Introduction
Introduction
Figure 1: Eruption of Mount Calbuco (Philippines) on 22 April 2015. © Aeveraal
Volcanic eruptions have a severe impact on human health, economy and traffic. They regularly cause natural disasters such as tsunamis and lava flows that are difficult to predict. Volcanic eruptions emit large amounts of gases, ash, and other aerosol particles into the atmosphere. The largest gaseous components by volume are water vapor and carbon dioxide (CO2). However, sulfur dioxide (SO2), which is a highly reactive gas and an important indicator of volcanic activity, is of much higher interest to scientists. Intense volcanic eruptions have an impact on the global environment and climate. In fact, they have a key role in the Earth's climate system due to the injection of particles and gases into the stratosphere, up to a height of around 20 km. Up there they can persist longer and be transported around the planet, thereby modifying the radiative budget of the atmosphere.
O2 is of special interest to climate scientists. While acting as a pollutant in the troposphere, SO2 converts to sulfuric acid (H2SO4) in the stratosphere and causes surface cooling by reflecting short wave solar radiation. The effect and intensity depend greatly on the total mass emitted and the altitude the plume reaches. In 1991, a major eruption from Mount Pinatubo, a stratovolcano in the Philippines, produced a persistent layer of small particles in the stratosphere that had a measurable impact on global temperatures for about two years.
In the short term, volcanic ash plumes have serious impacts on aviation. It is, therefore, very important to monitor the extent, height and duration of such events to properly estimate the impact of eruptions at various spatial and temporal scales, using data from different instruments on different satellites.
Target group
This module is intended for the operational meteorologist who wants to train his or her skills in identifying volcanic plumes, their composition and morphological characteristics from meteorological satellite data. Focus is placed on image data from geostationary satellites and especially on spectral channel combinations that are suited for detecting plumes from volcanic eruptions. The final part of the module contains an overview of current satellite sensors and satellite products able to monitor volcanic ash and SO2 plumes.