Extratropical Cyclone Response to Projected Reductions in Snow Extent over the Great Plains
Extratropical Cyclone Response to Projected Reductions in Snow Extent over the Great Plains
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DOI：
10.3390/atmos14050783
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发表时间：
2023-04
期刊：
影响因子：
2.9
通讯作者：
R. Clare;A. Desai;Jonathan E. Martin;M. Notaro;S. Vavrus
中科院分区：
文献类型：
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作者：
R. Clare;A. Desai;Jonathan E. Martin;M. Notaro;S. Vavrus
温带气旋在斜压性增强的地区发展，并沿着气候风暴路径前进。许多研究已经注意到陆地积雪对大气斜压的影响。然而，这些研究较少考察大陆积雪范围和人为气候变化预期的变化对气旋强度、轨迹和降水特征的作用。在这里，我们研究了预计未来北美积雪范围向极地移动将如何影响温带气旋。我们根据 14 个耦合模型比较项目第五阶段 (CMIP5) 模型的预测，施加了 20 世纪末至 21 世纪期间积雪退缩的第 10、50 和 90 个百分位数，以改变 15 个历史冷季气旋的积雪范围，这些气旋追踪北美大平原并在控制模型案例中忠实地再现，提供了一套全面的模型运行来评估假设。天气研究和预报模型 (WRF-ARW) 的高级研究版本的模拟在气旋发生前四天初始化。由于积雪范围减少，气旋轨迹平均向极地移动（μ = 27 +/- σ = 17 km），而最大海平面压力随着除雪量的增加而加深（μ = -0.48 +/- σ = 0.8 hPa）。在除雪面积和平均轨迹偏差（r2 = 0.23）之间观察到显着的线性相关性，特别是在仲冬（r2 = 0.59），并且海平面压力最大变化也存在类似的关系（r2 = 0.17）。在所有模拟中，与相应的控制模拟相比，82% 的扰动模拟气旋的平均中央海平面压力 (SLP) 有所下降。在 86% 的情况下，由于变暖，近地表风速增加，降水量增加，从固态到液态的优选相变，尽管趋势与积雪消退幅度无关。我们的研究结果与先前的研究一致，指出雪线斜压增强在调节风暴路径和强度方面的某些作用，为评估未来积雪消退对中纬度天气系统的影响提供了基准。
Extratropical cyclones develop in regions of enhanced baroclinicity and progress along climatological storm tracks. Numerous studies have noted an influence of terrestrial snow cover on atmospheric baroclinicity. However, these studies have less typically examined the role that continental snow cover extent and changes anticipated with anthropogenic climate change have on cyclones’ intensities, trajectories, and precipitation characteristics. Here, we examined how projected future poleward shifts in North American snow extent influence extratropical cyclones. We imposed 10th, 50th, and 90th percentile values of snow retreat between the late 20th and 21st centuries as projected by 14 Coupled Model Intercomparison Project Phase Five (CMIP5) models to alter snow extent underlying 15 historical cold-season cyclones that tracked over the North American Great Plains and were faithfully reproduced in control model cases, providing a comprehensive set of model runs to evaluate hypotheses. Simulations by the Advanced Research version of the Weather Research and Forecast Model (WRF-ARW) were initialized at four days prior to cyclogenesis. Cyclone trajectories moved on average poleward (μ = 27 +/− σ = 17 km) in response to reduced snow extent while the maximum sea-level pressure deepened (μ = −0.48 +/− σ = 0.8 hPa) with greater snow removed. A significant linear correlation was observed between the area of snow removed and mean trajectory deviation (r2 = 0.23), especially in mid-winter (r2 = 0.59), as well as a similar relationship for maximum change in sea-level pressure (r2 = 0.17). Across all simulations, 82% of the perturbed simulation cyclones decreased in average central sea-level pressure (SLP) compared to the corresponding control simulation. Near-surface wind speed increased, as did precipitation, in 86% of cases with a preferred phase change from the solid to liquid state due to warming, although the trends did not correlate with the snow retreat magnitude. Our results, consistent with prior studies noting some role for the enhanced baroclinity of the snow line in modulating storm track and intensity, provide a benchmark to evaluate future snow cover retreat impacts on mid-latitude weather systems.