An assessment of the plausible climate change in precipitation and surface air temperature (SAT) over the European region by the end of the 21st century is provided. The assessment is based on the results of output of the ocean–atmosphere models participating in the Coupled Model Intercomparison Project, phase 5 (CMIP5). Six climate models that best reproduce the historical behaviour of SAT over greater Europe were selected from the CMIP5 project using a performance-based selection method of CMIP5 general circulation models for further assessments. The analysis of historical simulations within the scope of the CMIP5 project reveals that six models (namely, CNRM-CM5, HadGEM2ES, GFDL-CM3, CanESM2, MIROC5 and MPI-ESM-LR) sufficiently reproduce historical tendencies and natural variability over the region of interest. The climate change in SAT and precipitation by the end of the 21st century (2070–2099) was examined within the scope of RCP4.5 and RCP8.5 scenarios for these selected models. Typical regional warming due to RCP4.5 (RCP8.5) scenario is assessed as 3–4.5 °C (as 4–8 °C) in summer and winter, while a significant reduction of precipitation (typically 20–40%) is obtained only in summer.

The Indian Ocean dipole (IOD) is one of the main modes characterizing the interannual variability of the large-scale ocean–atmosphere interaction in the equatorial zone of the World Ocean. A dipole manifests itself as an out-of-phase interannual fluctuation of the ocean–atmosphere characteristics in the western and eastern parts of the equatorial–tropical zone of the Indian Ocean. IOD can be a consequence of the ENSO (El Niño–Southern Oscillation) events in the Pacific Ocean, or it can be independent of them and arise due to the Indian Ocean inherent processes. Earlier, it was suggested that the generation of the long planetary waves in the Indian Ocean by the ENSO events is one of the mechanisms of the ENSO impact on the IOD. However, quite often, such a mechanism is not the case and IOD is generated itself as an independent Indian Ocean mode. We hypothesized that this generation is due to the growing oceanic disturbances, as a result of instability of the system of Indian Ocean zonal currents in the vicinity of the critical layer, in which the phase velocity of Rossby waves is equal to the average velocity of the zonal currents. In the present work, the study of the features of the formation of the critical layer in the equatorial–tropical zone of the Indian Ocean is continued using different oceanic re-analyses and standard theory of the Rossby waves. As a result of comparison of different re-analyses data with the RAMA (The Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction) measurements, the operative re-analysis ORAS5 output of European Centre for Medium-Range Weather Forecasts (ECMWF) on potential temperature, salinity, and the zonal component of the currents’ velocity for the period 1979–2018 was used. Monthly profiles of potential temperature, salinity, and the zonal component of the currents’ velocity were selected from the ORAS5 archive for the sections situated between 7.5–15.5° S and 50–100° E. From these data and for each month, using the standard theory of planetary waves, the phase velocity of the lowest baroclinic mode of the Rossby long waves was calculated and the critical layers were determined. For each critical layer, its length was calculated. The obtained time series of the length of the critical layers were compared to the variability of dipole mode index (DMI). It is shown that the majority of the cases of the IOD generation as inherent (independent on the Pacific processes) mode were accompanied by the critical layer formation in the region of interest. Usually, the critical layers occur in spring, one to two months before the onset of the positive IOD events. This indicates that the presence of instability in the system of the zonal currents can be a reason for the generation of IOD and the asymmetry of the amplitude of the dipole mode index between positive and negative events. During the extremely intense ENSO event of 1997–1998, which was accompanied by the strong IOD event, the critical layer in the equatorial–tropical zone of the Indian Ocean was absent. This ENSO event generated the oceanic planetary waves at the eastern edge of the Indian Ocean. Therefore, it is shown that the above mechanism of the ENSO–IOD interaction is a reality.

Long-term trends in the sea surface temperature in the Canary upwelling zone and their causes are analyzed on the basis of satellite data from the 1980s until the present. It is shown that...

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.

The issue of long-term tendencies in the sea surface temperature (SST) in the Benguela upwelling region and their causes is examined using the daily satellite data of the SST for 1985–2017 and the near-surface wind for 1988–2017. It is shown that in the Benguela upwelling region there has been a significant intensification of offshore winds in the last 20 years. This is accompanied by a decrease in the thermal upwelling index (taking into account the sign of the index or an increase in its absolute values) in the southern part of the Benguela upwelling, but it practically does not influence this indicator in its northern part. The probable cause for this difference is the change in the wind-field structure, which results in opposite trends in the magnitude of the wind stress curl in different parts of the Benguela upwelling. In the southern part of the Benguela upwelling, both the coastal upwelling and the vertical velocities due to the vorticity of the near-water wind intensify, while in its northern part the corresponding trends have opposite signs. This leads to a partial compensation of these two effects in the northern part of the Benguela upwelling. The cause for the change in the wind-field structure is the displacement of the center of the Subtropical High to the southeast and the concomitant reversal of the near-surface wind vectors in the coastal zone.