Mean Azimuthal Flow

The mean azimuthal flow is composed of the primary (tangential) and secondary (radial and vertical) circulations. The characteristic velocity of the primary circulation is us ually one order of magnitude greater than that of the secondary circulation. The temporal variations of the mean azimuthal flow are a measure of the intensity of the tropical cyclone. Observations in a number of tropic al cyclones show that the mean azimuthal flow varies on a time scale of 6-12 h.

Primary circulation for four mature hurricanes


Radius-height cross sections of the symmetric (azimuthal) mean Doppler-derived tangential wind (m/s) fields for Hurricanes (a) Gloria, (b) Emily, (c) Gilbert, and (d) Hugo. Radius-height reflectivity fields below can be compared to the wind fields.


Secondary (radial) circulation for four mature hurricanes


Radius-height cross sections of the symmetric (azimuthal) mean Doppler-derived radial wind (m/s) fields for Hurricanes (a) Gloria, (b) Emily, (c) Gilbert, and (d) Hugo. Radius-height reflectivity fields below can be compared to the wind fields.


Azimuthal mean reflectivity for four mature hurricanes


Radius-height cross sections of radar reflectivity (dBZ) fields for Hurricanes (a) Gloria, (b) Emily, (c) Gilbert, and (d) Hugo.

marks@aoml.noaa.gov

Updated Tue, Nov 14, 1995