A comparison of vertical velocity in cirrus obtained from aircraft and lidar divergence measurements diving FIRE.

Abstract

Evaluates the use of (1) divergence measurements from aircraft spiral descents and (2) conical Doppler lidar scans, for determining the vertical profiles of the vertical velocity on a cirrus cloud scale. The vertical velocity is obtained by integration of the anelastic form of the continuity equation. Errors in (1) include errors in the ground speed components and sideslip angle, also errors in the INS velocity measurements. The major error in the lidar scans is due to inhomogeneous particle distributions in the beam volume. Study of FIRE program data indicates that the errors in the two techniques can be reduced around 2 to 3 cm/sec (aircraft) and 5 cm/sec (Doppler). (C.J.U.)