EGU21-5487
https://doi.org/10.5194/egusphere-egu21-5487
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Manifestation of the Pacific Decadal Oscillation in the stationary planetary waves activity

Daria Sobaeva1,2, Yulia Zyulyaeva2, and Sergey Gulev2
Daria Sobaeva et al.
  • 1Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
  • 2Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow, Russian Federation

Strong quasi-decadal oscillations of the stratospheric polar vortex (SPV) intensity are in phase with the Pacific decadal oscillation (PDO). A stronger SPV is observed during the positive phase of the PDO, and during the negative phase, the intensity of the SPV is below the mean climate values. The SPV intensity anomalies, formed by the planetary waves and zonal mean flow interaction, lead to the weakening/intensification of the vortex.

This research aimed to obtain the differences in the characteristics and the spatial propagation pattern of the planetary waves in the middle troposphere and lower stratosphere during different PDO phases. We analyzed composite periods of years when the PDO index has extremely high and low values. Two periods were constructed for both positive and negative phases, the first consisting of years with El-Nino/La-Nina events and the second without prominent sea surface temperature anomalies in the tropics. 

During the wintertime in the Northern Hemisphere (December-February), wave 2 with two ridges (Siberian and North American Highs) and two troughs (Icelandic and Aleutian Lows) dominates in the middle troposphere, along with wave 1 dominating in the lower stratosphere. In the middle troposphere, at the positive phase ​​of the PDO, the amplitude of wave 2 is higher than in years with negative values of the PDO index. The differences in the Aleutian Low and the North American High intensity between the two phases are significant at the 97.5% level. In the lower stratosphere, the wave amplitude is lower at the negative phase ​​of the PDO, but we can also talk about a slight shift of the wave phase to the east. The regions of the heavy rains in the tropics during El-Nino events are the planetary waves source. They propagate from low to high latitudes, which results in modifying the characteristics and locations of the intensification of the stationary planetary waves in mid-latitudes.

How to cite: Sobaeva, D., Zyulyaeva, Y., and Gulev, S.: Manifestation of the Pacific Decadal Oscillation in the stationary planetary waves activity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5487, https://doi.org/10.5194/egusphere-egu21-5487, 2021.