Time evolution of storms producing terrestrial gamma-ray flashes using era5 reanalysis data, gps, lightning and geo-stationary satellite observations

In this article, we report the first investigation over time of the atmospheric conditions around terrestrial gamma-ray flash (TGF) occurrences, using GPS sensors in combination with geostationary satellite observations and ERA5 reanalysis data. The goal is to understand which characteristics are favorable to the development of these events and to investigate if any precursor signals can be expected. A total of 9 TGFs, occurring at a distance lower than 45 km from a GPS sensor, were analyzed and two of them are shown here as an example analysis. Moreover, the lightning activity, collected by the World Wide Lightning Location Network (WWLLN), was used in order to identify any links and correlations with TGF occurrence and precipitable water vapor (PWV) trends. The combined use of GPS and the stroke rate trends identified, for all cases, a recurring pattern in which an increase in PWV is observed on a timescale of about two hours before the TGF occurrence that can be placed within the lightning peak. The temporal relation between the PWV trend and TGF occurrence is strictly related to the position of GPS sensors in relation to TGF coordinates. The life cycle of these storms observed by geostationary sensors described TGF-producing clouds as intense with a wide range of extensions and, in all cases, the TGF is located at the edge of the convective cell. Furthermore, the satellite data provide an added value in associating the GPS water vapor trend to the convective cell generating the TGF. The investigation with ERA5 reanalysis data showed that TGFs mainly occur in convective environments with unexceptional values with respect to the monthly average value of parameters measured at the same location. Moreover, the analysis showed the strong potential of the use of GPS data for the troposphere characterization in areas with complex territorial morphologies. This study provides indications on the dynamics of con-vective systems linked to TGFs and will certainly help refine our understanding of their production, as well as highlighting a potential approach through the use of GPS data to explore the lightning activity trend and TGF occurrences.publishedVersio

A Combined IR-GPS Satellite Analysis for Potential Applications in Detecting and Predicting Lightning Activity

Continuous estimates of the vertical integrated precipitable water vapor content from the tropospheric delay of the signal received by the antennas of the global positioning system (GPS) are used in this paper, in conjunction with the measurements of the Meteosat Second Generation (MSG) spinning enhanced visible and infrared imager (SEVIRI) radiometer and with the lightning activity, collected here by the ground-based lightning detection network (LINET), in order to identify links and recurrent patterns useful for improving nowcasting applications. The analysis of a couple of events is shown here as an example of more general behavior. Clear signs appear before the peak of lightning activity on a timescale from 2 to 3 h. In particular, the lightning activity is generally preceded by a period in which the difference between SEVIRI brightness temperature (TB) at channel 5 and channel 6 (i.e., ∆TB) presents quite constant values around 0 K. This trend is accompanied by an increase in precipitable water vapor (PWV) values, reaching a maximum in conjunction with the major flash activity. The results shown in this paper evidence good potentials of using radiometer and GPS measurements together for predicting the abrupt intensification of lightning activity in nowcasting systems

Study of field emission of multiwalled C nanotubes synthesized by arc discharge

Carbon nanotubes (CNTs) were synthesized by a DC thermal plasma method. After optimizing the synthesis parameters such as the pressure, current etc, the synthesized products, and the anodic deposit in particular, were characterized by scanning electron and transmission electron microscopy. The morphology of the product was ascertained to be multiwalled carbon nanotubes in a large ratio. The diameters of these nanotubes were of the order of 30-50 nm with lengths extending up to a micron and sometimes even 2 or 3 μm. The field emission properties of these nanotubes were then studied. The CNTs were deposited on a metal stub which acted as the cathode. Care was taken to ensure complete coverage of the stub to remove any possibility of emission from the metallic stub itself. The emission studies were performed in a stainless steel chamber under a dynamic vacuum in the range of 10 -8 Torr. The field emitted current was detected using a phosphorus coated indium tin oxide (ITO) glass. The phosphorus coating also helped in imaging the tips of the nanotubes. This was crucial in estimating accurately the emitting area and thus the field enhancement factor. The I-V curves for the field emission were recorded for various distances between the electrodes. The results are shown here

Gamma ray storms: preliminary meteorological analysis of AGILE TGFs: Meteorology of AGILE TGF observations

