Projections of Hydroclimatic Extremes in Southeast Alaska under the RCP8.5 scenario

IF 1.6 4区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY
Rick Lader, U. Bhatt, J. Walsh, P. Bieniek
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引用次数: 1

Abstract

Parts of southeast Alaska experienced record drought in 2019, followed by record daily precipitation in late 2020 with substantial impacts to human health and safety, energy resources and fisheries. To help ascertain whether or not these types of events can be expected more frequently, this study investigated observed trends and projected changes of hydroclimatic extremes indices across southeast Alaska, including measures of precipitation variability, seasonality, magnitude and type. Observations indicated mixed tendencies of inter-annual precipitation variability, but there were consistent trends toward warmer and wetter conditions. Projected changes were assessed using dynamically downscaled climate model simulations at 4-km spatial resolution from 2031-2060 that were compared to a historical period from 1981-2010 using two models – NCAR CCSM4 and GFDL-CM3. Consistent directional changes were found for five of the analyzed indices. The CCSM indicated increased maximum 1-day precipitation (RX1; 12.6%), increased maximum consecutive 5-day precipitation (RX5; 7.4%), longer periods of consecutive dry days (CDD; 11.9%), fewer snow cover days (SNC; -21.4%) and lower snow fraction (SNF; -24.4%); for GFDL these changes were RX1 (19.8%), RX5 (16.0%), CDD (20.1%), SNC (-21.9%) and SNF (-26.5%). While both models indicated substantial snow losses, they also projected annual snowfall increases at high elevations; for CCSM this occurred above 1500 m and above 2500 m for GFDL. Significance testing was assessed at the 95% confidence level using Theil-Sen’s slope estimates for the observed time series and the Wilcoxon-Mann- Whitney U test for projected changes of the hydroclimatic extremes indices relative to their historical distributions.
RCP8.5情景下阿拉斯加东南部极端水文气候预估
阿拉斯加东南部部分地区在2019年经历了创纪录的干旱,随后在2020年底出现了创纪录的日降水,对人类健康和安全、能源资源和渔业产生了重大影响。为了帮助确定这些类型的事件是否可以更频繁地预测,本研究调查了阿拉斯加东南部水文气候极端指数的观测趋势和预测变化,包括降水变动性、季节性、强度和类型的测量。观测显示年际降水变率的混合趋势,但有一致的变暖和变湿趋势。利用NCAR CCSM4和GFDL-CM3两种模式,在4公里空间分辨率下对2031-2060年的动态缩尺气候模式模拟与1981-2010年的历史时期进行了比较,评估了预估变化。在分析的五个指标中发现了一致的方向性变化。CCSM显示最大1天降水量增加(RX1;12.6%),最大连续5天降水量增加(RX5;7.4%),连续干旱天数较长(CDD;11.9%),积雪日数较少(SNC;-21.4%)和较低的雪率(SNF;-24.4%);对于GFDL,这些变化分别是RX1(19.8%)、RX5(16.0%)、CDD(20.1%)、SNC(-21.9%)和SNF(-26.5%)。虽然这两个模型都显示了大量的积雪损失,但它们也预测了高海拔地区的年降雪量增加;CCSM出现在1500米以上,GFDL出现在2500米以上。使用对观测时间序列的Theil-Sen斜率估计和对水文气候极端指数相对于其历史分布的预估变化的Wilcoxon-Mann- Whitney U检验,在95%置信水平上进行显著性检验。
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来源期刊
Earth Interactions
Earth Interactions 地学-地球科学综合
CiteScore
2.70
自引率
5.00%
发文量
16
审稿时长
>12 weeks
期刊介绍: Publishes research on the interactions among the atmosphere, hydrosphere, biosphere, cryosphere, and lithosphere, including, but not limited to, research on human impacts, such as land cover change, irrigation, dams/reservoirs, urbanization, pollution, and landslides. Earth Interactions is a joint publication of the American Meteorological Society, American Geophysical Union, and American Association of Geographers.
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