Recreate the weather on Mount Everest 101 years ago. "Because there is a mountain there...... Did Mallory make it to the summit of Mount Everest?

Ladies and gentlemen, I'm Oya, a mountain disaster prevention weather forecaster. I started this series in 2019, and this is exactly 6 years and the 50th installment. I would like to continue to post mainly on the analysis of past accidents and the lessons learned from them, so thank you for your support.

This year's theme is about George Mallory, who famously said, "Because there is a mountain there." Mallory attempted to make the first ascent of Mount Everest in 1924, but was shipwrecked near the summit and never returned. Did you make it to the top of Mount Everest? is still being discussed, but I would like to consider it.

The official record for the first ascent of Mount Everest was made by Edmund Hillary of Great Britain and Sherpa Tenzing Norgay on May 29, 1953. However, there is still the possibility that George Mallory and Andrew Irvin may have made their first ascent 29 years earlier, on June 8, 1924. There is no doubt that this is one of the greatest mysteries in the history of world mountaineering.

Therefore, I would like to reconstruct the weather conditions of Mount Everest 101 years ago using reanalysis data by NOAA (National Oceanic and Atmospheric Administration) and approach the mystery from the perspective of mountain weather.

Looking back on the history of climbing the first ascent of Mount Everest

The world's highest peak, Mount Everest (8848 m above sea level), is located on the border between Nepal and China, and is called Everest in English, Sagarmatha in Nepal, and Chomolungma in China. Britain, which fell behind in its first conquest of the Arctic and Antarctica, formed an expedition from the 1920s with the prestige of the British Empire on the prestige of Mount Everest as the "third polar region" and aimed for the first ascent.

Until 1949, when Nepal lifted its isolation, Mount Everest could only be attacked from Tibet (China). The first British expedition in 1921 entered the mountains from Tibet and confirmed the route to the North Col (7020m) on the North Ridge. In 1922, the second expedition climbed the North Ridge Route and reached the highest altitude at the time, 8,321 m in front of the northeast ridge, but the ascent was abandoned due to bad weather and avalanche accidents. George Mallory, the protagonist of this article, participated in both the first and second rounds.

In the third expedition in 1924, Mallory (then 37 years old) and Andrew Irvine (22 years old) climbed the northeast ridge from the north ridge route to make the first ascent of Mount Everest. However, during the summit attack, the two disappeared and disappeared into Mount Everest.

Mallory's death, which had become a national hero, shocked the whole of Britain at the time. After that, the British sent the seventh expedition in 1938, but they were unable to make the first ascent of Mount Everest.

After World War II, in 1949, the Tibetan side was closed under Chinese control, and instead it was possible to enter the mountain from the Nepalese side, and mountaineering teams from not only the United Kingdom but also other countries competed for the first ascent of Mount Everest.

After pioneering a climbing route from the difficult point of the Western Coum's icefall to the southeast ridge, which is now the main route, it was finally on May 29, 1953, when British Edmund Hillary and Sherpa Tenzing Norgay were honored with the first ascent. From the Tibetan side, a Chinese team succeeded in making the first ascent of the North Ridge on May 25, 1960.

Many of you may know that the first ascent by Japan people was made in 1970 by Teruo Matsuura and Naoki Uemura of the Japan team, and in 1975, Junko Tabei of the Japan Women's Mountaineering Team became the first woman in the world to climb Mount Everest.

Mallory and Irvin's Footsteps in the Third Expedition

Follow Mallory's footsteps during the Third Expedition in 1924. On 6 June, Mallory departed Camp 4 (around 7000m) on the North Ridge Route with Irvine and proceeded to Camp 5 (7710m) and on 7 June to Camp 6 (8230m). Then, in the early morning of June 8, we climbed the northeast ridge and aimed for the summit of Mount Everest. According to a letter sent by Mallory at the time, the weather has been good so far.

Noël O'Dell, who was heading to Camp 6 to support the couple, said that at around 12:50 p.m. on the same day, the sky suddenly cleared and the summit of Mount Everest was revealed, and he saw them reach the second step of the northeast ridge (around 8600m).

