(Commentary) Salinity, Airflow, and Thermal Circulation

Explanatory session.

- ほうこうおんち

〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜

This is a chapter from when North America still existed.

The seawater near the equator evaporates due to the powerful sunlight. This water vapor moves east to west in low latitudes. In slightly higher latitudes, the vapor moves in the opposite direction, carried by winds blowing from west to east. The water vapor evaporated in the Atlantic equatorial region reaches the Pacific by crossing over the area near Panama. The air, which contains a large amount of water vapor from the low to middle latitudes of the Pacific, heads east, but encounters a giant barrier: the Rocky Mountains.

Here, the air rises, and the cooled air releases its moisture as rain. That rain then flows into the Pacific. As a result, compared to the Pacific, which receives water vapor from the Atlantic and returns it as rain, the Atlantic has a higher salinity because it continually evaporates and transports moisture to the Pacific. It is a small difference in salinity. However, that small difference affects ocean currents. The slightly more saline water sinks below the less saline water. This sinking causes the global ocean circulation to move.

What would happen in a world without North America, specifically without the Rocky Mountains? The moisture evaporated off the coast of Africa will still be carried to the Asian side, as before. However, the water vapor evaporated in the middle latitudes of the Pacific will not be blocked by mountain ranges and will instead move into the Atlantic. The salinity of the North Pacific and North Atlantic will tend to become uniform.

However, ocean circulation is on a millennial scale. Even if it starts right now, it will take time for the waters to completely mix and have the same salinity. The fastest responses are in the surface currents and the air.

Warm seawater off the coast of Africa is moved toward the Asian side by the Coriolis force. This seawater splits into two parts near Papua New Guinea. One flows toward the Indian Ocean, while the other moves north along the edge of the Eurasian continent. This becomes the source of the Kuroshio Current flowing off Japan. The Kuroshio reaches as far as the Sea of Okhotsk, where the salinity decreases because of freshwater flowing in from many rivers.

This low-salinity seawater flows north past the Kamchatka Peninsula and enters the Arctic Ocean. Due to the inflow of river water and the cold currents from the Arctic, the chilled seawater moves from the Arctic Ocean toward Europe. It then reaches the area north of Greenland. Here, the seawater splits into three currents: one that flows south along the western coast of Greenland (the West Greenland Current), another that flows south along the eastern coast of Greenland (the Norwegian Current), and one that continues toward northern Eurasia (the Circumpolar Current).

All three are cold currents. There are no warm currents that once reached high latitudes after hitting North America. The waters off Norway become an unusually cold sea area. And the North Sea, where the West Greenland Current and the Norwegian Current meet, becomes a turbulent zone with disrupted ocean currents.

Now, let's combine this with an atmospheric circulation model. The warm, moist air from the Pacific is carried without obstruction to Europe and Africa. In this region, the middle latitudes are in northern Africa and the Mediterranean. Since there are no high mountain ranges to generate clouds, it doesn't rain, but the climate becomes unusually humid. While it doesn't rain, deserts become capable of supporting plant growth. However, this could negatively impact certain crops. For example, wheat and soybeans in Egypt are sensitive to humidity.

There are regions where this moist air becomes rain. This occurs where it hits the Alps. To the south of the Alps, the southern parts of Italy and the western Balkans become humid.

What happens further north?

The strength of the warm current allows tropical cyclones to reach mid to high latitudes. The rain clouds from these storms are also carried far into Europe by the westerlies and the jet stream. However, there are no high mountain ranges that would cause rain north of the Alps. The air, which contains water vapor, penetrates deep into Europe. There, cold air from the Arctic arrives.

The low-salinity ocean currents are further supplemented with freshwater from rivers across Russia. This freshwater contributes to the formation of sea ice. Sea ice reflects sunlight, further accelerating the cooling. This chilled air mass is weak in the east. It is pushed back, especially during the summer, by the warmed air from the Pacific. When this cold air meets the moist, oceanic air, it causes rain. A region stretches from Poland to around Moscow, Russia, where rain continues incessantly. This area becomes cold. From spring to summer, it experiences a climate similar to Japan's rainy season.

