. Lidar and sun-photometer measurements were performed intensively over the Iberian Peninsula (IP) during the eruption of the Eyjafjallajokull volcano (Iceland) in April–May 2010. The volcanic plume reached all the IP stations for the first time on 5 May 2010. A thorough study of the event was conducted for the period 5–8 May. Firstly, the spatial and temporal evolution of the plume was described by means of lidar and sun-photometer measurements supported with backtrajectories. The volcanic aerosol layers observed over the IP were rather thin (

/pdf/monitoring-of-the-eyjafjallajokull-volcanic-aerosol-plume-4jwwgmozv6.pdf

Monitoring of the Eyjafjallajökull volcanic aerosol plume over the Iberian Peninsula by means of four EARLINET lidar stations

[1] An exceptionally strong outbreak of Saharan dust was observed in southern Portugal from 4 to 9 April 2011. The event was monitored with a multiwavelength Raman lidar, a CIMEL Sun photometer, the Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and two Moderate Resolution Imaging Spectroradiometer (MODIS). Those instruments provided vertically resolved and columnar information about the optical properties of the mineral dust plume. Maximum aerosol optical depths in the free troposphere of 1.8 and 1.9 were observed with Raman lidar at 355 and 532 nm, respectively. The mean extinction-related Angstrom exponents (355, 532 nm) from Raman lidar averaged over the whole period were 0.0 ± 0.2. Backscatter-related Angstrom exponents (355, 532 nm and 532, 1064 nm) were 0.4 on average. Mean lidar ratios calculated from Raman lidar measurements were 45 ± 8 sr at 355 nm and 53 ± 7 sr at 532 nm. The mean linear particle depolarization ratio at 532 nm was 0.28 ± 0.04. Furthermore, intrusion of Saharan dust into the planetary boundary layer could be observed with different ground-based in-situ instruments. Maximum particle mass concentration values (PM10) of 162 μg m−3 were detected at ground. The daily threshold of 50 μg m−3 for PM10 was exceeded on three subsequent days during the considered period. The ratio of coarse to fine mode particle number concentration reached maximum values larger than 1, coinciding with the maximum in PM10mass concentration. A comparison of ground-based Raman lidar measurements and CALIOP Level 2 data was done for one CALIPSO overpass. A good agreement was found for backscatter coefficients.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2011JD016527

Multi‐instrumental observation of an exceptionally strong Saharan dust outbreak over Portugal

[1] Multi-wavelength Raman light detection and ranging (lidar) observations were analyzed, which were performed in Evora, Portugal, during more than 2 years on a regular basis in the framework of the European Aerosol Research Lidar Network (EARLINET) An aerosol characterization in terms of the lidar ratios at 355 and 532 nm and the extinction and backscatter related Angstrom exponents is presented Aerosol layers in the free troposphere were classified according to their origin Clear differences in the intensive optical properties were found for layers of mineral dust from the Sahara and from Asia, of anthropogenic aerosol from Europe and from North America, as well as of biomass burning smoke from the Iberian Peninsula and from North America, respectively In general, the mean Angstrom exponents of aerosol layers of the same type, but from closer source regions, were smaller than those from aerosol layers transported over a longer distance This hints at the deposition of large particles along the transportation path, especially for anthropogenic aerosol and mineral dust Besides, the seasonal behavior of aerosol in the free troposphere over Evora was studied Seventy-three percent of the detected layers were observed during spring and summer On average, the layers were highest in summer with an overall mean layer height of (38 ±19) km above sea level (asl), and lowest in winter with (23 ±09) km asl

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/jgrd.50350

Two years of free-tropospheric aerosol layers observed over Portugal by lidar

Vertically resolved optical and microphysical properties of biomass burning aerosols, measured in 2011 with a multiwavelength Raman lidar, are presented. The transportation time, within 1-2 days (or less), pointed towards the presence of relatively fresh smoke particles over the site. Some strong layers aloft were observed with particle backscatter and extinction coefficients (at 355 nm) greater than 5 Mm−1 sr−1 and close to 300 Mm−1, respectively. The particle intensive optical properties showed features different from the ones reported for aged smoke, but rather consistent with fresh smoke. The Angstrom exponents were generally high, mainly above 1.4, indicating a dominating accumulation mode. Weak depolarization values, as shown by the small depolarization ratio of 5% or lower, were measured. Furthermore, the lidar ratio presented no clear wavelength dependency. The inversion of the lidar signals provided a set of microphysical properties including particle effective radius below 0.2 μm, which is less than values previously observed for aged smoke particles. Real and imaginary parts of refractive index of about 1.5-1.6 and 0.02i, respectively, were derived. The single scattering albedo was in the range between 0.85 and 0.93; these last two quantities indicate the nonnegligible absorbing characteristics of the observed particles.

/pdf/forest-fire-smoke-layers-observed-in-the-free-troposphere-54s81n0qqk.pdf

Forest Fire Smoke Layers Observed in the Free Troposphere over Portugal with a Multiwavelength Raman Lidar: Optical and Microphysical Properties

Solar and thermal radiative effects during the 2011 extreme desert dust episode over Portugal

BACKGROUND Information about airborne pollen concentrations is required by a range of end users, particularly from the health sector who use both observations and forecasts to diagnose and treat allergic patients. Manual methods are the standard for such measurements but, despite the range of pollen taxa that can be identified, these techniques suffer from a range of drawbacks. This includes being available at low temporal resolution (usually daily averages) and with a delay (usually 3-9 days from the measurement). Recent technological developments have made possible automatic pollen measurements, which are available at high temporal resolution and in real time, although currently only scattered in a few locations across Europe. MATERIALS & METHODS To promote the development of an extensive network across Europe and to ensure that this network will respond to end user needs, a stakeholder workshop was organised under the auspices of the EUMETNET AutoPollen Programme. Participants discussed requirements for the groups they represented, ranging from the need for information at various spatial scales, at high temporal resolution, and for targeted services to be developed. RESULTS The provision of real-time information is likely to lead to a notable decrease in the direct and indirect health costs associated with allergy in Europe, currently estimated between €50-150 billion/year.1 DISCUSSION & CONCLUSION: A European measurement network to meet end user requirements would thus more than pay for itself in terms of potential annual savings and provide significant impetus to research across a range of disciplines from climate science and public health to agriculture and environmental management.

The need for Pan-European automatic pollen and fungal spore monitoring: A stakeholder workshop position paper.

To extend and reinforce the action of the EARLINET-ASOS project, a network of Spanish and
Portuguese aerosol lidars (SPALINET) was created. In the first three years of the project six out of the ten systems
have been successfully intercompared, seven elastic algorithms have also been validated and six Raman algorithms
are currently being validated. Now the network focuses on future scientific objectives aiming at performing
coordinated measurements.

http://www.lidar.es/spalinet/public/media/file/publications/spalinet2009_manuscript_v1.pdf

Lucas Alados Arboledas

Papers

The need for Pan-European automatic pollen and fungal spore monitoring: A stakeholder workshop position paper.

SPALINET: The Spanish and Portuguese aerosol lidar network