My research group has covered a wide variety of research topics over the years, and new ones are starting all the time. Below is a brief look at what interests us.
This field of research deals with fair-weather electricity. By this we mean electricity measured in the atmosphere when no thunderstorms are active in the surrounding region. This electricity is generally related to global thunderstorms which produce electric currents flowing in the atmosphere between the ionosphere and the earth. In particular, we are interested in the AC fields produced by global lightning in the ELF range, known as the Schumann resonance.
Lightning activity in thunderstorms is closely related to the microphysics of clouds and storm dynamics. The storms with large amounts of lightning are often also very destructive, having large hail, strong winds, and excessive rainfall. These storms are often the cause of flash floods, which are often observed in the southern parts of Israel. We are researching the connections between lightning activity, rainfall and severe weather in a number of locations around the world.
Space Weather is a relatively new field of research looking at the interaction between solar storms and the Earth's environment. How do solar flares, X-rays, coronal mass ejections (CMEs) impact the Eath's magnetosphere, ionosphere, and atmosphere? The first nano-satellite of our university TAUSAT1 will be studying space weather at an altitude of 400km. Space weather can have negative impacts on satellites, radio communications, astronauts and even power utilities on the ground.
Sprites are a phenomenon discovered in the upper atmosphere in 1989. They are optical flashes of light that occur far above thunderstorms (50-100 km altitude), but are associated with a specific type of intense lightning in the storm below (positive lightning). The strong flashes that produce the sprites also produce strong radio signals that we can easily detect in Israel, even if the storm occurs in the United States. We worked with Ilan Ramon (Israel's first astronaut) to observe sprites from the space shuttle Columbia.
There is strong evidence that the Earth's temperatures are warming, and that this warming is caused in large part by our activities on our planet. We are at a critical time in history where we need to act now to prevent irreversible climate change. We are particularly interested in the impact of climate change on thunderstorms and severe weather (both regionally and globally). We have also started research related to new ideas for renewable energy that are based on our knowledge of thunderstorm electrification.
The El Nino phenomenon is the result of the warming of the tropical eastern Pacific Ocean which lasts for 6-18 months. This warming occurs every few years and results in the disruption of global weather patterns. We are interested in the link between the El Nino cycle and weather conditions in Israel and around the globe. We found in the 1990s that the rainfall in Israel is above/below normal during El Nino/La Nina winters (DJF). However, the El Nino is also related to thunderstorm activity around the globe, as well as forest fire activity in some countries.
Lightning is a major cause of wildfires in the mid- to high latitudes. Natural fires depend on the regional and perhaps global climate conditions, the availability of fuel (vegetation) and the amount of lightning. Our studies have shown that natural fires may increase dramatically in the future due to global warming. Furthermore, global biomass burning is likely contributing to the increase in greenhouse gases in the atmosphere. We have also shown that smoke particles from fires can influence lightning activity in regions of biomass burning.
We are researching many aspects of air pollution. Thunderstorms produce NOx gas that can form ozone (O3) that is the main ingredient of smog. We are also studying the impact of air pollution on solar panels used for generating solar energy. Another project is investigating the use of pigeons and bats to monitor air pollution with micro-sensors attached to their backs. And as mentioned above, smoke pollution from fires was found to impact the lightning activity in thunderstorms. More than 7 million people die of air pollution complications every year.
For more than a century people have claimed hearing sounds when seeing large shooting stars in the sky. It is impossible for the sound waves to be produced by the meteor since sound travels much slower than light. The only explanation is that the meteor produces radio waves (similar to lightning) that reach the observer with the light, and are then transformed to audible sound in vibrating objects close to the observer. We have carried out research searching for these electrophonic sounds from meteors, and we think we have found them.
In recent decades a number of groups around the globe have measured high levels of ultra low frequency (ULF) radio waves in the atmosphere close to the epicenter of earthquakes, weeks and even months prior to the earthquakes. It is not clear the source of these radio waves, and the reliability of these signals, but this provides hope that one day we may be able to forecast earthquakes. We have been carrying our research in the Dead Sea Rift Valley looking for these precursory signals. So far unsuccessful.
The electrical activity in most living creatures show similar patterns (frequencies) compared to what we measure in the atmosphere from global lightning activity (Schumann resonances). Could there be a connection? Could the natural background electricity in the atmosphere have impacted the evolution of biological systems over billions of years? We have performed some simple experiments to address these questions, and the findings are fascinating.
We are studying how the micro sensors inside our smartphones can be used to monitor and study the environment. These sensors can supply valuable information about our environment in real time and may be used in the future to predict forest fires, anomalous weather, while their data may be used to help improve future weather forecasts. With the number of smartphones now reaching billions around the globe, this source of information collected by the public may be a game changer in weather forecasting, particularly in developing countries.