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首页> 外文期刊>Journal of Geophysical Research, D. Atmospheres: JGR >The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999–2009)
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The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999–2009)

机译：圣保罗城市热岛对雷电活动的影响：年代际分析（1999–2009年）

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摘要

Eleven years of lightning data from the Brazilian Integrated National Lightning Detection Network were used to analyze the effects of the urban heat island (UHI) of Sao Paulo on lightning activity, extending the investigation of previous works. Cloud-to-ground lightning data were analyzed in both spatial and temporal perspectives, using different approaches: flash density, flash rate, thunderstorm hours (TH), and the cell initiation technique (CIT), which aims to identify the onset of thunderstorms. Land surface temperature (LST) from MODIS (Moderate Resolution Imaging Spectroradiometer) was used to analyze the UHI evolution over the years. MODIS data were validated using ground stations, distributed within the urban area. Different time intervals (seasonal and intraday) were used in an attempt to separate local convective systems from synoptic-scale events. The results indicate significant effects of the UHI (using LST) on THs and CIT. The CIT showed a nearly ring pattern, especially during the afternoon (14:00–18:00 LT) of summer months, reinforcing temperature contrast as a condition for storm initiation. The results also suggest an amplification of the UHI effects on thunderstorm activity by local factors (sea and country breeze, synoptic events, and terrain). Higher flash rates were also observed throughout the urban region, which influences the lightning density. Temporal analysis indicates that minimum temperature and lightning activity increase in wintertime. In summary, the results agree with previous studies about the UHI and indicate its importance on lightning occurrence, especially by increasing the temperature contrast and the instability in these regions.
机译：来自巴西综合国家雷电检测网络的11年闪电数据用于分析圣保罗的城市热岛（UHI）对雷电活动的影响，从而扩展了先前工作的研究范围。使用不同的方法从空间和时间角度对云对地闪电数据进行了分析：闪光密度，闪光率，雷暴时数（TH）和旨在识别雷暴发作的细胞引发技术（CIT）。来自MODIS（中等分辨率成像光谱仪）的地表温度（LST）用于分析多年来UHI的演变。 MODIS数据使用分布在市区内的地面站进行了验证。为了将局部对流系统与天气尺度事件分开，尝试使用不同的时间间隔（季节和日间）。结果表明，UHI（使用LST）对TH和CIT具有显着影响。 CIT显示出几乎是环形的模式，尤其是在夏季的下午（美国中部时间下午14：00-18：00），这增强了温度对比，这是引发风暴的条件。结果还表明，UHI对雷暴活动的影响受局部因素（海风和乡村风，天气事件和地形）的放大作用。在整个城市地区也观察到较高的闪光率，这会影响雷电密度。时间分析表明，冬季最低温度和闪电活动增加。总而言之，这些结果与先前关于UHI的研究相吻合，并表明了其对雷电发生的重要性，特别是通过增加温度对比度和这些区域的不稳定性。

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