A record number of airplanes were grounded in 2020 because of the COVID-19 wave and dwindling passenger numbers. As a result of the decreased aviation activity, the sky are now free of jets and the white, fluffy condensation trails they leave in their wake.

Aeronautical engineers from Massachusetts Institute of Technology (MIT) compared airplane exhaust trajectories from 2020 with those from years before to the outbreak of the pandemic According to their findings, on any given day in 2018 and again in 2019, tracks covered an area comparable to the combined size of Massachusetts and Connecticut in the United States. As a result of fewer flights in the United States, this is expected to fall by 20% by 2020.

As expected, airplane emissions are expected to fall in 2020. However, this shows that the MIT team's mapping method is effective. As a result of this research, scientists now have unprecedented access to the delicate and fleeting features of these traces at a massive, continental scale.

Traces in the atmosphere can now be predicted by scientists using this method. An important role in climate change is played by these cloud-like structures, and aviation is no exception. The MIT team is collaborating with major airlines to forecast where condensation trails may occur in the atmosphere and to direct planes away from those areas to prevent the production of those tracks.

Aircraft can be diverted in real time in order to avoid condensation traces. Steven Barrett, a professor and assistant chair of MIT's Department of Aeronautics and Astronautics, thinks there is a remarkable chance to halve the climate effect of flying by deleting most of the hints produced presently.

Environmental Research Letters is where Barrett and his colleagues reported their findings.

Training for algorithms
Carbon dioxide emissions from planes account for approximately half of the aviation industry's contribution to global warming. The remaining half is attributed to atmospheric condensation traces. Tails are generated by the combination of warm and cool air high in the atmosphere and the exhaust fumes of an airplane. The traces spread quickly and can act as blankets to hold the Earth's heat output, which is emitted in thin lines.

Even if one trail may not have much of an influence on the temperature, a large number of them do. However, computer modeling and limited satellite data are being used to determine the magnitude of this influence. It's difficult to tell the difference between thin clouds and real ones using typical computer techniques that look at data trails.

A NASA geostationary satellite, GOES-16, captured high-resolution photographs of the same region of the Earth, including the United States, for use by the MIT team in selecting and tracking hints on a broad scale.

In the beginning, the team received a slew of satellite photos and taught a group of people to analyse the data and identify whether or not each pixel in the image included a hint. They then practiced a computer system to discern between a condensation trail and a typical cloud using this labeled data set.

About 100,000 satellite photos were then used to run an algorithm on almost 6 trillion pixels, each of which represents an area approximately 2 square kilometers. A photo was shot every 15 minutes between January 1, 2018, and December 31, 2020, covering the entirety of the United States, as well as sections of Canada and Mexico.

Each pixel was automatically categorized as either a trace or not, and daily trace maps were generated across the United States. The principal flight paths of most U.S. airlines were depicted on these maps, with a few notable exceptions. When planes land and take off at airports in the lower atmosphere, condensation trails don't form. For example, trace holes have appeared around huge airports.

In spite of the fact that the algorithm has no idea where planes go, it was able to identify flight paths in satellite photos. Barrett cites this as evidence that the procedure is effective in capturing traces on a broad scale.

How to avoid the creation of condensation traces by dealing with the issue of cloud patterns
Each day, scientists used an algorithm to compute the total area covered by condensation trails in the United States. A total of 43,000 square kilometers of U.S. land was used every day in 2018 and 2019. As the COVID-19 pandemic broke out in March of 2020, that level of protection dropped by 20%. As the year progressed, evidence began to reappear, albeit slowly.

The researchers also looked at seasonal and daily trends. Predominantly, mornings were better than afternoons for tracks. Because natural cirrus clouds appear in the afternoon, the algorithm may have difficulty detecting traces in the centre of clouds later in the day, which could be artifacts. However, it can also serve as a useful indicator of the frequency with which hints are created.

These traces peaked in late winter and early spring, when the air is naturally cooler and more favourable to the development of condensate trace.

A new method developed by scientists can now forecast where traces will form in real time. Barrett claims that avoiding this might reduce a major portion of the aviation's contribution to global warming practically immediately.

Most aviation sustainability initiatives require a long time to implement. The ability to fly without leaving a condensation trail could be accomplished in the next few years with current aircraft and observational equipment by making simple adjustments to the way aircraft fly. Barrett points out that this is a short-term solution for cutting aviation's impact to global warming in half.

With the use of real-time satellite measurements, he and his team are attempting to prevent leaving behind large-scale condensation traces.