Widespread Frequent Methane Emissions From the Oil and Gas Industry in the Permian Basin.

Emissions of methane (CH) in the Permian basin (USA) have been derived for 2019 and 2020 from satellite observations of the Tropospheric Monitoring Instrument (TROPOMI) using the divergence method, in combination with a data driven method to estimate the background column densities. The resulting CH emission data, which have been verified using model data with known emissions, have a spatial resolution of approximately 10 km. The CH emissions show moderate spatial correlation with the locations of oil and gas production and drilling activities in the Permian basin, as well as with emissions of nitrogen oxides (NO).

Global fine-scale changes in ambient NO during COVID-19 lockdowns.

Nitrogen dioxide (NO) is an important contributor to air pollution and can adversely affect human health. A decrease in NO concentrations has been reported as a result of lockdown measures to reduce the spread of COVID-19. Questions remain, however, regarding the relationship of satellite-derived atmospheric column NO data with health-relevant ambient ground-level concentrations, and the representativeness of limited ground-based monitoring data for global assessment.

Abrupt decline in tropospheric nitrogen dioxide over China after the outbreak of COVID-19.

China's policy interventions to reduce the spread of the coronavirus disease 2019 have environmental and economic impacts. Tropospheric nitrogen dioxide indicates economic activities, as nitrogen dioxide is primarily emitted from fossil fuel consumption. Satellite measurements show a 48% drop in tropospheric nitrogen dioxide vertical column densities from the 20 days averaged before the 2020 Lunar New Year to the 20 days averaged after.

Impact of Coronavirus Outbreak on NO Pollution Assessed Using TROPOMI and OMI Observations.

Spaceborne NO column observations from two high-resolution instruments, Tropospheric Monitoring Instrument (TROPOMI) on board Sentinel-5 Precursor and Ozone Monitoring Instrument (OMI) on Aura, reveal unprecedented NO decreases over China, South Korea, western Europe, and the United States as a result of public health measures enforced to contain the coronavirus disease outbreak (Covid-19) in January-April 2020. The average NO column drop over all Chinese cities amounts to -40% relative to the same period in 2019 and reaches up to a factor of ~2 at heavily hit cities, for example, Wuhan, Jinan, while the decreases in western Europe and the United States are also significant (-20% to -38%). In contrast with this, although Iran is also strongly affected by the disease, the observations do not show evidence of lower emissions, reflecting more limited health measures.

Daily Satellite Observations of Methane from Oil and Gas Production Regions in the United States.

Production of oil and natural gas in North America is at an all-time high due to the development and use of horizontal drilling and hydraulic fracturing. Methane emissions associated with this industrial activity are a concern because of the contribution to climate radiative forcing. We present new measurements from the space-based TROPOspheric Monitoring Instrument (TROPOMI) launched in 2017 that show methane enhancements over production regions in the United States.

In-flight performance of the Ozone Monitoring Instrument.

The Dutch-Finnish Ozone Monitoring Instrument (OMI) is an imaging spectrograph flying on NASA's EOS Aura satellite since July 15, 2004. OMI is primarily used to map trace gas concentrations in the Earth's atmosphere, obtaining mid-resolution (0.4-0.

Unprecedented Arctic ozone loss in 2011.

Chemical ozone destruction occurs over both polar regions in local winter-spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was--for the first time in the observational record--comparable to that in the Antarctic ozone hole.

Prelaunch characterization of the Ozone Monitoring Instrument transfer function in the spectral domain.

A method and an experimental measurement setup to accurately characterize the instrument transfer function in the spectral domain for hyperspectral spectrometers in the ultraviolet-visible wavelength range are described. The application to the on-ground calibration of the Ozone Monitoring Instrument (OMI) on board the Earth Observing System Aura satellite is presented and discussed. With this method and setup, based on an echelle grating, a sampling of the instrument transfer function in the spectral domain can be selected and is not limited by the spectral resolution and sampling of the spectrometer that is being characterized.

Method of calibration to correct for cloud-induced wavelength shifts in the Aura satellite's Ozone Monitoring Instrument.

The in-flight wavelength calibration for the Ozone Monitoring Instrument is discussed. The observed variability in the wavelength scale is two orders of magnitude larger than caused by temperature changes in the instrument. These wavelength variations are the result of rapid changes in time in the radiance levels during an individual observation in the presence of clouds or snow and ice.

Molecules with large-amplitude torsional motion partially oriented in a nematic liquid crystal: ethane and isotopomers.

An NMR study on ethane and five isotopomers dissolved in the nematic liquid crystal Merck ZLI 1132 is performed. A consistent set of dipolar and quadrupolar couplings is obtained. The dipolar couplings are corrected for harmonic vibrational effects, while the contribution from the torsional motion is incorporated classically.

Ground-based zenith sky abundances and in situ gas cross sections for ozone and nitrogen dioxide with the Earth Observing System Aura Ozone Monitoring Instrument.

High-accuracy spectral-slit-function calibration measurements, in situ ambient absorption gas cell measurements for ozone and nitrogen dioxide, and ground-based zenith sky measurements with the Earth Observing System Aura Ozone Monitoring Instrument (OMI) flight instrument are reported and the results discussed. For use of high-spectral-resolution gas absorption cross sections from the literature in trace gas retrieval algorithms, accurate determination of the instrument's spectral slit function is essential. Ground-based measurements of the zenith sky provide a geophysical determination of atmospheric trace gas abundances.

Cavity-Ring-Down Spectroscopy on Water Vapor in the Range 555-604 nm.

The method of pulsed cavity-ring-down spectroscopy was employed to record the water vapor absorption spectrum in the wavelength range 555-604 nm. The spectrum consists of 1830 lines, calibrated against the iodine standard with an accuracy of 0.01 cm(-1); 800 of these lines are not obtained in the HITRAN 96 database, while 243 are not included in the newly recorded Fourier transform spectrum of the Reims group.