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首页> 外文期刊>Journal of hydrometeorology >Drought Variability over the Conterminous United States for the Past Century
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Drought Variability over the Conterminous United States for the Past Century

机译：过去的世纪对孔雀石的干旱变异性

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We examine the drought variability over the conterminous United States (CONUS) for 1915-2018 using the Noah-MP land surface model. We examine different model options on drought reconstruction, including optional representation of groundwater and dynamic vegetation phenology. Over our 104-yr reconstruction period, we identify 12 great droughts that each covered at least 36% of CONUS and lasted for at least 5 months. The great droughts tend to have smaller areas when groundwater and/or dynamic vegetation are included in the model configuration. We detect a small decreasing trend in dry area coverage over CONUS in all configurations. We identify 45 major droughts in the baseline (with a dry area coverage greater than 23.6% of CONUS) that are, on average, somewhat less severe than great droughts. We find that representation of groundwater tends to increase drought duration for both great and major droughts, primarily by leading to earlier drought onset (some due to short-lived recovery from a previous drought) or later demise (groundwater anomalies lag precipitation anomalies). In contrast, representation of dynamic vegetation tends to shorten major droughts duration, primarily due to earlier drought demise (closed stoma or dead vegetation reduces ET loss during droughts). On a regional basis, the U.S. Southwest (Southeast) has the longest (shortest) major drought durations. Consistent with earlier work, dry area coverage in all subregions except the Southwest has decreased. The effects of groundwater and dynamic vegetation vary regionally due to differences in groundwater depths (hence connectivity with the surface) and vegetation types.
机译：我们使用诺亚MP陆面模型研究了1915-2018年美国周边地区（CONUS）的干旱变化。我们研究了干旱重建的不同模型选项，包括地下水和动态植被物候的可选表示。在我们104年的重建期间，我们确定了12次大旱灾，每一次都覆盖了至少36%的美国，并持续了至少5个月。当地下水和/或动态植被包含在模型配置中时，大干旱的面积往往较小。我们检测到，在所有配置中，圆锥上的干燥区域覆盖率都有小幅下降趋势。我们确定了基准线内的45次主要干旱（干旱地区覆盖率超过美国大陆的23.6%），其平均程度略低于严重干旱。我们发现，无论是大干旱还是大干旱，地下水的代表性都倾向于增加干旱持续时间，主要是通过导致更早的干旱开始（一些是由于从以前的干旱中短暂恢复）或更晚的死亡（地下水异常滞后于降水异常）。相比之下，动态植被的表现往往会缩短主要干旱持续时间，这主要是由于干旱提前死亡（关闭气孔或死亡植被会减少干旱期间ET的损失）。就地区而言，美国西南部（东南部）的主要干旱持续时间最长（最短）。与之前的工作一致，除西南部外，所有次区域的旱地覆盖率都有所下降。由于地下水深度（因此与地表的连通性）和植被类型的差异，地下水和动态植被的影响在区域上有所不同。

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