Ubiquitous atmospheric production of organic acids mediated by cloud droplets.

Atmospheric acidity is increasingly determined by carbon dioxide and organic acids. Among the latter, formic acid facilitates the nucleation of cloud droplets and contributes to the acidity of clouds and rainwater. At present, chemistry-climate models greatly underestimate the atmospheric burden of formic acid, because key processes related to its sources and sinks remain poorly understood.

Global Significant Changes in Formaldehyde (HCHO) Columns Observed From Space at the Early Stage of the COVID-19 Pandemic.

Satellite HCHO data are widely used as a reliable proxy of non-methane volatile organic compounds (NMVOCs) to constrain underlying emissions and chemistry. Here, we examine global significant changes in HCHO columns at the early stage of the COVID-19 pandemic (January-April 2020) compared with the same period in 2019 with observations from the TROPOspheric Monitoring Instrument (TROPOMI). HCHO columns decline (11.

Inferring Changes in Summertime Surface Ozone-NO-VOC Chemistry over U.S. Urban Areas from Two Decades of Satellite and Ground-Based Observations.

Urban ozone (O) formation can be limited by NO, VOCs, or both, complicating the design of effective O abatement plans. A satellite-retrieved ratio of formaldehyde to NO (HCHO/NO), developed from theory and modeling, has previously been used to indicate O formation chemistry. Here, we connect this space-based indicator to spatiotemporal variations in O recorded by on-the-ground monitors over major U.

Global monitoring of volcanic SO degassing with unprecedented resolution from TROPOMI onboard Sentinel-5 Precursor.

Over the last four decades, space-based nadir observations of sulfur dioxide (SO) proved to be a key data source for assessing the environmental impacts of volcanic emissions, for monitoring volcanic activity and early signs of eruptions, and ultimately mitigating related hazards on local populations and aviation. Despite its importance, a detailed picture of global SO daily degassing is difficult to produce, notably for lower-tropospheric plumes, due largely to the limited spatial resolution and coverage or lack of sensitivity and selectivity to SO of current (and previous) nadir sensors. We report here the first volcanic SO measurements from the hyperspectral TROPOspheric Monitoring Instrument (TROPOMI) launched in October 2017 onboard the ESA's Sentinel-5 Precursor platform.