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The paper presents the preliminary results of the lidar&radiometer measurement campaign (LRMC-2017), estimation of statistical relations between aerosol mode concentrations retrieved from CALIOP and ground-based lidar stations and case study of fire smoke events in the Eurasian regions using combined ground-based and space lidar and radiometer observations.

Thunderstorms are known to have the potential to cause damage to the population. In Mexico, these weather events can bring threats such as lightning, hail, damaging winds, and even tornadoes. Various parameters and indices have been developed for mid‐latitude regions to improve forecasting and reduce the potential damage from thunderstorms; however, they do not consider the specific conditions of tropical and subtropical environments. This research used a comprehensive set of thunderstorm reports and the proximity‐sounding approach using ERA5 reanalysis data to examine five important instability indices commonly used for thunderstorm forecasting regarding their spatial and temporal characteristics. The results reveal significant variations in the values of the instability indices during thunderstorm events associated with different atmospheric systems in both the high‐activity and low‐activity seasons. The above suggests that no single index can reliably predict thunderstorms throughout Mexico and during all seasons. Analyses provide forecasters with a more comprehensive understanding of the various atmospheric conditions under which thunderstorms develop in the country, which can lead to more accurate forecasting and better disaster risk management for these natural phenomena. [ABSTRACT FROM AUTHOR]

This work introduces CAECENET, a new system capable of automatically retrieving columnar and vertically-resolved aerosol properties running the GRASP (Generalized Retrieval of Atmosphere and Surface Properties) algorithm using sun-sky photometer (aerosol optical depth, AOD; and sky radiance measurements) and ceilometer (range corrected signal; RCS) data as input. This method, so called GRASPpac, is implemented in CAECENET, which assimilates sun-sky photometers data from CÆLIS database and ceilometer data from ICENET database (Iberian Ceilometer Network). CAECENET allows for continuous and near-real-time monitoring of both vertical and columnar aerosol properties. The main characteristics and workflow of CAECENET are explained in detail. This work also explores the potential of CAECENET to monitor and analyze the evolution of transported aerosol events on a regional scale by means of the distribution of CAECENET stations across the Iberian Peninsula. As an example, this paper analyzes, using the CAECENET products, the case of a Saharan dust outbreak that occurred between the 3rd and 5th of October 2022. This was an intense event, with AOD at 440 nm values around 0.5 in Madrid and Valladolid, and reaching 1.55 in Granada. Transport from the Canadian wildfires at the end of June 2023 is also studied. Despite the long-range transport of the smoke particles in this event, measured volume concentrations reached and surpassed 80 μ m3/ μ m2 in some stations. The results obtained point to the utility of this CAECENET tool for analyzing changes in the height and speed of the event propagation, in the aerosol concentration, and how this affects the optical properties. [ABSTRACT FROM AUTHOR]

Covalent adaptable networks (CANs) represent a pioneering advance in polymer science, offering unprecedented versatility in materials design. Unlike conventional adhesives with irreversible bonds, CAN-based polyurethane adhesives have the unique ability to undergo chemical restructuring through reversible bonds. One of the strategies for incorporating these types of reactions in polyurethanes is by functionalisation with Diels–Alder (DA) adducts. By taking advantage of the reversible nature of the DA chemistry, the adhesive undergoes controlled crosslinking and decrosslinking processes, allowing for precise modulation of bond strength. This adaptability is critical in applications requiring reworkability or recyclability, as it allows for easy disassembly and reassembly of bonded components without compromising the integrity of the material. This study focuses on the sustainable synthesis and characterisation of a solvent-based polyurethane adhesive, obtained by functionalising a polyurethane prepolymer with DA diene and dienophiles. The characterisation of the adhesives was carried out using different experimental techniques: nuclear magnetic resonance spectroscopy (NMR), Brookfield viscosity, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and T-peel strength testing of leather/adhesive/rubber joints to determine the adhesive properties, both before and after the application of external stimuli. The conversion of both the DA and retro-Diels–Alder (r-DA) reactions was confirmed by 1H-NMR. The adhesive properties were not altered by the functionalisation of the adhesive prepolymer, showing similar thermal resistance and good rheological and adhesive properties, even exceeding the most demanding technical requirements for upper-to-sole joints in footwear. After the application of an external thermal stimuli, the bonded materials separated without difficulty and without damage, thus facilitating their separation, recovery and recycling. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols are one of the main factors that contribute to poor air quality. These aerosols are mostly concentrated within the atmospheric boundary layer (ABL) and mixing layer (ML). The ABL extends from ground level to the lowest level of the troposphere directly affected by surface temperature, solar irradiance, the orography and its proximity to coastal areas, causing turbulence in a daily cycle. This turbulence controls the vertical mixing of aerosols and pollutants and their dispersion in the ML. Therefore, proper characterization of these layers is of crucial importance in numerical weather forecasting and climate models; however, their estimation nowadays presents some spatial and temporal limitations. In order to deal with these limitations and to assess the influence of different meteorological conditions on the temporal evolution of the aforementioned layers, the evolution of the ML over Madrid (Spain) has been studied for the year 2020 by means of ceilometer profiles fed into the STRATfinder algorithm. This algorithm is able to give reliable estimates of the height of the ABL (ABLH) and ML (MLH). The results are compared with the ECMWF-IFS model predictions, which is able to compute the MLH under any meteorological condition. Then, the influence of the meteorology in the estimation of MLHs was established by classifying data based on the season and six different prevalent synoptic meteorological situations defined using ground-level pressure fields, as well as by splitting the days into four periods (morning, daytime, evening and nighttime). Our results show that both datasets, the STRATfinder values and the ECMWF-IFS model computations, are very sensitive to the meteorological conditions that play a main role in the MLH temporal evolution. For instance, high solar irradiance and ground radiation cause high turbulence and convection that lead to a well-developed ML. In cases in which the ML is well developed, both methods show similar results, and there are therefore better correlations between them. On the contrary, the results presented here show that the presence of high relative humidity and low temperatures hamper the growth of the ML, causing different errors in both MLH estimations and poor correlations between them. Furthermore, the ECMWF-IFS model has shown a sharp decrease, identified as an artificial behavior from 16:00 UTC, because of the influence of low solar zenith angles and the temporal interpolation. The STRATfinder algorithm also shows a sharp decrease just before the sunset because of the way the algorithm distinguishes between the ML and the residual layer. Thus, this study concludes that the MLH temporal evolution still needs to be characterized using complementary tools, since the methods presented here are strongly affected by the meteorological conditions and do not show enough reliability to work individually. However, ceilometer measurements offer great potential as a correction tool for ABL heights derived from models involved in air pollution dispersion assessments. [ABSTRACT FROM AUTHOR]

