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New knowledge about thunderstorm effects on the climate
For the first time researchers are able to describe thundercloud activity in the stratosphere. The research is based on videos captured by ESA astronaut Andreas Mogensen during his time at the International Space Station. The study has just been published in Geophysical Research Letters.
Researchers from DTU Space and the Danish Meteorological Institute have gained a completely new understanding of the effects of upward cloud-to-stratosphere lightning. This is thanks to the findings of a study looking at the activity of electrical discharges at the tops of thunderclouds. The study, which has just been published in the journal Geophysical Research Letters, may help reduce the uncertainty of our climate models.
The observations are based on videos sensationally captured by ESA astronaut Andreas Mogensen over India during his time at the International Space Station (ISS) in 2015. Here, he recorded a so-called blue jet, which is lightning propagating from thunderclouds and reaching an altitude of up to 50 km. But that is not all. For the first time ever, you can see the blue jet pulsating and generating numerous upward discharges in quick succession. You can also see a lot of blue flashes near the top of the cloud.
Solid scientific results
“We are surprised that Andreas Mogensen was able to do such interesting measurements during his short time in space. The videos show that the electrical discharges at the top of thunderclouds are far greater than previously assumed. We now know more about what types of cloud create such activity, and we can see that the lightning comes from clouds at an altitude of 17 km. These are solid scientific results which for the first time document how active the tops of thunderclouds are with blue emissions which are completely different to ordinary lightning,” says Torsten Neubert, Senior Executive Officer at DTU Space.
The pictures taken by Andreas Mogensen form part of the THOR research project. DTU Space is responsible for the scientific management of the THOR project and some instrument development, while Terma heads the technical consortium, and the Danish Meteorological Institute is responsible for forecasting the development of thunderclouds. For the first time ever, the THOR project will compare measurements from the space station with measurements from Earth. The aim is, among other things, to understand how thunderstorms transport water vapour, a highly active greenhouse gas.
Determining our climate models
Thunderclouds can transport water vapour from the Earth’s surface to the upper reaches of the troposphere and into the stratosphere. The blue jets and flashes also change the concentration of greenhouse gas emissions, which is another way in which thunderstorms can affect the stratosphere.
“Greenhouse gases in the atmosphere near the tropopause and in the stratosphere have a relatively greater effect on the radiation balance than gases at the Earth’s surface, and they are dispersed across longer distances and stay for longer in the atmosphere. The better we understand the tops of thunderstorms, the more accurate our climate models,” says Torsten Neubert.
He has high hopes for the ESA-led project Atmosphere-Space Interactions Monitor (ASIM), of which THOR is a part. ASIM is the largest Danish-led European space project since Ørsted, and consists of two main instruments for measuring light and X-ray radiation from thunderstorms.
The aim of ASIM is to provide researchers with greater insight into the newly discovered types of giant lightning bolts—called ‘sprites’, ‘blue jets’, and ‘giants’—that form above thunderclouds and can stretch all the way up to the ionosphere at an altitude of 80 km. Additionally, ASIM will measure the high-energy X-ray radiation that is a source of antimatter (positrons) in space around the Earth. The plan is for the instruments to be installed on ISS in November 2017.
source: Technical University of Denmark