Despite the recognition from their discovery that terrestrial gamma ray flashes (TGFs) originate from thunderstorms, little is known about the TGF-producing storms. The characteristics of such thunderstorms are investigated here using meteorological data, with the aim to set up a framework of analysis to be propagated to more complete TGF archives. In this work, we present the preliminary results. As first analysis, we considered 72 events detected by the Astrorivelatore Gamma ad Immagini Leggero (AGILE) from March 2015 to June 2015, estimating their electric activity in terms of flash production. To this end, we examined World Wide Lightning Location Network lightning data in the spatial and temporal proximity of each AGILE TGFs, searching for relationship between flash rate peak and distribution and the TGF occurrence. Moreover, we analyzed the low-Earth orbiting (LEO) satellite observation of the TGF-producing storms to define, through the capabilities of microwave sensors (both active and passive), the structure of the convective storms correlated with TGF events. In particular, we focused on the Global Precipitation Measurement (GPM) observations and show here a case study observed by the dual-frequency precipitation radar (DPR). Preliminary results indicate that the TGF often occur during the most active lightning phase of the storm, while the intensity of the storm is not a key ingredient for the production of a TGF. The multisensory capability of LEO satellites provide a picture of the storm structure, that, despite the poor coverage, is an unprecedented tool to study such cloud system over remote areas and open ocean. This study framework is meant to be applied to other TGF database, such as the ones collected by other space missions (e.g., FERMI, RHESSI)

Gamma ray storms: preliminary meteorological analysis of AGILE TGFs: Meteorology of AGILE TGF observations

Despite the recognition from their discovery that terrestrial gamma ray flashes (TGFs) originate from thunderstorms, little is known about the TGF-producing storms. The characteristics of such thunderstorms are investigated here using meteorological data, with the aim to set up a framework of analysis to be propagated to more complete TGF archives. In this work, we present the preliminary results. As first analysis, we considered 72 events detected by the Astrorivelatore Gamma ad Immagini Leggero (AGILE) from March 2015 to June 2015, estimating their electric activity in terms of flash production. To this end, we examined World Wide Lightning Location Network lightning data in the spatial and temporal proximity of each AGILE TGFs, searching for relationship between flash rate peak and distribution and the TGF occurrence. Moreover, we analyzed the low-Earth orbiting (LEO) satellite observation of the TGF-producing storms to define, through the capabilities of microwave sensors (both active and passive), the structure of the convective storms correlated with TGF events. In particular, we focused on the Global Precipitation Measurement (GPM) observations and show here a case study observed by the dual-frequency precipitation radar (DPR). Preliminary results indicate that the TGF often occur during the most active lightning phase of the storm, while the intensity of the storm is not a key ingredient for the production of a TGF. The multisensory capability of LEO satellites provide a picture of the storm structure, that, despite the poor coverage, is an unprecedented tool to study such cloud system over remote areas and open ocean. This study framework is meant to be applied to other TGF database, such as the ones collected by other space missions (e.g., FERMI, RHESSI)

Gamma ray storms: preliminary meteorological analysis of AGILE TGFs

Despite the recognition from their discovery that terrestrial gamma ray flashes (TGFs) originate from thunderstorms, little is known about the TGF-producing storms. The characteristics of such thunderstorms are investigated here using meteorological data, with the aim to set up a framework of analysis to be propagated to more complete TGF archives. In this work, we present the preliminary results. As first analysis, we considered 72 events detected by the Astrorivelatore Gamma ad Immagini Leggero (AGILE) from March 2015 to June 2015, estimating their electric activity in terms of flash production. To this end, we examined World Wide Lightning Location Network lightning data in the spatial and temporal proximity of each AGILE TGFs, searching for relationship between flash rate peak and distribution and the TGF occurrence. Moreover, we analyzed the low-Earth orbiting (LEO) satellite observation of the TGF-producing storms to define, through the capabilities of microwave sensors (both active and passive), the structure of the convective storms correlated with TGF events. In particular, we focused on the Global Precipitation Measurement (GPM) observations and show here a case study observed by the dual-frequency precipitation radar (DPR). Preliminary results indicate that the TGF often occur during the most active lightning phase of the storm, while the intensity of the storm is not a key ingredient for the production of a TGF. The multisensory capability of LEO satellites provide a picture of the storm structure, that, despite the poor coverage, is an unprecedented tool to study such cloud system over remote areas and open ocean. This study framework is meant to be applied to other TGF database, such as the ones collected by other space missions (e.g., FERMI, RHESSI)

A Joint LINET and ISS-LIS View of Lightning Distribution over the Mt. Cimone Area within the GAMMA-FLASH Program

