About

Professor Ronald C. Cohen's research focuses on developing and applying new experimental and modeling strategies for understanding the chemical composition of the Earth's atmosphere both in the present and in the past, as well as for predicting future changes. His work involves studying atmospheric chemistry to better understand air quality and climate dynamics. As the principal investigator, he leads efforts to advance knowledge in atmospheric sciences, contributing to the scientific community's understanding of environmental and climate-related issues.

Research topics

• Environmental science
• Geography
• Meteorology
• Atmospheric sciences
• Geology
• Physics
• Chemistry
• Business
• Oceanography
• Climatology
• Waste management
• Environmental health
• Environmental chemistry

Selected publications

• Observing U.S. Regional Variability in Lightning NO₂ Production Rates

  Journal of Geophysical Research Atmospheres · 2020 · 42 citations

  • Environmental science
  • Meteorology
  • Climatology

  Abstract Lightning is a large and variable source of nitrogen oxides (NO x ≡ NO + NO 2 ) to the upper troposphere. Precise estimates of lightning NO x (LNO x ) production rates are needed to constrain tropospheric oxidation chemistry; however, controls over LNO x variability are poorly understood. Here, we describe an observational analysis of variability in LNO 2 with lightning type by exploiting U.S. regional differences in lightning characteristics in the Southeast, South Central, and North Central United States. We use satellite NO 2 measurements from the Ozone Monitoring Instrument with Berkeley High Resolution vertical column densities, a combined lightning data set derived from the Earth Networks Total Lightning Network and National Lightning Detection Network TM measurements, and hourly winds from the European Centre for Medium‐Range Weather Forecasts climate reanalysis data set (ERA5) over May–August 2014–2015. We find evidence that cloud‐to‐ground (CG) strokes produce a factor of 9–11 more NO 2 than intracloud (IC) strokes for storms with stroke rates of at least 2,800 strokes·cell −1 ·hr −1 . We show that regional differences in LNO 2 production rates are generally consistent with regional patterns CG and IC stroke frequency and stroke current density. A comparison of stroke‐based and flash‐based CG/IC LNO 2 estimates suggests that CG LNO 2 is potentially underestimated when derived with flash data due to the operational definition of CG lightning. We find that differences in peak current explain a large portion of CG/IC LNO 2 variability, but that other factors must also be important, including minimum stroke rate. Because IC and CG strokes produce NO x in distinct areas of the atmosphere, we test the sensitivity of our results against the atmospheric NO 2 vertical distribution assumed in the a priori profiles; we show that the relative CG to IC LNO 2 was generally insensitive to the assumed NO 2 vertical distribution.

  DOI

• Observed Impacts of COVID‐19 on Urban CO ₂ Emissions

  Geophysical Research Letters · 2020 · 157 citations

  Senior authorCorresponding
  • Environmental science
  • Meteorology
  • Atmospheric sciences

  Abstract Governments restricted mobility and effectively shuttered much of the global economy in response to the COVID‐19 pandemic. Six San Francisco Bay Area counties were the first region in the United States to issue a “shelter‐in‐place” order asking non‐essential workers to stay home. Here we use CO 2 observations from 35 Berkeley Environment, Air‐quality and CO 2 Network (BEACO 2 N) nodes and an atmospheric transport model to quantify changes in urban CO 2 emissions due to the order. We infer hourly emissions at 900‐m spatial resolution for 6 weeks before and 6 weeks during the order. We observe a 30% decrease in anthropogenic CO 2 emissions during the order and show that this decrease is primarily due to changes in traffic (–48%) with pronounced changes to daily and weekly cycles; non‐traffic emissions show small changes (–8%). These findings provide a glimpse into a future with reduced CO 2 emissions through electrification of vehicles.

  DOI

• The Role of Temperature and NO<i>_x</i> in Ozone Trends in the Los Angeles Basin

  Environmental Science & Technology · 2020 · 142 citations

  Senior authorCorresponding
  • Environmental science
  • Environmental chemistry
  • Atmospheric sciences

  and the likely effects of additional emission reductions on the occurrence of high ozone in the region.

  DOI

Recent grants

• The Atmospheric N Cycle: Biospheric Emissions and Chemical Transformations

  NSF · $547k · 2014–2018

• Ground-Based Observations of Nitrogen Oxides and Nitrates

  NSF · $385k · 2005–2008

• Nitrogen Oxide Chemistry: Connecting Ambient Concentrations to Mechanisms of Emission, Oxidaton and Aerosol Formation

  NSF · $222k · 2011–2013

• International Collaboration in Chemistry: Measuring the effects of surfactants on cloud microphysics

  NSF · $502k · 2013–2017

• EAGER: A Prototype Dense Observing Network for Air Quality (AQ) and Greenhouse Gas (GHG) Emissions Monitoring

  NSF · $103k · 2010–2012

Frequent coauthors

• P. J. Wooldridge

  University of California, Berkeley

  376 shared

• P. O. Wennberg

  California Institute of Technology

  349 shared

• J. A. Neuman

  Cooperative Institute for Research in Environmental Sciences

  194 shared

• R. S. Gao

  NOAA Chemical Sciences Laboratory

  193 shared

• R. J. Salawitch

  Earth System Science Interdisciplinary Center

  189 shared

• T. P. Bui

  Bay Area Environmental Research Institute

  183 shared

• J. J. Margitan

  California Institute of Technology

  181 shared

• D. W. Fahey

  175 shared

Labs

• Cohen ResearchPI

Awards & honors

• NASA Group Achievement Award (2005)
• NASA Group Achievement Award (1998)
• Hellman Family Faculty Fund (1999)
• Regents Junior Faculty Fellowship (1998)

Similar researchers at University of California, Berkeley

• Peidong Yangh-262
• Jennifer A. Doudnah-230
• Jeffrey R. Longh-189
• John F. Hartwigh-180
• Rasmus Nielsenh-180