Testing ground-based observations of wave activity in the (lower and upper) atmosphere as possible (complementary) indicators of streamer events

Abstract

For a better understanding of atmospheric dynamics, it is very important to know the general conditions (dynamics and chemistry) of the atmosphere. Planetary waves (PWs) are global-scale waves, which are well-known as main drivers of the large-scale weather patterns in mid-latitudes on timescales from several days up to weeks in the troposphere. When PWs break, they often cut pressure cells off the jet stream. A specific example is so-called streamer events, which occur predominantly in the lower stratosphere at mid-latitudes and high latitudes. For streamer events, we check whether there are any changes in gravity wave (GW) or infrasound characteristics related to these events in ionospheric and surface measurements (continuous Doppler soundings, two arrays of microbarometers) in the Czech Republic. Phenomena in infrasound arrival parameters undoubtedly related to streamer events were not identified in observations of two stations located in Central Europe. Simulations of infrasound propagation show influences of the streamer events on the waveguide formed near the tropopause. Microbarom propagation is influenced by the tropopause waveguide in a limited azimuth sector and at limited distances. Due to the typical occurrence of the streamer events over the North Atlantic, infrasound stations in western Europe can be of particular interest for future studies of streamer event signatures in infrasound arrivals. Arrivals to Central Europe are through the waveguide formed between the ground and the upper stratosphere. The upper-stratosphere waveguide is not influenced by the streamer events. Supplementary ground-based measurements of GW using the WBCI array in the troposphere showed that GW propagation azimuths were more random during streamer and streamer-like events compared to those observed during calm conditions. GW propagation characteristics observed in the ionosphere by continuous Doppler soundings during streamer events did not differ from those expected for the given time period.