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Abstract—The paper presents the results of a study of spatiotemporal variability of the characteristics of the wind field in the free atmosphere of the Northern Hemisphere in the SEVIRI radiometer field of view of European geostationary meteorological satellites of the second generation Meteosat 8–Meteosat 11 in the time interval 2007–2021. It is noted that the maximum wind speeds, as well as the maximum average monthly and seasonal anomalies of the wind speed modulus, are observed over the Atlantic. A feature of the temporal variability of the area-averaged wind speed modulus is revealed, which consists in a change in the sign of the trend at the turn of 2015–2017 from positive to negative. At the same time, positive linear trends in the time intervals from 2007 to the points of a change in the sign of the trend over the Atlantic, the entire region under consideration and Eurasia, including the European territory of the Russian Federation, are significantly different from zero with a probability of more than 95% and the negative trend is significant only over the Atlantic. A high correlation was noted in the area of seasonal wind speed variations with the area of Arctic sea ice and temperature characteristics of the troposphere at levels of 500 and 200 hPa. Based on the analysis of the relationship between wind speed variability and the main climatic characteristics and large-scale atmospheric processes, a scheme is proposed for the effect of the accelerating reduction in the area of Arctic sea ice associated with global warming on wind speed in the free atmosphere. [ABSTRACT FROM AUTHOR]

The warming in the first half of the 20th century in the Northern Hemisphere (NH) (early 20th century warming (ETCW)) was comparable in magnitude to the current warming, but occurred at a time when the growth rate of the greenhouse gas (GG) concentration in the atmosphere was 4–5 times slower than in recent decades. The mechanisms of the early warming are still a subject of discussion. The ETCW was most pronounced in the high latitudes of the NH, and the recent reconstructions consistently indicate a significant negative anomaly of the Arctic sea ice area during early warming period linked with enhanced Atlantic water inflow to the Arctic and amplified warming in high latitudes of the NH. Assessing the contributions of internal variability and external natural and anthropogenic factors to this climatic anomaly is key for understanding historical and modern climate dynamics. This paper considers mechanisms of ETCW associated with various internal variability and external anthropogenic and natural factors. An analysis of the findings on the topic of long-term studies of climate variations in the NH during the period of instrumental observations does not allow one to attribute the ETCW to one particular mechanism of internal climate variability or external forcing of the climate. Most likely, this event was caused by a combined effect of long-term climatic fluctuations in the North Atlantic and the North Pacific with a noticeable contribution of external radiative forcing associated with a decrease in volcanic activity, changes in solar activity, and an increase in GG concentration in the atmosphere due to anthropogenic emissions. Furthermore, this climate variation in high latitudes of the NH has been enhanced by a number of positive feedbacks. An overview of existing research is given, as are the main mechanisms of internal and external climate variability in the NH in the early 20th century. Despite the fact that the internal variability of the climate system is apparently the main mechanism that explains the ETCW, the quantitative assessment of the contribution of each factor remains uncertain, since it significantly depends on the initial conditions in the models and the lack of instrumental data in the early 20th century, especially in polar latitudes. [ABSTRACT FROM AUTHOR]

Comparative estimation of long-term trends in the variability of the largest Atlantic upwellings (Canary and Benguela) has been carried out in this paper. Satellite data on the sea surface temperature and three surface wind datasets prepared by different scientific groups have been used. The difference in the calculated absolute vertical velocities due to alongshore wind drift and horizontal wind-field nonuniformity reach tens of percent. All time series demonstrate the common tendency for the intensification of the upwellings from the 1980s to the early 1990s. This confirms published materials concerning the intensification of Canary and Benguela upwellings under global warming. However, since the late 1990s, the intensification of the upwellings has nearly ceased. This proves the highly important role of the natural interdecadal climate variations in the variability of intensity of generation of upwellings during the period of regular satellite measurements. [ABSTRACT FROM AUTHOR]

Observations and results of numerical experiments with climate models under different green-house-gas emission scenarios point to a reconstruction of the thermal and circulation atmospheric regime induced by global climate changes. In particular, an increase in atmospheric static stability, a poleward shift of midlatitude storm tracks, a decrease in the frequency of extratropical cyclones, and a change in their intensity are found at tropical and middle latitudes. This paper, using a simplified idealized model of baroclinic instability, investigates the influence of small variations in the basic atmospheric parameters governing the development of baroclinic instability, namely, static stability and the vertical quasi-zonal flow velocity shear induced by a meridional temperature gradient, on variations in the growth rate of the amplitude of synopticscale unstable waves. Analytical expressions are derived for absolute and relative sensitivity functions to estimate the absolute and relative contribution of variations in the static stability and the vertical flow velocity shear to a change in the growth rate of the amplitude of unstable modes. [ABSTRACT FROM AUTHOR]