Effects of wildfire smoke on atmospheric polarization
Effects of wildfire smoke on atmospheric polarization
复制标题
野火烟雾对大气偏振的影响
DOI：
--
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
E. Forbes
中科院分区：
文献类型：
--
作者：
J. Shaw;N. Pust;E. Forbes
一台连续工作的全天偏振成像仪记录了从晴朗晴朗到烟雾弥漫时的天窗偏振模式。这一转变包括一段时间，当地的野火羽状物使部分天空充满了烟雾，造成了气溶胶的高度不对称分布。烟羽中的多次散射强烈地降低了天空烟雾区域的极化程度。一旦烟羽扩散到覆盖整个当地天空，各处的极化程度都大大降低了。然而，这个例子与之前观测到的烟雾事件不同，因为尽管通常的天窗偏振模式在整个事件中持续存在，但这次烟雾覆盖的天空沿着最大偏振带呈现出空间不对称的轮廓。这种朝向地平线的偏振减弱的模式被假设为光学上厚但物理上薄的烟雾层的结果。天窗偏振观测补充了光学深度测量和从太阳辐射计获取的气溶胶大小分布。
A continuously operating all-sky polarization imager recorded the skylight polarization pattern as conditions transitioned from clear and clean to extremely smoky. This transition included a period when a local wildfire plume filled part of the sky with smoke, creating a highly asymmetric distribution of aerosols. Multiple scattering in the smoke plume strongly reduced the degree of polarization in the smoky region of the sky. Once the smoke plume spread out to cover the entire local sky, the degree of polarization was strongly reduced everywhere. However, this example differed from previously observed smoke events because, even though the usual skylight polarization pattern generally persisted throughout the event, this time the smoke-covered sky exhibited a spatially asymmetric profile along the band of maximum polarization. This pattern of reduced polarization toward the horizon is hypothesized to be a result of an optically thick but physically thin smoke layer. The skylight polarization observations are supplemented with optical depth measurements and aerosol size distribution retrievals from a solar radiometer.