Multisensor Characterization of the Incandescent Jet Region of Lava Fountain-Fed Tephra Plumes
Multisensor Characterization of the Incandescent Jet Region of Lava Fountain-Fed Tephra Plumes
复制标题
熔岩喷泉喷出的火山灰羽流白炽射流区域的多传感器表征
作者：
L. Mereu;S. Scollo;C. Bonadonna;V. Freret;F. Marzano
爆炸性玄武岩喷发将大量火山碎屑物质喷射到大气中，形成高达喷发口上方几公里的柱体，对近端和远端群落造成严重破坏。在这里，我们分析了由 X 波段偏振天气雷达和 L 波段多普勒定点雷达以及热红外 (TIR) 相机收集的与意大利埃特纳火山熔岩喷泉喷出的火山灰羽相关的数据。我们清楚地识别出一股喷流，主要由火山羽流的第一部分中的火山喷流和与热气体混合的炸弹组成，这里称为白炽喷流区域（IJR）。在埃特纳火山，由于 TIR 摄像机配置，IJR 通常对应于热图像饱和的区域。我们发现 IJR 与极化雷达数据中的独特特征相关，因为它代表具有相对较高反射率和较低共极相关系数的区域。通过分析最近发生在 2013 年和 2015 年的五次埃特纳火山喷发，我们提出了一种喷射区域雷达检索算法（JR3A），该算法基于结合偏振 X 波段可观测量与 L 波段雷达约束的决策树，旨在爆炸性喷发期间的 IJR 高度检测。由于海拔不同，IJR 的高度并不完全对应熔岩喷泉的高度，X 波段气象雷达检测到的火山岩和块体可能会到达该高度。尽管如此，它可以用作熔岩喷泉高度的代表，以获得混合物的出口速度的第一近似值，从而获得质量喷发率的第一近似值。 JR3A 对 IJR 高度的估计值与从 TIR 图像中恢复的相应值之间的比较显示出相当好的一致性，在晴朗的空气条件下，差异小于 20%，而 JR3A 对 IJR 高度值的估计值与仅从 L 波段雷达数据得出的值之间的差异大于 40%。在预警系统中使用 X 波段偏振天气雷达的优点是它可以在所有天气条件下提供信息。事实上，我们表明，当 TIR 摄像机数据无法处理时，JR3A 反演也可以在阴天条件下获得。
Explosive basaltic eruptions eject a great amount of pyroclastic material into the atmosphere, forming columns rising to several kilometers above the eruptive vent and causing significant disruption to both proximal and distal communities. Here, we analyze data, collected by an X-band polarimetric weather radar and an L-band Doppler fixed-pointing radar, as well as by a thermal infrared (TIR) camera, in relation to lava fountain-fed tephra plumes at the Etna volcano in Italy. We clearly identify a jet, mainly composed of lapilli and bombs mixed with hot gas in the first portion of these volcanic plumes and here called the incandescent jet region (IJR). At Etna and due to the TIR camera configuration, the IJR typically corresponds to the region that saturates thermal images. We find that the IJR is correlated to a unique signature in polarimetric radar data as it represents a zone with a relatively high reflectivity and a low copolar correlation coefficient. Analyzing five recent Etna eruptions occurring in 2013 and 2015, we propose a jet region radar retrieval algorithm (JR3A), based on a decision-tree combining polarimetric X-band observables with L-band radar constraints, aiming at the IJR height detection during the explosive eruptions. The height of the IJR does not exactly correspond to the height of the lava fountain due to a different altitude, potentially reached by lapilli and blocks detected by the X-band weather radar. Nonetheless, it can be used as a proxy of the lava fountain height in order to obtain a first approximation of the exit velocity of the mixture and, therefore, of the mass eruption rate. The comparisons between the JR3A estimates of IJR heights with the corresponding values recovered from TIR imagery, show a fairly good agreement with differences of less than 20% in clear air conditions, whereas the difference between JR3A estimates of IJR height values and those derived from L-band radar data only are greater than 40%. The advantage of using an X-band polarimetric weather radar in an early warning system is that it provides information in all weather conditions. As a matter of fact, we show that JR3A retrievals can also be obtained in cloudy conditions when the TIR camera data cannot be processed.
影响因子：
3.5
作者：
Bonadonna, Costanza;Folch, Arnau;Puempel, Herbert
通讯作者：
Puempel, Herbert