TY  - JOUR
A1  - Castino, Fabiana
A1  - Bookhagen, Bodo
A1  - De la Torre, Alejandro
T1  - Atmospheric dynamics of extreme discharge events from 1979 to 2016 in the southern Central Andes
JF  - Climate dynamics : observational, theoretical and computational research on the climate system
N2  - During the South-American Monsoon season, deep convective systems occur at the eastern flank of the Central Andes leading to heavy rainfall and flooding. We investigate the large- and meso-scale atmospheric dynamics associated with extreme discharge events (> 99.9th percentile) observed in two major river catchments meridionally stretching from humid to semi-arid conditions in the southern Central Andes. Based on daily gauge time series and ERA-Interim reanalysis, we made the following three key observations: (1) for the period 1940-2016 daily discharge exhibits more pronounced variability in the southern, semi-arid than in the northern, humid catchments. This is due to a smaller ratio of discharge magnitudes between intermediate (0.2 year return period) and rare events (20 year return period) in the semi-arid compared to the humid areas; (2) The climatological composites of the 40 largest discharge events showed characteristic atmospheric features of cold surges based on 5-day time-lagged sequences of geopotential height at different levels in the troposphere; (3) A subjective classification revealed that 80% of the 40 largest discharge events are mainly associated with the north-northeastward migration of frontal systems and 2/3 of these are cold fronts, i.e. cold surges. This work highlights the importance of cold surges and their related atmospheric processes for the generation of heavy rainfall events and floods in the southern Central Andes.
KW  - South American monsoon system
KW  - cold surges
KW  - orographic barrier
KW  - mesoscale convective systems
KW  - extreme discharge
KW  - daily-discharge time
KW  - series ERA-interim
Y1  - 2019
U6  - https://doi.org/10.1007/s00382-020-05458-1
SN  - 0930-7575
SN  - 1432-0894
VL  - 55
IS  - 11-12
SP  - 3485
EP  - 3505
PB  - Springer
CY  - Berlin ; Heidelberg [u.a.]
ER  -