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Future Changes in the Free Tropospheric Freezing Level and Rain–Snow Limit: The Case of Central Chile.
- Source :
- Atmosphere; Nov2020, Vol. 11 Issue 11, p1259-1259, 1p
- Publication Year :
- 2020
-
Abstract
- The freezing level in the free troposphere often intercepts the terrain of the world's major mountain ranges, creating a rain–snow limit. In this work, we use the free tropospheric height of the 0 ° C isotherm ( H 0 ) as a proxy of both levels and study its distribution along the western slope of the subtropical Andes (30 ° –38 ° S) in present climate and during the rest of the 21st century. This portion of the Andes corresponds to central Chile, a highly populated region where warm winter storms have produced devastating landslides and widespread flooding in the recent past. Our analysis is based on the frequency distribution of H 0 derived from radiosonde and surface observations, atmospheric reanalysis and climate simulations. The future projections primarily employ a scenario of heavy greenhouse gasses emissions (RCP8.5), but we also examine the more benign RCP4.5 scenario. The current H 0 distribution along the central Chile coast shows a gradual decrease southward, with mean heights close to 2600 m ASL (above sea level) at 30 ° C S to 2000 m ASL at 38 ° S for days with precipitation, about 800 m lower than during dry days. The mean value under wet conditions toward the end of the century (under RCP8.5) is close to, or higher than, the upper quartile of the H 0 distribution in the current climate. More worrisome, H 0 values that currently occur only 5% of the time will be exceeded in about a quarter of the rainy days by the end of the century. Under RCP8.5, even moderate daily precipitation can increase river flow to levels that are considered hazardous for central Chile. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 20734433
- Volume :
- 11
- Issue :
- 11
- Database :
- Complementary Index
- Journal :
- Atmosphere
- Publication Type :
- Academic Journal
- Accession number :
- 147180683
- Full Text :
- https://doi.org/10.3390/atmos11111259