Variability of characteristics of high-altitude jet streams based on satellite data. Models and forecasts

    High–altitude jet streams (JS) are an integral and very important component of the general circulation of the atmosphere. They concentrate the main kinetic energy of the Earth's atmosphere. The wind speed in them can exceed 100 m/s. JS are associated with the occurrence of some abnormal weather phenomena.

    The report examines the spatial and temporal variability of the Northern Hemisphere JS characteristics in the field of view of the European geostationary meteorological satellites of the second generation with a  subsatellite point of 0 degrees.  The areas of the jet stream determined by satellite data are JS sections with a horizontal plane at a level of approximately 350 gPa. The following main JS characteristics were calculated: the maximum wind speed on the axis (V_m), JS center latitude (φ) and longitude (λ), average area (S), the maximum gradient (shift) of horizontal wind speed on the cyclonic (G_c) and anticyclonic (G_a) sides, as well as the effective "life time" (τ).

    Using correlation and cross-wavelet analyses, the relationships of the JS characteristics with the upper troposphere temperature (T) at different levels and the Arctic sea ice area (S_ice) are considered. The greatest connection with T is typical for S and φ. In this case, variations of T and S occur in counter phase, and T and φ occur in phase.

    The significant relationship between the interannual S_ice variations is also observed with the area S and latitude φ of the JS center. Variations in the annual S_ice and S occur mainly in phase, while the S_ice and φ variations are close to antiphase. At the same time, the S variations are ahead of the S_ice variations by 1.5-2.5 months.

    The relationship of JS characteristics with large-scale atmospheric processes is investigated. With the general trend towards synchronicity of annual variations of S and the North Atlantic Oscillation (NAO), there are two time intervals when this trend is disrupted or weakened. The first period (2009 – early 2010) preceded the well-known abnormal weather events of 2010, which covered most of Eurasia, the second period (2013) may be associated with weather anomalies in the United States.  A comparison of the variation of the NAO index and the JS center latitude φ demonstrates their antiphase. At the same time, the features of 2013 saved.

    A comparison of variations in JS characteristics and temperature anomalies in Europe and on the European territory of Russia (ETR) has shown that when the JS center shifts northward relative to the long-term average position, in a large part of Europe and in the northern regions of the ETR the average monthly temperature is highly likely to fall below the climatic norm, and vice versa.

    Statistical models of the temporal variability of JS parameters have been constructed, in which temperature characteristics of the troposphere, the area of Arctic sea ice, and indices of large-scale processes used as predictors. The models describe from 50 to 70% of the temporal variability of S, φ and V_m. Based on the use of an AutoRegressive Integrated Moving Average model, the prediction of future changes in JS characteristics for up to 4 years was carried out.