Let all American planes lie down. Is this "bi

The year 2023 has come, and everyone has gradually returned to a vibrant state, while the sun seems unable to bear loneliness, and came to join the fun: on January 6, January 9 and January 10, Beijing time, the sun has erupted and produced three strong flares. Subsequently, on January 11, Eastern Time, the civil aviation transportation in the United States was paralyzed and all flights in the United States were grounded.

Some media reported that the solar activity during this period was associated with the grounded flights in the United States, claiming that the geomagnetic storm caused by these "epic" solar flares led to the grounded flights in the United States.

。 。 In the extreme ultraviolet observation image of the X1.9 class flare on January 9, the flash on the left is the flare burst. The image source: NASA But is this really the case?

The simple and direct answer is that the recent flares are not the culprit of the suspension of American flights. These flares are far from "epic", but the solar flares, including flares, can indeed affect the civil aviation flights of specific routes.

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What is the reason for the grounding of American flights?

According to the information released on the website of the Federal Aviation Administration (FAA) of the United States about the grounded event, the reason for the collective grounding of flights across the United States is that the NOTICE To Air Missions (NOTAM) system that issued the NOTAM was paralyzed. Before and during flight, pilots and all departments related to flight operation should obtain key information related to flight safety and efficiency through this system. According to the preliminary findings of FAA at present, the cause of the paralysis of the NOTAM system comes from its own system problems and has no connection with solar flares.

。 。 FAA issued a statement on the flight grounding, which pointed out that the failure of NOTAM system may be due to the problem of its own database file. Image source: FAA 02

Is it really an "epic" solar flare?

To find out whether the three flares recently erupted are "epic", we should look at them from the level of flares. Flare is a kind of local explosion phenomenon with sudden enhancement of radiation on the sun. The classification of flare levels is determined by the maximum value of soft X-ray intensity (strictly speaking, "flux", which is not expanded here) released by flare bursts.

First of all, we assign the flare from weak to strong to A, B, C, M, X and other grades, and then determine the value after the letter according to the specific intensity of a flare event. We can simply understand the letter as the "grade" of the flare, and the number after the letter as the "score" of the flare in the grade.

The three flares that have erupted in January 2023 are X1.2, X1.9 and X1.0, which are indeed the strongest X in the flare family, but there is still a big gap from the "epic" level.

The strongest flare recorded in history is the X28 flare that erupted on November 4, 2003. However, the rating of X28 does not come from accurate measurement, because the flare intensity has exceeded the range of the measuring equipment on the satellite at that time, and the actual rating may be higher than that of X28.

The "fractional line" of the 15 strongest flares in history is also at X9.0, far higher than the intensity of these flares in January 2023. Therefore, for example, several X-level flares in January 2023 are like people in the crowd who are about 1.8 meters tall. Although they can be called tall, they are not as high as Yao Ming and cannot be called "epic".

From the actual impact on the earth, the impact of these flares on the earth is mainly concentrated on the short-wave communication anomalies caused by the changes in the ionosphere. After the eruption of the X1.9 flare, the United States Space Weather Prediction Center issued a R3 level warning of the quality of high-frequency radio communications near the Earth. The agency's early warning for radio communication is divided into five levels, and R3 level is at the middle level, and this level of early warning will be sent out 175 times on average during the 11-year solar activity week. However, the environment of high-energy particles near the Earth has not changed much, and there is only one weak geomagnetic storm in the first half of January 2023. In short, the impact of these flares on the space environment near the Earth is relatively limited.

At the same time, the flare itself cannot directly induce geomagnetic storms. Although flares and another solar burst phenomenon, coronal mass ejection (CME), often appear in pairs, just like lightning can not wet the earth, and the raindrops falling from the sky are the source of all things, the strong geomagnetic storms are generally caused by CME, not flares.

。 。 Coronal mass ejections and solar flares often occur together, and the eruption process may also be related, but it is not the same phenomenon. Image source: NASA 03

Solar flare

What is the impact on civil aviation?

