# About the weather for tomorrow

At the beginning of spring, the mysterious but really existing

Below is a brief excursion into the history of meteorology and how Roshydromet and other modern meteorological services work.

Meteorology has a long history - the first meteorologist, apparently, was Aristotle, who wrote a treatise of the same name on weather changes; in the following centuries, they monitored the weather and systematized knowledge of it all over the world. However, meteorology, as we know it - and this is dynamic meteorology, that is, weather forecasting using mathematical equations of hydromechanics and thermodynamics - has arisen relatively recently.

We owe the term “weather forecast” to the hot-tempered captain Robert Hot Coffee Fitz Roy, who had been swimming with Darwin for almost five years during Beagle’s second voyage in the middle of the century before last. Fitz Roy discovered that weather characteristics are related to air pressure, and in his adult years he headed the meteorological department at the Ministry of Commerce, created several models of barometers and arranged the collection of data from captains who arrived at the port - in short, he did what all modern meteorologists do.

Modern meteorologists use the equations of the Norwegian Wilhelm Bjerknes, the founder of the Bergen school of science in meteorology - the solution of the hydrodynamic equations derived by him is nothing more than a weather forecast. These equations found practical application only in the fifties of the last century, when computers began to appear that could calculate them for a sufficiently large territory - the first weather forecast was considered by American meteorologists on the very first ENIAC computer with the help of John von Neumann - meteorology has not been without its known history people.

The first domestic weather calculations began in 1961 on the

Since March last year, two

Nevertheless, the accuracy of forecasts is growing. Atmospheric processes are calculated using a grid overlaid on a map of the country. Even 20 years ago, the step of such a grid was 300 kilometers - you could easily miss some small cyclone. This spring, Roshydromet began to calculate two weather models for limited territories (they are called mesoscale), one of them is a three hundred kilometer region above Moscow. The step of such a grid is 3 kilometers, so with such a scale and the availability of computing power, you can even go on to describe individual physical processes, which, of course, favorably affects the quality of the forecast.

Roman Vilfand, head of Roshydromet: “Now the weather forecast in Moscow can be calculated in increments of 3 kilometers, but in general we plan to increase this resolution to 3 kilometers in 3 years. For the Sochi Olympics, we will strive to describe processes in half a kilometer, because in conditions of Sochi’s complex orography, an even more detailed description of the weather is needed than on the plain. Sochi will be a special project for us. It’s too early to talk about an administrative decision, but as part of our research and other programs, we are preparing for the Olympics. ”

25-27 years ago, the quality of the weather forecast for one day ahead was the same as it is now on the third day - noticeable progress. Modern computing resources allow you to increase the period of time for which the forecast is made. Now the forecast in Roshydromet is built for a maximum of six days. The success of such a forecast for the first day is 95-96%, in the forecast for each next day, the success decreases by 2-3%. By the end of this year, seven-day forecasts will appear in Roshydromet, and then with the growth of computing capacities it will be possible to increase the forecast period. But not infinitely. There is the notion of a predictability limit, introduced by the American scientist Edward Lorenz (American mathematician and meteorologist, known as the author of the “butterfly effect”) - according to this limit, the weather can be predicted for two, maximum three weeks in advance.

However, with the growth of computing power, there are ways to improve the quality of the forecast even with errors in the initial data. If the usual forecasting method is called deterministic - that is, once determined, then in recent years the ensemble forecasting method has gained popularity . For this, errors in the initial data are artificially “outraged”, and the weather forecast is calculated not once, but 10, 20, 30 — in developed computer centers, ensembles are counted up to 50-60 times. An ensemble forecast allows you to create a "probability tree" - "what if the weather changes in one or another probable direction?" It is clear that such probabilistic calculations are possible only on the most modern supercomputer equipment, and there the margin for growth is absolutely incredible.

Employees of Roshydromet note that in order to proceed to probabilistic calculations, it is also necessary to prepare a consumer who is accustomed to extremely simple, deterministic forecasts: “+15, sunny, no precipitation,” which leaves no doubt. Forty years ago, probabilistic forecasting methods were introduced in the United States, but the population did not accept them. Now - perhaps due to the informatization of all segments of the population - the reaction to such forecasts is more favorable.

The competitiveness of domestic meteorology is largely determined by the technical base - in those years when new equipment was purchased and installed, as was the case in the nineties with the

Here is how

Feel free to join the ranks of Intel's readers on Habré.

Thank you for your attention, to be continued.

**ChipMan,**together with several colleagues, visited the Roshydromettsentr, where for several hours he talked with the heads of Roshydromet and his computer center and looked at supercomputer racks.Below is a brief excursion into the history of meteorology and how Roshydromet and other modern meteorological services work.

Meteorology has a long history - the first meteorologist, apparently, was Aristotle, who wrote a treatise of the same name on weather changes; in the following centuries, they monitored the weather and systematized knowledge of it all over the world. However, meteorology, as we know it - and this is dynamic meteorology, that is, weather forecasting using mathematical equations of hydromechanics and thermodynamics - has arisen relatively recently.

We owe the term “weather forecast” to the hot-tempered captain Robert Hot Coffee Fitz Roy, who had been swimming with Darwin for almost five years during Beagle’s second voyage in the middle of the century before last. Fitz Roy discovered that weather characteristics are related to air pressure, and in his adult years he headed the meteorological department at the Ministry of Commerce, created several models of barometers and arranged the collection of data from captains who arrived at the port - in short, he did what all modern meteorologists do.

