Search results for "Atmospheric composition"
showing 9 items of 9 documents
Detection and evaluation of an early divergence problem in northern Fennoscandian tree-ring data
2013
Although not yet fully understood, reduced sensitivity of tree growth to temperature at high northern latitudes during the last ˜ 40 years is often linked to concurrent anthropogenic changes of atmospheric composition and global warming. The idea that a temporal localization of the problem could improve its understanding initiated a search for erratic growth-patterns in earlier periods of high quality dendrochronological archives. An extensive network of maximum latewood density (MXD) measurements from northern Fennoscandia likely represents one of the most reliable regional summer-temperature reconstructions. The strong coherence between proxy and instrumental data is, however, interrupted…
Spectral Observations of Optical Emissions Associated with Terrestrial Gamma-Ray Flashes
2021
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.
COARSEMAP: synthesis of observations and models for coarse-mode aerosols
2017
Coarse mode aerosols influence Earth's climate and biogeochemistry by interacting with long-wave radiation, promoting ice nucleation, and contributing important elements to biogeochemical cycles during deposition. Yet coarse mode aerosols have received less emphasis in the scientific literature. Here we present first efforts to globally synthesize available mass concentration, compositionand optical depth data and modeling for the coarse mode aerosols (<10 μm) in a new project called "COARSEMAP" (http://www.geo.cornell.edu/eas/PeoplePlaces/Faculty/mahowald/COARSEMAP/). We seek more collaborators who have observational data, especially including elemental or composition data, and/or who a…
Impact of rocket exhaust plumes on atmospheric composition and climate – an overview
2013
Rockets are the only direct anthropogenic emission sources into the upper atmosphere. Gaseous rocket emissions include CO, N2, H2, H2O, and CO2, while solid rocket motors (SRM) additionally inject significant amounts of aluminum oxide (Al2O3) particles and gaseous chlorine species into the atmosphere. These emissions strongly perturb local at- mospheric trace gas and aerosol distributions. Here, the previous aircraft measurements in various rocket exhaust plumes including several large space shuttle launch vehicles are compiled. The observed changes of the lower stratospheric composition in the near field are summarized.
Emission of Bromine and Iodine from Mt. Etna volcano
2005
Constraining fluxes of volcanic bromine and iodine to the atmosphere is important given the significant role these species play in ozone depletion. However, very few such measurements have been made hitherto, such that global volcanic fluxes are poorly constrained. Here we extend the data set of volcanic Br and I degassing by reporting the first measurements of bromine and iodine emissions from Mount Etna. These data were obtained using filter packs and contemporaneous ultraviolet spectroscopic SO2 flux measurements, resulting in time-averaged emission rates of 0.7 kt yr(-1) and 0.01 kt yr(-1) for Br and I, respectively, from April to October 2004, from which we estimate global Br and I flu…
Aviation Contrail Cirrus and Radiative Forcing Over Europe During 6 Months of COVID‐19
2021
Abstract The COVID‐19 pandemic led to a 72% reduction of air traffic over Europe in March–August 2020 compared to 2019. Modeled contrail cover declined similarly, and computed mean instantaneous radiative contrail forcing dropped regionally by up to 0.7 W m−2. Here, model predictions of cirrus optical thickness and the top‐of‐atmosphere outgoing longwave and reflected shortwave irradiances are tested by comparison to Meteosat‐SEVIRI‐derived data. The agreement between observations and modeled data is slightly better when modeled contrail cirrus contributions are included. The spatial distributions and diurnal cycles of the differences in these data between 2019 and 2020 are partially caused…
Neutral Iron Emission Lines From The Day-side Of KELT-9b -- The GAPS Programme With HARPS-N At TNG XX
2020
We present the first detection of atomic emission lines from the atmosphere of an exoplanet. We detect neutral iron lines from the day-side of KELT-9b (Teq $\sim$ 4, 000 K). We combined thousands of spectrally resolved lines observed during one night with the HARPS-N spectrograph (R $\sim$ 115, 000), mounted at the Telescopio Nazionale Galileo. We introduce a novel statistical approach to extract the planetary parameters from the binary mask cross-correlation analysis. We also adapt the concept of contribution function to the context of high spectral resolution observations, to identify the location in the planetary atmosphere where the detected emission originates. The average planetary li…
ARES I: WASP-76 b, A Tale of Two HST Spectra
2020
We analyse the transmission and emission spectra of the ultra-hot Jupiter WASP-76b, observed with the G141 grism of the Hubble Space Telescope's Wide Field Camera 3 (WFC3). We reduce and fit the raw data for each observation using the open-source software Iraclis before performing a fully Bayesian retrieval using the publicly available analysis suite TauRex 3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of titanium oxide (TiO) and vanadium oxide (VO) or non-grey clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyse this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these vi…
Introduction to the special issue on molecular spectroscopy, atmospheric composition and climate change
2018
International audience