Alexander Konoshonkin, an associate professor at TSU and head of the laboratory of the Institute of Atmospheric Optics named after V.E. Zuyev, Siberian Branch of the Russian Academy of Sciences, has completed a project to develop a theoretical model of light scattering on cirrus clouds during laser probing. This model will help to produce more accurate weather forecasts and to explain and predict global climate change.
Cirrus clouds are located 8-12 kilometers above the earth and are clouds of the upper tier. They consist of ice crystals that can change their position in space. The amount of solar energy entering the earth's atmosphere can change depending on the orientation of the crystals, and that means that cirrus clouds are directly related to the planet’s weather and climate and largely determine the amount of heat in the atmosphere.
- The dimensions of the crystals in the cloud vary considerably, from 10 microns to 1 mm. First, we studied the regular hexagonal crystals, and then turned our attention to non-ideal crystals, because when the shape of the crystal changes by even one degree, the characteristics of the light scattering change qualitatively. This made it possible to more accurately interpret the data obtained with the high-altitude polarization lidar of TSU, and it is better for predicting, for example, the air temperature at the earth's surface, - said Alexander Konoshonkin.
Ice crystals have the form of convex hexagons, plates, or columns and can grow and join with each other. According to the scientist, the shape of the crystals depends on the weather conditions. Thus, crystals in the form of a plate can be produced in the upper layers of the atmosphere at -40 ° C, and at -60 ° C we obtain columns. For each type of crystal, their orientation in space and their density are characterized by their own optical effects. The knowledge of these properties helped to build a model of light scattering through cirrus clouds during laser probing.
- We examined how the lidar radiation passes through the clouds. It is a signal emanating from one point and returning sharply backward, and it was enough to choose only one point from the entire scattering area. The next goal is to calculate the model for the flow of light through the cirrus clouds: how much heat has passed, how much has reflected, how much settled in the upper layers of the atmosphere, how much it reached the lower layers, and so on, - added Alexander Konoshonkin.
The scientist plans to submit the final model to Roshydromet to integrate it into the overall weather forecasting program. Currently, the service takes into account the contribution of cirrus clouds to changes in weather and climate only approximately, and therefore the calculations of radiophysicist will make weather forecasts more accurate.