The strong radiative effects of fire aerosols have been well accepted in the climate community. However, there have been few studies on the aerosol effects at a monthly to subseasonal range. We used the National Centers for Environmental Prediction (NCEP) reanalysis datasets and Community Atmosphere Model Version 5 (CAM5) to explore the impacts of Amazon fire aerosols on the subseasonal climate. With the reanalysis datasets, we found that most of the abnormal high emissions tended to happen more frequently/intensely under a dry and warm condition during the La Niña years. And the composite analysis of the abnormal high emissions showed that there is a La Niña-like pattern of sea surface temperature anomalies (SSTA), precipitation, and circulation anomalies. To isolate the aerosol impacts from the SSTA, we removed the linear regressions of the Nino3.4 SST index, and found that significant anomalies in the pressure field still persisted in the midlatitude. Five wavetrains can be found in the mid-high latitudes of both hemispheres induced by Amazon fire aerosols. Through prescribing climatological mean SST and La Niña-like SSTA in CAM5 simulations respectively, we found that only the latter could reproduce the aerosol impact on circulation in the mid-high latitudes, i.e., five-wave anomalies, although with biased locations. This indicates that the Amazon wildfire aerosol impacts are highly coupled with the La Niña-like SSTA. This study emphasizes that Amazon fire aerosols indeed result in significant circulation anomalies in the mid-high latitudes and including fire aerosols may improve model forecasting skills at the monthly to subseasonal timescale.

中文翻译：

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亚马逊火气溶胶对中高纬度地区次季节环流的影响

火灾气溶胶的强烈辐射效应已被气候界广泛接受。然而，关于气溶胶在每月到次季节范围内的影响的研究很少。我们使用国家环境预测中心 (NCEP) 再分析数据集和社区大气模型版本 5 (CAM5) 来探索亚马逊火灾气溶胶对次季节气候的影响。通过再分析数据，我们发现，大多数异常高排放往往在拉尼娜年干燥温暖的条件下发生得更频繁/更强烈。对异常高排放的综合分析表明，存在海表温度异常（SSTA）、降水和环流异常的类拉尼娜模式。为了隔离海温异常的气溶胶影响，去掉Nino3.4海温指数的线性回归，发现中纬度地区气压场仍然存在明显异常。在亚马逊火气溶胶引起的两个半球的中高纬度地区可以发现五个波列。通过在CAM5模拟中分别规定气候平均海温和类拉尼娜海温异常，我们发现只有后者才能再现气溶胶对中高纬度环流的影响，即五波异常，尽管位置有偏差。这表明亚马逊山火气溶胶影响与类拉尼娜海温异常高度耦合。