Defining and Predicting Heat Waves in Bangladesh
Defining and Predicting Heat Waves in Bangladesh
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DOI：
10.1175/jamc-d-17-0035.1
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发表时间：
2017-10-01
影响因子：
3
通讯作者：
Mason, Simon
中科院分区：
文献类型：
--
作者：
Nissan, Hannah;Burkart, Katrin;Mason, Simon
本文提出了一个热浪的定义，孟加拉国，可用于触发准备措施的热预警系统（HEWS），并探讨了与热浪相关的气候机制。HEWS要求热浪的定义既与人类健康结果有关，又可预测。孟加拉国没有制定这样的定义。使用广义加性回归模型，热浪的定义提出，需要升高的最低和最高日温度超过95百分位连续3天，确认夜间条件对健康影响的重要性。根据这一定义，热浪期间死亡率增加约20%;这一结果可以作为公共卫生干预措施的论据，以防止与热有关的死亡。此外，从天气到季节性时间尺度都存在对这些热浪的可预测性，为采取一系列备灾措施提供了机会。热浪与缺乏正常的季风前降雨有关，这些降雨是由强烈的低空西风和弱南风造成的，可以提前大约10天探测到。这种环流模式发生在比正常情况下干燥的背景下，从4月到6月整个热浪季节的土壤湿度和降水量低于平均水平。低土壤湿度增加了10-30天热浪发生的可能性，这表明通过监测土壤湿度条件可以对热浪风险进行亚季节预报。
This paper proposes a heat-wave definition for Bangladesh that could be used to trigger preparedness measures in a heat early warning system (HEWS) and explores the climate mechanisms associated with heat waves. A HEWS requires a definition of heat waves that is both related to human health outcomes and forecastable. No such definition has been developed for Bangladesh. Using a generalized additive regression model, a heat-wave definition is proposed that requires elevated minimum and maximum daily temperatures over the 95th percentile for 3 consecutive days, confirming the importance of nighttime conditions for health impacts. By this definition, death rates increase by about 20% during heat waves; this result can be used as an argument for public-health interventions to prevent heat-related deaths. Furthermore, predictability of these heat waves exists from weather to seasonal time scales, offering opportunities for a range of preparedness measures. Heat waves are associated with an absence of normal premonsoonal rainfall brought about by anomalously strong low-level westerly winds and weak southerlies, detectable up to approximately 10 days in advance. This circulation pattern occurs over a background of drier-than-normal conditions, with below-average soil moisture and precipitation throughout the heat-wave season from April to June. Low soil moisture increases the odds of heat-wave occurrence for 10-30 days, indicating that subseasonal forecasts of heat-wave risk may be possible by monitoring soil-moisture conditions.