Modern means of crosswind (today)

Since 1980s, with the wide application of remote sensing, computing technology and meteorological satellite data, the world weather forecast has made a new leap, and the traditional weather map has been replaced by numerical weather forecast. The so-called numerical weather forecast is to describe the laws of atmospheric motion with seven differential agendas of fluid mechanics and thermodynamics. The seven agendas contain seven unknowns-maximum temperature, minimum temperature, precipitation, humidity, air pressure, wind direction and wind speed. By solving the equations with a large-scale high-speed computer, we can get the space-time analysis of seven unknowns in the future, that is, the future weather distribution. More than 30 countries in the world carry out numerical forecasting business, and developed countries have established global and limited regional forecasting models, with the highest running speed of computers reaching 4 billion times per second. The numerical prediction model of total stress has more than 30 vertical layers, and the horizontal resolution is 60 kilometers. The prediction can be effective for 10 days in the middle and high latitudes and for 5 days in the low latitudes. The horizontal resolution of the limited area prediction model is 15km, which can reach 2km in the United States and Germany.

Meteorological centers in developed countries regularly publish the weather forecast of cities or regions in China every day (Japan divides the whole country into 19 1 grid with a distance of 20 kilometers), and the forecast period is 7-8 days, rolling daily. According to the local conditions and the experience of forecasters, local meteorological stations revise the forecasts sent by meteorological centers. Almost all countries' meteorological departments implement vertical leadership, and developed countries set up stations according to climatic zones. The United States implements a two-level management system, namely, the National Meteorological Center and the Meteorological Service Desk. There are nine state-level centers-National Meteorological Center (which publishes seven-day forecasts for cities across the country every day), National Hurricane Forecasting Center, National Severe Storm Forecasting Center, National Environmental Simulation Center, National Operation Control Center, National Hydrometeorological Forecasting Center, National Aviation Forecasting Center, National Ocean Forecasting Center and National Climate Forecasting Center. There are 1 16 meteorological service desks, each equipped with advanced Doppler weather radar. Nine national centers undertake the tasks of national weather forecast, severe weather warning, aviation and navigation weather forecast. The meteorological service desk is responsible for receiving the forecast information released by the National Center, editing and modifying the latest local meteorological data and the experience of forecasters, and making local weather forecasts. However, the meteorological service desk has no right to correct the severe weather warning issued by the National Center for three reasons: first, only the National Center can obtain all numerical forecast products, meteorological satellites, weather radars and ground observation data once an hour nationwide; Second, the forecaster of the National Center is employed through national open recruitment and competition. They have both theoretical and practical experience. Thirdly, after three years of comparison, it is proved that the modification will lead to the decline of forecast quality. Japan's meteorological system is divided into three levels: meteorological agency, regional meteorological station and local meteorological station. The forecast department of Meteorological Agency issues 19 1 regional weather forecast and severe weather warning nationwide every day.

China carries out numerical forecast at 1982, and forecasts the situation in the northern hemisphere for three days every day. 1995 Cray supercomputer (with a peak operation speed of 2 billion times per second) imported from the United States makes global situation forecast for seven days every day. From 65438 to 0997, the global ten-day situation forecast was made every day. At present, the horizontal resolution of global forecast is 120km, and that of limited area forecast is 55km. China's meteorological system is divided into five levels: China Meteorological Bureau, regional meteorological bureau, provincial meteorological bureau, municipal meteorological bureau and county meteorological bureau, with more than 60,000 meteorological departments nationwide. Compared with developed countries, the main gaps in China's meteorological undertakings are:

1, the data assimilation system is backward, and the data of meteorological satellites, commercial aircraft and weather radar have not yet entered the numerical prediction system. The quantitative measurement of precipitation by weather radar has not been carried out, and the satellite cloud picture still stays at the level of "reading pictures".

2. The application of numerical forecast products has not yet formed a business.

3. The serious repetition of weather forecasting work is mainly due to the lack of guidance products, low quality and inadequate guidance provided by national centers and provincial meteorological stations. In order to serve, subordinate stations can only make long, medium and short weather forecasts independently.

Collect data through various devices, such as radar and satellite. Then use a supercomputer to analyze and calculate the future weather trend with a certain algorithm.

Because it is calculated, according to the nonlinear relationship, a little error can make a huge difference, so the weather forecast can only predict the short-term weather situation, and the long-term weather forecast may be completely inaccurate. There is a physics book "Chaos" about the related things caused by this phase.

Similarly, the forecast of Typhoon Mai Sha entering Beijing last year was completely wrong, which was also based on this.