Nation saw great steps in weather prediction

A mathematical breakthrough by a Chinese meteorologist six decades ago that dramatically improved the accuracy of weather forecasts has seen him honored with the country's top scientific award.

Chinese meteorology has advanced greatly over the past century, with the country now matching many developed countries in its use of high-end technologies to monitor atmospheric conditions and make accurate forecasts. But those achievements would not have been possible without basic theoretical research led by meteorologist Zeng Qingcun, an academician of the Chinese Academy of Sciences.

His scientific breakthroughs are still widely used today in weather forecasting and the study of global climate change, meteorological hazards and disaster risk reduction.

It was because of these contributions that he received the State Preeminent Science and Technology Award, the highest scientific award in China.

Zeng, 85, was born in 1935 in Yangjiang, Guangdong province. Growing up in a peasant family in the countryside, he was involved in farm work when he was young and knew how changes in the weather could affect harvests.

In 1952, Zeng enrolled in Peking University to study physics and was assigned to the field of atmospheric physics.

In 1954, an overnight frost froze about 40 percent of the wheat in Henan province, dealing a severe blow to food production.

"If we could predict the weather in advance and take precautions, we would reduce great losses," Zeng said, adding that the event reinforced his understanding of the significance of weather prediction.

Weather forecasts in China in the 1950s were highly dependent on observations and personal experience.

"In the past, people drew a weather map and used their previous experiences to predict the weather, which is obviously too subjective," Zeng said.

"You need to use science. You have to understand why the weather changes this way and what rules the changes follow. According to the rules, you can write them into equations and solve them mathematically, this is called numerical weather forecasting."

Numerical weather prediction was pioneered in the 1920s by a British scientist. However, such models require vast data sets and very complex calculations and it was not until the 1950s, with the advent of computers, that the United States embarked on numerical weather prediction.

The equations used－known as primitive equations－are now the core of every general circulation model for atmospheric research, taking into account the fundamentals of atmospheric dynamics, including the Earth's rotation, fluid dynamics and thermodynamics.

The models can simulate real-world atmospheric activities such as the formation and evolution of tropical cyclones.

They are so complicated that the ability to solve them is one of the indicators used to determine the power of today's supercomputers.

Due to their complexity, scientists in the 1950s focused on simpler models that left the indicators out, but that limited the accuracy and timeliness of their forecasts.

In 1957, Zeng was sent to the Soviet Union to pursue his studies in numerical weather prediction.

His tutor assigned him a dissertation topic that had puzzled the world: how to use primitive equations to approximate atmospheric flows and predict short-range weather.

Zeng said many of his teachers and classmates urged the tutor not to give such a difficult project to a young man, saying it could affect his graduation prospects.

But Zeng's tutor trusted his mathematical capabilities and Zeng did not fail the tutor's expectations.

In 1961, Zeng's dissertation was published in Russian. In it, he described a mathematical integration method called "semi-implicit scheme" he designed to separately solve the primitive equations for atmospheric motions on different time scales.

The Moscow World Meteorological Center has applied the scheme in operational predictions since 1963, raising forecast accuracy by 61 percent.

"Zeng is the first in the world to solve the most complicated equations using a semi-implicit scheme, which opened a new chapter in the world's numerical weather predictions. It is a milestone contribution," said Wang Huijun, a CAS academician who works at Nanjing University of Information Science and Technology.

In 2016, the World Meteorological Organization awarded Zeng the IMO Prize, the most important award in meteorology.