The second step is the most difficult part of the North Ridge route, and it is a rock wall of about 30 meters with an almost vertical top. Nowadays, the difficulty level has been reduced by the ladder installed by the Chinese team, but there are many negative opinions (Reinhold Messner, etc.) as to whether it was possible to climb with the mountaineering equipment of Mallory's time. However, there is no doubt that Mallory had top-notch mountaineering skills for his time.

After Odell saw the two men, clouds covered the area near the summit of Mount Everest, and this was the last time he saw them alive. By the time Odell arrived at Camp 6 at 2 p.m., the weather had deteriorated and the wind and snow had become stronger, and two people had not come down even if they waited, so they left Camp 6 at 4:30 p.m. and descended to Camp 4.

The weather cleared up and cleared that night, but we couldn't find the two of them. Odell climbed to Camp 5 on June 9 and Camp 6 on June 10 to search for them, but there were no clues, and the weather showed signs of deterioration, so he finally gave up on the search for the two men and descended the mountain.

Mallory and Irvin's bodies and the whereabouts of the focus camera

Mallory's body was found near an altitude of 8,160 meters on the north face of Mount Everest by a research expedition dispatched on the 75th anniversary of Mallory's distress in 1999. The camera brought by Mallory and his friends, which is a major clue as to whether they reached the summit, has not been found and has not yet been found.

Irvin's body had never been found, but in September 2024, the news that a National Geographic documentary film crew found the remains of a pair of climbing boots, socks embroidered with Irvin, and feet in the center of the Rombuk Glacier beneath the north face of Mount Everest made headlines. If the camera is found alongside Irvin's body, the history of the first ascent of Mount Everest could change.

⇒External Link: Remains of Andrew 'Sandy' Irvine believed to have been found on Everest (National Geographic)

Pre-monsoon (spring) and post-monsoon (autumn)

Using data from the Japan Meteorological Agency, the average monthly precipitation and temperature in Kathmandu, Nepal, at the foot of Mount Everest in 1982~2014 are summarized in a graph. Figure 1 It is shown in . In summer, a large amount of moist air enters the Asian continent from the Indian Ocean and the South China Sea, bringing the rainy season to the Asian continent.

Figure 1 As you can see, the rainy season is from June to September, when there is a lot of precipitation. The moist monsoon that blows from the Indian Ocean and the South China Sea is called the monsoon. From there, the rainy season brought by the monsoon also came to be called the monsoon.

There are many sunny days before and after the monsoon, making it a good season for Himalayan mountaineering, and we call it pre-monsoon and post-monsoon, respectively. It's not that it's no longer good in June, and depending on the year, the weather may be good until early June. The rest of the season from December to March is the winter season, which is a difficult time for Himalayan mountaineering due to extreme cold and fierce winds.

Weather at 12 o'clock (local time) on June 8, 1924 reproduced by NOAA reanalysis data

First, I tried to recreate the local weather conditions at 12 o'clock on June 8, the last time Odell saw Mallory and Irvin, using NOAA (National Oceanic and Atmospheric Administration) reanalysis data. When we investigated the altitude at which the atmospheric pressure was 350 hPa, it was 8590 m, which is almost the same altitude as the second step, where there are testimonies that the two people witnessed the climb. The temperature was -18°C and the wind speed was 6 m/s, which was very good for the weather conditions for climbing Mount Everest.

Figure 2 shows a weather map that reproduces the wind speed (colored) and isoaltitude line (solid line, corresponding to the isobar line on the surface weather map) at a height of 350 hPa (altitude about 8600 m) at the same time on June 8.

It can be seen that the westerly winds are blowing from west to east, meandering over the Iranian Plateau, northern India, and the Tibetan Plateau of China. The area around Mount Everest in eastern Nepal was on the south side of the westerly wind flow, and the wind was weak.

In the same way, a weather map of 150 hPa (altitude about 14000 m) in the sky is reproduced. Figure 3 Are. At this altitude, a jet stream was blowing that maximized the wind speed of the westerly wind, and the jet stream was flowing over the Tibetan Plateau north of Nepal. On the south side of the jet stream, there was a high pressure system centered near Bangladesh (H in the figure), and it was found that the sky above Mount Everest was covered by high pressure. This anticyclone is truly the "Tibetan anticyclone".

