Why Tethered Balloon Systems Still Matter in the Age of Satellites and Drones
Authors
Recently, I was thinking about why tethered balloon systems (TBS) are still important in the era of space-based observations and drones. The difference between satellites and drones is quite clear. Drones can capture data much closer to the Earth’s surface and can be deployed wherever needed. Satellites, on the other hand, provide reliable and continuous observations over large areas and revisit the same location regularly over long periods.
However, there is something in between these two systems, and that is the tethered balloon. Although tethered balloons are widely used in atmospheric research, they often receive less attention compared to satellites and UAVs. In some situations, especially when they are noticed in sensitive or urban areas, they can even attract public attention. Yet, they provide a type of information that is extremely difficult to obtain from other observation platforms.
One of the most important applications of tethered balloons is atmospheric profiling. Today, we can measure temperature and other atmospheric parameters from satellites, and we can also collect observations at specific altitudes using various instruments. However, understanding the planetary boundary layer remains a challenge. This layer, which roughly extends from the ground up to about 1 to 2 kilometres, is where most of the important interactions between the Earth’s surface and the atmosphere take place.
Aerosol-cloud interactions, trace gas exchange, pollutant transport, turbulent mixing and surface-atmosphere dynamics all occur within this planetary boundary layer. To understand these processes, it is essential to measure temperature, humidity, pressure, wind and other atmospheric properties continuously from the surface upwards. This is where tethered balloons become particularly useful.
The question is whether tethered balloons only measure temperature. The answer is no. They can measure aerosol properties, thermodynamic structure, humidity, pressure, wind speed and direction, turbulence, cloud microphysics, liquid water content and even supercooled liquid water content inside mixed-phase clouds. Many of these observations are difficult or impossible for satellites to retrieve directly from space.
What makes tethered balloons special is their ability to provide high-frequency, in-situ vertical profiles for several hours and sometimes even days. They can remain at a fixed location and continuously observe how the atmosphere changes with height and time. Neither satellites nor most ground-based remote sensing systems can provide this level of detail within the lower atmosphere.
The real strength of tethered balloons lies in their role as part of an integrated observation system. They do not replace satellites, weather stations or UAVs. Instead, they complement them by filling an important observational gap.
There are several examples from around the world where tethered balloons have been used successfully. One notable case is the JIMU-1 tethered balloon system from China, which was deployed over the Qinghai-Tibet Plateau. It reached an altitude of more than 9,000 metres and provided valuable three-dimensional cloud physics and atmospheric observations in one of the most climate-sensitive regions of the world. Such regions are often poorly sampled by conventional observations and satellite datasets alone cannot provide the complete picture.
This highlights an important point. Neither ground measurements nor space-based observations can always fully capture the atmospheric interactions taking place between the surface and the free atmosphere. Tethered balloons help bridge that gap.
Of course, tethered balloons are not needed for every climate study. They have their own limitations, including operational constraints and limited endurance compared to satellites. However, they become highly valuable when studying complex atmospheric conditions where detailed vertical information is required.
One area where they can make a major contribution is urban climate research. Cities around the world are facing increasing challenges from heat stress and air pollution. The planetary boundary layer rises and falls throughout the day as part of the natural diurnal cycle. Understanding how this invisible atmospheric dome above a city behaves is critical for understanding both heat and pollution.
Studies have shown that when the planetary boundary layer becomes deeper, pollutants can disperse more effectively. When it becomes shallower, pollutants become trapped near the surface. Under stagnant atmospheric conditions, these changes can significantly influence air quality and increase health risks for urban populations.
Urban heat island effects are also closely linked to boundary layer processes. This is one reason why countries such as China and the United States invest heavily in studying urban boundary layer dynamics. Understanding these processes is essential if we want to develop effective solutions for heat mitigation, pollution control and climate adaptation in cities.
For me, this is where the future importance of tethered balloon systems lies. They are not only valuable for studying climate-sensitive regions such as mountains and high-altitude environments, but also for addressing some of the pressing challenges faced by modern cities. Many of the problems related to urban heat, air quality and local climate are strongly influenced by atmospheric processes that occur within the planetary boundary layer.
If we want to understand these processes better, we need detailed atmospheric profiling. Tethered balloons provide exactly that. In many ways, they remain one of the most effective tools for observing the lower atmosphere and understanding the climate physics that directly affects our daily lives.