Numerical simulations of windblown dust over complex terrain: the Fiambalá Basin episode in June 2015
On 13 June 2015, the London Volcanic Ash Advisory Centre (VAAC) warned the Buenos Aires VAAC about a possible volcanic eruption from the Nevados Ojos del Salado volcano (6879 m), located in the Andes mountain range on the border between Chile and Argentina. A volcanic ash cloud was detected by t...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/6759/2017/acp-17-6759-2017.pdf |
| Summary: | On 13 June 2015, the London Volcanic Ash Advisory Centre (VAAC) warned the
Buenos Aires VAAC about a possible volcanic eruption from the Nevados Ojos
del Salado volcano (6879 m), located in the Andes mountain range on
the border between Chile and Argentina. A volcanic ash cloud was detected by
the SEVIRI instrument on board the Meteosat Second Generation (MSG)
satellites from 14:00 UTC on 13 June.
<br><br>
In this paper, we provide the first comprehensive description of this event
through observations and numerical simulations. Our results support the
hypothesis that the phenomenon was caused by wind remobilization of ancient
pyroclastic deposits (ca. 4.5 ka Cerro Blanco eruption) from the
Bolsón de Fiambalá (Fiambalá Basin) in northwestern
Argentina. We have investigated the spatiotemporal distribution of aerosols
and the emission process over complex terrain to gain insight into the key
role played by the orography and the condition that triggered the long-range
transport episode.
<br><br>
Numerical simulations of windblown dust were performed using the
ARW (Advanced Research WRF) core of the WRF (Weather Research and Forecasting)
model (WRF-ARW) and FALL3D modeling system with meteorological fields downscaled to a
spatial resolution of 2 km in order to resolve the complex orography
of the area. Results indicate that favorable conditions to generate dust
uplifting occurred in northern Fiambalá Basin, where orographic effects
caused strong surface winds. According to short-range numerical simulations,
dust particles were confined to near-ground layers around the emission areas.
In contrast, dust aerosols were injected up to 5–6 km high in central
and southern regions of the Fiambalá Basin, where intense ascending
airflows are driven by horizontal convergence.
<br><br>
Long-range transport numerical simulations were also performed to model the
dust cloud spreading over northern Argentina. Results of simulated vertical
particle column mass were compared with the MSG-SEVIRI retrieval product. We
tested two numerical schemes: with the default configuration of the FALL3D
model, we found difficulties to simulate transport through orographic
barriers, whereas an alternative configuration, using a numerical scheme to
more accurately compute the horizontal advection in abrupt terrains,
substantially improved the model performance.</p> |
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| ISSN: | 1680-7316 1680-7324 |