Representativeness of aerosol measurements: EARLINET-CALIPSO correlative study

The high variability of tropospheric aerosols, both in space and time, is the main cause of the high uncertainty about radiative forcing related to tropospheric aerosols and their interaction with clouds. Because of the lack of high resolution aerosol global vertical profiles, the vertical mixing has not been considered so far in studies of spatial and temporal variability. The CALIPSO mission provides the first opportunity to investigate the 4-D aerosol and cloud fields in detail. However, because of the CALIOP small footprint and the revisit time of 16 days, correlative ground-based lidar observations are necessary in order to investigate the representativeness of these satellite observations. EARLINET, the European Aerosol Research Lidar Network, started correlative measurements for CALIPSO in June 2006, right after the CALIPSO launch. An integrated study of CALIPSO and EARLINET correlative measurements opens new possibilities for spatial (both horizontal and vertical) and temporal representativeness investigation of polar-orbit satellite measurements also in terms of revisit time.Postprint (published version

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

Lidar observations of the Eyjafjallajökull volcanic ash plume at Leipzig, Germany

From 16-24 April 2010 multiwavelength EARLINET Raman lidar and AERONET Sun photometer measurements were performed at the Leibniz Institute for Tropospheric Research (IfT) in Leipzig (51.3° N, 12.5° E), Germany, to monitor the ash layers originating from the eruptions of the Eyjafjallajökull volcano in southern Iceland. We observed the first ash plumes on 16 April 2010. They showed strong depolarization which indicates non-spherical particles. Extinction coefficients were as high as 500 Mm -1. We estimate ash mass concentrations of the order of 1000 μg/m 3 in the main plume. For an aged ash plume on 19 April 2010 we observed much lower extinction coefficients of around 50 Mm -1 which lead to estimated ash mass concentrations of the order of 100 μg/m 3

Correction to “Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008–2009”

Peer reviewe

Representativeness of aerosol measurements: EARLINET-CALIPSO correlative study

The high variability of tropospheric aerosols, both in space and time, is the main cause of the high uncertainty about radiative forcing related to tropospheric aerosols and their interaction with clouds. Because of the lack of high resolution aerosol global vertical profiles, the vertical mixing has not been considered so far in studies of spatial and temporal variability. The CALIPSO mission provides the first opportunity to investigate the 4-D aerosol and cloud fields in detail. However, because of the CALIOP small footprint and the revisit time of 16 days, correlative ground-based lidar observations are necessary in order to investigate the representativeness of these satellite observations. EARLINET, the European Aerosol Research Lidar Network, started correlative measurements for CALIPSO in June 2006, right after the CALIPSO launch. An integrated study of CALIPSO and EARLINET correlative measurements opens new possibilities for spatial (both horizontal and vertical) and temporal representativeness investigation of polar-orbit satellite measurements also in terms of revisit time

Investigation of representativeness of CALIPSO aerosol optical properties products by EARLINET correlative measurements

The almost six-years long database of aerosol and cloud vertical profiles provided by CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) is at the present the longest database of aerosol optical properties at global scale. This database is a unique tool for the characterization of aerosol 4D distribution at global scale. However, CALIPSO has a small footprint and a revisiting time of 16 days, and therefore how well these measurements represent the atmospheric conditions of a surrounding area over a longer time is a big issue to be investigated. Because of its geographic coverage and the large number of advanced Raman aerosol lidars, EARLINET, the European Aerosol Research Lidar Network, offers a unique opportunity for the validation and full exploitation of the CALIPSO mission. CALIPSO Level 2 and Level 3 data products are investigated in terms of their representativeness by comparison with EARLINET measurements. Comparisons for the Level 2 profiles available in both version 2 (40 km as horizontal resolution) and version 3 (5 km) releases highlight the issue of finding a best compromise between the high resolution and the high signal-to-noise ratio. Representativeness of monthly averages provided in Level 3 data is investigated using EARLINET-CALIPSO correlative measurements. The study will furthermore benefit from the availability of the 12-years long-term database of EARLINET climatological data available from May 2000.Peer ReviewedPostprint (published version

Investigation of representativeness of CALIPSO aerosol optical properties products by EARLINET correlative measurements

The almost six-years long database of aerosol and cloud vertical profiles provided by CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) is at the present the longest database of aerosol optical properties at global scale. This database is a unique tool for the characterization of aerosol 4D distribution at global scale. However, CALIPSO has a small footprint and a revisiting time of 16 days, and therefore how well these measurements represent the atmospheric conditions of a surrounding area over a longer time is a big issue to be investigated. Because of its geographic coverage and the large number of advanced Raman aerosol lidars, EARLINET, the European Aerosol Research Lidar Network, offers a unique opportunity for the validation and full exploitation of the CALIPSO mission. CALIPSO Level 2 and Level 3 data products are investigated in terms of their representativeness by comparison with EARLINET measurements. Comparisons for the Level 2 profiles available in both version 2 (40 km as horizontal resolution) and version 3 (5 km) releases highlight the issue of finding a best compromise between the high resolution and the high signal-to-noise ratio. Representativeness of monthly averages provided in Level 3 data is investigated using EARLINET-CALIPSO correlative measurements. The study will furthermore benefit from the availability of the 12-years long-term database of EARLINET climatological data available from May 2000.Peer Reviewe

Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008-2009

In the framework of regular European Aerosol Research Lidar Network (EARLINET) observations, aerosol layers have been monitored with a multiwavelength aerosol Raman lidar in the upper troposphere and lower stratosphere over Leipzig (51.4 degrees N, 12.4 degrees E), Germany, since the summer of 2008. The origins of these layers are eruptions of different volcanoes on the Aleutian Islands, Kamchatka, Alaska, and on the Kuril Islands. FLEXPART transport simulations show that the volcanic aerosol is advected from Alaska to central Europe within about 7 days. The aerosol layers typically occurred in the upper troposphere above 5 km height and in the lower stratosphere below 25 km height. The optical depths of the volcanic aerosol layers are mostly between 0.004 and 0.025 at 532 nm. The wavelength dependence of the backscatter coefficients and extinction coefficients indicate Angstrom exponents from 1.0-2.0. Lidar ratios in the stratosphere are found in the range from 30-60 sr (355 nm) and 30-45 sr (532 nm). The estimation of the effective radius, surface-area, and mass concentrations of a volcanic aerosol layer, observed well within the stratosphere at end of August 2009, reveals values of 0.1-0.2 mu m, 5-10 mu m(2) cm(-3), and 0.3-0.5 mu g m(-3), respectively.Peer reviewe

Representativeness of aerosol measurements: EARLINET-CALIPSO correlative study

The high variability of tropospheric aerosols, both in space and time, is the main cause of the high uncertainty about radiative forcing related to tropospheric aerosols and their interaction with clouds. Because of the lack of high resolution aerosol global vertical profiles, the vertical mixing has not been considered so far in studies of spatial and temporal variability. The CALIPSO mission provides the first opportunity to investigate the 4-D aerosol and cloud fields in detail. However, because of the CALIOP small footprint and the revisit time of 16 days, correlative ground-based lidar observations are necessary in order to investigate the representativeness of these satellite observations. EARLINET, the European Aerosol Research Lidar Network, started correlative measurements for CALIPSO in June 2006, right after the CALIPSO launch. An integrated study of CALIPSO and EARLINET correlative measurements opens new possibilities for spatial (both horizontal and vertical) and temporal representativeness investigation of polar-orbit satellite measurements also in terms of revisit time