How to break the "curse" that the longer the time span, the less accurate the weather forecast?
The National Natural Science Foundation of China's Climate System Prediction Basic Science Center accurately grasps the pulse of climate
Our reporter Zhang Ye
Weather and climate are closely related to people's lives.
From listening to the Central Meteorological Observatory’s weather forecast for the next day at 7:30 pm every night, to checking the weather for the next 15 days on a smart phone at any time, it is enough to show people's concern about the weather and climate.
However, careful people will find that the weather forecast results within 24 hours are more accurate. The later the time, the more prone to deviations in the forecast results, and the weather conditions after a month can hardly be accurately predicted.
On December 10, the National Natural Science Foundation of China's Climate System Prediction Basic Science Center was inaugurated at Nanjing University of Information Science and Technology.
As the first basic science center to settle in Jiangsu, the project is led by Professor Wang Huijun of Nanjing University of Information Science and Technology, and jointly implemented with Sun Yat-sen University.
As the chief expert of the project, Wang Huijun said that the center will focus on solving scientific problems such as 10-30 days extended weather forecast, the El Niño phenomenon within two years, and future global climate change, and it is expected to become one of the important think tanks for global climate prediction.
Bridging the "gap" between weather forecasting and climate prediction
"Previous research on weather forecasting is divided into weather forecasting and climate forecasting. The time limit for weather forecasting is generally 1-10 days, and the time limit for climate forecasting is one or two months to several years, with an extended period of 10-30 days. Relatively speaking, the weather forecasts for China don’t involve much.” Luo Jingjia, a professor at Nanjing University of Information Technology, told reporters.
Weather forecasts and climate predictions look the same literally, but the research methods are different.
Luo Jingjia said that weather forecasts generally take into account factors such as temperature, pressure, and temperature. These are the results of changes in the atmosphere itself, and this change is very fast; while climate change is much slower. Scientists need to consider the atmosphere when making predictions. The exchange of material and energy between multiple layers such as, ocean and land.
Extended-range weather forecasting is somewhere in between. It is necessary to observe the clouds and understand the weather, but also to calculate the influence of the ocean on various indicators of the atmosphere and land. If you simply use traditional weather forecasting methods, deviations will easily occur.
At present, in the field of global atmospheric science, extended weather forecasting is an unresolved problem.
In 2013, the World Meteorological Organization took extended-range forecasting as one of its key tasks and proposed the international "Subseason to Seasonal Prediction Plan". At present, 11 business models around the world participate in this plan, mainly focusing on sub-seasons with high impact weather. Predictability (that is, forecasting changes in extreme weather such as torrential rains, cold waves, and droughts within a few weeks), and models developed in my country are also among them.
From the time scale, the weather forecast in the extended period can be regarded as the "gap" between conventional weather forecast and climate prediction.
"It is very difficult to fill this gap. It is necessary to accurately describe the process of multi-scale interaction between weather and climate systems in climate models." said Xu Bangqi, a professor at Nanjing University of Information Science and Technology. The research team will strengthen the inter-seasonal oscillation and its scale interaction. Mechanism research and new extended-range forecasting theories and methods are proposed. "It is expected to improve the accuracy of extended-range forecasting. Residents can avoid abnormal weather when traveling, and disaster prevention departments can also take relevant preventive measures in advance."
Challenge the world-class climate prediction problem
"This summer, the middle and lower reaches of the Yangtze River suffered heavy rainfall, and some areas experienced large floods that exceeded the historical warning level. This is the El Niño phenomenon at work." Luo Jingjia told reporters.
The El Niño phenomenon refers to the abnormal and continuous warming of sea water temperature in the tropical ocean areas of the central and eastern Pacific Ocean, which affects the entire world climate.
East Asia is close to the Pacific Ocean, and climate change is closely related to El Niño.
According to Luo Jingjia, the research team has developed a high-precision climate prediction system that can not only couple different models of the atmosphere, ocean, and land surface, to make targeted predictions of the climate in the next two years, but also combine artificial Intelligent algorithms improve the accuracy of predictions, and the accuracy of the prediction of El Niño phenomenon 18 months in advance has been increased to more than 80%.
Currently, only this system in the world can provide real-time El Niño prediction results for the next two years.
In March of this year, they submitted the forecast of heavy rainfall in the Yangtze River Basin this summer to relevant authorities based on this system.
"In the future, we will continue to optimize this system. For example, the forecast of rainfall intensity and distribution area will be more accurate." Luo Jingjia said.
In addition, East Asia is affected by monsoons all year round.
“The land-sea system in the monsoon region is complex, with the Qinghai-Tibet Plateau to the west, the Pacific sub-high pressure belt to the east, the cold Siberian high to the north, and the sea temperature to the south to be higher.” Professor Yang Song from Sun Yat-sen University said that the world is affected by both winter monsoon and summer. The monsoon affects only East Asia, and it is very difficult to accurately predict climate change in this region.
However, my country's disaster reduction and prevention, the construction of ecological civilization, and the response to climate change all require stable support from meteorological science research.
Wang Huijun told reporters that climate prediction is a world-class scientific problem with strong social needs. So far, a complete climate prediction theory has not been established, and no country in the world has a mature climate prediction business system.
"The purpose of establishing the Climate System Prediction Basic Science Center is to focus on the three major scientific problems in climate prediction research: El Niño and Southern Oscillation (ENSO) and sea temperature prediction, extended-range weather forecast, and interannual-interdecadal climate prediction. , We will start scientific research on monsoon system dynamics theory, refined land surface process model, tropical air-sea interaction, intraseasonal oscillation, interannual-decadal climate prediction theory, and strive to achieve several key breakthroughs to improve climate prediction science Level and accuracy."