Modern meteorologists use the equations of the Norwegian Wilhelm Bjerknes, the founder of the Bergen school of science in meteorology - the solution of the hydrodynamic equations derived by him is nothing more than a weather forecast. These equations found practical application only in the fifties of the last century, when computers began to appear that could calculate them for a sufficiently large territory - the first weather forecast was considered by American meteorologists on the very first ENIAC computer with the help of John von Neumann - meteorology has not been without its known history people.

The first domestic weather calculations began in 1961 on the

**M20**computerperforming 20 thousand operations per second. M20 failure time - 15 minutes; the weather model was considered much longer, so the employees of the Hydrometeorological Center had to go to various tricks. The specific nature of weather computing is such that computer equipment is used twenty-four hours a day, seven days a week, all year round - the weather never ceases to change, so the Hydrometeorological center was and remains a serious testing ground for supercomputers: until the mid-seventies, when domestic computer developments replaced by analogues of IBM machines, the Hydrometeorological Center received the first serial numbers of Soviet computers.Since March last year, two

**SGI Altix**supercomputer systems have been launched at the Hydrometeorological Center11 and 16 TFlops - more than a billion times faster than the first M20 computer. Meanwhile, weather forecasts have since not become a billion times more accurate. The accuracy of weather forecasting is related to computing resources, but not linearly. First, the equations mentioned have only approximate solutions. Secondly, literally until recently, these equations had to be simplified so that the weather forecast was calculated quickly enough, otherwise an accurate daily forecast could be considered a couple of years. Thirdly, the accuracy and efficiency of measuring weather stations and probes will always remain an unresolved problem - all instruments have errors, and it is clear that data from probes and weather stations do not come at once - collecting and normalizing data is also a separate difficult task.Nevertheless, the accuracy of forecasts is growing. Atmospheric processes are calculated using a grid overlaid on a map of the country. Even 20 years ago, the step of such a grid was 300 kilometers - you could easily miss some small cyclone. This spring, Roshydromet began to calculate two weather models for limited territories (they are called mesoscale), one of them is a three hundred kilometer region above Moscow. The step of such a grid is 3 kilometers, so with such a scale and the availability of computing power, you can even go on to describe individual physical processes, which, of course, favorably affects the quality of the forecast.

Roman Vilfand, head of Roshydromet: “Now the weather forecast in Moscow can be calculated in increments of 3 kilometers, but in general we plan to increase this resolution to 3 kilometers in 3 years. For the Sochi Olympics, we will strive to describe processes in half a kilometer, because in conditions of Sochi’s complex orography, an even more detailed description of the weather is needed than on the plain. Sochi will be a special project for us. It’s too early to talk about an administrative decision, but as part of our research and other programs, we are preparing for the Olympics. ”

25-27 years ago, the quality of the weather forecast for one day ahead was the same as it is now on the third day - noticeable progress. Modern computing resources allow you to increase the period of time for which the forecast is made. Now the forecast in Roshydromet is built for a maximum of six days. The success of such a forecast for the first day is 95-96%, in the forecast for each next day, the success decreases by 2-3%. By the end of this year, seven-day forecasts will appear in Roshydromet, and then with the growth of computing capacities it will be possible to increase the forecast period. But not infinitely. There is the notion of a predictability limit, introduced by the American scientist Edward Lorenz (American mathematician and meteorologist, known as the author of the “butterfly effect”) - according to this limit, the weather can be predicted for two, maximum three weeks in advance.

However, with the growth of computing power, there are ways to improve the quality of the forecast even with errors in the initial data. If the usual forecasting method is called deterministic - that is, once determined, then in recent years the ensemble forecasting method has gained popularity . For this, errors in the initial data are artificially “outraged”, and the weather forecast is calculated not once, but 10, 20, 30 — in developed computer centers, ensembles are counted up to 50-60 times. An ensemble forecast allows you to create a "probability tree" - "what if the weather changes in one or another probable direction?" It is clear that such probabilistic calculations are possible only on the most modern supercomputer equipment, and there the margin for growth is absolutely incredible.

Employees of Roshydromet note that in order to proceed to probabilistic calculations, it is also necessary to prepare a consumer who is accustomed to extremely simple, deterministic forecasts: “+15, sunny, no precipitation,” which leaves no doubt. Forty years ago, probabilistic forecasting methods were introduced in the United States, but the population did not accept them. Now - perhaps due to the informatization of all segments of the population - the reaction to such forecasts is more favorable.

The competitiveness of domestic meteorology is largely determined by the technical base - in those years when new equipment was purchased and installed, as was the case in the nineties with the

**Cray Y-MP**supercomputer, we found ourselves in the top ten meteorological services of the planet. As soon as there was a pause in the re-equipment of the Roshydromet computer center, we began to lag behind foreign colleagues. However, there are a number of standards within the World Meteorological Organization that provide weather information from around the globe. Each country tries to make its contribution to the Global Telecommunication System, with the help of which meteorologists collect information, because the weather from neighbors plays a significant role in their forecast. In the 90s, when the meteorological network began to collapse in our country, for obvious reasons, American meteorologists instantly felt this - the quality of their forecasts on the 4th ... 5th day noticeably worsened - especially in the absence of weather data in Siberia. It is clear that the opposite is true:Here is how

**Vladimir Antsypovich**, head of the Roshydromet computing center, comments on this : “Meteorology is an unusual industry. There are no problems, conflicts or complex relationships between the national meteorological services that make up the World Meteorological Organization. Absolutely everyone is interested in making each national meteorological service work better and make observations more accurate. ”Feel free to join the ranks of Intel's readers on Habré.

Thank you for your attention, to be continued.

**Good luck!**