Particle backscatter and extinction profiling with the spaceborne high-spectral-resolution Doppler lidar ALADIN: methodology and simulations

Abstract

The European Space Agency will launch the Atmospheric Laser Doppler Instrument (ALADIN) for global wind profile observations in the near future. The potential of ALADIN to measure the optical properties of aerosol and cirrus, as well, is investigated based on simulations. A comprehensive data analysis scheme is developed that includes (a) the correction of Doppler-shifted particle backscatter interference in the molecular backscatter channels (cross-talk effect), (b) a procedure that allows us to check the quality of the cross-talk correction, and (c) the procedures for the independent retrieval of profiles of the volume extinction and backscatter coefficients of particles considering the height-dependent ALADIN signal resolution. The error analysis shows that the particle backscatter and extinction coefficients, and the corresponding extinction-to-backscatter ratio (lidar ratio), can be obtained with an overall (systematic+statistical) error of 10%-15%, 15%-30%, and 20%-35%, respectively, in tropospheric aerosol and dust layers with extinction values from 50 to 200 Mm(-1); 700-shot averaging (50 km horizontal resolution) is required. Vertical signal resolution is 500 m in the lower troposphere and 1000 m in the free troposphere. In cirrus characterized by extinction coefficients of 200 Mm(-1) and an optical depth of >0.2, backscatter coefficients, optical depth, and column lidar ratios can be obtained with 25%-35% relative uncertainty and a horizontal resolution of 10 km (140 shots). In the stratosphere, only the backscatter coefficient of aerosol layers and polar stratospheric clouds can be retrieved with an acceptable uncertainty of 15%-30%. Vertical resolution is 2000 m.

Airborne wind lidar observations over the North Atlantic in 2016 for the pre-launch validation of the satellite mission Aeolus

“…The obtained data will allow for greater accuracy of the initial atmospheric state in NWP models and thus improve the quality of weather forecasts (Tan and Andersson, 2005) as well as the understanding of atmospheric dynamics and climate processes (ESA, 2008). As a secondary product, the wind lidar system, which is scheduled for launch in 2018, will provide information on cloud top heights and on the vertical distribution of clouds and aerosol properties such as backscatter and extinction coefficients Ansmann et al, 2007). 10…”

Middle East versus Saharan dust extinction-to-backscatter ratios

“…Dust-related extinction coefficient profiles are also used to estimate ice nuclei concentrations up to cirrus level (Mamouri and Ansmann, 2015). Present and upcoming spaceborne lidar activities (Stoffelen et al, 2005;Ansmann et al, 2007;Illingworth et al, 2014) need lidar-ratio information for all relevant aerosol types such as urban haze, biomass burning smoke, desert dust and marine particles in key areas of climate relevance for a consistent interpretation of the space-lidar-derived aerosol and cloud products.…”

Airborne Multiwavelength High Spectral Resolution Lidar (HSRL-2) observations during TCAP 2012: vertical profiles of optical and microphysical properties of a smoke/urban haze plume over the northeastern coast of the US

“…Space missions of HSRL systems will be launched by NASA (http://www.nasa-usa.de/mission_pages/ station/research/experiments/1037.html) and ESA (Stoffelen et al, 2005;Ansmann et al, 2007;Flamant et al, 2008) in the next couple of years and . These lidar missions however do not provide the necessary number of measurement channels in order to carry out detailed investigations of particle microphysical properties.…”