Chinanews.com, Beijing, August 11 (Reporter Sun Zifa) Although nearly three months have passed since the Gansu "Silver Marathon Accident" that killed 21 people and injured 8 people, the analysis of the causes behind the accident and the summary of experience and lessons have attracted the academic community and the public. stay tuned.
The latest issue of the "Progress in Atmospheric Science", a professional journal of the Institute of Atmospheric Physics, Chinese Academy of Sciences, published a research paper by atmospheric science experts that pointed out that the direct cause of the "Silver Marathon accident" was the lack of disaster and impact forecasts. It is recommended that disaster and impact forecasts should be vigorously developed in the future. Etc., in order to improve the value of weather forecasts and avoid the recurrence of this type of accident tragedy.
The cover article of "Progress in Atmospheric Science" jointly completed by the team of Professor Qinghong Zhang from the Department of Atmospheric and Oceanic Sciences of the School of Physics of Peking University, the United Nations National Meteorological Center, senior scientist Sun Juanzhen of the National Center for Atmospheric Research, and Academician Mu Mu of Fudan University stated that the day of the accident The competition area is affected by the transit of a common large-scale cold front weather system. At noon of the day, the competition field experienced a small probability of occurrence of low temperature, strong wind and precipitation at the same time (the probability of occurrence in the past 6 years is 0.1%).
They used local site observations, operational ensemble forecasts and other data to analyze the impact system, extremes and predictability of the weather in the CP2-CP3 stage where the accident occurred, and clarified "high-impact weather" and "extreme weather" from an academic perspective. The definition of, summarizing the lessons learned from this tragedy.
How bad is the weather?
According to experts, on the day of the event, a cold front system with a length of more than 3,000 kilometers moved from northwest to southeast, affecting the track.
About 7 hours before the start of the game, the ground front passed CP3, and the ground temperature was 12.6 degrees Celsius. Affected by the cold air behind the front, the temperature of CP3 continued to drop and dropped to a minimum of 3.0 degrees Celsius 3 hours after the start of the game (12 noon). At the same time, gusts reached a maximum value of 11.2 m/s at around 11 o'clock, and precipitation occurred from 11 to 19 o'clock, and it was more likely to appear as hail or sleet (rather than freezing rain or hail).
Taking into account the effects of wind chill and precipitation at the same time, the somatosensory temperature of CP3 reached the lowest minus 5.1 degrees Celsius at 12 noon that day.
How extreme is the weather?
Since the automatic weather stations near CP2 to CP3 were built late, experts extracted the hourly temperature, gusts, and precipitation of May 2016-2021 from 13 observation stations near CP3 and constructed the somatosensory temperature for the extremes of this weather event. The analysis results show that the weather during the time of the disaster is undoubtedly an extremely cold event and an extreme windy event.
Schematic diagram of the climbing stage from CP2 (River Valley) to CP3 (Mountain Top) where the accident occurred.
Photo courtesy of Institute of Atmospheric Sciences, Chinese Academy of Sciences
They pointed out that although extreme weather has a clear and quantitative definition, high-impact weather does not have a clear and quantitative definition and needs to be linked to human activities.
As this extreme weather occurred during the marathon, causing casualties and other impacts, it is also a high-impact weather.
Can the weather be forecast?
Experts say that the deterministic forecast of the European Centre for Medium-Range Weather Forecast (ECMWF) forecasts the time of the cold front passing CP3 very well 30 hours in advance, and China's Global/Regional Assimilation Forecast System (GRAPES) forecast model also makes similar forecasts.
They also tested the effect of the ECMWF and GRAPES ensemble forecasting models on the weather process. Among them, the ECMWF model for temperature forecasting has a better effect. This model has a significant role in guiding wind forecasts, and even half of the ensemble members 10 days in advance. A strong wind process is forecast to occur.
For precipitation forecasts, both models also have good performance.
What are the lessons learned?
Experts said that although the numerical weather model has provided more accurate forecast information, and the local weather station also issued a gale warning signal before the game, the tragedy of the "Silver Marathon accident" still occurred. Three lessons can be summarized from this, hoping to remind the society Vigilance and concern from all walks of life:
First, accurate weather forecasts do not directly mean that tragedies can be avoided. Disaster forecasting, impact forecasting, and early warning systems should be developed to meet the needs of different users to reduce the risk of people's life and property loss.
The second is that probabilistic forecasting has not yet been accepted by the public, but it can provide very valuable information for scientific decision-making.
Therefore, it should be issued by the government meteorological agency and popularized to the public in order to be widely accepted and applied.
The third is to disseminate the knowledge of how to assess high-impact weather to the public. If the organizers and participants of the Silver Marathon can make a good impact forecast and assessment in advance, this disaster may be avoided.
"Successful disaster prevention requires cooperation between scientists in different fields, government departments at all levels, the news media, and the public. The 10-year International High Impact Weather Program (HIWeather) initiated by the World Meteorological Organization (WMO) provides a good Demonstration." Professor Zhang Qinghong concluded. (Finish)