367 research outputs found
Analysis of Thunderstorms Producing Terrestrial Gamma Ray Flashes With the Meteosat Second Generation
No full textUp to now, only few works focused on the meteorological context leading to the production of Terrestrial Gamma ray Flashes (TGFs). In this study, we carry out, for the first time, an analysis on large scale of the meteorological scenario linked to 278 TGFs detected by RHESSI, AGILE, and Fermi, by using the Meteosat Second Generation geostationary satellites. These satellites are useful as they continuously monitor the same geographic region in time, allowing investigations on thunderstorms' development; moreover, they are endowed with channels and products that provide information about the meteorological context under analysis, such as the cloud top temperature and altitude, the cloud extension, the drop effective radius and the cloud phase. Our work confirms what previously found in other studies about the TGF-associated thunderstorms, by using a different approach and by using for the first time the Meteosat satellites: we find TGFs mostly linked to the development phase of deep convective thunderstorm systems, exhibiting typical characteristics of tropical storms, and providing a first picture on large scale of the TGF-associated thunderstorm systems
Aspects of reproductive biology of the european hake (Merluccius merluccius) in the northern and central adriatic sea (gsa 17-central mediterranean sea)
No full textThe study focused on the macroscopic, histological, and biometric analysis of European hake females in GSA 17 (Central-North Adriatic Sea). From 2013 to 2015, 976 females were collected and analyzed monthly. Though females in spawning conditions were found during the whole year, the trend of GSI showed a peak of the reproductive season from April to July in 2014 and 2015. HSI and Kn reached the highest values in September, after the spawning peaks. In 2013, the trend of these indices did not highlight an evident peak, probably due to an adverse event that occurred in the previous winter in the Adriatic shelf. The length at first maturity (L50) was estimated by macroscopic and histological approaches, resulting in 30.81 cm for the macroscopical length and 33.73 cm for the histological length; both values are higher than the current catching legal size. For the first time in this area, batch and relative fecundity were estimated. Relative fecundity was similar to the Mediterranean and the Atlantic stocks, whereas batch fecundity values were lower compared to other fishing grounds. Overall, the analysis of reproductive parameters plays a fundamental role in the sustainable management of this resource in an area as overfished as the Central-North Adriatic Sea
Maturity assignment based on histology-validated macroscopic criteria: Tackling the stock decline of the Mediterranean swordfish (Xiphias gladius)
No full textEffective stock assessment relies on the evaluation of the reproductive potential of a population, but this is often achieved using fast, inexpensive, and inaccurate macroscopic indicators of gonadal maturity. Indeed, this approach suffers from high error rates as a result of misclassification and operator errors. Although histology is considered the gold standard to assign reproductive stages, it represents a time-consuming and expensive method. Therefore, cost-effective approaches are currently needed to assess the species-specific reproductive potential and define the correct size at first maturity (L50). In the present study a histology-calibrated method based on the gonadal index (GI) was developed to assign maturity stages to the overfished Mediterranean swordfish (Xiphias gladius), supported by histological classification of gonadal development, an estimation of L50, and an analysis of the reproductive output of this species. The performance of this new method had an overall agreement of 90% with histological data, and the L50 calculated by the GI-based method compared with histology analysis was not statistically different (p > 0.05). Moreover, in order to apply this method without bias, a thorough validation of the relationship between length and gonad weight was carried out and the suitability of the GI to compare individuals of different size and maturity stages was confirmed. The present findings provide a comprehensive picture of the patterns characterizing Mediterranean swordfish reproduction and a promising method to assign maturity stages based on a macroscopic indicator. This method has the potential to be extensively applied during routine fish sampling activities in the field because of its simple requirements
X and gamma-ray detection with a silicon drift detector coupled to a CsI(Tl) scintillator operated with pulse shape discrimination technique
No full textLa terra si muove con il senso : 48. Edizione Premio Suzzara
No full textCatalogo della mostra, 48° edizione del Premio Suzzara, (Suzzara - Mn, 15 settembre – 3 novembre 2013) a cura di Elisabetta Modena, Marco Scotti e Paola Boccaletti. Artisti invitati: Mario Airò, Elisabetta Di Maggio, Eva Marisaldi, Liliana Moro
La terra si muove con il senso : 48. Edizione Premio Suzzara
No full textCatalogo della mostra, 48° edizione del Premio Suzzara, (Suzzara - Mn, 15 settembre – 3 novembre 2013) a cura di Elisabetta Modena, Marco Scotti e Paola Boccaletti. Artisti invitati: Mario Airò, Elisabetta Di Maggio, Eva Marisaldi, Liliana Moro
GPM-DPR Observations on TGFs Producing Storms
No full textUnique spaceborne measurements of the three-dimensional structure of convective
clouds producing terrestrial gamma ray flashes (TGFs) were performed using both active and passive
microwave sensors on board the Global Precipitation Measurement (GPM)-Core Observatory satellite,
finding coherent features for nine TGF-producing storms. The delineation of cloud structure using the
radar reflectivity factor shows convective cells with significant vertical development and thick layers with
high ice content. Compared to other cumulonimbus clouds in the tropics, the TGFs counterparts have
higher reflectivity values above 3 and 8 km altitude showing in all cases a cumulonimbus tower and the
TGFs locations are very close, or coincident, to these high Z columns, where reflectivity exceeds 50dBz.
Using the GPM Microwave Imager radiometer, most thunderstorms show a very strong depression of
polarization corrected temperature (PCT) at channel 89GHz, indicating a strong scattering signal by ice
in the upper cloud layers. At channel 166GHZ, the difference between vertical and horizontal brightness
temperature signal always returns positive values, from 0.2 up to 13.7K indicating a complex structure
with randomly/vertically oriented ice particles. The PCT was used to characterize the analyzed storms
in terms of hydrometeor types, confirming in 7/9 cases a high likelihood of hail/graupel presence. To
perform analysis on the TGFs parent flashes, radio atmospherics data from the Earth Networks Total
Lightning Network lightning network were used. Waveform data indicate that all cases are intra-cloud
events and TGFs typically take place during the peak of flash rate production. Finally, the analysis of the
most intense event is shown
First Assessment of Microplastic Contamination in Wild Specimens of Gelatinous Zooplankton From the Northern Adriatic Sea (Italy)
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