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The effect of mineral aerosol optical properties and vertical distribution on clear-sky, instantaneous and daily-average aerosol direct radiative effects (DREs) and heating rates (HRs) is analyzed in the solar (S, 0.3–4 μm) and terrestrial (T, 4–80 μm) spectral domain, respectively. The used radiative transfer model is based on lidar, sun-sky photometer, and radiosonde measurements. The study focuses on the Sahara dust outbreak of July 16, 2009 which advected dust particles from north-western Africa over south-eastern Italy. Clear-sky, instantaneous aerosol DREs and HRs undergo large changes within few hours, for the variability of the dust aerosol properties and vertical distribution. The daily-average, clear-sky aerosol S-DRE is near −5 Wm−2 and −12 Wm−2 at the top of the atmosphere (ToA) and surface (sfc), respectively. The daily-average aerosol T-DRE offsets the S-DRE by about one third at the ToA and by about one half at the surface. The daily average aerosol HR integrated over the whole aerosol column is 0.5 and −0.3 K day−1 in the S and T domain, respectively. Thus, the all-wave integrated HR is 0.2 K day−1. These results highlight the importance of accounting for the interaction of dust particles with T and S radiation. Sensitivity tests indicate that the uncertainties of the aerosol refractive index, size distribution, and vertical distribution have on average a large impact on aerosol HRs in the S and T domain, respectively. Refractive index and aerosol size distribution uncertainties also have a large impact on S- and T-DREs. The aerosol vertical distribution that has a negligible impact on aerosol S-DREs, is important for aerosol T-DREs. It is also shown that aerosol HRs and DREs in the terrestrial domain are affected by the water vapour vertical distribution.

The all-sky direct radiative effect by anthropogenic aerosol (DREa) is calculated in the solar (0.3–4 μm) and infrared (4–200 μm) spectral ranges for six Mediterranean sites. The sites are differently affected by pollution and together reflect typical aerosol impacts that are expected over land and coastal sites of the central Mediterranean basin. Central to the simulations are aerosol optical properties from AERONET sun-/sky-photometer statistics for the year 2003. A discussion on the variability of the overall (natural + anthropogenic) aerosol properties with site location is provided. Supplementary data include MODIS satellite sensor based solar surface albedos, ISCCP products for high- mid- and low cloud cover and estimates for the anthropogenic aerosol fraction from global aerosol models. Since anthropogenic aerosol particles are considered to be smaller than 1 μm in size, mainly the solar radiation transfer is affected with impacts only during sun-light hours. At all sites the (daily average) solar DREa is negative all year round at the top of the atmosphere (ToA). Hence, anthropogenic particles produce over coastal and land sites of the central Mediterranean a significant cooling effect. Monthly DREa values vary from site to site and are seasonally dependent as a consequence of the seasonal dependence of available sun-light and microphysical aerosol properties. At the ToA the monthly average DREa is −(4±1) W m−2 during spring-summer (SS, April–September) and −(2±1) W m−2 during autumn-winter (AW, October–March) at the polluted sites. In contrast, it varies between −(3±1) W m−2 and −(1±1) W m−2 on SS and AW, respectively at the less polluted site. Due to atmospheric absorption the DREa at the surface is larger than at the ToA. At the surface the monthly average DREa varies between the most and the least polluted site between −(7±1) W m−2 and −(4±1) W m−2 during SS, and between −(4±3) W m−2 and −(1±1) W m−2 during AW. The DREa at infrared wavelengths is positive but negligible, especially at the ToA (−2). The average of DREa monthly-means referring to all sites has allowed getting a ToA- and sfc-DREa yearly-mean value of −(3±2) and −(5±3) W m−2, respectively at solar wavelengths. Last data, even if refer to a particular year, indicate that the radiative energy-balance of Central Mediterranean land and coastal sites is quite affected by anthropogenic particles.

