Hubble Space Telescope detects sub-solar water atmosphere on Ganymede

<p>Ganymede’s tenuous atmosphere is produced by charged particle sputtering and sublimation of its icy surface. Previous far-ultraviolet observations of the OI1356 Å and OI1304 Å oxygen emissions were used to derive sputtered molecular oxygen, O<sub>2,</sub> as an atmospheric constituent. We present a new analysis of high-sensitivity spectra and spectral images of Ganymede’s oxygen emissions acquired by the COS and STIS instruments on the Hubble Space Telescope. The COS eclipse observations constrain atomic oxygen, O, to be at least two orders of magnitude less abundant than O<sub>2</sub>. We then show that dissociative excitation of water vapor, H<sub>2</sub>O, is found to increase the OI1304 Å emissions relative to the OI1356 Å emissions around the sub-solar point, where H<sub>2</sub>O is more abundant than O<sub>2</sub>. Away from the sub-solar region, the emissions are more than two times brighter at OI1356 Å than at OI1304 Å, and O<sub>2</sub> prevails as found in previous analyses. A ~6-fold higher H<sub>2</sub>O/O<sub>2</sub> mixing ratio on the warmer trailing hemisphere compared to the colder leading hemisphere, a spatial concentration at the sub-solar region, and the ratio-estimated H<sub>2</sub>O densities identify icy surface sublimation as a local dayside atmospheric source.<br />Our analysis provides the first evidence for a sublimated atmosphere on an icy moon in the outer solar system.</p>

Air Quality Measurement and Analysis by TROPOMI, OMI, MLS, OMPS, TANSO-FTS , and MERRA-2

<p>Global and regional air quality measurements play an important role in the everyday life of people, inasmuch as atmospheric constituents such as ozone (O<sub>3</sub>), carbon monoxide (CO), nitrogen dioxide (NO<sub>2</sub>), sulfur dioxide (SO<sub>2</sub>), methane (CH<sub>4</sub>), and aerosols may cause severe<!-- I guess I’m conservative in my wording; I’d say “significant” rather than “severe”. --> threats to human health and agriculture productivity. Space-based sensors on satellites<!-- Redundant with “Space-based”; you could say “Satellite sensors” instead (which I prefer to “Space-based”) --> are able to detect these atmospheric constituents directly and indirectly at high spatial and temporal scales. The TROPOspheric Monitoring Instrument (TROPOMI) on the Copernicus Sentinel-5 Precursor (Sentinel-5P) satellite provides measurements of O<sub>3</sub>, NO<sub>2</sub>, SO<sub>2</sub>, CH<sub>4</sub>, CO, formaldehyde (HCHO), aerosols, and cloud in ultraviolet-visible (UV-VIS), near infrared (NIR), and shortwave infrared (SWIR) spectral ranges. The Ozone Monitoring Instrument (OMI) aboard the Aura mission measures ozone, aerosols, clouds, surface UV irradiance, and trace gases including NO<sub>2</sub>, SO<sub>2</sub>, HCHO, BrO, and OClO using UV electromagnetic spectrum bands. The Ozone Mapping Profiler Suite (OMPS) on the Suomi National Polar-Orbiting Partnership (Suomi-NPP or SNPP) provides environmental data products including O<sub>3</sub>, NO<sub>2</sub>, SO<sub>2, </sub>and aerosols. The Microwave Limb Sounder (MLS) on Aura has been monitoring atmospheric chemical species (CO, volcanic SO<sub>2</sub>, O<sub>3</sub>, N<sub>2</sub>O, BrO), temperature, humidity, and cloud ice since 2004.<!-- MLS measures more than the species indicated here. Do you want to add an "etc." rather than list all? --> MLS measurements help understand stratospheric ozone chemistry, and the effects of air pollutants injected into the upper troposphere and low stratosphere. The Thermal And Near infrared Sensor for carbon Observation - Fourier Transform Spectrometer (TANSO-FTS) on the Greenhouse Gases Observing Satellite (GOSAT) covers a wide spectral range from VIS to thermal infrared (TIR), which enables remote observations of the greenhouse gases carbon dioxide (CO<sub>2</sub>) and CH<sub>4</sub>. Furthermore, atmospheric constituent data are also available in the second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) NASA's atmospheric reanalysis data collection. MERRA-2 uses an upgraded version of the Goddard Earth Observing System Model, version 5 (GEOS-5) data assimilation system, enhanced with more aspects of the Earth system. <!-- Check this. I added “atmospheric constituent data”, because the sentence didn’t make sense without it, and I believe that’s what this sentence was about. --></p><p>The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) supports over a thousand data collections in the focus areas of Atmospheric Composition, Water & Energy Cycles, and Climate Variability. Some of these data collections include atmospheric composition products from the ongoing TROPOMI, OMI, OMPS, MLS, TANSO-FTS, and MERRA-2 missions and projects. The GES DISC web site (https://disc.gsfc.nasa.gov) provides multiple tools designed to help data users easily search, subset, visualize, and download data from these diverse sources in a unified way. We will demonstrate several methodologies employing these tools to monitor air quality.</p>

