自1982年以来,沙赫尔极端风暴的频率增加了三倍
Christopher M Taylor1,2, Danijel Belušić1,3, Françoise Guichard4
1Centre for Ecology and Hydrology, Wallingford OX10 8BB, UK.
Nature
|April 28, 2017
概括
全球变暖正在加剧极端降雨事件. 来自西非萨赫勒地区的卫星数据显示,与全球气温相关的强度中层次对流系统 (MCS) 的频率显著增加.
科学领域:
- 大气科学
- 气候科学
- 水文学
背景情况:
- 由于气候变化,全球水文循环正在加剧,导致极端降雨和洪水的频率越来越高.
- 气候模型难以准确地描绘对流降雨,特别是中等规模的对流系统 (MCS),这对于强烈的风暴至关重要.
- 了解MCS对于预测区域气候影响和洪水风险至关重要.
研究的目的:
- 通过卫星观测,研究西非萨赫勒地区强烈中等层次对流系统 (MCS) 的频率趋势.
- 确定MCS强化与全球土地温度,区域降雨量和温度梯度等因素之间的关系.
- 评估观察到的趋势对萨赫勒地区未来极端降雨预测的影响.
主要方法:
- 对35年的卫星数据进行分析,以识别和跟踪西非萨赫勒地区的中等层次对流系统 (MCS).
- 对MCS频率,全球陆地温度,萨赫勒雨量和温度梯度之间的关系进行相关分析.
- 对非洲地区温度趋势的研究,以了解局部变暖的影响.
主要成果:
- 35年来,西非萨赫勒地区的MCS频率持续上升.
- 强烈的MCS频率与萨赫里亚年降雨恢复的相关性很弱,但与全球陆地温度的相关性很强.
- 在撒哈拉以南的一个狭窄带集中MCS加剧,在撒哈拉雨季没有局部变暖.
结论:
- 撒哈拉地区的气候变暖,以日益增长的南极温度梯度显示,正在推动沙赫尔地区的气候变化加剧.
- 观察到的趋势挑战了传统的气候模型预测, 表明萨赫勒地区可能会比预测中的极端降雨量增加得更大.
- 这些发现突显了热带对全球变暖的敏感性, 并强调了需要改进的气候模型.
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