Daily averaged retrievals of AERONET sun photometer measurements from March 2003 to March 2004 are used to provide preliminary results on the characterization of aerosol properties and changes over south–east Italy (40°20′N, 18°6′E). It is shown that aerosol optical and microphysical properties and the dominating aerosol types depend on seasons. Aerosol-parameter frequency distributions reveal the presence of individual modes that lead to the assumption that moderately absorbing urban–industrial and marine-polluted aerosols dominate in spring–summer and autumn–winter, respectively. It is shown that aerosol optical depths (AODs), single scattering albedos (SSAs), and Angstrom coefficients (A) of urban–industrial (spring–summer) aerosols are characterized by lognormal distributions with peak values of 0.20±0.03, 0.94±0.01, and 1.58±0.03, respectively. On the contrary AOD, SSA and A values of maritime-polluted (autumn–winter) aerosols are characterized by lognormal distributions with peak values of 0.049±0.008, 0.974±0.003, and 0.7±0.1, respectively. It is also shown that the frequency distribution of real n and imaginary k refractive indices permits inference of the dominant aerosol constituents: sea-salt, water soluble, soot, and mineral particles. Finally, it is shown that dust outbreaks do not significantly affect the seasonal evolution of aerosol parameters, and that sunphotometry retrievals along dust events are in satisfactory accord with experimental findings indicating that moderately-absorbing (0.005≤ k ≤0.05) dust particles with a high content of illite are mainly advected over the Mediterranean basin during Sahara dust storms.

Functional relationships linking at λ0=351 nm aerosol extinction αλ0aer and backscatter coefficient βλ0aer of maritime and desert type aerosols are determined to allow for inversion of the single-wavelength lidar signals. Such relationships are derived as mean behavior of 20,000 extinction versus backscatter computations, performed for aerosol size distributions and compositions whose describing parameters are randomly chosen within the naturally observed variability. For desert-type aerosols, the effect of the particle non-sphericity is considered and it is shown that the extinction to backscatter ratio of non-spherical dust particles can be up to 60% larger than the values obtained for spherical particles. Aerosol extinction and backscatter coefficient profiles obtained inverting the single-wavelength lidar signal with the modeled relationships are then compared to the same profiles measured by a combined elastic-Raman lidar operating at 351 nm. Analytical back trajectories and satellite images are used to characterize advection patterns during lidar measurements and to properly choose the modeled functional relationship. A good accordance between the two techniques is found for advection patterns over the lidar site typical of maritime and dust conditions. Maximum differences between the model-based αλ0aer and βλ0aer vertical profiles and the corresponding ones measured by the combined elastic-Raman lidar technique are of 30% and 40% in maritime and desert dust conditions, respectively. The comparison of elastic-Raman lidar measurements and model-based results also reveals that particle non-sphericity must be taken into account when mineral dust-type aerosols are directly advected over the measurement site.

The all-sky direct radiative effect by anthropogenic aerosol (DREa) is calculated in the solar (0.3–4 μm) and infrared (4–200 μm) spectral ranges for six Mediterranean sites. The sites are differently affected by pollution and together reflect typical aerosol impacts that are expected over land sites of the central Mediterranean basin. Central to the simulations are aerosol optical properties from AERONET sun-/sky-photometer statistics for the year 2003. A discussion on the variability of the overall (natural+anthropogenic) aerosol properties with site location is provided. Supplementary data include MODIS satellite sensor based solar surface albedos, ISCCP products for high- mid- and low cloud cover and estimates for the anthropogenic aerosol fraction from global modelling. Since anthropogenic aerosol particles are considered to be smaller than 1 μm in size, mainly the solar radiation transfer is affected with impacts only during sun-light hours. At all sites the (daily average) solar DREa is negative all year round at the top of the atmosphere (ToA). Hence, anthropogenic particles produce over land sites of the central Mediterranean a significant cooling effect. Monthly DREa values vary from site to site and are seasonal dependent as a consequence of the seasonal dependence of available sun-light and microphysical aerosol properties. At the ToA the monthly average DREa is −(4±1) W m−2 during spring-summer (SS, April–September) and −(2±1) W m−2 during autumn-winter (AW, October–March) at the polluted sites. In contrast, it varies between −(3±1) W m−2 and −(1±1) W m−2 on SS and AW, respectively at the less polluted site. Due to atmospheric absorption the DREa at the surface is larger than at the ToA. At the surface the monthly average DREa varies between the most and the least polluted site between −(7±1) W m−2 and −(4±1) W m−2 during SS, and between −(4±3) W m−2 and −(1±1) W m−2 during AW. The DREa at infrared wavelengths is positive but negligible, especially at the ToA (