Asteroseismology of the DOV star PG 1159−035

ABSTRACT Grids of DOV star models are evolved by wdec with fixed atmospheric constituent to the spectral values of XC/XHe/XO = 50/33/17. The core compositions are from white dwarf models at highest Teff evolved by mesa. The eigenfrequencies are calculated and used to fit the observed modes. Based on 264.1 h of photometric observations on PG 1159−035, Winget et al. identified 125 individual frequencies. Costa et al. identified 198 pulsation modes for PG 1159−035 according to the WET photometric data from 1983, 1985, 1989, and 2002. Both of them derived frequency splitting values of δσl = 1 ∼ 4.2 $\mu$Hz and δσl = 2 ∼ 6.9 $\mu$Hz. According to the values of δσl = 1 and δσl = 2, 20 triplets and 9 quintuplets are selected and used to constrain the fitting models. Our optimal model has Teff = 129 000 K, M* = 0.63 M⊙, log g = 7.59, log(Menv/M*) = −5.0, and σRMS = 1.97 s. The values of Teff and log g are consistent with that values of Córsico et al. The calculated modes of minimum rate of period change correspond to modes with maximum kinetic energy distributed in the envelope. The observed rates of period change with positive and negative values can also be partially reproduced. In particular, there are negative rates of period change for the calculated modes from our optimal model, which is not found in previous work.

The vertical distribution of volcanic SO₂ plumes measured by IASI

Sulfur dioxide (SO2) is an important atmospheric constituent that plays a crucial role in many atmospheric processes. Volcanic eruptions are a significant source of atmospheric SO2 and its effects and lifetime depend on the SO2 injection altitude. The Infrared Atmospheric Sounding Interferometer (IASI) on the METOP satellite can be used to study volcanic emission of SO2 using high-spectral resolution measurements from 1000 to 1200 and from 1300 to 1410 cm−1 (the 7.3 and 8.7 µm SO2 bands) returning both SO2 amount and altitude data. The scheme described in Carboni et al. (2012) has been applied to measure volcanic SO2 amount and altitude for 14 explosive eruptions from 2008 to 2012. The work includes a comparison with the following independent measurements: (i) the SO2 column amounts from the 2010 Eyjafjallajökull plumes have been compared with Brewer ground measurements over Europe; (ii) the SO2 plumes heights, for the 2010 Eyjafjallajökull and 2011 Grimsvötn eruptions, have been compared with CALIPSO backscatter profiles. The results of the comparisons show that IASI SO2 measurements are not affected by underlying cloud and are consistent (within the retrieved errors) with the other measurements. The series of analysed eruptions (2008 to 2012) show that the biggest emitter of volcanic SO2 was Nabro, followed by Kasatochi and Grímsvötn. Our observations also show a tendency for volcanic SO2 to reach the level of the tropopause during many of the moderately explosive eruptions observed. For the eruptions observed, this tendency was independent of the maximum amount of SO2 (e.g. 0.2 Tg for Dalafilla compared with 1.6 Tg for Nabro) and of the volcanic explosive index (between 3 and 5).

