Long-term aerosol and cloud database from correlative EARLINET-CALIPSO observations

The European Aerosol Research Lidar Network, EARLINET, performs correlative observations during CALIPSO overpasses based on a sophisticated measurement strategy since June 2006. Within a dedicated activity supported by the European Space Agency (ESA), sixteen EARLINET stations contributed about 1500 measurements during an intensive observational period from May 2008 to October 2009. From these measurements, we establish a long-term aerosol and cloud database of correlative EARLINET-CALIPSO observations. This database shall provide a basis for homogenizing long-term space-borne observations conducted with different lidar instruments operating at different wavelengths on various platforms over the next decade(s). The database is also used to study the quality and representativeness of satellite lidar cross sections along an orbit against long-term lidar network observations on a continental scale.Postprint (published version

EARLINET instrument intercomparison campaigns: overview on strategy and results

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.Peer ReviewedPostprint (published version

EARLINET: 12-year of aerosol profiling over Europe

EARLINET has been collecting high quality aerosol optical profiles over Europe since 2000. The comparison with automatic collected dataset of aerosol optical depth (AOD) from AERONET and MODIS demonstrates the effectiveness of EARLINET regular measurement schedule for climatological studies. The analysis of optical properties in the local boundary layer indicates that the general decrease of AOD observed by different platforms over Europe in the last decade could be due to the modification of aerosol properties (towards less absorbing and larger particles) in the lower troposphere.Peer Reviewe

EARLINET: 12-year of aerosol profiling over Europe

EARLINET has been collecting high quality aerosol optical profiles over Europe since 2000. The comparison with automatic collected dataset of aerosol optical depth (AOD) from AERONET and MODIS demonstrates the effectiveness of EARLINET regular measurement schedule for climatological studies. The analysis of optical properties in the local boundary layer indicates that the general decrease of AOD observed by different platforms over Europe in the last decade could be due to the modification of aerosol properties (towards less absorbing and larger particles) in the lower troposphere.Peer Reviewe

The Earlinet contribution to the EarthCare mission.

Postprint (author’s final draft

Long-term aerosol and cloud database from space-borne lidar and ground-based lidar network observations

In June 2006, the satellite-borne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) began its observations onboard CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations; Winker et al., 2007). This date is regarded the starting point of a unique long-term, global, 4-dimensional aerosol and cloud data set. The forthcoming missions ADM-Aeolus (Atmospheric Dynamics Mission; Stoffelen et al., 2005; Ansmann et al., 2006) of the European Space Agency ESA and EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer) of ESA and the Japan Aerospace Exploration Agency JAXA (ESA, 2004), with their lidar instruments ALADIN (Atmospheric Laser Doppler Lidar Instrument) and ATLID (Atmospheric Lidar), respectively, will continue such kind of observations. It is expected that the long-term data set gained in this way will substantially improve our knowledge on the role of aerosols and clouds in the Earth's climate system.Peer Reviewe

Long-term aerosol and cloud database from space-borne lidar and ground-based lidar network observations

In June 2006, the satellite-borne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) began its observations onboard CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations; Winker et al., 2007). This date is regarded the starting point of a unique long-term, global, 4-dimensional aerosol and cloud data set. The forthcoming missions ADM-Aeolus (Atmospheric Dynamics Mission; Stoffelen et al., 2005; Ansmann et al., 2006) of the European Space Agency ESA and EarthCARE (Earth Clouds, Aerosols, and Radiation Explorer) of ESA and the Japan Aerospace Exploration Agency JAXA (ESA, 2004), with their lidar instruments ALADIN (Atmospheric Laser Doppler Lidar Instrument) and ATLID (Atmospheric Lidar), respectively, will continue such kind of observations. It is expected that the long-term data set gained in this way will substantially improve our knowledge on the role of aerosols and clouds in the Earth's climate system.Peer ReviewedPostprint (published version

EARLINET correlative measurements for CALIPSO: first intercomparison results

A strategy for European Aerosol Research Lidar Network (EARLINET) correlative measurements for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) has been developed. These EARLINET correlative measurements started in June 2006 and are still in progress. Up to now, more than 4500 correlative files are available in the EARLINET database. Independent extinction and backscatter measurements carried out at high-performance EARLINET stations have been used for a quantitative comparison with CALIPSO level 1 data. Results demonstrate the good performance of CALIPSO and the absence of evident biases in the CALIPSO raw signals. The agreement is also good for the distribution of the differences for the attenuated backscatter at 532 nm ((CALIPSO-EARLINET)/EARLINET (%)), calculated in the 1–10 km altitude range, with a mean relative difference of 4.6%, a standard deviation of 50%, and a median value of 0.6%. A major Saharan dust outbreak lasting from 26 to 31 May 2008 has been used as a case study for showing first results in terms of comparison with CALIPSO level 2 data. A statistical analysis of dust properties, in terms of intensive optical properties (lidar ratios, Ångström exponents, and color ratios), has been performed for this observational period. We obtained typical lidar ratios of the dust event of 49 ± 10 sr and 56 ± 7 sr at 355 and 532 nm, respectively. The extinction-related and backscatter-related Ångström exponents were on the order of 0.15–0.17, which corresponds to respective color ratios of 0.91–0.95. This dust event has been used to show the methodology used for the investigation of spatial and temporal representativeness of measurements with polar-orbiting satellites.Peer ReviewedPostprint (published version