Ground-based particulate matter (PM) samplers, an XeF Raman lidar operating in the framework of the European Aerosol Research Lidar Network (EARLINET), and a sun/sky radiometer operating in the framework of the Aerosol Robotic Network (AERONET) have been used to characterize vertical profiles, optical and microphysical properties, and chemical composition of aerosols during the 29 June–1 July 2005 dust outbreak that occurred over the central-eastern Mediterranean. Aerosol backscatter coefficient, total depolarization, and lidar ratio vertical profiles revealed that a well-mixed dust layer extending from ∼0.5 to 6 km was present over southeastern Italy on 30 June. Sun/sky radiometer measurements revealed a bimodal lognormal size distribution during all measurement days. The particle volume distribution was found to be well correlated either to the PM mass distribution measured at ground by a seven-stage cascade impactor and to the fine to total suspended PM mass ratio measured by ground-based PM samplers. Scanning electron microscopy and ion chromatography analyses on PM samples revealed that coarse-mode aerosols were mainly made of carbonate, aluminum-silicate, and sea salt particles. Carbon, sulfate, and nitrate particles were the main components of fine-mode aerosols representing more than 50% of the total aerosol load; the significant role of fine-mode anthropogenic particles during a dust event is highlighted. Finally, the potential capabilities of complementary measurements by passive and active remote sensing techniques and in situ observations to retrieve the vertical distribution of the particle number and mass concentration are analyzed and discussed.

Aerosol direct radiative effect (DRE) calculations are presented to illustrate the annual cycle of the aerosol impact on the radiative energy balance of the Earth- atmosphere system over southeast Italy. Meteorological parameters from radiosondes, aerosol vertical profiles by lidar, aerosol optical and microphysical properties by ground- based Sun/ sky photometry and satellite ( MODIS) derived data of solar surface albedo, all referring to the 2003 - 2004 years, constitute the necessary input to radiative transfer simulations. The monthly evolution of both the solar and infrared aerosol direct radiative effect is examined at the top of the atmosphere (ToA), within the atmosphere and at the Earth's surface. Aside from cloud-free conditions (clear-sky), all-sky conditions are also addressed by adopting ISCCP monthly products. Model results reveal a strong seasonality of the solar aerosol DRE for southeast Italy, which is mainly driven by the available sunlight, but it is also modulated by variations in aerosol properties. Under cloud-free conditions, winter aerosol DREs are within -(6 +/- 2) W/m(2) at the ToA and -(7 +/- 2) W/m(2) at the surface, while summer aerosol DREs are within -(9 +/- 1) W/m(2) at the ToA and -(15 +/- 3) W/m(2) at the surface. The larger difference in summer indicates that the heating of the aerosol layer (atmospheric forcing) is much stronger in summer and actually largest in early fall. Under all-sky conditions the solar aerosol direct radiative effect decreases to -(4 +/- 1) W/m(2) and -(3 +/- 1) W/m(2) in winter and to -(12 +/- 3) W/m(2) and -(7 +/- 1) W/m(2) in summer, at surface and ToA, respectively. Model results also reveal that solar aerosol DREs dominates infrared aerosol DREs. The performed sensitivity studies demonstrate the relatively weak impact of meteorological parameters and aerosol vertical profiles and the strong impact of solar surface albedo values. Finally, it is shown that the simulated all-sky aerosol DRE at the surface is consistent with radiometer measurements.

