during extended winter.

摘要

本研究全面分析了低频变率模式（LFVMs）对北美西北部（NWNA）延长冬季（11-2月）平均和极端温度和降水的影响。最大协方差分析用于量化 LFVM 与区域气候变量之间的协变，然后进行综合分析，以使用高分辨率网格观测评估每个 LFVM 在局部尺度上对极值的影响。本研究通过描述与一套 LFVM 相关的区域气候变化的空间模式来扩展先前的分析。这包括北大西洋涛动（NAO）的负相位与西北西北和哥伦比亚中部盆地的极端降水之间的关联，以及北热带大西洋（NTA）的正相位与西北西北地区最低和最高温度升高之间的关联，除了西弗雷泽盆地。总体而言，分析表明，在延长冬季期间，LFVM 效应在 NWNA 东部和中南部地区更为明显。