Typical features of lightning distribution in the mountain area of Mt. Cimone (2165 m a.s.l., Northern-Central Italy) have been studied through detections provided by the ground-based LIghtning NETwork data (LINET) and the Lightning Imaging Sensor (LIS) onboard the International Space Station (ISS-LIS). This study was performed within the context of the Gamma-Flash program, which includes the in situ observation of high-energy radiation (e.g., Terrestrial Gamma-ray Flashes (TGFs), gamma-ray glows) and neutron emissions from thunderstorms at the mountain-top “O. Vittori” climate observatory. LINET VLF/LF radio measurements allowed the characterization of both cloud-to-ground (CG) and intra-cloud (IC) strokes’ geographical distribution and an altitude of occurrence from 2012 through 2020. The lightning distribution showed a remarkable clustering of CGs at the mountain top in contrast to a homogeneous distribution of ICs, highlighting the likely impact of orography. IC strokes peaked around 4 to 6 km altitude, in agreement with the observed typical cloud range. The joint exploitation of ISS-LIS optical observations of LINET detections extended the study to further features of flashes not seen in radio wavelengths and stands as the cross-validation of the two detection methods over such a complex orography. These results gave the quantitative indication of the expected occurrence of lightning and ionizing radiation emissions in the Mt. Cimone area and an example of mountain-driven changes in lightning occurrence

Time evolution of storms producing terrestrial gamma-ray flashes using era5 reanalysis data, gps, lightning and geo-stationary satellite observations

In this article, we report the first investigation over time of the atmospheric conditions around terrestrial gamma-ray flash (TGF) occurrences, using GPS sensors in combination with geostationary satellite observations and ERA5 reanalysis data. The goal is to understand which characteristics are favorable to the development of these events and to investigate if any precursor signals can be expected. A total of 9 TGFs, occurring at a distance lower than 45 km from a GPS sensor, were analyzed and two of them are shown here as an example analysis. Moreover, the lightning activity, collected by the World Wide Lightning Location Network (WWLLN), was used in order to identify any links and correlations with TGF occurrence and precipitable water vapor (PWV) trends. The combined use of GPS and the stroke rate trends identified, for all cases, a recurring pattern in which an increase in PWV is observed on a timescale of about two hours before the TGF occurrence that can be placed within the lightning peak. The temporal relation between the PWV trend and TGF occurrence is strictly related to the position of GPS sensors in relation to TGF coordinates. The life cycle of these storms observed by geostationary sensors described TGF-producing clouds as intense with a wide range of extensions and, in all cases, the TGF is located at the edge of the convective cell. Furthermore, the satellite data provide an added value in associating the GPS water vapor trend to the convective cell generating the TGF. The investigation with ERA5 reanalysis data showed that TGFs mainly occur in convective environments with unexceptional values with respect to the monthly average value of parameters measured at the same location. Moreover, the analysis showed the strong potential of the use of GPS data for the troposphere characterization in areas with complex territorial morphologies. This study provides indications on the dynamics of con-vective systems linked to TGFs and will certainly help refine our understanding of their production, as well as highlighting a potential approach through the use of GPS data to explore the lightning activity trend and TGF occurrences

The protein scaffold of the lipocalin odorant-binding protein is suitable for the design of new biosensors for the detection of explosive components

The detection of hazard exposure is a current priority, including the detection of traces of explosive molecules in different environments like luggage storage rooms and public places, and is becoming a major requirement for homeland security. In the present study we carried out a preliminary investigation on the binding capacities of four forms of the lipocalin odorant- binding protein ( OBP) for the detection of explosive components such as diphenylamine, dimethylphthalate, resorcinol and dinitrotoluene. The experimental results, showing that OBP binds these compounds with affinity constants ranging between 80 nM and 10.6 mM, indicate that this protein can be used as a probe for the realization of a biosensor to sense explosive compounds

Effect of different carbon nanotubes on cell viability and proliferation

Carbon nanotubes ( CNTs) are a focus of intense research for their potential applications in multiple diverse applications, including innovative biomedical applications. Due to their very recent discovery, little information is available about the biocompatibility and toxicity of this new class of nanoparticle, and a systematic study on biological interference is lacking. Thus, we decided to explore the toxicity of three different types of carbon nanotube, differing in preparation ( arc discharge versus catalysed chemical vapour deposition); size ( 10 - 50 versus 100 - 150 nm wide x 1 - 10 mu m long); contaminants ( amorphous C, graphite, fullerenes or iron) and morphological type ( multi- walled, MW, or single- walled, SW) on human leukemic U937 cells. We found that these carbon nanotubes exert a strong effect on the proliferation of the reporter U937 monocytic cell. However, these CNTs did not significantly affect the cell viability. These results show that CNTs, though not directly exerting a direct cytotoxic effect, are nonetheless able to deeply alter cell behaviour, and thus we recommend thorough analyses to limit health risk due to uncontrolled exposure