Tibetan anticyclone, which causes extreme heat in Japan, brings good weather on Mount Everest

The Tibetan High is one of the culprits of the extreme heat in Japan's summer in combination with the Pacific High, but under the Tibetan High the winds are weak and clouds are unlikely to form, making it ideal for climbing the Himalayas in the pre-monsoon.

The Pacific High is a tall anticyclone from the ground to around 300 hPa (about 10,000 m altitude), while the Tibetan High is an even higher high pressure system that appears around 300 hPa to 100 hPa (altitude from about 10,000 m to 17,000 m). At the 8,000-meter peak in the Himalayas, the movement of the Tibetan anticyclone determines the success or failure of the ascent.

We examined whether the temperature of -18°C and wind speed of 6m/s at an altitude of around 8600m on the day of the disappearance of Mallory and Irvin reproduced in the previous section are actually weather conditions that can occur in early June, in 2013 and 2022, when Everest was similarly covered by the Tibetan anticyclone in recent years.

The results of analysis using data from the Japan Meteorological Agency's GSM (Global Forecast Model) were -18°C and wind speed of 7 m/s at an altitude of 8600 m on Everest at 6 p.m. (local time) on June 9, 2013, and -18 °C and wind speed of 4 m/s at an altitude of 8600 m on June 8, 2022 (local time). Therefore, I think that we have been able to verify that the Tibetan anticyclone actually brings good weather to Everest.

Incidentally, in the former year, 2013, Yuichiro Miura set a wonderful record on May 23 at the age of 80, becoming the world's oldest person to climb Mount Everest. At the summit of Mount Everest at 9 o'clock, there was no wind and clear, and the temperature was -20 ° C. Source: WEATHERNEWS SORA [Gota Miura] What is really important equipment in the mountains? ）。 And at this time, we were able to confirm that Everest was covered by a strong Tibetan anticyclone.

How monsoon moist air affected Everest

Even though Everest was covered by the Tibetan anticyclone, the monsoon season was about to begin, when Mallory and his friends were shipwrecked on June 8, when very moist air enters from the Indian Ocean. To see how monsoon moist air from tropical oceans affected it, we created a reproduction of the flow of water vapor. Figure 4 It is shown in . The amount of precipitable water (colored) indicates the amount of water vapor, and the arrows represent the wind flow at 925 hPa (altitude of about 750 m). Moist air mainly enters from the lower layers up to an altitude of 1000 m from the sea surface and the ground surface.

Moist air entering from the Bay of Bengal in the Indian Ocean is heading from eastern India and Bangladesh to eastern Nepal, but it can be seen that the moist air that reaches the vicinity of Mount Everest is considerably reduced due to being blocked by the mountains of the vanguard in eastern Nepal. In other words, it can be assumed that the influence of moist air on Mount Everest was limited, and even if clouds were generated by the updraft caused by the valley breeze from the afternoon and the weather became bad, it would have been temporary because it was covered by the Tibetan anticyclone above.

Summary and summary of the survey from a meteorological perspective

Summarizing the results of the analysis of NOAA reanalysis data and the testimonies of survivors, it is clear that on June 8, when Mallory and Irvin headed to the summit of Mount Everest, the weather temporarily broke down in the afternoon, but recovered at night, and there was no major deterioration in the weather until June 10.

However, the monsoon season was just around the corner, when moist air from the Bay of Bengal came in, and I think that the view was sometimes blocked by clouds rising from below and the accompanying wind and snow. However, the bad weather was temporary, and it is presumed that the weather was sufficient to make it to and from the summit.

If this is the case, it is highly likely that Mallory and his friends were not in distress but due to some kind of accident on the way to the summit of Mount Everest or while descending from the summit. This time, I think we were able to verify this conclusion not only with the testimonies of survivors, but also with NOAA's reanalysis data.

There is a harsh opinion that even if you reach the top, you will not call it a summit unless you descend the mountain alive. However, when asked why she climbs Mount Everest, Mallory replied, "Because it's there."

Even if you don't know Mallory's name, I think many people can relate to Mallory's quote, "Because there's a mountain there." And I think one of the reasons why many people go to the mountains is because there are mountains there.