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Clouds cover substantial parts of the Earth's surface and they are one of the most essential components of the global climate system impacting the Earth's radiation balance as well as the water cycle redistributing water around the globe as precipitation. Therefore, continuous observation of clouds is of primary interest in climate and hydrological studies. This work documents the first efforts in Italy in remote sensing clouds and precipitation using a combination of K- and W-band (24 and 94 GHz, respectively) radar profilers. Such a dual-frequency radar configuration has not been widely used yet, but it could catch on in the near future given its lower initial cost and ease of deployment for commercially available systems at 24 GHz, with respect to more established configurations. A field campaign running at the Casale Calore observatory at the University of L'Aquila, Italy, nestled in the Apennine mountain range is described. The campaign features are preceded by a review of the literature and the underpinning theoretical background that might help newcomers, especially in the Italian community, to approach cloud and precipitation remote sensing. This activity takes place in interesting time for radar sensing clouds and precipitation, stimulated both by the launch of the ESA/JAXA EarthCARE satellite missions scheduled in 2024, which will have on-board, among other instruments, a W-band Doppler cloud radar and the proposal of new missions using cloud radars currently undergoing their feasibility studies (e.g., WIVERN and AOS in Europe and Canada, and U.S., respectively).

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Hypovitaminosis D is increasingly recognized as a cofactor in several diseases. In addition to bone homeostasis, vitamin D status influences immune system, muscle activity and cell differentiation in different tissues. Vitamin D is produced in the skin upon exposure to UVB rays, and sufficient levels of serum 25(OH)D are dependent mostly on adequate sun exposure, and then on specific physiologic variables, including skin type, age and Body Mass Index (BMI). In contrast with common belief, epidemiologic data are demonstrating that hypovitaminosis D must be a clinical concern not only in northern Countries. In our study, we investigated vitamin D status in a male population enrolled in a urology clinic of central Italy. In addition, we evaluated the correlation between vitamin D status and UVB irradiance measured in our region. The two principal pathologies in the 95 enrolled patients (mean age 66years) were benign prostate hypertrophy and prostate carcinoma. >50% of patients had serum 25(OH)D values in the deficient range (<20ng/mL), and only 16% of cases had serum vitamin D concentration higher than 30ng/mL (optimal range). The seasonal stratification of vitamin D concentrations revealed an evident trend with the minimum mean value recorded in April and a maximum mean value obtained in September. UVB irradiance measured by pyranometer in our region (Abruzzo, central Italy) revealed a large difference during the year, with winter months characterized by an UV irradiance about tenfold lower than summer months. Then we applied a mathematical model in order to evaluate the expected vitamin D production according to the standard erythemal dose measured in the different seasons. In winter months, the low available UVB radiation and the small exposed skin area resulted not sufficient to obtain the recommended serum doses of vitamin D. Although in summer months UVB irradiance was largely in excess to produce vitamin D in the skin, serum vitamin D resulted sufficient in September only in those patients who declared an outdoor time of at least 3h per day in the previous summer. In conclusion, hypovitaminosis D is largely represented in elderly persons in our region. Seasonal fluctuation in serum 25(OH)D was explained by a reduced availability of UVB in winter and by insufficient solar exposure in summer. The relatively high outdoor time that emerged to be correlated with sufficient serum 25(OH)D in autumn warrants further studies to individuate potential risk co-variables for hypovitaminosis D in elderly men.

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We report the design and the performances of a Raman lidar for long-term monitoring of tropospheric aerosol backscattering and extinction coefficients, water vapor mixing ratio, and cloud liquid water. We focus on the system's capabilities of detecting Raman backscattering from cloud liquid water. After describing the system components, along with the current limitations and options for improvement, we report examples of observations in the case of low-level cumulus clouds. The measurements of the cloud liquid water content, as well as the estimations of the cloud droplet effective radii and number densities, obtained by combining the extinction coefficient and cloud water content within the clouds, are critically discussed.

RESUMEN

In the framework of the European Aerosol Research Lidar Network to Establish an Aerosol Climatology (EARLINET), 19 aerosol lidar systems from 11 European countries were compared. Aerosol extinction or backscatter coefficient profiles were measured by at least two systems for each comparison. Aerosol extinction coefficients were derived from Raman lidar measurements in the UV (351 or 355 nm), and aerosol backscatter profiles were calculated from pure elastic backscatter measurements at 351 or 355, 532, or 1064 nm. The results were compared for height ranges with high and low aerosol content. Some systems were additionally compared with sunphotometers and starphotometers. Predefined maximum deviations were used for quality control of the results. Lidar systems with results outside those limits could not meet the quality assurance criterion. The algorithms for deriving aerosol backscatter profiles from elastic lidar measurements were tested separately, and the results are described in Part 2 of this series of papers [Appl. Opt. 43, 977-989 (2004)]. In the end, all systems were quality assured, although some had to be modified to improve their performance. Typical deviations between aerosol backscatter profiles were 10% in the planetary boundary layer and 0.1 x 10(-6) m(-1) sr(-1) in the free troposphere.