Chinese authorities report that an observation balloon that was seen over key locations in USAbelongs to Beijing, but they insist that its purpose was meteorological research and claim it was deflected by unexpected winds.

The BBC studied wind direction and other relevant data to determine the balloon’s likely path.

Where was the Chinese hot air balloon seen?

The balloon was spotted over Canadian territory before it appeared on Wednesday over the US city of Billings, Montana, where residents saw it take off into the sky.

US authorities say they are tracking the balloon in US airspace with a manned aircraft, noting that it flew over important military installations.

China has veered off course

Beijing says a strong westerly wind has “drifted the car” which has “limited autonomous navigation capabilities”, causing it to veer off course.

Simon King of BBC Weather reports that the North Pacific region between China and North America is dominated by westerly winds (that is, they blow from west to east).

“In this particular area of ​​the Pacific, wind speeds between 9,000 and 12,000 meters have been 240 kilometers per hour or faster in recent days,” King said. “It’s not unusual for the area to have wind speeds at this altitude.”

“Wind currents in the North Pacific over the past few days have pushed the balloon northwest towards Alaska and then southwest towards Montana through Canada,” he explains.

“Most weather balloons reach a height of about 30,000 meters and explode after a few hours, the equipment falls to Earth on parachutes. It’s unusual for a balloon like this to stay [στον ουρανό] days, as in this particular case.

Dr. Marina Miron, a defense studies researcher at King’s College London, says the hot air balloon may have been more technologically advanced than China claims.

“Perhaps someone was holding the balloon from the ground,” she says. “He could raise or lower the balloon so that it hit the air currents blowing in different directions.”

“It would be desirable if it hovered over the data collection point. It’s something you can do with a balloon, but not with a satellite.”

Can we trace its course?

Not with great certainty. We do not have the information that we would have in the case of a commercial flight, so we will have to turn to other sources of information.

One method used to calculate the path of objects at such a high altitude is to use a model based on wind speed and direction.

The US National Oceanic and Atmospheric Administration (NOAA) developed such a model (known as HYSPLIT) based on winds above 14,000 meters.

“Its main purpose,” says Simon King, “is to control the movement and spread of infectious and dangerous elements in the atmosphere.”

“The model also works the other way around—so-called ‘reverse lookup’—so if we can see where the data in question comes from,” he notes.

“In the case of a balloon over the US, the return path can show where the wind carrying the balloon came from, and by analyzing the direction and speed of the wind, [μπορούμε να δούμε] And where will he go next?

American meteorologist Dan Satterfield used the model in question to calculate the likely path of a Chinese balloon and shared his findings online.

Starting from where it was seen on February 1 in Montana, Satterfield calculated the balloon’s likely return course based on wind data and found that it likely came from central China.

It should be noted, however, that this was not the actual path traveled by the balloon, but merely an analysis based on a model developed by NOAA.

^{Source: BBC}