TY - JOUR
T1 - Effects of ambient rotation on dust devils
AU - Ito, Junshi
AU - Niino, Hiroshi
AU - Nakanishi, Mikio
N1 - Publisher Copyright:
© 2011, the Meteorological Society of Japan.
PY - 2011
Y1 - 2011
N2 - A previous Doppler-lidar observation near a sea-breeze front revealed that small-scale vertical vortices, similar to dust devils, have a preferred direction of rotation, which suggests that their rotation was affected by meso-scale vertical vorticity associated with the front. In contrast, planetary vorticity is believed to have a negligible effect on dust devils. This paper investigates the effects of ambient rotation on dust devils by means of a large eddy simulation, which yielded the following findings: when the ambient rotation is as small as the earth's rotation, only a tiny asymmetry is found in the occurrences of vertical vortices of different signs; as the ambient rotation is increased, it significantly affects the rotational direction of the vortices, and the magnitude of their vertical vorticity attains a maximum for an ambient vorticity of about 10-3 s-1; a further increase in the ambient rotation changes the structure of convection in the convective mixed layer and suppresses horizontal convergence, so that vertical vorticity of the vortices is reduced.
AB - A previous Doppler-lidar observation near a sea-breeze front revealed that small-scale vertical vortices, similar to dust devils, have a preferred direction of rotation, which suggests that their rotation was affected by meso-scale vertical vorticity associated with the front. In contrast, planetary vorticity is believed to have a negligible effect on dust devils. This paper investigates the effects of ambient rotation on dust devils by means of a large eddy simulation, which yielded the following findings: when the ambient rotation is as small as the earth's rotation, only a tiny asymmetry is found in the occurrences of vertical vortices of different signs; as the ambient rotation is increased, it significantly affects the rotational direction of the vortices, and the magnitude of their vertical vorticity attains a maximum for an ambient vorticity of about 10-3 s-1; a further increase in the ambient rotation changes the structure of convection in the convective mixed layer and suppresses horizontal convergence, so that vertical vorticity of the vortices is reduced.
UR - http://www.scopus.com/inward/record.url?scp=84877655696&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84877655696&partnerID=8YFLogxK
U2 - 10.2151/sola.2011-042
DO - 10.2151/sola.2011-042
M3 - Article
AN - SCOPUS:84877655696
VL - 7
SP - 165
EP - 168
JO - Scientific Online Letters on the Atmosphere
JF - Scientific Online Letters on the Atmosphere
SN - 1349-6476
IS - 1
ER -