Advancing our understanding of atmospheric composition and climate

The Chemical Sciences Laboratory (CSL) is one of ten NOAA Research Laboratories located throughout the United States organized under the office of Oceanic & Atmospheric Research (OAR). CSL is one of four individual OAR labs located within the David Skaggs Research Center (DSRC) in Boulder, Colorado. The research conducted at CSL aims to advance scientific understanding of the chemical and physical processes that affect Earth's atmospheric composition and climate.

A new study finds that injecting SO₂ at higher latitudes, rather than in the tropics, could mitigate some undesirable side effects of SAI – but all options come with trade-offs.

One potential method of climate intervention, known as stratospheric aerosol injection (SAI), aims to mimic the planet cooling effects of volcanic eruptions by injecting sulfur dioxide (SO₂) directly into the stratosphere where it forms sunlight-reflecting sulfate aerosols. Although the overall goal of SAI is straightforward (reflect more sunlight), when it comes to considering how such an intervention could or would be implemented, a complex patchwork of side effects and trade-offs emerges.

In a new study published in Atmospheric Chemistry and Physics, scientists from NOAA CSL and CIRES, in collaboration with Cornell and Indiana University, carefully examined a range of potential injection strategies by using a chemistry-climate model to simulate SAI while varying both the amount of SO₂ injected into the stratosphere and the latitudes where it is injected.

What they found was a complicated picture: a diverse range of outcomes beyond just decreased surface temperatures, that included impacts on the stratospheric ozone layer, large-scale circulation patterns, and regional weather and precipitation, that vary both spatially and seasonally.

A recent study published in the journal Science found that the Hunga Tonga–Hunga Ha’apai eruption in January 2022 was so intense that it partially depleted Earth’s ozone layer in the following weeks — marking the first time on record that scientists observed such a rapid and strong decrease of stratospheric ozone miles resulting from volcanic activity. The research was led by Stephanie Evan, a CNRS researcher at the Maïdo Observatory on Reunion Island, with colleagues from NOAA CSL and CIRES. The rapid mobilization of NOAA and CIRES researchers to Reunion within a week following the eruption to assist in chemical measurements of the plume, an effort dubbed TR²EX, was part of NOAA's Earth's Radiation Budget research initiative.

The eruption injected huge amounts of water into the stratosphere and caused a large, rapid loss of ozone. Evan et al. collected in situ data on water, aerosols, and ozone in the volcanic plume and combined them with remote sensing observations to show that heterogeneous chlorine activation on humidified volcanic aerosols was the cause of the massive ozone loss that occurred. This loss was primarily triggered by the synergistic effects of strong humidification, radiative cooling, and added aerosol surface area, and this observation supports the suggestion that excess midlatitude stratospheric water associated with convection changes due to global warming could drive increases in lower stratospheric ozone loss. 

In a second paper, published a few weeks later in PNAS, CIRES researcher Elizabeth Asher (CSL at the time of the study, now with GML) showed that the plume also exhibited rapid aerosol formation as a result of the massive amount of water vapor ejected. The large H₂O enhancements contributed as much as ~30% to ambient aerosol surface area and likely accelerated SO₂ oxidation and aerosol formation rates in the plume to approximately three times faster than under normal stratospheric conditions.

Dr. Amy Hawes Butler has received the 2023 AGU Atmospheric Sciences Ascent Award for her research explaining how processes in the stratosphere link to the troposphere and can improve predictability of weather on times scales of weeks to months.

Dr. Butler studies the interaction between the stratosphere and troposphere with an eye toward using the state of the stratosphere to improve predictability of weather at the surface. She is a recognized leader in the interactions between the stratosphere and troposphere. She has led or contributed to numerous studies on the stratosphere’s influence on surface weather and tropospheric composition; she has excelled in these studies.

In addition to her research accomplishments, Dr. Butler excels at communication. She is a go-to expert regularly contacted by the media to discuss the polar vortex, sudden stratospheric warmings, and associated weather/climate impacts. She has put together explanatory videos covering atmospheric dynamics topics that are clear and easily understood by a lay audience, regularly contributes to NOAA weather blogs, and has an active social media presence where she explains weather phenomena.

Dr. Karen H. Rosenlof has been elected as a Fellow of the American Geophysical Union (AGU), in recognition of seminal contributions to the understanding of stratospheric dynamics and transport, and the processes that control stratospheric water vapor. AGU Fellows embody AGU's values by fostering equity, integrity, diversity, and open science; by mentoring; through public engagement; and in their communications.

Election to AGU Fellow is an honor reserved for less than 0.1% of AGU's membership in any given year. Karen's election to this honor is well deserved. Her research at NOAA has focused on the climate system and how it is changing. Her scientific impact is evident in both her leadership of chemistry and climate processes, and her research of stratospheric dynamics, stratosphere-troposphere interactions, and stratospheric composition including water vapor, ozone, and aerosols. Karen and the other 2023 Fellows will be recognized at the Fall Meeting of the AGU, to be held in December in San Francisco.

CSL's Ann Thorne receives a NOAA Silver Sherman Award. This award was initiated during Dr. Kathy Sullivan's tenure as NOAA Administrator, to recognize individuals who excel in their work, achieve a milestone that contributes significantly or critically towards a particular program's goal, or demonstrate leadership toward process improvement of a significant magnitude. Dr. Sullivan was particularly invested in reaching down into the organization to recognize those who made extraordinary efforts to keep the mission moving forward.

Ann is recognized "for going above and beyond her core duties at the NOAA Chemical Sciences Laboratory by taking on extra responsibilities related to students, education and outreach, especially mentoring of interns and organizing the summer intern program, and related to diversity, equity, inclusion, and accessibility issues for CSL, ESRL, and OAR. She has volunteered many times to help other laboratories, for example to cover absences in human resources staff, because her goal over three decades of service has been to make all the ESRL laboratories successful."