After a short summer, the rainy season-like conditions return in the fall and winter. And in the winter, the area is covered by continental cold air, and with no warm currents to moderate the climate, it becomes abnormally cold. Eastern Europe is also an important grain-producing region. However, when the climate changes and prolonged rains set in, crop failures occur. Rye, for example, is sensitive to excessive rainfall.

In the Southern Hemisphere, there is a saying: "Roaring Forties, Furious Fifties, and Screaming Sixties."

Compared to the Northern Hemisphere, the Southern Hemisphere has a larger ocean area, which allows winds to blow without weakening.

In the vast regions of the North Pacific, North Atlantic, and the former North American Sea, which together form the "Great Northern Ocean," a somewhat weaker version of this phenomenon of "Roaring Forties, Furious Fifties, and Screaming Sixties" begins to occur.

At 40°N, from Madrid to Ankara, moist strong winds blow.

At 50°N, around the English Channel, Ardennes, Frankfurt, and Prague, powerful air currents rage above, and especially the windward side of the UK becomes fortified against aerial attacks. This strong wind zone, while the weather changes, remains a key battlefield due to the unchanging terrain of Europe.

At 60°N, the wind that runs from the southern tip of Greenland to Oslo and the Baltic Sea is initially blocked by the 2.000-meter-high Scandinavian Mountains. Here, cold rain falls, further cooling the ocean currents. Then, a dry, cold wind blows. Although better than the Southern Hemisphere, the birth of the Great Northern Ocean causes high-latitude regions to be constantly tumultuous.

It seems that the disappearance of North America has had a greater impact on its eastern side. But what about the western side?

The vast Pacific Ocean acts as a cushion, and East Asia has had a strong protective guardian: the Himalayas and the monsoon. Winds from the now warmer Indian Ocean are still blocked by mountains that rise to 8.000 meters, causing the air to cool, and the stronger updrafts result in even more intense monsoons blowing from southern China to Japan. This monsoon system, which has been further warmed, intensifies typhoons and prevents oppressive heat from lingering in the atmosphere, constantly bringing changes in weather. It's true that it's become hotter, and the rain has increased. However, the heat and cold don't stay in one place for too long, which is fortunate as the region benefits from such protective winds.

The influence of the warm current does not reach far inland. Cold air from the Siberian high-pressure system, along with freshwater from the Amur River and ice forming at its estuary, cools the now-warmed Kuroshio Current. The meeting point of the warm and cold currents, or the oceanic front, moves north from off Sanriku to around Hokkaidō, encompassing the Kuril Islands.

One of the benefits of this warming has been in rice cultivation. In Japan, young officers and non-commissioned officers often rose up due to the numerous farmers in the Tōhoku region facing bankruptcy from cold damage, and the soldiers coming from those regions were sympathetic to their plight. This issue was alleviated.

Additionally, the temperature of the Sea of Japan also rose, causing more severe winter snowfall. However, this heavy snow creates large amounts of meltwater, which works positively for rice cultivation. It was fortunate that rice, a crop from the southern wetlands, was cultivated, unlike wheat, a crop from northern dry regions.

These influences were minimal in 1940 but gradually intensified over time. The first to be affected might have been the pilots of the German Luftwaffe, who faced the stronger westerlies. The headwinds increased their fuel consumption slightly, shortening the already limited flight time of German fighter planes and leading to more casualties among bombers.

Meanwhile, British pilots reported that their Spitfire fighters, with their large wings and excellent aerial performance, were often tossed about by strong air currents. In response, Britain showcased its characteristic ingenuity by developing aircraft with powerful engines capable of generating strong torque to counter the wind, making the planes highly maneuverable but with a very "peaky" control system.

〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜

This is an explanation of ocean currents, air currents, air masses, water vapor, and the salinity of seawater. Biological, geopolitical, and resource-related topics will be covered in a later chapter.

(Since the effects will take time to manifest, some investigations will be conducted later.)

- ほうこうおんち