Observed modes of sea surface temperature variability in the South Pacific region

The South Pacific (SP) region exerts large control on the climate of the Southern Hemisphere at many times scales. This paper identifies the main modes of interannual sea surface temperature (SST) variability in the SP which consist of a tropical-driven mode related to a horseshoe structure of positive/negative SST anomalies within midlatitudes and highly correlated to ENSO and Interdecadal Pacific Oscillation (IPO) variability, and another mode mostly confined to extratropical latitudes which is characterized by zonal propagation of SST anomalies within the South Pacific Gyre. Both modes are associated with temperature and rainfall anomalies over the continental regions of the Southern Hemisphere. Besides the leading mode which is related to well known warmer/cooler and drier/moister conditions due to its relationship with ENSO and the IPO, an inspection of the extratropical mode indicates that it is associated with distinct patterns of sea level pressure and surface temperature advection. These relationships are used here as plausible and partial explanations to the observed warming trend observed within the Southern Hemisphere during the last decades.The authors would like to thank Scott Power for his comments on an earlier version of the manuscript and the two anonymous reviewers whose suggestions led to a substantial improvement of the paper. This study was supported by Grants UBACyT-20020100100803, UBACyT-20020120300051, PIP-11220120100586 and the SPECS (GA 308378) EU-funded Project. JG-S was partially supported by the H2020-funded MSCA-IF-EF DPETNA project (GA No. 655339). The authors acknowledge the Red Española de Supercomputación (RES) and PRACE for awarding access to MareNostrum 3 at the Barcelona Supercomputing Center through the HiResClim project. The support of Virginie Guémas and Oriol Mula-Valls at the Barcelona Supercomputing Center is warmly appreciated.Peer ReviewedPostprint (author's final draft

Relationship between circulation types and precipitation over Spain

Póster presentado en: Advances in weather and circulation type classifications & applications (COST 733 Mid-term Conference) celebrado en Cracovia, Polonia, del 22 al 25 de octubre de 2008.This work has been developed in the WG4: "Testing methods for various applications" in the framework of Action COST733

Revisiting the ENSO Teleconnection to the Tropical North Atlantic

One of the most robust remote impacts of El Niño–Southern Oscillation (ENSO) is the teleconnection to tropical North Atlantic (TNA) sea surface temperature (SST) in boreal spring. However, important questions still remain open. In particular, the timing of the ENSO–TNA relationship lacks understanding. The three previously proposed mechanisms rely on teleconnection dynamics involving a time lag of one season with respect to the ENSO mature phase in winter, but recent results have shown that the persistence of ENSO into spring is necessary for the development of the TNA SST anomalies. Likewise, the identification of the effective atmospheric forcing in the deep TNA to drive the regional air–sea interaction is also lacking. In this manuscript a new dynamical framework to understand the ENSO–TNA teleconnection is proposed, in which a continuous atmospheric forcing is present throughout the ENSO decaying phase. Observational datasets in the satellite era, which include reliable estimates over the ocean, are used to illustrate the mechanism at play. The dynamics rely on the remote Gill-type response to the ENSO zonally compensated heat source over the Amazon basin, associated with perturbations in the Walker circulation. For El Niño conditions, the anomalous diabatic heating in the tropical Pacific is compensated by anomalous diabatic cooling, in association with negative rainfall anomalies and descending motion over northern South America. A pair of anomalous cyclonic circulations is established at upper-tropospheric levels in the tropical Atlantic straddling the equator, displaying a characteristic baroclinic structure with height. In the TNA region, the mirrored anomalous anticyclonic circulation at lower-tropospheric levels weakens the northeasterly trade winds, leading to a reduction in evaporation and of the ocean mixed layer depth, hence to positive SST anomalies. Apart from the dominance of latent heat flux anomalies in the remote response, sensible heat flux and shortwave radiation anomalies also appear to contribute. The “lagged” relationship between mature ENSO in winter and peaking TNA SSTs in spring seems to be phase locked with the seasonal cycle in both the location of the mechanism’s centers of action and regional SST variance.This work has been supported by the EU/H2020-funded MSCA-IF-EF DPETNA project (GA 655339) and JG-S was partially supported by the Spanish MINECO-funded DANAE Project (CGL2015-68342-R). Technical support at BSC (Computational Earth Sciences group) is sincerely acknowledged. The authors are grateful to the anonymous reviewers for their comments, which helped to improve the scope of the manuscript.Peer ReviewedPostprint (published version

Climate model validation in the Euro-Atlantic domain using circulation types

In the present study the mid-tropospheric circulation of the re-analysis produced by the European Centre for Medium-Range Weather Forecasts and of three climate models from the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC,2001) has been analyzed. The analysis is based on a circulation-type approach, with principal component analysis in T-mode, followed by a rotation varimax procedure. This study has been performed over the Euro-Atlantic region and for the extended winter season

Distribution characteristics of wintertime teleconnections in climate change

Póster presentado en: 7th EMS Annual Meeting and 8th European Conference on Applications of Meteorology 2007 (ECAM) celebrado del 1 al 5 de octubre de 2007 en San Lorenzo del Escorial, Madrid

Impact of climate change in an objective circulation type classification

Póster presentado en: 7th EMS Annual Meeting and 8th European Conference on Applications of Meteorology 2007 (ECAM) celebrado del 1 al 5 de octubre de 2007 en San Lorenzo del Escorial, Madrid