Climatology of extreme cold events in the central Peruvian Andes during austral summer: origin, types and teleconnections

Juan Sulca, Mathias Vuille, Paul Roundy, Ken Takahashi, Jhan Carlo Espinoza, Yamina Silva, Grace Trasmonte, Ricardo Zubieta

Producción científica: Contribución a una revistaArtículorevisión exhaustiva

4 Citas (Scopus)

Resumen

The climatological and large-scale characteristics of the extreme cold events (ECEs) in the central Peruvian Andes (Mantaro basin (MB)) during austral summer (January–March) are examined using reanalysis, gridded and in situ surface minimum temperature (Tmin) data for the 1979–2010 period. To describe the influence of the Madden–Julian Oscillation (MJO) on ECEs in the MB, two ECE groups are defined on the basis of the sign of the outgoing long-wave radiation (OLR) anomalies in the MJO band (30–100 days, 0–9 eastward) at 12.5°S, 75°W. Type-1 ECEs occur during the suppressed convection phase of the MJO (OLR anomalies ≥+2 W/m2) while Type-2 ECEs occur during the enhanced convection phase of the MJO (OLR anomalies ≤−2 W/m2). ECEs in the MB are associated with the advection of cold and dry air along the east of the Andes through equatorward propagation of extratropical Rossby wave trains (ERWTs). This cold advection weakens the Bolivian High–Nordeste Low (BH-NL) system over South America (SA) at upper-tropospheric levels. The MJO is an important driver of ECEs in the MB, favouring the cold advection along the Andes during specific MJO phases. Fifty-nine per cent of Type-1 ECE's and 86% of Type-2 ECE's occur in MJO Phases 7-2. Type-1 and 2 ECEs feature a weakened BH over SA at upper-tropospheric levels. For Type-1, ERWTs emanate from southeastern Africa in MJO Phases 8-1 while ERWTs are strengthened when crossing the subtropical southern Pacific Ocean during MJO Phases 2 and 7. With respect to Type-2, MJO Phases 7-2 feature circumpolar Rossby wave trains propagating toward SA. Ultimately, MJO Phases 7-2 induce negative Tmin anomalies over MB, while MJO Phases 3-6 induce positive Tmin anomalies. El Niño and La Niña strengthen negative Tmin anomalies over the MB during MJO Phases 7-8 while they weaken positive Tmin anomalies over the MB during MJO Phases 3-6.

Idioma originalInglés
Páginas (desde-hasta)2693-2714
Número de páginas22
PublicaciónQuarterly Journal of the Royal Meteorological Society
Volumen144
N.º717
DOI
EstadoPublicada - oct. 2018
Publicado de forma externa

Huella

Profundice en los temas de investigación de 'Climatology of extreme cold events in the central Peruvian Andes during austral summer: origin, types and teleconnections'. En conjunto forman una huella única.

Citar esto