11º Seminário da DIMNT – MJO impacts on South America monsoon season and their modulation by ENSO in MetUM-GOML3 model – 14 de dezembro de 2022, 14h30 às 15h30 – Divisão de Modelagem Numérica do Sistema Terrestre

Biografia: Dr. Fernandes is an Oceanographer with a Ph.D. in Water Resources Engineering from the Federal University of Paraná (UFPR). Her presentation at this seminar was part of her Ph.D. investigation titled The interaction between El Niño-Southern Oscillation (ENSO) and Madden-Julian Oscillation (MJO) in South America: observations and model simulations, done during a visit to the Meteorology Department, University of Reading, United Kingdom. Laís has been working since July 2022 as a postdoc at Portland State University, United States. Her current investigation focuses on understanding how the ENSO modulation of the MJO teleconnections impacts the lifecycle of the North Pacific Atmospheric Rivers (ARs) and their associated extreme precipitation events over the United States.

Resumo da palestra: The impacts of the Madden-Julian Oscillation (MJO) on the South American monsoon season (December, January, and February – DJF) and their possible changes during positive (El Niño – EN) and negative (La Niña – LN) phases of the El Niño-Southern Oscillation (ENSO) are analyzed in the UK Met Office Unified Model Global Ocean Mixed Layer configuration (MetUM-GOML3). Experiments sixty years long, with and without ENSO cycle, considering lower (200 km) and higher (90 km) spatial resolution, are performed to assess if the ENSO influences the MJO and its teleconnections to South America (SA). Simulations without ENSO show: (1) an established MJO extratropical teleconnection triggered by enhanced convection in the central-east subtropical South Pacific (SP) (source region), and its strongest impact on precipitation over SA in phase 8, earlier than in observations (phase 1); (2) an extratropical teleconnection, triggered by suppressed convection over the same region, with strongest impact on precipitation over SA in phase 4, with opposite sign; (3) increased horizontal resolution enhances the MJO convection and the anomalous circulation-precipitation dipole over SA, mainly over subtropical SA. However, the extratropical teleconnections at upper levels are slightly shifted east at higher resolution due to an enhanced SA westerly jet with respect to the lower resolution. The ENSO affects the basic state and the MJO convective anomalies, which modulate the MJO teleconnections and their impacts on SA in simulations with ENSO cycles. The extratropical teleconnections and their impacts are stronger under ENSO with respect to those in simulations without ENSO. Hence, both EN and LN states in the model generate forcing in the central-east subtropical SP that more efficiently triggers teleconnections than simulations without ENSO, indicating nonlinear ENSO effects on MJO anomalies over SA.

Divisão de Modelagem Numérica do Sistema Terrestre – CPTEC/INPE

CPTEC/INPE

11º Seminário da DIMNT – MJO impacts on South America monsoon season and their modulation by ENSO in MetUM-GOML3 model – 14 de dezembro de 2022, 14h30 às 15h30