EARLINET instrument intercomparison campaigns: overview on strategy and results

Abstract

This paper introduces the recent European Aerosol

Research Lidar Network (EARLINET) quality-assurance efforts

at instrument level. Within two dedicated campaigns

and five single-site intercomparison activities, 21 EARLINET

systems from 18 EARLINET stations were intercompared

between 2009 and 2013. A comprehensive strategy

for campaign setup and data evaluation has been established.

Eleven systems from nine EARLINET stations

participated in the EARLINET Lidar Intercomparison 2009

(EARLI09). In this campaign, three reference systems were

qualified which served as traveling standards thereafter.

EARLINET systems from nine other stations have been compared

against these reference systems since 2009.We present

and discuss comparisons at signal and at product level from

all campaigns for more than 100 individual measurement

channels at the wavelengths of 355, 387, 532, and 607 nm.

It is shown that in most cases, a very good agreement of the

compared systems with the respective reference is obtained.

Mean signal deviations in predefined height ranges are typically

below 2 %. Particle backscatter and extinction coefficients

agree within 2 10􀀀4 km􀀀1 sr􀀀1 and 0.01 km􀀀1,

respectively, in most cases. For systems or channels that

showed larger discrepancies, an in-depth analysis of deficiencies

was performed and technical solutions and upgrades

were proposed and realized. The intercomparisons have reinforced

confidence in the EARLINET data quality and allowed

us to draw conclusions on necessary system improvements

for some instruments and to identify major challenges

that need to be tackled in the future.