Wasaburo Ooishi and the jet stream

In his recent book The Bomber Mafia: A Dream, A Temptation And The Longest Night Of The Second World War, journalist Malcolm Gladwell writes about some of the weaponry that emerged from the crucible of World War Two.

Gladwell’s narrative centres on the story of the US military’s determination to drop bombs on Japan. This objective required the capture of islands in the North Pacific, specifically Guam and Tinian in the Marianas chain, to be used as bases from which B-29 Superfortress bombers could reach the Japanese mainland.

Gladwell’s story also turns on two conflicting philosophies of aerial warfare. 

On one side was Dutch-born Carl Lukas Norden, inventor of the Norden bombsight, which the US National Aviation Hall of Fame describes as a “complex assemblage of more than 2000 cams, gears, mirrors, lenses and other components … Technically, the sight could place a bomb inside a 100-foot (30m) circle from four miles up (about 6.5km). But the bombardiers claimed that it could ‘put a bomb in a pickle barrel from 20,000 feet’.” 

Norden and his supporters within the US military believed that if one warring country could destroy an enemy’s crucial industries and cripple its ability to fight through the use of highly accurate aerial bombardment, the mass carnage of a ground war, as seen across Europe during World War One, could be avoided. 

On the other side were the chemists working in a laboratory at Harvard University, in Cambridge, Massachusetts, led by organic chemist Louis Fieser. They came up with a substance for use in incendiary bombs that Gladwell describes as “gasoline mixed with aluminium naphthenate plus aluminium palmitate: napalm”.

Whether the B-29 Superfortress bombers targeting Japan were to drop high-explosive bombs onto carefully selected targets, or incendiary bombs intended to indiscriminately destroy swathes of highly flammable Japanese homes, Gladwell notes that the Marianas were within range (2,600km) of Japan “only under perfect conditions”.

Finally, in late 1944, the bombers set off for Japan, loaded with high-explosive ordinance and equipped with Norden bombsights. But after all the invention and planning, the mission was a failure. As Gladwell describes it, the bombardiers couldn’t make their bombsights line up on their targets. From out of nowhere, the planes found themselves swept along by 125-knot tailwinds. “‘We’re going 480 miles an hour [770km/h]. It’s impossible – it can’t be’,” he quotes one bombardier as saying.

The US bombers had “discovered” Earth’s jet stream, a fast-flowing air current on the edge of the stratosphere that flows from west to east.

“The jet stream is arguably the greatest weather system on Earth,” says Tim Woollings, a climate scientist in the Oxford University Department of Physics. “If you were only given one piece of information from which to infer something about the weather, then across much of the Earth’s surface you’d want it to be about the jet stream.”

British meteorologist James Glaisher is credited with its initial discovery; he made a series of ascents by balloon during the 1860s. But 50 years later, unbeknownst to the Americans, the jet stream was rediscovered by Japanese meteorologist Wasaburo Ooishi (sometimes spelled Oishi).

Ooishi was born on 15 March 1874, in Tosu, Saga, on the Japanese island of Kyushu. A 2013 article in New Scientist magazine explains that in the mid-1920s, Ooishi, in his job as a meteorologist, released hundreds of research balloons near Mount Fuji, and saw something odd. Once the balloons had climbed high into the atmosphere above the clouds, they began hurtling eastwards over the Pacific. Persistent high-level winds, often stronger than a hurricane, were blowing from west to east over Japan.

Other people had observed something similar in Europe, but Ooishi was the first to put two and two together and pinpoint the existence of a permanent tunnel of wind circling Earth travelling between 100 and 400 km/h.

In 1926 Ooishi reported on his findings to Japan’s Aerological Observatory. However, along with his duties as a meteorologist, Ooishi was coincidentally deputy director of the Japan Esperanto Society. Esperanto is an international language, created in 1887 by L L Zamenhof, a Polish ophthalmologist. The idea behind the creation of a common language was to facilitate communication among people from different countries. But apparently Ooishi’s pioneering discovery wasn’t communicated to the ears of the US military high command.

While the Americans were working out how to deal with their new “discovery”, the Japanese were conceiving a bold plan based on Ooishi’s findings that was effectively the world’s first intercontinental weapon: an incendiary balloon bomb, the Fu-Go, set aloft from Japan and designed to travel across the entire Pacific Ocean on the jet stream to terrorise the American civilian population on their home soil.

All up, around 9,300 hydrogen-filled balloon bombs were launched between November 1944 and April 1945, each carrying around 450kg of gear and explosives on a trip calculated to take three days. The challenges were enormous. As hydrogen expands when warmed by the sun and contracts when cooled at night, a control system was devised to discard sandbag ballast when its altimeter dropped below a certain height. Likewise, when a balloon exceeded a certain altitude, the balloon vented hydrogen. After three days, a flash of gunpowder released the bombs suspended beneath the balloons.

The plan was bold, but not particularly successful. Only about 300 made the distance, the rest landing in the ocean, and only one causing any significant damage, killing a pregnant woman and five children who discovered a grounded device while on a picnic in Oregon. 

The balloons’ origins were a mystery to the Americans – no one could believe they had sailed all the way from Japan. But their potential threat was recognised, and all news of them was censored in the US.

Remains of the balloons have continued to be found right up until 2014. An intact balloon is on display in the Canadian War Museum.

Ooishi died in 1950.