ACOM Director's Message

“The goal of atmospheric chemistry research is to anticipate and prepare for future environmental challenges with an enhanced predictive capability that foresees environmental changes and societal impacts, rather than just reacting to them after they occur.”
- The Future of Atmospheric Chemistry Research: Remembering Yesterday,
Understanding Today and Anticipating Tomorrow
The National Academies Press, 2016.

The objectives of the NSF Atmospheric Chemistry Program are to (1) characterize the chemical composition of the atmosphere and its variability; (2) understand the processes by which chemical species react and are transported in the atmosphere; (3) quantify the major fluxes of chemical substances into and out of the atmosphere; (4) understand the natural and anthropogenic causes of atmospheric chemical variability and the effects of chemical change on climate; and (5) characterize the oxidative capacity of the atmosphere and its variability.
- National Science Foundation Atmospheric Chemistry Program, May 2018.

We are very pleased to present the 2019 Annual Report that highlights major research accomplishments by the Atmospheric Chemistry Observations and Modeling (ACOM) Laboratory.

During this past year, ACOM has started to implement its new plan for its research and support activities developed for the period 2019-2023. The plan builds on ACOM’s strengths and takes into account the recommendations made by a “Blue Ribbon Panel” convened by NCAR in 2017 to suggest ways by which atmospheric chemistry could be made more prominent in the Center and how ACOM could better contribute to the success of the community.

As a laboratory belonging to a National Center, ACOM has a particular responsibility: support the broad agenda of the US research community, in particular the university groups that conduct fundamental research in atmospheric chemistry. To embrace the broad agenda of the community, ACOM must therefore have a broad interest and maintain different competences supporting experimental as well as modeling aspects. At the same time, it must tackle difficult, focused and intellectually challenging frontier questions that are in line with national and international research priorities. In this regard, the overall objective of ACOM is to advance the fundamental knowledge required to improve our predictive capability of short-term chemical weather and long-term chemical climate.

Topospheric Chemical Mechanisms: Oxidation of biogenic, pyrogenic and anthropogenic species under different NOx environments

The major focus of ACOM’s research in the period 2019 to 2023 will be a detailed investigation of reactive carbon chemistry in the atmosphere under different NOx environments. With effective measures taken to reduce the anthropogenic emissions of nitrogen oxides (NOx), chemical regimes in the atmosphere are gradually changing. Low NOx chemical paths are becoming increasingly more important for the degradation of natural and anthropogenic hydrocarbons, thus modifying the oxidizing power of the atmosphere and hence the formation of ozone and multiphase organic species (e.g., secondary organic aerosols).

At the same time, an increasing fraction of the world’s population will be living in urban areas. Ensuring that populated areas experience healthy air is therefore an important consideration for the development of smart and sustainable cities. ACOM will also therefore provide a quantitative description of the reactive carbon photochemistry under moderate to high NOx environments.

The Role of the Whole Atmosphere for Tropospheric Predictability

The influence of the complex interactions between chemical, radiative and dynamical processes taking place in the middle and upper atmosphere on the chemistry of the lower atmosphere and on climate variability and change remains poorly quantified. Jointly with the Climate and Global Dynamics (CGD) Laboratory and the High-Altitude Observatory (HAO), ACOM will further develop the Whole Atmosphere Community Climate Model (WACCM) and investigate the two-way stratospheric-troposphere coupling across times scales, and how these interactions will be evolving as stratospheric ozone in polar regions is recovering and climate is changing. A specific project will investigate how persistent convection in the Asian monsoon region transports and modifies chemical species of anthropogenic and biomass burning origins in the upper troposphere and lower stratosphere.

Development of a Unified Community Multi-scale Modeling Infrastructure for Chemistry and Aerosols (MUSICA)

Within five years, ACOM will develop together with partners in the community a computationally feasible global modeling framework that allows for simulation of large-scale atmospheric phenomena, while still resolving chemistry at emission and exposure relevant scales (down to ~4 km, through regional refinement). The multi-scale modeling infrastructure for Chemistry and Aerosols (MUSICA) and its components will be open source and flexible in order to facilitate community co-development and use for research and operational purposes. Its development will involve new strategic partnerships with universities and other interested research centers.

Development of an advanced observations capability

In order to support key research activities conducted by the university community and to meet the science goals of the Laboratory, ACOM will modernize it observational capabilities, and specifically acquire and develop state-of-the-art instruments based on chemical ionization mass spectrometry for the quantification of complex multi-functional organics both in the laboratory and in the atmosphere, specifically from the NSF GV and C-130 aircraft.

In cooperation with the NCAR Earth Observing Laboratory (EOL), ACOM will continue to support the community by deploying instruments for a myriad of chemical species, both in situ and via remote sensing techniques.

Guy Brasseur
Guy Brasseur
ACOM Director
Gabriele Pfister
Gabriele Pfister
ACOM Deputy Director