GML Seminars

Visitor Information: The Visitors Center and entrance to the Boulder Department of Commerce facilities are located on Broadway at Rayleigh Road. All visiting seminar attendees, including pedestrians and bike riders, are required to check in at the Visitors Center at the Security Checkpoint to receive a visitor badge. Seminar attendees need to present a valid photo ID and mention the seminar title or the speaker's name to obtain a visitor badge. .

Upcoming Seminars

Title:	Some Remaining Challenges for the Montreal Protocol and Recovery of the Stratospheric Ozone Layer
Speaker:	Stephen Montzka Dr. Steve Montzka is GML’s Senior Scientist. This month marks his 35th year at NOAA, where he has dedicated himself to making and interpreting global-scale measurements of trace gases that influence stratospheric ozone and climate. His work at NOAA/GML has provided new insights into atmospheric processes and has also been a touchstone for the international policy community in their efforts to heal the ozone layer.
Date/Time:	Thursday, March 5, 2026 01:00 PM MST (-0700)
Location:	David Skaggs Research Center, Room GC402 Google Meet
Abstract The success of the Montreal Protocol is readily apparent in the tremendous production declines reported since 1987 for ozone-depleting substances in controlled uses. Atmospheric measurements confirm that these production declines have led to substantial decreases in emissions and concentrations of nearly all ozone-depleting gases. Ozone depletion, however, remains substantial, such that its recovery will be possible only with continued declines in long-lived chlorine and bromine. A number of challenges have emerged in recent years that threaten to delay ozone-layer recovery. In this presentation, we will explore some of these challenges, including ongoing emissions of CFC-11, particularly in the years following our discovery of its continued use after its global ban. We will also present the first globally-distributed measurements of CFC-113a, which show large increases of this long-lived ozone-depleting gas. While the cause for this increase is not understood, it may be related to its use as an intermediate in the production of HFCs. Finally, we’ll show how concentration changes measured for short-lived chlorinated solvents such as CH2Cl2 and, for the first time, 1,2-dichloroethane –chemicals not controlled by the Montreal Protocol – have added substantially to the amount of chlorine reaching the stratosphere.

Title:	Insights from balloon-borne measurements of stratospheric aerosol and water vapor following volcanic and pyrocumulonimbus injections (2019-2024)
Speaker:	Elizabeth (Lizzy) Asher Dr. Elizabeth Asher is a CIRES research scientist at NOAA in the Global Monitoring Laboratory Ozone and Water Vapor division. Her research focuses on perturbations and long-term changes to stratospheric water vapor and aerosol related to volcanoes, wildfires and other anthropogenic activities that can impact Earth’s radiative balance. She is a co-author of the Atmospheric Processes and their Role in Climate (APARC) Report on the Global Atmospheric Impacts of the 2022 Hunga Volcano Eruption.
Date/Time:	Thursday, March 5, 2026 01:00 PM MST (-0700)
Location:	David Skaggs Research Center, Room GC402 Google Meet
Abstract Volcanic eruptions and large wildfires can inject sulfur dioxide (SO2), ash, organic aerosol, and water (as well as small amounts of other chemical compounds) into the stratosphere. These perturbations can have impacts on surface temperatures, on stratospheric ozone chemistry, and at least in the case of the most powerful smoke-filled vortices, also on stratospheric dynamics. National Oceanic and Atmospheric Administration (NOAA) balloon-borne instruments from geographically distributed sites in the Balloon Baseline Stratospheric Aerosol Profiles (B2SAP) network have sampled fresh and/or aged plumes of four volcanic eruptions between 2019 and 2024, i.e., Raikoke, La Soufrière, Ulawun, Hunga-Tonga, and one large PyroCB event, i.e., the Australian New Year’s Pyrocumulonimbus (ANY PyroCB). B2SAP balloon payloads repeatedly measured atmospheric state variables, ozone, water vapor, and aerosol number and size at a greater resolution than satellites, particularly near the tropopause. After the ANY PyroCB, New Zealand aerosol profiles revealed a bimodal aerosol size distribution, which cannot be directly measured from space, and a thin layer of elevated water vapor. Profiles of aerosol extinction, based on Mie calculations and measured particle size distributions, compare favorably with space-based and ground-based remote sensing measurements of extinction, and water vapor sonde profiles have been used to validate numerous state-of-the-art NASA satellites. Enhancements of aerosol and water vapor can be tracked for months as was demonstrated after the Hunga-Tonga eruption. These measurements have been used to calculate the aerosol burden, e.g., of a volcanic plume as well as estimate the SO2 lifetime in the plume, to test global sectional aerosol models, to highlight transport through the mean meridional circulation (Brewer-Dobson), and to study if recent small to moderate additions of stratospheric aerosol may have contributed to water vapor entry through the tropical tropopause layer. This work has advanced our understanding of stratospheric dynamics, aerosol processes and interactions with the troposphere.

Title:	Next-Generation Modeling of Global Natural Methane Fluxes with Knowledge-Guided Machine Learning
Speaker:	Youmi Oh Dr. Youmi Oh studies how environmental change alters surface-atmosphere interactions with bottom-up biogeochemistry models, top-down atmospheric chemistry and transport models, and knowledge-guided machine learning for her research. Her current research at NOAA focuses on developing and improving NOAA’s atmospheric methane data assimilation system, the CarbonTracker-CH4. She is also a principal investigator of the AI for Natural Methane Working Group, a collaborative network of ~50 researchers spanning diverse expertise in modeling and observations.
Date/Time:	Thursday, March 5, 2026 01:00 PM MST (-0700)
Location:	David Skaggs Research Center, Room GC402 Google Meet
Abstract Natural methane sources account for ~40% of the global methane emissions but remain the most uncertain component in the global methane budget. The Artificial Intelligence for Natural Methane Working Group (AI4NM) aims to build a harmonized global natural methane dataset using Knowledge-Guided Machine Learning (KGML) to estimate the spatial and temporal variability of global methane emissions from wetlands and uptake by soil sinks. Our KGML framework integrates process-based and machine-learning models, synthesizing diverse direct and indirect observations to enhance model efficiency, interpretability, and performance across scales. We explore various knowledge-guided (KG) constraints, including pretraining, loss functions, and model architectures. In this presentation, I will give a brief introduction of KGML and how our working group has implemented KGML for estimating natural methane fluxes.

Archives

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