Precipitation in Arizona, USA, represents a fundamental resource for the needs of agriculture, people, and the environment. However, due to the risk associated with flash flooding, extreme precipitation also constitutes a natural hazard. Available research on precipitation in Arizona has been limited in scope and focus and there currently exists no comprehensive assessment of statewide, historical, mean, and extreme precipitation. We use daily precipitation records from 43 Global Historical Climate Network daily (GHCNd) weather stations to examine trends in mean and extreme precipitation across Arizona from 1950 to 2020. We use a suite of standardized precipitation indices and explore the statistical significance of historical changes at the annual, monthly, and seasonal scales. Our analysis returns a motley collection of results displaying a great degree of spatial variability and sensitivity to the temporal scale of analysis. Mean total precipitation at the statewide scale underwent a small decreasing trend of 0.15 mm year⁻¹, with considerable interannual variability being a dominant feature. The majority of stations experienced no statistically significant change in extreme precipitation at the annual scale. Monsoon season mean precipitation followed a similar pattern to annual means, with an overall reduction of 0.14 mm year⁻¹ across the state. One fourth of stations, all located at elevations lower than 650 m, recorded decreases in monsoon precipitation intensity. Winter season analysis presents a different picture, displaying a positive statewide trend of 0.11 mm year⁻¹ in mean precipitation. One tenth of stations recorded increases in extreme precipitation intensity and decreases in the number of consecutive dry days. Results of our observational analysis indicate a lack of a clear consensus on the climatological trends of mean/extreme precipitation in Arizona during the study period. Our findings are in contrast to those from other similarly arid areas across the world and highlight the role of regional differences in modulating the potential hydrometeorological impacts associated with climate change. However, while we do not find widespread, significant, modification in the spectrum of precipitation changes examined, the hydrologic system of the state has been – and will continue to be - impacted by the ongoing temperature increase associated with the buildup of greenhouse gases and continued population growth.

美国亚利桑那州的降水是满足农业、人类和环境需求的基本资源。然而，由于山洪爆发的风险，极端降水也构成自然灾害。关于亚利桑那州降水的现有研究范围和重点有限，目前还没有对全州降水、历史降水、平均降水和极端降水的综合评估。我们使用 43 个全球历史气候网络每日 (GHCNd)气象站的每日降水记录来检查 1950 年至 2020 年亚利桑那州平均降水量和极端降水量的趋势。我们使用一套标准化降水指数，并探讨历史变化的统计显着性。年度、月度和季节尺度。我们的分析返回了一系列杂乱无章的结果，显示出很大程度的空间变异性和对分析时间尺度的敏感性。全州范围内的平均总降水量呈现0.15毫米年^-1，显着的年际变化是主要特征。大多数站点的年尺度极端降水没有出现统计上显着的变化。季风季节平均降水量与年平均降水量相似，全州全年总体减少 0.14 毫米^-1四分之一的站点（全部位于海拔低于 650 m）记录季风降水强度下降。冬季分析呈现出不同的情况，显示全州平均降水量呈正趋势，年^-1。十分之一的站点记录极端降水强度增加，连续干旱天数减少。我们的观测分析结果表明，对于研究期间亚利桑那州平均/极端降水的气候趋势缺乏明确的共识。我们的研究结果与世界其他类似干旱地区的研究结果形成鲜明对比，强调了区域差异在调节与气候变化相关的潜在水文气象影响方面的作用。然而，虽然我们没有发现所检查的降水变化范围存在广泛、显着的变化，但该州的水文系统已经并将继续受到与温室气体积累相关的持续气温升高的影响，并继续受到影响。人口增长。