The European Aerosol Research Lidar Network, EARLINET, was founded in 2000 as a research project for establishing a quantitative, comprehensive, and statistically significant database for the horizontal, vertical, and tempo- ral distribution of aerosols on a continental scale. Since then EARLINET has continued to provide the most extensive col- lection of ground-based data for the aerosol vertical distribu- tion over Europe. This paper gives an overview of the network's main de- velopments since 2000 and introduces the dedicated EAR- LINET special issue, which reports on the present innova- tive and comprehensive technical solutions and scientific re- sults related to the use of advanced lidar remote sensing tech- niques for the study of aerosol properties as developed within the network in the last 13 years. Since 2000, EARLINET has developed greatly in terms of number of stations and spatial distribution: from 17 sta- tions in 10 countries in 2000 to 27 stations in 16 countries in 2013. EARLINET has developed greatly also in terms of technological advances with the spread of advanced multi- wavelength Raman lidar stations in Europe. The develop- ments for the quality assurance strategy, the optimization of instruments and data processing, and the dissemination of data have contributed to a significant improvement of the net- work towards a more sustainable observing system, with an increase in the observing capability and a reduction of oper- ational costs. Consequently, EARLINET data have already been ex- tensively used for many climatological studies, long-range transport events, Saharan dust outbreaks, plumes from vol- canic eruptions, and for model evaluation and satellite data validation and integration. Future plans are aimed at continuous measurements and near-real-time data delivery in close cooperation with other ground-based networks, such as in the ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) www.actris.net, and with the modeling and satellite commu- nity, linking the research community with the operational world, with the aim of establishing of the atmospheric part of the European component of the integrated global observ- ing system.

https://www.dwd.de/DWD/forschung/projekte/ceilomap/files/amt-7-2389-2014.pdf

EARLINET: towards an advanced sustainable European aerosol lidar network

. The Cloud-Aerosol Lidar with Orthogonal Polarization
(CALIOP) version 4.10 (V4) level 2 aerosol data products, released in
November 2016, include substantial improvements to the aerosol subtyping and
lidar ratio selection algorithms. These improvements are described along
with resulting changes in aerosol optical depth (AOD). The most fundamental
change in the V4 level 2 aerosol products is a new algorithm to identify aerosol
subtypes in the stratosphere. Four aerosol subtypes are introduced for
stratospheric aerosols: polar stratospheric aerosol (PSA), volcanic ash,
sulfate/other, and smoke. The tropospheric aerosol subtyping algorithm was
also improved by adding the following enhancements: (1) all aerosol subtypes
are now allowed over polar regions, whereas the version 3 (V3) algorithm
allowed only clean continental and polluted continental aerosols; (2) a new
“dusty marine” aerosol subtype is introduced, representing mixtures of
dust and marine aerosols near the ocean surface; and (3) the “polluted
continental” and “smoke” subtypes have been renamed “polluted
continental/smoke” and “elevated smoke”, respectively. V4 also revises
the lidar ratios for clean marine, dust, clean continental, and elevated
smoke subtypes. As a consequence of the V4 updates, the mean 532 nm AOD
retrieved by CALIOP has increased by 0.044 (0.036) or 52 % (40 %) for
nighttime (daytime). Lidar ratio revisions are the most influential factor
for AOD changes from V3 to V4, especially for cloud-free skies. Preliminary
validation studies show that the AOD discrepancies between CALIOP and
AERONET–MODIS (ocean) are reduced in V4 compared to V3.

/pdf/the-calipso-version-4-automated-aerosol-classification-and-4u5tjok927.pdf

The CALIPSO Version 4 Automated Aerosol Classification and Lidar Ratio Selection Algorithm

Extracellular polysaccharides from cyanobacterial soil crusts: A review of their role in dryland soil processes

Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011. This decrease in RNDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in RNDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming.

Evidence for A Weakening Relationship between Interannual Temperature Variability and Northern Vegetation Activity

Multi-decadal satellite measurements of global volcanic degassing

Nabro volcano (13.37°N, 41.70°E) in Eritrea erupted on 13 June 2011 generating a layer of sulfate aerosols that persisted in the stratosphere for months. For the first time we report on ground-based lidar observations of the same event from every continent in the Northern Hemisphere, taking advantage of the synergy between global lidar networks such as EARLINET, MPLNET and NDACC with independent lidar groups and satellite CALIPSO to track the evolution of the stratospheric aerosol layer in various parts of the globe. The globally averaged aerosol optical depth (AOD) due to the stratospheric volcanic aerosol layers was of the order of 0.018 ± 0.009 at 532 nm, ranging from 0.003 to 0.04. Compared to the total column AOD from the available collocated AERONET stations, the stratospheric contribution varied from 2% to 23% at 532 nm.

/pdf/stratospheric-aod-after-the-2011-eruption-of-nabro-volcano-nkaayoxrvg.pdf

Shi Hu

Papers

Stratospheric AOD after the 2011 eruption of Nabro volcano measured by lidars over the Northern Hemisphere

Responses of photosynthetic activity in the drought-tolerant cyanobacterium, Nostoc flagelliforme to rehydration at different temperature

Contributions of ecological programs to vegetation restoration in arid and semiarid China

Dust deposition and its significance to soil nutrients in the Otindag Desert, China