Data on Arctic and Sub-Arctic summer heat events are limited due to the sparse network of surface observation stations. Here, we analyze large heat events within 60°–80°N using land surface temperature (LST) observations from the moderate resolution imaging spectroradiometer (MODIS) sensor aboard the Terra satellite. Our heatwave (HW) detection method uses exceedances of the climatological 90th percentile of LST across summer months, and a spatio-temporal density-based clustering algorithm to distinguish space-time coherent events across Northern Hemispheric high latitudes for the summers of 2000–2022. We find a close link between HW duration, spatial extent and amplitude across the study region (correlations ranging from 0.63 to 0.73). MODIS-derived burned area data show that wildfire seasons are significantly correlated to summer HW activity, particularly in Siberia (r = 0.87 at p < 0.05) and Alaska and NW Canada (r = 0.45 at p < 0.05), and are also spatially co-located. MODIS active fire data also show substantial increase during larger heat events. For the strongest HWs in Siberia, the peak in daily fire count (from the MODIS active fire archive) lags behind peak HW activity. We conclude that there is a close link between intense fire summers and extensive HWs over boreal and shrub tundra regions (Interior Alaska, the Canadian Prairies and Eastern Siberia).

中文翻译：

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观察到北部高纬度地区热浪和野火之间的联系

由于地面观测站网络稀疏，有关北极和亚北极夏季高温事件的数据有限。在这里，我们使用 Terra 卫星上的中等分辨率成像光谱辐射计 (MODIS) 传感器的陆地表面温度 (LST) 观测结果来分析 60°–80°N 范围内的大型热事件。我们的热浪 (HW) 检测方法使用整个夏季 LST 气候学第 90 个百分位的超出值，以及基于时空密度的聚类算法来区分 2000 年至 2022 年夏季北半球高纬度地区的时空相干事件。我们发现整个研究区域的 HW 持续时间、空间范围和幅度之间存在密切联系（相关性范围从 0.63 到 0.73）。 MODIS 得出的烧毁面积数据表明，野火季节与夏季 HW 活动显着相关，特别是在西伯利亚（r = 0.87 在p < 0.05) 以及阿拉斯加和加拿大西北部 (r = 0.45 在p < 0.05)，并且在空间上位于同一位置。 MODIS 活跃火灾数据还显示，在较大的高温事件期间，火灾会大幅增加。对于西伯利亚最强的 HW，每日火灾计数的峰值（来自 MODIS 活跃火灾档案）滞后于 HW 活动的峰值。我们得出的结论是，夏季的强烈火灾与北方和灌木苔原地区（阿拉斯加内陆、加拿大大草原和东西伯利亚）的大范围火灾之间存在密切联系。