EGU2020-11318, updated on 03 Jan 2024
https://doi.org/10.5194/egusphere-egu2020-11318
EGU General Assembly 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Transition of the ENSO teleconnection to the Euro-Atlantic region from early to late winter: Role of the Indian Ocean

Muhammad Adnan Abid1,2, Fred Kucharski1,2, Franco Molteni3, In-Sik Kang4, Adrian Tompkins1, and Mansour Almazroui2
Muhammad Adnan Abid et al.
  • 1The Abdus Salam International Centre for Theoretical Physics, Earth System Physics, Trieste, Italy (madnanabid@gmail.com)
  • 2Centre of Excellence for Climate Change Research (CECCR)/Department of Meteorology, King Abdulaziz University, Jeddah, Saudi Arabia
  • 3European Centre for Medium-Range Weather Forecasts (ECMWF), UK
  • 4Indian Ocean Center, SOED, Second Institute of Oceanography, Hangzhou, China

El Niño Southern Oscillation (ENSO) have a weak influence on the seasonal mean Euro-Atlantic circulation anomalies during the boreal winter (Dec-Feb) season. Therefore, monthly ENSO teleconnections to Euro-Atlantic region were studied during the boreal winter season for the period 1981-2015 using reanalysis and hindcast dataset. It is shown that the ENSO-forced signal to the Euro-Atlantic circulation anomalies does not persist throughout the boreal winter season. During earlier winter, a positive ENSO phase strongly enforces rainfall dipole anomalies in the tropical Indian Ocean, with increased rainfall over the western tropical Indian Ocean, and reduced in the eastern tropical Indian ocean.  This Indian Ocean rainfall dipole weakens in late winter. During early winter, the Indian Ocean rainfall dipole modifies the subtropical South Asian jet (SAJET) which forces a wavenumber-3 response projecting spatially onto the positive North Atlantic Oscillation (NAO) pattern. On contrary, during late winter, the response in the Euro-Atlantic sector is dominated by the well-known ENSO wavetrain from the tropical Pacific region, involving Pacific North American (PNA) pattern anomalies that project spatially on the negative phase of the NAO. Atmospheric General Circulation Model (AGCM) numerical experiments forced with an Indian Ocean heating dipole anomaly support the hypothesis that the Indian Ocean modulates the SAJET that enforces the Rossby wave propagation to the Euro-Atlantic region in early winter. Moreover, the ECMWF-SEAS5 hindcast dataset reproduces the observed ENSO-forced inter-basin tropical teleconnections transition from early to late winter and their response to the Euro-Atlantic circulation anomalies quite well. Therefore, it is important to understand the tropical inter-basin transition, which may lead to improve the sub-seasonal to seasonal variability and predictability of the Euro-Atlantic circulation anomalies. 

How to cite: Abid, M. A., Kucharski, F., Molteni, F., Kang, I.-S., Tompkins, A., and Almazroui, M.: Transition of the ENSO teleconnection to the Euro-Atlantic region from early to late winter: Role of the Indian Ocean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11318, https://doi.org/10.5194/egusphere-egu2020-11318, 2020.

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