The European Aerosol Research Lidar Network – EARLINET

The European Aerosol Research Lidar Network, EARLINET, was established in 2000 as a research project with the goal of creating a quantitative, comprehensive, and statistically significant database for the horizontal, vertical, and temporal distribution of aerosols over continental Europe.

The present status of EARLINET  was achieved by using the exchange of expertise and also instruments optimization obtained with significant efforts. Since 2000, EARLINET has strongly extended its observing capacity. At the moment, EARLINET has 27 active stations that provide aerosol extinction and/or backscatter coefficient profiles to the EARLINET database. An important number (more than 21) of the EARLINET stations are located in the same area with AERONET (AErosol RObotic NETwork) sun photometers, offering the opportunity to analyze together lidar and sun photometer data during daytime.

EARLINET systematic measurements are scheduled on Monday around noon (one daytime per week), when the PBL is usually well developed, and two nighttime measurements per week (Monday and Thursday), with low background light suitable for Raman extinction measurements. Special events like Saharan dust outbreaks, forest fires, photochemical smog, and volcanic eruptions are also monitored in order to consolidate European aerosol climatology. Beside these special events, correlative measurements during overpasses of CALIPSO, the NASA-CNES (Centre National d’Etudes Spatiales, France) satellite mission “Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation” are performed. A strategy for correlative measurements has been defined by EARLINET on the basis of the ground track data analysis provided by NASA.

To obtain the necessary confidence for aerosol radiative forcing assessment, EARLINET measurements must fulfill stringent stability and absolute accuracy standards. A rigorous quality assurance program was developed and addresses the instrument performance and algorithms evaluation. All these quality assurance rules have been developed to ensure instrument standardization and consistent lidar retrievals within the network in a standardized data exchange format. Quality assurance is not yet fully developed, most of the rules being under development within the ACTRIS-2 project, which started in May 2015.

The Latin America Lidar Network – LALINET

Latin America Lidar Network – LALINET (previously known as ALINE), is the lidar network for aerosol research in South America which started to be operational in September 2013, even though the history of LALINET started in 2001, with voluntary membership. The overall goal of this network is monitoring vertical profiles of particle optical properties to establish the first database of aerosol properties with vertical resolution over South America, contributing among others to air quality studies, space agencies validation purposes and the scientific knowledge in general. Moreover, the aerosol microphysical properties and profiling of other atmospheric components such as water vapour, ozone and clouds are also considered.

Since most of the products are made for research purposes, each instrument has its own configuration, specification and capabilities, and major differences can be encounter between the stations. For this reason, the standardization of data processing and instrumentation is needed.

A major milestone of the network was completed in 2013, when the South-American lidar station network signed an agreement with the World Meteorological Organisation (WMO), recognising the contribution of LALINET to GALION (GAW Aerosol Lidar Observation Network), program of the Global Atmosphere Watch (GAW).

The recording schedule of LALINET is similar with EARLINET, with routine recordings from 12:00 to 15:00 respectively 21:00 to 00:00 UTC, every Monday and Thursday. Distribution of the 9 stations in South America on North to South axis starts from Argentina – 46oS to Columbia – 6oN and from East to West: from Brazil – 47oW to Chile – 73oW. The nine stations are divided in seven groups. Besides, new stations will extend the LALINET coverage in few years.