Experts reveal the weather protection work behind the celebrations of the centennial of the founding of the party——
The strongest class with 35 people provides accurate hour-by-hour forecasts
In Beijing in June and July, high temperatures, thunderstorms, strong winds, hail and other weather are "frequent visitors."
In a season where strong convective weather is so frequent, how did the party’s centennial celebration series “run away” with the weather, and successfully completed again and again?
Yesterday, experts from the special class of meteorological forecast service for the celebration of the Beijing Meteorological Bureau made their collective appearance for the first time, revealing the tense and exciting guarantee moments behind the celebrations for the centenary of the founding of the party.
Challenge to "precisely forecast two locations at the same time"
"The weather in June is like the 72 changes of Monkey King. All kinds of strong convective weather come and go unpredictable." Speaking of the weather in Beijing after the flood, Lei Lei, chief forecaster of the Beijing Meteorological Observatory, made an analogy. In this weather background, it is difficult to give a fixed, fixed, and quantitative forecast one to three days in advance.
Coupled with the influence of factors such as Beijing's mountainous terrain on three sides and the complex underlying surface of a megacity, accurate weather forecasts are even more difficult.
"Compared with previous major events, this forecast needs to pay attention to the weather of the celebrations held at Tiananmen Square and the theatrical performances held at the National Stadium. The two events are held at different times and locations, and have different high demand for weather conditions." Lei Lei said that making weather forecasts for two events at the same time during the flood season is a very big challenge.
In order to cope with and solve this problem and challenge, 35 forecasting experts from Beijing Meteorological Observatory, National Meteorological Center, Beijing Army, scientific research institutes and civil aviation department jointly formed the "strongest lineup" forecasting special class.
Beginning in November 2020, the forecasting class has analyzed the types of high-impact weather, weather background conceptual models, and forecast difficulties in the Tiananmen area in the past 20 years before and after "7.1."
Especially for the period from June 20th to July 5th from 2010 to 2020, the daily weather analysis and statistics were carried out to condense the typical case weather system and key points of forecasting.
Through repeated "digging" details and holding seminars on high-impact weather during the same period in history, experts have gradually become aware of the situation in the target area.
Observe the seat temperature in the square to avoid heatstroke
"Our usual weather forecast is to use shutters to predict the static temperature in the air, but the human body's perception of temperature under different ground environments is different." Lei Lei said, for example, Tiananmen Square has a large area and the ground is made of cement. , It may be more sunny and windy during the day, but the temperature will drop faster at night.
In order to further refine the forecast, the forecast team surveyed the observation environment of Tiananmen Square and the Bird's Nest on the spot, and the results confirmed that there are indeed differences in the wind and temperature of the meteorological observatory and the inside of Tiananmen Square and the Bird's Nest.
Through on-site exploration, experts have a good idea of the characteristics of the meteorological elements of the two locations. At the same time, they have tried and completed some unconventional weather forecasts: in response to the needs of avoiding heatstroke due to high temperature of attendees, they urgently carried out temperature observations and fine-tuned seats with different materials. To ensure the safety of the fireworks display on the top of the Bird’s Nest and the WIA air show, we provide live and forecast services of meteorological elements such as wind speeds and directions at different altitudes; provide visibility and cloud bottom according to the needs of aircraft flight performances in Tiananmen Forecast services such as altitude and cloud cover.
"Different venues and different activities have different requirements for meteorological information." Zhao Wei, chief forecaster of the Beijing Meteorological Observatory responsible for on-site service guarantees, further explained the necessity of unconventional forecasts. "For example, fireworks are set off during the Bird’s Nest performance. We need to make fine forecasts for key time nodes of fireworks display, with minute-level forecasts of wind direction, wind speed and relative humidity, and rainfall during audience withdrawal. Another example is the comfort of people in Tiananmen in sunny and hot weather. It has a lot to do with the temperature changes after the seats of different materials are exposed to the sun, so we provide a refined temperature forecast service." Zhao Wei said that the on-site service personnel will timely feedback the demand information to the Meteorological Bureau and the expert team through on-site experience and understanding. It will focus on these contents and give precautionary suggestions in the weather consultation and service.
Six live events with high temperature and strong convection competed on stage
According to Zhao Wei, the three on-site guarantee times for the Bird's Nest performances are June 22, 25 and 28 respectively.
The three performances encountered different weather: on the 22nd, Beijing was sunny and sunny during the day, and the temperature was high, and gusts were obvious during the performance; on the 25th, there were strong convective weather such as thunder and lightning, short-term heavy rainfall, strong winds, and hail in Beijing. The gale was suspended for more than half an hour; there was a risk of scattered thundershowers on the 28th, and the temperature and humidity were high and the body felt sultry.
Similarly, the three on-site guarantee activities of the Tiananmen celebration meeting also encountered three different types of weather: June 12, Tiananmen had a high temperature above 35℃; June 26, Beijing had a small shower; June 30 to July 1. The weather during the celebration ceremony was particularly complicated on August 30. “Thundershowers appeared on the night of the 30th, sporadic showers on the morning of the 1st, and thunderstorms and strong winds on the afternoon of the 1st.” Zhao Wei said that during the six on-site guarantees, high temperatures and strong convection competed on the scene. The weather is complex and changeable, which fully reflects the characteristics of Beijing’s weather at the end of June. It also proves from the side how difficult the forecast is, the multiple support tasks, and the pressure on the on-site weather service.
At noon on July 1, the celebration meeting in Tiananmen Square ended, but the weather service guarantee did not stop.
According to forecasts, during the dismissal of the conference in the afternoon, the Tiananmen area will be affected by the squall line system and there will be thunderstorms and winds.
“In order to ensure the smooth progress of the dismantling activities and the safety of tens of thousands of workers on site, we use multi-band radar networking products, precision three-dimensional monitoring network data in key areas, and core technology forecast products such as the'Rui Tu' model system. An accurate nowcast was made during the thunderstorm on the afternoon of the day. The two echo bands were searched for precipitation gaps, and the work time was “grabbed” for the dismantling work, ensuring the smooth progress of the later dismantling work."
Text/Reporter Zhao Tingting