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Main Title: Using Convective Available Potential Energy (CAPE) and Dew-Point Temperature to Characterize Rainfall-Extreme Events in the South-Central Andes
Author(s): Ramezani Ziarani, Maryam
Bookhagen, Bodo
Schmidt, Torsten
Wickert, Jens
de la Torre, Alejandro
Hierro, Rodrigo
Type: Article
Language Code: en
Abstract: The interactions between atmosphere and steep topography in the eastern south–central Andes result in complex relations with inhomogenous rainfall distributions. The atmospheric conditions leading to deep convection and extreme rainfall and their spatial patterns—both at the valley and mountain-belt scales—are not well understood. In this study, we aim to identify the dominant atmospheric conditions and their spatial variability by analyzing the convective available potential energy (CAPE) and dew-point temperature ( Td ). We explain the crucial effect of temperature on extreme rainfall generation along the steep climatic and topographic gradients in the NW Argentine Andes stretching from the low-elevation eastern foreland to the high-elevation central Andean Plateau in the west. Our analysis relies on version 2.0 of the ECMWF’s (European Centre for Medium-Range Weather Forecasts) Re-Analysis (ERA-interim) data and TRMM (Tropical Rainfall Measuring Mission) data. We make the following key observations: First, we observe distinctive gradients along and across strike of the Andes in dew-point temperature and CAPE that both control rainfall distributions. Second, we identify a nonlinear correlation between rainfall and a combination of dew-point temperature and CAPE through a multivariable regression analysis. The correlation changes in space along the climatic and topographic gradients and helps to explain controlling factors for extreme-rainfall generation. Third, we observe more contribution (or higher importance) of Td in the tropical low-elevation foreland and intermediate-elevation areas as compared to the high-elevation central Andean Plateau for 90th percentile rainfall. In contrast, we observe a higher contribution of CAPE in the intermediate-elevation area between low and high elevation, especially in the transition zone between the tropical and subtropical areas for the 90th percentile rainfall. Fourth, we find that the parameters of the multivariable regression using CAPE and Td can explain rainfall with higher statistical significance for the 90th percentile compared to lower rainfall percentiles. Based on our results, the spatial pattern of rainfall-extreme events during the past ∼16 years can be described by a combination of dew-point temperature and CAPE in the south–central Andes.
Issue Date: 8-Jul-2019
Date Available: 8-Nov-2019
DDC Class: 550 Geowissenschaften
Subject(s): eastern south–central Andes
extreme rainfall
deep convection
convective available potential energy
dew-point temperature
Sponsor/Funder: DFG, GRK 2018, Erdoberflächenprozesse, Tektonik und Lagerstätten: Das andine Vorlandbecken von Argentinien
Journal Title: Atmosphere
Publisher: MDPI
Publisher Place: Basel
Volume: 10
Issue: 7
Article Number: 379
Publisher DOI: 10.3390/atmos10070379
EISSN: 2073-4433
Appears in Collections:FG GNSS-Fernerkundung, Navigation und Positionierung » Publications

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