Suchergebnisse

Halos and elves are transient luminous events produced in the lower ionosphere as a consequence of lightning-driven electromagnetic fields. These events can influence the upper atmospheric chemistry and produce optical emissions. We have developed different two-dimensional self-consistent models that couple electrodynamical equations with a chemical scheme to simulate halos and elves produced by vertical cloud-to-ground lightning discharges, compact intracloud discharges and energetic in-cloud pulses. The optical emissions from radiative relaxation of excited states of molecular and atomic nitrogen and oxygen have been calculated. We have upgraded previous local models of halos and elves to calculate for the first time the vibrationally detailed optical spectra of elves triggered by compact intracloud discharges and energetic in-cloud pulses. According to our results, the optical spectra of elves do not depend on the type of parent lightning discharge. Finally, we have quantified the local chemical impact in the upper atmosphere of single halos and elves. In the case of the halo, we follow the cascade of chemical reactions triggered by the lightning-produced electric field during a long-time simulation of up to 1 s. We obtain a production rate of NO molecules by single halos and elves of 10 and 10 molecules/J, respectively. The results of these local models have been used to estimate the global production of NO by halos and elves in the upper atmosphere at ∼10 Tg N/year. This global chemical impact of halos and elves is 7 orders of magnitude below the production of NO in the troposphere by lightning discharges. ©2018. American Geophysical Union. All Rights Reserved. ; This work was supported by the Spanish Ministry of Science and Innovation, MINECO, under projects ESP2015-69909-C5-2-R and ESP2017-86263-C4-4-R and by the EU through the H2020 Science and Innovation with Thunderstorms (SAINT) project (Ref. 722337) and the FEDER program. F.J.P.I. acknowledges a PhD research contract, code BES-2014-069567. A.L. was supported by the European Research Council (ERC) under the European Union's H2020 program/ERC grant agreement 681257. The simulation data and plot codes presented here are available from figshare repository at https://figshare.com/s/f1c9f6c7 bc728d6669dd. Alternatively, requests for the data and codes used to generate or displayed in figures, graphs, plots, or tables are also available after a request is made to the authors F.J.P.I. (fjpi@iaa.es), A. L. (aluque@iaa.es), or F. J. G.V. (vazquez@iaa.es).

Halos and elves are transient luminous events produced in the lower ionosphere as a consequence of lightning-driven electromagnetic fields. These events can influence the upper atmospheric chemistry and produce optical emissions. We have developed different two-dimensional self-consistent models that couple electrodynamical equations with a chemical scheme to simulate halos and elves produced by vertical cloud-to-ground lightning discharges, compact intracloud discharges and energetic in-cloud pulses. The optical emissions from radiative relaxation of excited states of molecular and atomic nitrogen and oxygen have been calculated. We have upgraded previous local models of halos and elves to calculate for the first time the vibrationally detailed optical spectra of elves triggered by compact intracloud discharges and energetic in-cloud pulses. According to our results, the optical spectra of elves do not depend on the type of parent lightning discharge. Finally, we have quantified the local chemical impact in the upper atmosphere of single halos and elves. In the case of the halo, we follow the cascade of chemical reactions triggered by the lightning-produced electric field during a long-time simulation of up to 1 s. We obtain a production rate of NO molecules by single halos and elves of 10 and 10 molecules/J, respectively. The results of these local models have been used to estimate the global production of NO by halos and elves in the upper atmosphere at ∼10 Tg N/year. This global chemical impact of halos and elves is 7 orders of magnitude below the production of NO in the troposphere by lightning discharges. ©2018. American Geophysical Union. All Rights Reserved. ; This work was supported by the Spanish Ministry of Science and Innovation, MINECO, under projects ESP2015-69909-C5-2-R and ESP2017-86263-C4-4-R and by the EU through the H2020 Science and Innovation with Thunderstorms (SAINT) project (Ref. 722337) and the FEDER program. F.J.P.I. acknowledges a PhD research contract, code BES-2014-069567. A.L. was supported by the European Research Council (ERC) under the European Union's H2020 program/ERC grant agreement 681257. The simulation data and plot codes presented here are available from figshare repository at https://figshare.com/s/f1c9f6c7 bc728d6669dd. Alternatively, requests for the data and codes used to generate or displayed in figures, graphs, plots, or tables are also available after a request is made to the authors F.J.P.I. (fjpi@iaa.es), A. L. (aluque@iaa.es), or F. J. G.V. (vazquez@iaa.es).

