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Atmospheric dynamics of extreme discharge events from 1979 to 2016 in the southern Central Andes
- 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 differentDuring 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.…
Author details: | Fabiana CastinoORCiDGND, Bodo BookhagenORCiDGND, Alejandro De la TorreORCiD |
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DOI: | https://doi.org/10.1007/s00382-020-05458-1 |
ISSN: | 0930-7575 |
ISSN: | 1432-0894 |
Title of parent work (English): | Climate dynamics : observational, theoretical and computational research on the climate system |
Publisher: | Springer |
Place of publishing: | Berlin ; Heidelberg [u.a.] |
Publication type: | Article |
Language: | English |
Date of first publication: | 2019/12/22 |
Publication year: | 2020 |
Release date: | 2024/01/10 |
Tag: | South American monsoon system; cold surges; daily-discharge time; extreme discharge; mesoscale convective systems; orographic barrier; series ERA-interim |
Volume: | 55 |
Issue: | 11-12 |
Number of pages: | 21 |
First page: | 3485 |
Last Page: | 3505 |
Funding institution: | Deutsche Forschungsgemeinschaft (DFG)German Research Foundation (DFG); Brandenburg Ministry of Science, Research and Cultural Affairs, Germany; [IGK2018] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
Mathematisch-Naturwissenschaftliche Fakultät / Institut für Umweltwissenschaften und Geographie | |
DDC classification: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer review: | Referiert |
Publishing method: | Open Access / Hybrid Open-Access |
License (German): | CC-BY - Namensnennung 4.0 International |