[1] A 2.5-year data set of Raman lidar measurements performed in Lecce within the European Aerosol Research Lidar Network and a numerical model are used to characterize continental aerosols over southeast Italy. Continental conditions are selected by means of back trajectories, limiting the data set to cases of advection from the European continent. The model is used to constrain the relevant aerosol microphysical parameters needed to reproduce the altitude-resolved optical properties measured by lidar, namely, aerosol extinction (α), backscatter (β), and lidar ratio (LR = α/β) at 351 nm. The observed variability of α, β, and LR is simulated by randomly varying, within appropriate ranges, all the microphysical parameters describing the aerosol composition and size distribution (assumed as bimodal). An optimal model configuration capable of reproducing within ±10% the mean optical properties retrieved by lidar, including their vertical pattern, is presented and discussed with sensitivity studies. Results indicate rather clean continental aerosols to characterize the site, with water-soluble fine-mode aerosols (dry modal radius of 0.05–0.10 μm) accounting for 98–99% of the total number of particles. The (dry) imaginary refractive index of fine-mode particles is extended up to 0.02 to better fit the lidar data. This suggests some mixing of water-soluble substances with more absorbing material. Coarse-mode particles (modal radius 0.4–0.5 μm) are shown to play a crucial role in determining the observed vertical profile of β and LR. Finally, an altitude-resolved relationship linking α to β is derived. This could be usefully employed in continental conditions to invert the lidar measurements when only the elastic signal is available (for example, in daylight).

Active and passive remote sensing devices such as lidars and sunphotometers, respectively, are peculiar tools to follow the spatial and temporal evolution of aerosol loads and get complementary data to properly characterize aerosol optical and microphysical properties. A XeF-based Raman lidar is routinely used at the physics department of Lecce’s University (40° 20′ N, 18° 6′ E), to monitor aerosol vertical distributions and characterize aerosol optical properties by the vertical profiles of the backscatter and extinction coefficient, lidar ratio, and depolarization ratio. In addition, a sun/sky radiometer operating within AERONET is used to supplement lidar measurements and better infer aerosol types and properties by columnar values of the particle size distribution, the real and imaginary refractive index, the single scattering albedo and the Angstrom exponent (A). The main objective of this paper is to provide some results on the spatial and temporal evolution of the aerosol properties over south-east Italy, in the central-east Mediterranean basin, by using lidar and sunphotometer measurements. Specifi cally, results on the characterization of the aerosol load from July 18 to July 21, 2005 are reported and particular attention is devoted to the Sahara dust outbreak that has occurred over south-east Italy on July 18 and 19, 2005.

[1] Systematic Raman lidar measurements performed from May 2000 to August 2002 in the framework of the European Aerosol Research Lidar Network are analyzed and discussed. Main results on height dependence and seasonal cycle of extinction α(z) and backscatter β(z) coefficients, aerosol optical depths AOD(z), and lidar ratios S(z) are presented. Yearly-averaged vertical profiles of extinction and backscatter coefficients reveal that both α(z) and β(z) decrease more than 75% within the lowermost 2 km. Yearly-averaged lidar ratios increase from about 42–48 sr in the lowermost 2 km to between 67–72 sr in the air masses above 2 km. The changes in lidar ratios are indicative of changes in the physical characteristics of the monitored aerosols and suggest that over the monitoring site, the lowermost air masses (z 2 km) are characterized by lidar ratios typical of continental aerosol type. The seasonal cycle analysis reveals that the average maximum height zM at which aerosols are detected by the lidar that is about 5 km in spring-summer, and decreases up to about 3 km in autumn-winter. Monthly AODs span the 0.16–0.26 range in autumn-winter and the 0.26–0.4 range in spring-summer. The scarce renovation of air masses, occurring in spring-summer as a consequence of the weather stability, favours the accumulation of the atmospheric aerosol particles and may account for the larger AODs and zM values.

