Chemical activity of low altitude (50 km) sprite streamers

A three-stage simulation is used to explore the chemical influence of low altitude (50 km) sprite streamers on the atmosphere, including the chemical trail after the streamer has faded away. In the first stage (streamer phase) a 2D electrodynamical streamer model quantifies the generation of NOx and N2O, and the removal of ozone (O3) by a downward propagating streamer during Δtstreamer = 80 μs. This streamer propagation leads to a distinctive region in the streamer channel, the glow, where the electric field is enhanced. In the second stage (glow phase), the computed densities of the first stage are used as initial conditions for a 0D model to study the chemical evolution of the streamer channel, where we assume a remanent field of 100 Td for the glow and 0 Td elsewhere. This stage lasts Δtglow = 85 μs, the typical glow lifetime at 50 km. Finally, in the third stage (post-streamer phase), we use the same 0D model, switch off the field in the glow region and let the whole streamer wake evolve roughly 100 s (100 s − Δtglow). Results show a key species such as O3 is mainly depleted during the streamer phase while NOx and N2O are predominantly produced during the same phase. We also compute the local increase of NO2 by sprite streamers at ∼50 km and find out that it could account for the measurable NO2 anomaly over thunderstorms reported from satellite-based measurements

Global Distribution of Key Features of Streamer Corona Discharges in Thunderclouds

We present nighttime worldwide distributions of key features of Blue LUminous Events (BLUEs) detected by the Modular Multispectral Imaging Array of the Atmosphere-Space Interaction Monitor. Around 10% of all detected BLUEs exhibit an impulsive single pulse shape. The rest of BLUEs are unclear (impulsive or not) single, multiple or with ambiguous pulse shapes. BLUEs exhibit two distinct populations with peak power density <25 µWm−2 (common) and ≥25 µWm−2 (rare) with different rise times and durations. The altitude (and depth below cloud tops) zonal distribution of impulsive single pulse BLUEs indicate that they are commonly present between cloud tops and a depth of ≤4 km in the tropics and ≤1 km in mid and higher latitudes. Impulsive single pulse BLUEs in the tropics are the longest (up to ∼4 km height) and have the largest number of streamers (up to ∼3 × 109). Additionally, the analysis of BLUEs has turned out to be particularly complex due to the abundance of radiation belt particles (at high latitudes and in the South Atlantic Anomaly [SAA]) and cosmic rays all over the planet. True BLUEs can not be fully distinguished from radiation belt particles and cosmic rays unless other ground-based measurements associated with the optically detected BLUEs are available. Thus, the search algorithm of BLUEs presented in Soler et al. (2021), https://doi.org/10.1029/2021gl094657 is now completed with a new additional step that, if used, can considerably smooth the SAA shadow but can also underestimate the number of BLUEs worldwide.publishedVersio

Global Frequency and Geographical Distribution of Nighttime Streamer Corona Discharges (BLUEs) in Thunderclouds

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 E~11 BLUEs occur around the globe every second at local midnight and the average BLUE land/sea ratio is E~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/AustraliapublishedVersio

Effects on short term outcome of non-invasive ventilation use in the emergency department to treat patients with acute heart failure: A propensity score-based analysis of the EAHFE Registry

Objective: To assess the effects of non-invasive ventilation (NIV) in emergency department (ED) patients with acute heart failure (AHF) on short term outcomes. Methods: Patients from the EAHFE Registry (a multicenter, observational, multipurpose, cohort-designed database including consecutive AHF patients in 41 Spanish EDs) were grouped based on NIV treatment (NIV+ and NIV–groups). Using propensity score (PS) methodology, we identified two subgroups of patients matched by 38 covariates and compared regarding 30-day survival (primary outcome). Interaction was investigated for age, sex, ischemic cardiomyopathy, chronic obstructive pulmonary disease, AHF precipitated by an acute coronary syndrome (ACS), AHF classified as hypertensive or acute pulmonary edema (APE), and systolic blood pressure (SBP). Secondary outcomes were intensive care unit (ICU) admission; mechanical ventilation; in-hospital, 3-day and 7-day mortality; and prolonged hospitalization (>7 days). Results: Of 11, 152 patients from the EAHFE (age (SD): 80 (10) years; 55.5% women), 718 (6.4%) were NIV+ and had a higher 30-day mortality (HR = 2.229; 95%CI = 1.861–2.670) (p 85 years, p < 0.001), AHF associated with ACS (p = 0.045), and SBP < 100 mmHg (p < 0.001). No significant differences were found in the secondary endpoints except for more prolonged hospitalizations in NIV+ patients (OR = 1.445; 95%CI = 1.122–1.862) (p = 0.004). Conclusion: The use of NIV to treat AHF in ED is not associated with improved mortality outcomes and should be cautious in old patients and those with ACS and hypotension

Comparison of six lightning parameterizations in CAM5 and the impact on global atmospheric chemistry

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, O3, 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, O3, 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 O3 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

A review of the impact of transient luminous events on the atmospheric chemistry: Past, present, and future

Atmospheric electricity has been intensively studied during the last 30 years after the discovery in 1989 of different forms of upper atmospheric electrical discharges (so–called Transient Luminous Events) triggered by lightning in the troposphere. In spite of the significant number of investigations that led to important new results unveiling how lightning produces a zoo of transient electrical discharges from the upper troposphere to the mesosphere, there is still no clear understanding about how all sort of TLEs – including those that occur inside thunderclouds – can contribute to the chemistry of the atmosphere both at the local and global scale. This review paper aims at presenting a perspective on the TLE atmospheric chemistry research done in the past, in the present as well as to describe some of the challenges that await ahead to find the true scientific importance of the non-equilibrium atmospheric chemistry triggered by TLEs. This review comes to conclude that while the global chemical impact of elves and halos are almost negligible, the large scale chemical impact of sprites, blue jets and blue starters and that of impulsive cloud corona discharges might be non–negligible in terms of their possibly measurable contribution to important greenhouse gases such as ozone and nitrous oxide (N2O). Being the third strongest greenhouse gas (after carbon dioxide and methane) and by having the ability to deplete ozone, precise determination of atmospheric N2O sources is of increasing and pressing demand. A new era in atmospheric electricity is just emerging in which dedicated scientific space missions (ISS–LIS, ASIM) together with geostationary lightning sensors (since 2016) and new micro–scale and parameterizations of TLEs in general atmospheric chemistry circulation models will hopefully help to start clarifying the full role of TLEs in the chemistry of the atmosphere

Sprite streamer at 50 km altitude

Reduced electric field and species density produced by a simulated positive sprite streamer 80 micro-s after the onset of the simulation between altitudes 50 km and 49.7 km. The file claw0040.hdf corresponds to the data in each grid-cell. The ZIP files contain text files of the temporal evolution of the data in particular points

IAA : Información y actualidad astronómica (48)

El número contiene las siguientes contribuciones: Rayos en el Sistema Solar.--Galaxias activas: alimentando al monstruo.--Estrellas de la población III.--Planetas azules en torno a estrellas rojas.--Cien años de agujeros negros.--La imagen con mayor resolución de la historia de la astronomía muestra las entrañas de un núcleo galáctico.--La concentración de dióxido de carbono también aumenta en la alta atmósfera.--Se cuestionan los resultados obtenidos hasta ahora en el estudio de estrellas pulsantes.--Estudian la historia de la galaxia Andrómeda a través de sus cadáveres estelares.--Rosetta confirma que el cometa 67P se formó por la fusión de dos objetos.--Sala limpia.--El origen del universo.--Destacados.La página web de esta revista ha sido financiada por la Sociedad Española de Astronomía (SEA).N