Numerical simulations of windblown dust over complex terrain: The Fiambalá Basin episode in June 2015
Other literature type
Mingari, Leonardo A.
Collini, Estela A.
Osores, María Soledad
Viramonte, José G.
(issn: 1680-7324, eissn: 1680-7324)
On the 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. Further studies concluded that the phenomenon was caused by remobilization
of ancient pyroclastic deposits (circa 4.5 Ka Cerro Blanco eruption)
from the Bolsón de Fiambalá (Fiambalá Basin) in northwestern Argentina.
In this paper, we provide the first comprehensive description of the
dust episode through observations and numerical simulations.
We have investigated the spatio-temporal 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
Numerical simulations of windblown dust were performed
using the WRF-ARW/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 indicated that favourable 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. On the other hand, 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.
Long-range transport numerical simulations were also performed to model
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.