Our department's research focuses on understanding the atmospheric "engine" that connects the weather we experience near the ground to the edge of space, 100 kilometers up. The atmosphere is constantly moving, driven by powerful waves that are much larger and more energetic than ocean waves. These include Planetary Waves (vast systems generated by continents and mountain ranges) and Gravity Waves (smaller ripples caused by storms and winds flowing over hills). These waves transport massive amounts of energy and momentum from the lower atmosphere all the way into the mesosphere. When these waves break, they generate extreme turbulence, heating of the atmosphere and dramatically shifting global circulation patterns.

To track this complex vertical transport, we use highly specialized ground-based systems, primarily powerful Lidar instruments. By observing how light scatters off atmospheric molecules, we can precisely measure temperature, density, and wind speeds up to the mesosphere. Crucially, our scientists also develop sophisticated sensors to be carried on sounding rockets that fly directly into the upper atmosphere. These rocket sensors are essential for taking in-situ (direct) measurements, particularly capturing the fine-scale details of atmospheric turbulence—the key process that drives vertical mixing. Our research quantifies how much energy is transferred by these waves and how turbulence dissipates it, allowing us to model the entire atmosphere as a single, coupled system. This detailed understanding of atmospheric coupling is fundamental to predicting space weather and ensuring we accurately understand how changes in the lower atmosphere directly impact the fragile environment near the boundary of space.

Our skies are filled with tiny particles that have an enormous influence on the atmosphere and climate. We investigate the microphysical properties, origin, and fate of these aerosols and particles across the middle atmosphere, covering both natural and human-made sources. Every day, Earth is bombarded by space rocks, which ablate upon entry to create Meteor Smoke Particles (MSP)—nanometer-sized dust that drifts down into the stratosphere. These particles are essential for global atmospheric processes, influencing everything from chemistry to the global radiation budget. We use novel Lidar methods to track these tiny particles deep into the atmosphere, allowing us to precisely characterize their shape and size, and distinguish them from other particles like volcanic ash. This is a complex task due to their small scale and low concentration, requiring advanced optical techniques.

This tracking is critical because MSPs act as the essential building blocks, or nucleation sites, for the highest clouds on Earth: Noctilucent Clouds (NLCs). These shimmering blue clouds are highly sensitive indicators of atmospheric change. Our ongoing research investigates how both natural MSPs and new anthropogenic aerosols (from spacecraft re-entry or rocket exhaust) change the overall particle budget. We study how these changes affect NLC formation, revealing subtle signals of long-term environmental change in the upper atmosphere. Understanding the chemical and physical processes governing these particles is key to solving how they influence the climate system, particularly in regions where they interact with water vapor to form clouds.

With the increasing number of satellite launches and space activities, the composition of the upper atmosphere is changing. During the re-entry of spacecraft into Earth's atmosphere, metals such as lithium, aluminum, copper, and titanium are released. These materials, which naturally occur only in trace amounts at such altitudes, are influencing the mesosphere and upper stratosphere to an extent not previously documented. This influence is expected to intensify further in the coming years.
Our department contributes to systematically recording and analyzing these developments. Using specialized multi-color resonance lidars, we measure even the smallest concentrations of anthropogenic metals at altitudes of around 90 km. This requires precisely distinguishing the optical signatures of individual metals from the natural background—a challenging task. Now, it is necessary to investigate how these metals chemically transform, how long they remain in the atmosphere, and how they interact with surrounding gases and natural aerosols.
This work provides important scientific insights to determine baseline levels, assess potential impacts on ozone and cloud formation, and inform international bodies about the long-term consequences of these new atmospheric influences. Our goal is to better understand the interactions between the atmosphere and space, thereby enabling sustainable use of near-Earth space for future generations.
 

The mesosphere and lower thermosphere (MLT), located roughly 50 to 100 kilometers up, are exceptionally sensitive to climate change. This region acts as a giant thermometer for the upper atmosphere, responding dramatically to changes in greenhouse gas concentrations. While increasing carbon dioxide (CO₂) traps heat and warms the air near the ground, it paradoxically leads to dramatic cooling in the MLT as the increased density of CO₂ allows thermal energy to radiate out to space more efficiently. Our research is dedicated to rigorously measuring and verifying this predicted high-altitude cooling effect, which is one of the clearest and most robust signatures of global climate change.

We maintain some of the longest and most continuous atmospheric datasets in the world, with Lidar records spanning over 30 years. This dedication to long-term monitoring is vital because it allows us to filter out natural, cyclical atmospheric variations (like solar activity, volcanic eruptions, and seasonal changes) from permanent, forced climate change trends. We precisely quantify changes in temperature, winds, and other key dynamic parameters in the upper atmosphere. By confirming the patterns of MLT cooling and relating them to observations of phenomena like Noctilucent Clouds (which become brighter and occur more frequently as the mesosphere cools and moistens), we provide essential scientific evidence that validates global climate models across the entire vertical extent of the Earth's atmosphere. This comprehensive approach is necessary to understand the full, complex impact of greenhouse gas emissions on the entire planet.

Discoveries at the frontier of atmospheric science are only possible through continuous advancement in technology and instrumentation. Our department acts as a center for applied physics and engineering, dedicated to designing and building the next generation of specialized instruments for remote sensing and in-situ measurements. This includes tackling technical challenges in making systems more efficient and robust for deployment in harsh environments. We are constantly advancing our Lidar technology, focusing on key challenges such as making laser systems more powerful, compact, and reliable so they can eventually be deployed on satellites or sounding rockets to provide extended or global atmospheric coverage.

A major focus is on Rocket Sensor Development: we design, test, and precisely calibrate the complex scientific payloads—new generations of specialized in-situ sensors—that are launched aboard sounding rockets. These instruments must be engineered and hardened against the extreme conditions encountered during a rocket flight, including intense vibration, temperature extremes, and the vacuum of spaceflight. They provide unique, high-resolution measurements of atmospheric composition and dynamics unattainable by remote sensing methods alone. To ensure reliable, continuous scientific output from all our instruments, we also dedicate significant effort to developing the advanced software for instrument control. This crucial software enables automated, day-and-night operations of our Lidar network at remote sites and includes robust data processing pipelines necessary for the rapid ingestion and analysis of the massive, terabyte-scale amounts of data collected daily. Furthermore, this development work drives innovation in the field of scientific automation.