skip to main content
Idioma:

Mean State Biases and Interannual Variability Affect Perceived Sensitivities of the Madden‐Julian Oscillation to Air‐Sea Coupling

Klingaman, N. P. ; Demott, C. A.

Journal of advances in modeling earth systems, 2020-02, Vol.12 (2), p.n/a [Periódico revisado por pares]

Washington: John Wiley & Sons, Inc

Texto completo disponível

Citações Citado por
  • Título:
    Mean State Biases and Interannual Variability Affect Perceived Sensitivities of the Madden‐Julian Oscillation to Air‐Sea Coupling
  • Autor: Klingaman, N. P. ; Demott, C. A.
  • Assuntos: air‐sea coupling ; Atmosphere ; Atmospheric models ; Climate ; Climate models ; Cold ; El Nino ; El Nino phenomena ; El Nino-Southern Oscillation event ; El Nino‐Southern Oscillation ; Experiments ; General circulation models ; Interannual variability ; Madden-Julian oscillation ; Ocean mixed layer ; Oceans ; Propagation ; Rain ; Rainfall ; Regions ; Sea surface ; Sea surface temperature ; Simulation ; Southern Oscillation ; sub‐seasonal variability ; super‐parameterization ; Surface temperature ; Tropical climate ; tropical convection ; Variability
  • É parte de: Journal of advances in modeling earth systems, 2020-02, Vol.12 (2), p.n/a
  • Descrição: Atmosphere‐ocean feedbacks often improve the Madden‐Julian oscillation (MJO) in climate models, but these improvements are balanced by mean state biases that can degrade the MJO through changing the basic state on which the MJO operates. The Super‐Parameterized Community Atmospheric Model (SPCAM3) produces perhaps the best representation of the MJO among contemporary models, which improves further in a coupled configuration (SPCCSM3) despite considerable mean state biases in tropical sea surface temperatures and rainfall. We implement an atmosphere‐ocean‐mixed‐layer configuration of SPCAM3 (SPCAM3‐KPP) and use a flux‐correction technique to isolate the effects of coupling and mean state biases on the MJO. When constrained to the observed ocean mean state, air‐sea coupling does not substantially alter the MJO in SPCAM3, in contrast to previous studies. When constrained to the SPCCSM ocean mean state, SPCAM3‐KPP fails to produce an MJO, in stark contrast to the strong MJO in SPCCSM3. Further KPP simulations demonstrate that the MJO in SPCCSM3 arises from an overly strong sensitivity to El Niño–Southern Oscillation events. Our results show that simulated interannual variability and coupled‐model mean state biases affect the perceived response of the MJO to coupling. This is particularly concerning in the context of internal variability in coupled models, as many previous MJO sensitivity studies in coupled models used relatively short (20‐ to 50‐year) simulations that undersample interannual‐decadal variability. Diagnosing the effects of coupling on the MJO requires simulations that carefully control for mean state biases and interannual variability. Plain Language Summary Many studies suggest that feedbacks between the atmosphere and ocean are essential for simulating the Madden‐Julian oscillation, which controls weekly to monthly tropical rainfall. However, model experiments that diagnose the effect of these feedbacks are often not performed in a controlled manner, because introducing atmosphere‐ocean feedbacks changes other aspects of the simulation, including the background climate and phenomena such as the El Niño–Southern Oscillation. These changes may affect the Madden‐Julian oscillation as well, separately from direct atmosphere‐ocean feedbacks, but these changes are often erroneously considered part of the sensitivity of the Madden‐Julian oscillation to atmosphere‐ocean feedbacks. We demonstrate that in one model that simulates the Madden‐Julian oscillation well, the Super‐Parameterized Community Atmospheric Model, intraseasonal atmosphere‐ocean feedbacks alone do not substantially alter the Madden‐Julian oscillation. Rather, the previously perceived improvement to the Madden‐Julian oscillation from atmosphere‐ocean feedbacks arises from a too strong response of the Madden‐Julian oscillation to El Niño events. Future studies must carefully control for how introducing atmosphere‐ocean feedbacks affects other aspects of the simulation, to better isolate the effect of those feedbacks on the Madden‐Julian oscillation. Key Points The response of the Madden‐Julian oscillation (MJO) to coupling is sensitive to the representation of interannual variability Diagnosing intraseasonal coupled feedbacks to the MJO requires controling for interannual variability and mean state biases Air‐sea coupling is not essential to simulate the MJO in the Super‐Parameterized Community Atmospheric Model
  • Editor: Washington: John Wiley & Sons, Inc
  • Idioma: Inglês
Voltar para lista de resultados

  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

Buscando em bases de dados remotas. Favor aguardar.