Title
Climatology of extreme cold events in the central Peruvian Andes during austral summer: origin, types and teleconnections
Date Issued
October 2018
Access level
restricted access
Resource Type
journal article
Publisher(s)
John Wiley and Sons Ltd
Abstract
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. © 2018 Royal Meteorological Society
Start page
2693
End page
2714
Volume
144
Issue
717
Number
2
Language
English
DOI
Scopus EID
2-s2.0-85055668389
Source
Quarterly Journal of the Royal Meteorological Society
ISSN of the container
0035-9009
1477-870X
Sponsor(s)
The authors are grateful for funding obtained from the US State Department (award S-LMAQM-11-GR-086 under the ACCION umbrella to M. Vuille), and would like to thank the National Peruvian Weather Service (SENAMHI) and the Instituto Geofísico del Perú (IGP) for providing daily minimum temperature data from climatological stations in the Mantaro basin, W. Lavado-Casimiro and A. Huerta for providing gridded daily minimum temperature from the PISCO dataset and N. Quispe for useful comments in the initial part of this study. We are very grateful to two anonymous reviewers who provided us with valuable comments, which helped us to significantly advance our results and to substantially improve the article. This work was performed using computational resources, HPC-Linux-Cluster, from the Laboratorio de Dinámica de Fluidos Geofísicos Computacionales (http://scah.igp.gob.pe/laboratorios/dfgc) at the Instituto Geofísico del Perú (grants 101-2014-FONDECYT, SPIRALES2012 IRD-IGP, Manglares IGP-IDRC#106714, PPR 068 programme).
Sources of information:
Directorio de Producción Científica