So, after excluding the direct connection between the flare event and the flight grounding, can the civil aviation industry rest assured of the impact of the solar flare? The answer is also negative.

When flying from North America to East Asia, taking into account the shortest path on the sphere and the direction of atmospheric circulation, it is more economical and efficient to use the route over the Arctic than to cross the Pacific Ocean. Airlines can save fuel costs and flight time for the crew and passengers.

Taking the route from Boston to Hong Kong as an example, using the polar route can save 138 minutes of flight time and $33000 of flight cost each time. However, during the period from the end of October to the beginning of November 2003, a series of strong solar eruptions, including the strongest X28 flare in history, made some routes in the Arctic unusable. The FAA required airlines to choose routes at lower latitudes to continue their flights, resulting in an increase in fuel consumption and flight time.

。 。 Polar air routes from October to November 2003. Image source: NOAA The main culprit of route interruption is the interruption of high-frequency (HF) radio communication in the polar region. Due to the scarcity of land and the lack of people in the Arctic region, the very high frequency (VHF) radio transceiver commonly used for air traffic control cannot be arranged along the air route, and can only rely on the HF band with a long transmission distance. At the top of the earth's atmosphere, there is a layer called the "ionosphere". The quality of HF radio communication is directly controlled by the ionosphere. When the ionosphere changes dramatically due to the flare, the HF band that could be transmitted remotely is no longer available, and the air traffic controllers cannot effectively command the air traffic in the polar region, so some polar routes have to be stopped. In low latitude areas, although HF radio transmission during trans-ocean flight is also affected, it can still rely on GEO communication satellites to maintain a part of communication, while the Arctic is the blind area of GEO communication satellites.

。 。 The radiation warning area from October to November 2003 is marked in red. Image source: NOAA Even if HF communication in the Arctic can barely be restored, radiation is also a risk to be considered in polar flight. The polar region is the region where the radiation effect of solar activity affects civil aviation flight most strongly. Of course, if you don't commute between North America and East Asia several times a week, don't worry about it. During the period of relatively calm solar activity, the radiation dose received by a single flight across the polar region is between 0.1-0.2 mSV. The upper limit of the radiation dose received during the annual flight recommended by the relevant authorities is 1 mSV.

However, if the solar activity is extremely intense, you should pay attention to the radiation situation at this time. In 1859, there was a real "epic" solar flare. If the same event occurs now, the radiation received by a single polar flight can be as high as 20mSV. If you are still flying in the polar region at this time, it will bring health risks to passengers and crew members. Of course, the space weather monitoring and forecasting agencies of all countries are also keeping an eye on the situation of "aviation radiation". During the period from October to November 2003, the relevant agencies issued a notice recommending that the cruise altitude of long-distance flights flying at 35 degrees above latitude should be reduced from 40000 feet to 36000 feet. Although this will also increase fuel consumption, it can make more use of the radiation shielding effect of the atmosphere to protect the health of passengers and crew.

The solar activity has an 11-year cycle. As the sun gradually wakes up from the "deep sleep" at the end of 2019 and moves towards the maximum period from 2024 to 2025, there will be more and more solar activities in the next few years, which may have an impact on all aspects of the earth.

Today, with the development of Internet communication, some reports exaggerate and deduce some news facts in an unrealistic way in order to improve their attention. It is suggested that you should pay more attention to the information released by mainstream media and authoritative channels as much as possible.

Reference:

[1] The "Review of the Week" and monitoring data released by the Space Environment Prediction Center of the Chinese Academy of Sciences, http://www.sepc.ac.cn/ 。

[2] NOAA，2004，Service Assessment：Intense Space Weather Storms October 19 – November 07, 2003

[3] NOAA, 2004, Technical Memorandum OAR SEC-88, HALLOWEEN SPACE WEATHER STORMS OF 2003

Product: Popular Science China

Author: Li Huichao, Harbin Institute of Technology (Shenzhen)

. Supervised by: Computer Network Information Center of the Chinese Academy of Sciences.