This study quantifies the influences of anthropogenic forcing to date on precipitation over Aotearoa New Zealand (ANZ). Large ensembles of simulations from the weather@home regional climate model experiments are analysed under two scenarios, a natural (NAT) or counter-factual scenario which excludes human-induced changes to the climate system and an anthropogenic (ANT) or factual scenario. The impacts of anthropogenic forcing on precipitation are analysed in the context of large-scale circulation types characterized using an existing Self Organizing Map classification. The combined effect of both thermodynamics and dynamics are compared with values expected from the Clausius–Clapeyron (C–C) relation. Changes in the precipitation intensity due to greenhouse gas-forced temperature rise are lower than the expected C–C value. However extreme precipitation changes approach the C–C value for some circulation types. Specifically westerly flows enhance precipitation change across ANZ relative to the C–C rate, particularly over the West Coast. Conversely, northwesterly flows reduce the change over the North Island relative to the C–C value. Moreover, the wet day frequency generally reduces in the ANT scenario relative to NAT, reductions are largest on the West Coast of the South Island for westerly flows. Additionally, the frequency of days with extreme precipitation rises over ANZ for most circulation patterns, except in Northland and for northwesterly flows. This underscores the combined influence of dynamics and thermodynamics in shaping both precipitation intensity and frequency patterns across ANZ.

中文翻译：

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人为因素对新西兰不同环流类型地区降水的影响


本研究量化了迄今为止人为强迫对新西兰 （ANZ） 降水的影响。在两种情景下分析了weather@home区域气候模式实验的大量模拟，一种是自然 （NAT） 或反事实情景，排除了人为引起的气候系统变化，另一种是人为 （ANT） 或事实情景。人为强迫对降水的影响是在大尺度环流类型的背景下分析的，使用现有的自组织地图分类进行表征。将热力学和动力学的综合效应与 Clausius-Clapeyron （C-C） 关系的预期值进行了比较。温室气体强迫温度升高引起的降水强度变化低于预期的 C-C 值。然而，对于某些环流类型，极端降水变化接近 C-C 值。具体来说，西风气流增强了整个 ANZ 相对于 C-C 速率的降水变化，尤其是在西海岸。相反，西北气流会减少北岛相对于 C-C 值的变化。此外，相对于 NAT，在 ANT 情景下，雨日频率通常会降低，南岛西海岸的西风气流减少幅度最大。此外，对于大多数环流模式，ANZ 上空极端降水天数的频率会增加，北部地区和西北气流除外。这强调了动力学和热力学在塑造整个 ANZ 降水强度和频率模式方面的综合影响。