This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.-- Data presented here are available from figshare repository (https://bit.ly/2ww816g).Alternatively, requests for data and codes used to generate figures, graphs, plots, or tables may be made to the authors F. J. G. V (vazquez@iaa.es) or F. J. P. I. (fjpi@iaa.es). ; We present simulations performed with six lightning parameterizations implemented in the Community Atmosphere Model (CAM5). The amount of lightning-produced nitrogen oxides (LNOx) by the various schemes considered is estimated. We provide some insight on how the lightning NO injected in the atmosphere influences the global concentrations of key chemical species such as OH, HO2, H2O2, NOx, O-3, SO2, CO, and HNO3. The vertical global averaged densities of HO2, H2O2, CO, and SO2 are depleted due to lightning while those of NO, NO2, O-3, OH, and HNO3 increase. Our results indicate that the parameterizations based on the upward ice flux (ICEFLUX) exhibit the largest global and midlatitude spatial correlations (0.73 and 0.632 for ICEFLUX and 0.72 and 0.553 for cloud top height) with respect to satellite global flash rate observations. Five out of the six lightning schemes investigated exhibit larger LNOx per flash in the midlatitudes than in the tropics. In particular, it is found that the ICEFLUX midlatitude LNOx per flash exhibits the largest difference with respect to its predicted tropical LNOx per flash, in agreement with available observations. When using CAM5, the ICEFLUX lightning parameterization could be considered a reliable lightning scheme (within its intrinsic uncertainties) in terms of its geographical distribution. Both ICEFLUX and cloud top height results agree with the enhancements of NO2 and O-3 produced by lightning over tropical Atlantic and Africa and the weaker lightning background over the tropical Pacific reported by Martin et al. (2007) in the periods and locations (upper troposphere) where lightning is expected to dominate the trace gas observations.©2019. The Authors. ; This work was supported by the Spanish Ministry of Science and Innovation, MINECO under Project ESP2017-86263-C4-4-R and by the EU through the H2020 Science and Innovation with Thunderstorms (SAINT) project (Ref. 722337) and the FEDER program. F. J. P. I. acknowledges support by a PhD research contract, Code BES-2014-069567 and by the EU through the European Research Council (ERC) under the European Union's H2020 programm/ERC Grant 681257. F. J. G. V. acknowledges support from the Spanish Ministry of Education and Culture under the Salvador de Madariaga Program PRX17/00078. Authors F. J. G. V. and F. J. P. I. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). H. H. acknowledges support from the DLR project KliSAW. The National Center for Atmospheric Research is sponsored by the National Science Foundation. The CESM project is supported by the National Science Foundation and the Office of Science (BER) of the U.S. Department of Energy. Computing resources were provided by the Climate Simulation Laboratory at NCAR's Computational and Information Systems Laboratory (CISL), sponsored by the National Science Foundation and other agencies. ; Peer reviewed

We investigate the attenuation of whistler waves generated by hypotetical Venusian lightning occurring at the altitude of the cloud layer under different ionospheric conditions. We use the Stanford full-wave method for stratified media of Lehtinen and Inan (2008) to model wave propagation through the ionosphere of Venus. This method calculates the electromagnetic field created by an arbitrary source in a plane-stratified medium (i.e., uniform in the horizontal direction). We see that the existence of holes in electronic densities and the magnetic field configuration caused by solar wind play an important role in the propagation of electromagnetic waves through the Venusian ionosphere. ©2017. American Geophysical Union. All Rights Reserved. ; This work was supported by the Spanish Ministry of Science and Innovation, Ministerio de Economia y Competitividad (MINECO) under projects ESP2015-69909-C5-2-R and FIS2014-61774-EXP, by the Research Council of Norway under contracts 208028/F50, 216872/F50, and 223252/F50 (CoE), and by the EU through the FEDER program. F. J. P. I. acknowledges a PhD research contract, code BES-2014-069567. N. L. was supported by the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement 320839. A. L. was supported by the European Research Council (ERC) under the European Union's H2020 program/ERC grant agreement 681257. ; Peer reviewed

