Figure 2 (top panel), as already mentioned, shows a map of the mean difference
of the surface atmospheric pressure between two consequent climate scenarios,
namely the relatively warmer (1975–1999) and the cooler (1950–1974) periods. As
one can see in this case, the pressure distribution in the tropical zone of the Pacific
Ocean is similar to the distribution characteristic of the El Niño events (Fig. 1). In
both cases, the region of the positive anomalies of the atmospheric pressure is
surrounded by the zones of negative anomalies. However, in the case of the
interannual GAO at the polar latitudes, the negative anomalies are replaced with the
positive ones, and in the case of the inter-decadal GAO they remain negative up to
the Pole.
The difference in the temperature distribution in the tropical Pacific (Fig. 2,
bottom panel) is similar to the distribution shown in Fig. 1, i.e., the presence of
positive T anomalies in the eastern zone. Therefore, in many studies [3, 12–15]
these changes in the pressure and temperature are called the inter-decadal oscillations like El Niño. However, Fig. 2 (top panel) shows that changes in the pressure
considered here are global but not limited to the tropical Pacific. Therefore, it is
more correct to call them inter-decadal global oscillations, what we do and offer.
If we consider the properties of the respective thermal perturbations, the most
significant positive temperature anomaly (Fig. 1) occurs, as expected, in the eastern
tropical Pacific under the influence of the El Niño events induced by the GAO.
A smaller positive anomaly is observed in the northern part of the Pacific, including
the territory of Alaska and the Chukchi Peninsula.
An extensive negative temperature anomaly covers the mid-latitudes of the
Pacific, Northeast Asia, the southern and northeastern parts of the North American
continent. The main distinguishing feature of the spatial distribution of temperature
anomalies generated by the inter-decadal GAO (Fig. 2) is presented by a four-core
structure of the positive anomaly in the northwest of North America and in the
northeast of the Eurasian continent, as well as by the negative anomalies in the
North Pacific and Atlantic oceans. There are grounds to believe that this pattern
reflects qualitatively the phase redistribution of heat forced by the GAO in the
ocean-atmosphere-continent system.
The interannual GAO is obviously related to the seasonal cycle of the atmospheric processes, and its appearance coincides with the periods of the equilibrium
state of the climate system [8]. This condition occurs whenever the Sun is above the
Earth’s equator (radiation equilibrium), and the system of the global monsoon
circulation becomes unstable after its change to the interphase mode. The initial
moment of the GAO as shown in [16] is linked directly to the atmospheric pressure
increase in the equatorial-tropical region of the Atlantic and Indian oceans (thermal
tide) where negative sea surface temperature anomalies were reported to exist in
this period.
We suggest that the inter-decadal GAO (Fig. 2) appears as a shift in the
dynamics of the climate system, which is followed by a change of the climate
scenario either on the regional or even the global scale. According to our estimates
[17], this process is related immediately to the intensification of the heat flux from
the oceans to the atmosphere, which is succeeded by the climate warming on land.
The Global Atmosphere Oscillations in the Context …
353
of the surface atmospheric pressure between two consequent climate scenarios,
namely the relatively warmer (1975–1999) and the cooler (1950–1974) periods. As
one can see in this case, the pressure distribution in the tropical zone of the Pacific
Ocean is similar to the distribution characteristic of the El Niño events (Fig. 1). In
both cases, the region of the positive anomalies of the atmospheric pressure is
surrounded by the zones of negative anomalies. However, in the case of the
interannual GAO at the polar latitudes, the negative anomalies are replaced with the
positive ones, and in the case of the inter-decadal GAO they remain negative up to
the Pole.
The difference in the temperature distribution in the tropical Pacific (Fig. 2,
bottom panel) is similar to the distribution shown in Fig. 1, i.e., the presence of
positive T anomalies in the eastern zone. Therefore, in many studies [3, 12–15]
these changes in the pressure and temperature are called the inter-decadal oscillations like El Niño. However, Fig. 2 (top panel) shows that changes in the pressure
considered here are global but not limited to the tropical Pacific. Therefore, it is
more correct to call them inter-decadal global oscillations, what we do and offer.
If we consider the properties of the respective thermal perturbations, the most
significant positive temperature anomaly (Fig. 1) occurs, as expected, in the eastern
tropical Pacific under the influence of the El Niño events induced by the GAO.
A smaller positive anomaly is observed in the northern part of the Pacific, including
the territory of Alaska and the Chukchi Peninsula.
An extensive negative temperature anomaly covers the mid-latitudes of the
Pacific, Northeast Asia, the southern and northeastern parts of the North American
continent. The main distinguishing feature of the spatial distribution of temperature
anomalies generated by the inter-decadal GAO (Fig. 2) is presented by a four-core
structure of the positive anomaly in the northwest of North America and in the
northeast of the Eurasian continent, as well as by the negative anomalies in the
North Pacific and Atlantic oceans. There are grounds to believe that this pattern
reflects qualitatively the phase redistribution of heat forced by the GAO in the
ocean-atmosphere-continent system.
The interannual GAO is obviously related to the seasonal cycle of the atmospheric processes, and its appearance coincides with the periods of the equilibrium
state of the climate system [8]. This condition occurs whenever the Sun is above the
Earth’s equator (radiation equilibrium), and the system of the global monsoon
circulation becomes unstable after its change to the interphase mode. The initial
moment of the GAO as shown in [16] is linked directly to the atmospheric pressure
increase in the equatorial-tropical region of the Atlantic and Indian oceans (thermal
tide) where negative sea surface temperature anomalies were reported to exist in
this period.
We suggest that the inter-decadal GAO (Fig. 2) appears as a shift in the
dynamics of the climate system, which is followed by a change of the climate
scenario either on the regional or even the global scale. According to our estimates
[17], this process is related immediately to the intensification of the heat flux from
the oceans to the atmosphere, which is succeeded by the climate warming on land.
The Global Atmosphere Oscillations in the Context …
353