Universidad Complutense de Madrid
E-Prints Complutense

Southern hemisphere sensitivity to ENSO patterns and intensities: impacts over subtropical South America

Impacto

Downloads

Downloads per month over past year

Martín Gómez, Verónica and Barreiro, Marcelo and Mohino Harris, Elsa (2020) Southern hemisphere sensitivity to ENSO patterns and intensities: impacts over subtropical South America. Atmosphere, 11 (1). ISSN 2073-4433

[img]
Preview
PDF
Creative Commons Attribution.

2MB

Official URL: http://dx.doi.org/10.3390/atmos11010077


URLURL Type
https://www.mdpi.com/Publisher


Abstract

El Niño flavors influence Subtropical South American (SSA) rainfall through the generation of one or two quasi-stationary Rossby waves. However, it is not yet clear whether the induced wave trains depend on the El Niño pattern and/or its intensity. To investigate this, we performed different sensitivity experiments using an Atmospheric General Circulation Model (AGCM) which was forced considering separately the Canonical and the El Niño Modoki patterns with sea surface temperature (SST) maximum anomalies of 1 and 3 ◦C. Experiments with 3 ◦C show that the Canonical El Niño induces two Rossby wave trains, a large one emanating from the western subtropical Pacific and a shorter one initiated over the central-eastern subtropical South Pacific. Only the shorter wave plays a role in generating negative outgoing longwave radiation (OLR) anomalies over SSA. On the other hand, 3 ◦C El Niño Modoki experiments show the generation of a large Rossby wave train that emanates from the subtropical western south Pacific and reaches South America (SA), promoting the development of negative OLR anomalies over SSA. Experiments with 1 ◦C show no impacts on OLR anomalies over SSA associated with El Niño Modoki. However, for the Canonical El Niño case there is a statistically significant reduction of the OLR anomalies over SSA related to the intensification of the upper level jet stream over the region. Finally, our model results suggest that SSA is more sensitive to the Canonical El Niño, although this result may be model dependent.


Item Type:Article
Additional Information:

© The Authors. The authors acknowledge NOAA’s National Centers for Environmental Information for providing the ERSST.v4, OLR data and the NCEP-DOE Reanalysis II (all of them available at http://www.esrl.noaa. gov/psd). The authors also thank Franco Molteni and Fred Kucharski for developing and freely providing the Speedy model.

Uncontrolled Keywords:El Niño; Variability; Pacific; Modoki; Oceans; NiO
Subjects:Sciences > Physics > Atmospheric physics
ID Code:60277
Deposited On:30 Apr 2020 11:41
Last Modified:30 Apr 2020 11:41

Origin of downloads

Repository Staff Only: item control page