Evaluation of antibacterial and antifungal compounds for selective inhibition of denitrification in soils

Nitrous oxide (N2O) is an atmospheric constituent implicated in climate warming and stratospheric ozone depletion.

The vertical distribution of volcanic SO₂ plumes measured by IASI

Sulphur dioxide (SO2) is an important atmospheric constituent that plays a crucial role in many atmospheric processes. Volcanic eruptions are a significant source of atmospheric SO2 and its effects and lifetime depend on the SO2 injection altitude. The Infrared Atmospheric Sounding Instrument (IASI) on the Metop satellite can be used to study volcanic emission of SO2 using high-spectral resolution measurements from 1000 to 1200 cm−1 and from 1300 to 1410 (the 7.3 and 8.7 μm SO2 bands). The scheme described in Carboni et al. (2012) has been applied to measure volcanic SO2 amount and altitude for fourteen explosive eruptions from 2008 to 2012. The work includes a comparison with independent measurements: (i) the SO2 column amounts from the 2010 Eyjafjallajökull plumes have been compared with Brewer ground measurements over Europe; (ii) the SO2 plumes heights, for the 2010 Eyjafjallajökull and 2011 Grimsvötn eruptions, have been compared with CALIPSO backscatter profiles. The results of the comparisons show that IASI SO2 measurements are not affected by underlying cloud and are consistent (within the retrieved errors) with the other measurements. The series of analysed eruptions (2008 to 2012) show that the biggest emitter of volcanic SO2 was Nabro, followed by Kasatochi and Grímsvötn. Our observations also show a tendency for volcanic SO2 to be injected to the level of the tropopause during many of the moderately explosive eruptions observed. For the eruptions observed, this tendency was independent of the maximum amount of SO2 (e.g. 0.2 Tg for Dalafilla compared with 1.6 Tg for Nabro) and of the volcanic explosive index (between 3 and 5).

Observations of volcanic SO₂ from MLS on Aura

Sulfur dioxide (SO2) is an important atmospheric constituent, particularly in the aftermath of volcanic eruptions. These events can inject large amounts of SO2 into the lower stratosphere, where it is oxidised to form sulfate aerosols; these in turn have a significant effect on the climate. The MLS instrument on the Aura satellite has observed the SO2 mixing ratio in the upper troposphere and lower stratosphere from August 2004 to the present, during which time a number of volcanic eruptions have significantly affected those regions of the atmosphere. We describe the MLS SO2 data and how various volcanic events appear in the data. As the MLS SO2 data are currently not validated we take some initial steps towards their validation. First we establish the level of internal consistency between the three spectral regions in which MLS is sensitive to SO2. We compare SO2 column values calculated from MLS data to total column values reported by the OMI instrument. The agreement is good (within about 1 DU) in cases where the SO2 is clearly at altitudes above 147 hPa.

Observations of volcanic SO₂ from MLS on Aura

Sulphur dioxide (SO2) is an important atmospheric constituent, particularly in the aftermath of volcanic eruptions. These events can inject large amounts of SO2 into the lower stratosphere, where it is oxidised to form sulphate aerosols; these in turn have a significant effect on the climate. The MLS instrument on the Aura satellite has observed the SO2 mixing ratio in the upper troposphere and lower stratosphere from August 2004 to the present, during which time a number of volcanic eruptions have significantly affected those regions of the atmosphere. We describe the MLS SO2 data and how various volcanic events appear in the data. As the MLS SO2 data are currently not validated we take some initial steps towards their validation. First we establish the level of internal consistency between the three spectral regions in which MLS is sensitive to SO2. We compare SO2 column values calculated from MLS data to total column values reported by the OMI instrument. The agreement is good in cases where the SO2 is clearly at altitudes above 147 hPa.