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. ; High speed spectra (between ∼380 nm and ∼800 nm) of meter-long lightning-like discharges recorded at 672,000 fps and 1,400,000 fps (with 1.488 and 0.714 μs time resolutions and 160 ns exposure time) show optical emissions of neutral hydrogen, singly ionized nitrogen, oxygen, and doubly ionized nitrogen which are similar to those found in natural lightning optical emissions. The spectra recorded in the near ultraviolet-blue range (380–450 nm) and visible-near infrared (475–793 nm) exhibited features of optical emissions corresponding to several molecular species (and emission bands) like cyanide radical (CN) (Violet bands), N2 (Second Positive System), N2+ (first negative system), C2 (Swan band) and CO (Quintet and Ångström bands). Molecular species can be formed at regions of the lightning-like channel where the gas temperature would be milder and/or in the corona sheath surrounding the heated channel. We have quantified and compared electron densities and temperatures derived from different sets of neutral and ion line emissions and have found different sensitivities depending on the lines used. Temperatures derived from ion emissions are higher and change faster than those derived from neutral emissions. © 2021. The Authors. ; This work has received funding from the European Union Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement SAINT 722337. Additionally, this work was supported by the Ministerio de Ciencia e Innovacion-Agencia Estatal de Investigacion, under project PID2019-109269RB-C43 and FEDER program. F. J. Perez-Invernon acknowledges the sponsorship provided by the Federal Ministry for Education and Research of Germany through the Alexander von Humboldt Foundation. T. N. K, F. J. Gordillo-Vazquez, M. Passas, and J. Sanchez acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andaluca (SEV-2017-0709). The authors acknowledge Prof. J. Montanya (of UPC) and LABELEC for having granted access to high voltage facilities in Terrassa (Spain). ; We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed

©2020. The Authors. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.https://creativecommons.org/licenses/by-nc/4.0/ ; Narrow bipolar events (NBEs) (also called narrow bipolar pulses [NBPs] or compact intracloud discharges [CIDs]) are energetic intracloud discharges characterized by narrow bipolar electromagnetic waveforms identified from ground-based very low frequency (VLF)/low-frequency (LF) observations. The simplified ray-theory method proposed by Smith et al. (1999, https://doi.org/10.1029/1998JD200045; 2004, https://doi.org/10.1029/2002RS002790) is widely used to infer the altitude of intracloud lightning and the effective (or virtual) reflection height of the ionosphere from VLF/LF signals. However, due to the large amount of high-frequency components in NBEs, the propagation effect of the electromagnetic fields for NBEs at large distance depends nontrivially on the geometry and the effective conductivity of the Earth-ionosphere waveguide (EIWG). In this study, we investigate the propagation of NBEs by using a full-wave Finite-Difference Time-Domain (FDTD) approach. The simulated results are compared with ground-based measurements at different distances in Southern China, and we assess the accuracy of the simplified ray-theory method in estimating the altitude of the NBE source and the effective reflection height of the ionosphere. It is noted that the evaluated NBE altitudes have a slight difference of about ±1 km when compared with the full-wave FDTD results, while the evaluated ionospheric reflection heights are found to be bigger than those obtained from FDTD model by about 5 km. ©2020. The Authors. ; This work was supported by the European Research Council (ERC) under the European Union H2020 Programme/ERC Grant 681257. The ground-based VLF/LF measurements related to this article can be obtained from CAS Key Laboratory of Geo-space Environment in the School of Earth and Space Sciences at University of Science and Technology of China in Hefei, China (http://222.195.83.28/) ; Peer reviewed

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. ; Blue LUminous Events (BLUEs) are transient corona discharges occurring in thunderclouds and characterized by strong 337.0 nm light flashes with absent (or weak) 777.4 nm component. We present the first nighttime climatology of BLUEs as detected by the Modular Multispectral Imaging Array of the Atmosphere-Space Interaction Monitor showing their worldwide geographical and seasonal distribution. A total (land and ocean) of (Formula presented.) 11 BLUEs occur around the globe every second at local midnight and the average BLUE land/sea ratio is (Formula presented.) 7:4. The northwest region of Colombia shows an annual nighttime peak. Globally, BLUEs are maximized during the boreal summer-autumn, contrary to lightning which is maximed in the boreal summer. The geographical distribution of nighttime BLUEs shows three main regions in, by order of importance, the Americas, Europe/Africa and Asia/Australia. © 2021 The Authors. ; ASIM is a mission of ESA's SciSpace programme for scientific utilization of the ISS and non-ISS space exploration platforms and space environment analogues. ASIM and the ASIM Science Data Centre are funded by ESA and by National grants of Denmark, Norway and Spain. This work was supported by the Spanish Ministry of Science and Innovation under project PID2019-109269RB-C43 and the FEDER program. S. Soler acknowledges a PhD research contract through the project PID2019-109269RB-C43. F. J. Pérez-Invernón acknowledges the sponsorship provided by the Federal Ministry for Education and Research of Germany through the Alexander von Humboldt Foundation. A. Luque and D. Li were supported by the European Research Council (ERC) under European Union H2020 programme/ERC grant agreement 681257. S. Soler, F. J. Gordillo-Vázquez, A. Luque and D. Li acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). ; Peer reviewed