An intense and long-lasting Saharan dust outbreak over the Iberian Peninsula (IP) in springtime 2021 is studied in this work with the aim of investigating the optical and mass contribution of both the fine and coarse dust particles along their transport by crossing the IP from the south-west to the north-east. Five Iberian lidar stations (El Arenosillo/Huelva, Granada, Torrejón/Madrid and Barcelona in Spain and Évora in Portugal) were monitoring the transport and evolution of the Saharan dust particles across the Iberian Peninsula from 25 March until 7 April 2021. Particular meteorological conditions determined the aerosol scenario along the overall dust event, differing the first part of the event (25–31 March), with the strongest dust incidence on 29–31 March at the south and central stations, and 1 April at Barcelona, from the second one (1–7 April). Both the fine dust (Df) and coarse dust (Dc) components of the total particle backscatter coefficient (total dust, DD = Dc + Df) were separately derived. The dust plume was well-mixed and no significant differences were found in the vertical structure of both the Dc and Df particle backscatter coefficients. The vertical total dust mass concentration, and its Df / DD ratio, were estimated from the extinction profiles using the well-defined conversion factors for North African dust. From the beginning of the dust outbreak until 1 April, the vertical Df / DD mass ratio was nearly constant in time at each station and also almost constant in altitude with values ~ 10 %. Regarding the columnar properties, the dust optical depth at 532 nm (DOD532), the relative mass loading and the centre-of-mass height were calculated, distinguishing the corresponding fine- and coarse-dust contributions. Firstly, the dust outbreak crossed the Iberian Peninsula from South-West to North-East and the mean DOD532 was decreasing along that dust pathway, reporting values from SW to NE stations of 0.34 at El Arenosillo/Huelva, 0.28 at Granada, 0.20 at Évora, 0.28 at Torrejón/Madrid and 0.14 at Barcelona, although its Df / DD ratio kept almost constant (28–30 %). On the other hand, a similar pattern was found for the total dust mass loading and its Df / DD ratio, i.e. mostly decreasing mean mass values were reported: 586 mg m-2 (El Arenosillo/Huelva), 483 mg m-2 (Granada), 332 mg m-2 (Évora), 464 mg m-2 (Torrejón/Madrid) and 248 mg m-2 (Barcelona), being constant its Df / DD ratio (~ 10 %) along the SW-NE dust pathway In addition, the episode-mean centre-of-mass height increased with latitude in overall, showing a high variability, i.e. being greater than 0.5 km at the southern sites (El Arenosillo/Huelva, Granada, Évora) and ~1.0 km at Torrejón/Madrid and Barcelona. However, despite the relatively high intensity of the dust intrusion, the expected ageing of the dust particles was barely observed. This is on the basis that the Iberian Peninsula is relatively close to the Saharan dust sources and then, under certain dust transport conditions, any potential ageing processes in the dust particles remain unappreciated. It must be highlighted the different relative contribution of the fine dust particles to the total dust found for their optical properties (~ 30 %), associated to the radiative effect of dust, with respect to the mass features (~ 10 %), linked to air quality issues, along the overall dust event by crossing the IP. Finally, the methodology introduced, which is mainly based on the two-step POLIPHON algorithm, shows the relevance of the use of the polarized lidar measurements, mainly with elastic systems, for separating the aerosol properties for the dust fine and coarse particles as an added value to the simple one-step approach used for simple dust/non-dust separation. [ABSTRACT FROM AUTHOR]