Considerations on ejection velocity estimations from infrared radiometer data: A case study at Stromboli volcano

Synchronous recordings of normal Strombolian explosions with a thermal camera and infrared radiometers provide a unique opportunity to understand signals from less expensive radiometers. Using records from Stromboli volcano, we analyze in particular the limitations of using signals from infrared radiometers alone to quantify the plume ascent kinetics. We conclude that infrared radiometers pointing close to the vent, either single or coupled, are often insufficient for velocity retrieval due to the complex structure and dynamics of the plumes and their evolution with time. In addition to practical implementation difficulties in the field, this is mainly due to the rapid succession and overlapping of thermal components in the radiometer's field of view. Optimized geometries of radiometer fields of view and new retrieval methodologies are proposed to improve velocity estimates from one or coupled radiometers.