Reply on RC2

Abstract

The Balloon Lidar Experiment (BOLIDE) which was part of the PMC Turbo balloon mission has captured near-vertical profiles of polar mesospheric clouds (PMC) during a 6-day flight along the Arctic circle in July 2018. The high-resolution soundings (20 m vertical and 10 s temporal resolution) reveal highly structured layers with large gradients in volume backscatter coefficient. We systematically screen the BOLIDE dataset for small-scale variability by assessing these gradients at high resolution. We find longer tails of the probability density distributions of these gradients compared to a normal distribution, indicating intermittent behaviour. The high occurrence rate of large gradients is assessed in relation to the 15-min-averaged layer brightness and the spectral power of short-period (5–62 min) gravity waves based on PMC layer altitude variations. We find that variability on small scales occurs during weak, moderate and strong gravity wave activity. Layers with below-average brightness are less likely to show small-scale variability in conditions of strong gravity wave activity. We present and discuss signatures of this small-scale variability and possibly related dynamical processes, and identify potential cases for future case studies and modelling efforts.