Observations of meteoric smoke particles in the middle atmosphere with a novel lidar method. (O-MSP-LI)

点击翻译按钮获取中文摘要

Meteoric smoke particles (MSP) are known to be formed by recondensation of extraterrestrial material as meteoroids enter the atmosphere. They are of crucial importance for the formation of noctilucent clouds (NLCs) since they act as their nucleation nuclei. They undergo sedimentation/advection and sink to lower altitudes mainly in the winter vortex, so they are also found in stratospheric sulfate particles. Despite the great importance of MSPs for the physics & chemistry of the stratosphere, many aspects of MSPs are not or are insufficiently understood. The reason lies in the extreme difficulty to detect MSPs. For lidar measurements, MSPs are difficult to detect because the aerosol to Rayleigh backscatter signal ratio is only around 〖10〗^(-3). MSPs are also difficult to detect in satellite measurements, as possible MSP signatures in satellite measurements are still ambiguous. As a result, the scientific goal of this proposal is to investigate the spatial and seasonal existence of MSPs and their separation from the Junge layer using a novel lidar method in combination with available satellite measurements. The Leibniz Institute for Atmospheric Physics (IAP) and the University of Greifswald (UG) have excellent expertise in this field. The IAP is one of the world's few institutes in the field of lidar technology for "Middle Atmosphere Research" and thus one of the leading research institutes that can carry out temperature, wind, turbulence, and aerosol measurements. With Prof. von Savigny, the UG has more than 20 years of experience with aerosols in the middle atmosphere from passive satellite measurements. The proposal is separated into 4 topics: (1) The MSP identification in unique lidar measurements of stratospheric aerosols at high latitudes. For this, we use existing measurements from Davis (69° S) and Norway (69° N). With these aerosol measurements above the Junge layer in an altitude range previously not accessible with lidar, we investigate the sedimentation of MSPs within the polar vortex. (2) We verify that MSPs are observable in past and current satellite measurements and that these agree with lidar observations. (3) We significantly improve the sensitivity of lidar measurements. For this purpose, MSPs in the upper stratosphere/lower mesosphere are detected with the novel lidar system VAHCOLI. In addition, we carry out depolarization measurements to characterize the particle shape. We compare new VAHCOLI measurements with an established method of stratospheric aerosol observation (ALOMAR multicolor lidar, IAP) that provides particle size and number density. (4) We test the ability of the WACCM model to reproduce the observed MSP properties by seasonally comparing all available measurements with model simulations.