An overview of the first decade of Polly<sup>NET</sup>: an emerging network of automated Raman-polarization lidars for continuous aerosol profiling

Abstract

Abstract.A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63 • N to 52 • S and 72 • W to 124 • E has been achieved within the Raman and polarization lidar network Polly NET . This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. Polly NET is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design with different capabilities ranging from single wavelength to multiwavelength systems, and now apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at polly.tropos.de. The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Ångström exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the Polly NET locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm as this operating wavelength is available for all Polly lidar systems. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of Polly NET to support the establishment of a global aerosol climatology that covers the entire troposphere.

Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

“…The overall relative errors of the lidarderived aerosol properties range between 5 and 15 % for the backscatter coefficients, 10 and 30% for the extinction coefficients, 20 and 40 % for the Ångström exponents, 15 and 40 % for the lidar ratios and approximately 5 and 10 % for the linear particle depolarization ratio (Hänel et al, 2012;Baars et al, 2016;. A detailed discussion on the influence of aerosol optical depth errors to Ångström exponent errors can be found in Wagner and Silva (2008).…”

Profiling of Saharan dust from the Caribbean to western Africa – Part 1: Layering structures and optical properties from shipborne polarization/Raman lidar observations

“…These profiles are available with good accuracy down to very low heights because the overlap effect widely cancels out. The advanced aerosol lidar enabled us to measure profiles of the particle backscatter coefficients (180 • scattering coefficient) at 355, 532, and 1064 nm, particle extinction coefficient at 355 and 532 nm, the respective lidar ratios (extinction-to-backscatter ratios) as well as the particle linear depolarization ratio at 355 and 532 nm Engelmann et al, 2016;Baars et al, 2016). A discussion of the uncertainties in the retrieval products is also given in these articles.…”

Ship-borne aerosol profiling with lidar over the Atlantic Ocean: from pure marine conditions to complex dust–smoke mixtures

“…Small particles show a strong wavelength dependence; thus, Å is greater than 1. In contrast, the scattering on large particles is almost wavelength independent and Å is approximately zero (Eck et al, 1999;Müller et al, 2007;Baars et al, 2016).…”