AERONET sun photometer measurements performed at five different sites of the Central Mediterranean during strong Saharan dust outbreaks are used to characterize optical and physical properties of dust particles. Sun photometer retrievals are combined at two of the five sites with lidar observations. It is shown that at low aerosol optical depths (AODs) the dust particle properties are quite dependent on dust load and monitoring site location. Differences on retrieved particle properties reduce with increasing dust load. AERONET retrievals at AOD (440 nm) ≥ 0.6 are then used in this paper to characterize dust particles over the central Mediterranean basin leading to columnar averaged values of the real refractive index n > = 1.5 ± 0.1, the imaginary refractive index k > = 0.004 ± 0.002, the single scattering albedo SSA > = 0.89 ± 0.03, and the Angstrom exponent A > = 0.2 ± 0.1. It is shown that A represents the best marker to trace the temporal evolution of dust events. Volume size distributions show a dominant coarse mode peaking at 1.7–3 μm. In particular, the average coarse mode that is centred at ≅ 2.2 μm at Lampedusa, which is ∼200 km away from the northwest Africa coast, gets peaked at ≅ 1.7 μm at Lecce, which is ∼800 km away. Lidar retrievals are used to characterize the vertical distribution of dust particles by the vertical profiles of the backscatter and extinction coefficients, the lidar ratio, and the depolarization ratio. Lidar retrievals show that over the Mediterranean basin, dust layers generally extend from 1 up to 6 km and that their vertical distribution can significantly change within a few hours. It is also shown that at high values of the AODs dust particles are characterized by lidar ratios spanning the 50–70 sr range and depolarization ratios larger than 30%.

A numerical model is used to investigate the dependence at 351 nm of desert-aerosol extinction and backscatter coefficients on particle imaginary refractive index (mi). Three ranges (-0.005 < or = mi < or = -0.001, -0.01 < or = mi < or = -0.001, and -0.02 < or = mi < or = -0.001) are considered, showing that backscatter coefficients are reduced as /mi/ increases, whereas extinction coefficients are weakly dependent on mi. Numerical results are compared with extinction and backscatter coefficients retrieved by elastic Raman lidar measurements performed during Saharan dust storms over the Mediterranean Sea. The comparison indicates that a range of -0.01 to -0.001 can be representative of Saharan dust aerosols and that the nonsphericity of mineral particles must be considered.

We studied 193 hands of 113 patients referred for typical carpal tunnel syndrome (CTS). Ninety-five (49%) hands had normal median distal motor latency (≤4.2 ms) and normal or borderline sensory conduction velocity from digit 2 stimulation (≥45 m/s). In these cases we performed three median to ulnar comparative tests: (1) difference between median and ulnar distal motor latencies recorded from the second lumbrical and interossei muscles (2L-INT); (2) difference between median and ulnar sensory latencies from digit 4 stimulation (D4M-D4U); and (3) difference between median and ulnar mixed nerve latencies from palmar stimulation (PM-PU). The 2L-INT difference was ≥0.6 ms in 10% of hands. PM-PU and D4M-D4U were ≥0.5 ms in 56% and 77% of hands, respectively. The greater sensitivity of D4M-D4U might be explained by the funicular topography and consequent greater susceptibility to compression of the cutaneous fibers from the third interspace which, at the distal carpal tunnel, are clumped superficially in the anteroulnar portion of the median nerve just beneath the transverse ligament. © 1993 John Wiley & Sons, Inc.

il saggio affronta la tematica delle nuove competenze del management e contestualmente delle formazione che si profila necessaria sia per il management già occupato sia per la nuova leva dei manager che devono inserisi in azienda.