AGES+ Coordinating Activities

Aircraft: NCAR/NSF C-130

Greater New York Oxidant Trace gas Halogen and Aerosol Airborne Mission (GOTHAAM)

Science Objectives

NYMA map
GOTHAAM will probe atmospheric chemistry in the diverse chemical environments (biogenic, urban, marine) found in the New York Metropolitan Area. The inset is a wind rose showing the origin of surface winds in the summertime. Southerly flow is most common, followed by southwesterly and northeasterly.

The New York Metropolitan Area (NYMA) is home to more than 20 million people and experiences high levels of pollution. In the summer of 2021, 7 of 11 monitoring stations in the NYMA reported ozone levels in exceedance of the EPA National Ambient Air Quality Standard (last accessed 2022 June 2). Total PM2.5 loading has improved significantly in recent decades due to air quality regulations, but a growing contribution of organic matter to the total aerosol burden may have implications for particle toxicity and regulatory policy. Encompassing rural, urban, and marine environments, the NYMA is subject to a complex mixture of emissions, chemistry, and coastal meteorology that ultimately determine the production and fate of harmful pollutants.

The Greater New York Oxidant Trace Gas Halogen and Aerosol Airborne Mission (GOTHAAM) is an NSF-funded investigation of the detailed chemical processes controlling atmospheric composition in the NYMA. State-of-the-art in situ instrumentation will be deployed on the NCAR/NSF C-130 aircraft in July and August – rescheduled to 2025 – to address four related objectives.

  1. Quantify the relative contributions from various volatile organic compound (VOC) sources (biogenic, fossil fuel combustion, consumer products) and how they contribute to chemical reactivity.
  2. Determine the relative potential contribution of each VOC class to secondary organic aerosol (SOA) as the anthropogenic plume evolves.
  3. Quantify the relative importance of oxidation pathways for both gas phase and aerosol species and characterize how processes vary diurnally and between chemical systems (biogenic/urban/marine).
  4. Investigate how nighttime processes influence next-day chemistry and composition.

GOTHAAM observations will improve understanding of formation of O3 and PM2.5 pollution in the NYMA. By sharing and disseminating results, GOTHAAM will help air quality agencies in the region and other similar mega cities take action to mitigate harmful pollution.

Proposed Payload

The NCAR/NSF C-130 payload is optimized to address GOTHAAM objectives. Multi-instrument VOC measurements will thoroughly characterize VOC sources and oxidation products in the high and intermediate volatility range (Objectives 1, 2, 3). Direct observations of key oxidants will constrain the lifetime of reactive carbon and nitrogen (Objective 3). Measurements of gas-phase aerosol precursors and aerosol composition will elucidate major pathways leading to secondary pollutants (Objectives 2, 3). Simultaneous observations of halogenated gases, sulfur-containing gases, and aerosol properties will illuminate how the marine atmosphere processes urban outflow (Objectives 3, 4). In combination, the GOTHAAM payload can yield a comprehensive picture of atmospheric chemistry in the NYMA.

Core instrumentation for GOTHAAM

Species MeasuredTechniquePIInstitution
OH, HO2, RO2, H2SO4NO3- CIMSLee MauldinCU Boulder
oVOCs, halogens, ClNO2, HONO, N2O5, etcI- CIMSJoel ThorntonU Washington
VOCsPTR-TOF VocusJoel ThorntonU Washington
Organic gasesTOGA-TOFEric ApelNCAR ACOM
HCHOISAFReem Hannun / Glenn WolfeUMD / NASA
NOx, ∑NOy, O3ChemiluminescenceAle FranchinNCAR ACOM
Speciated PANsTD-CIMSFrank FlockeNCAR ACOM
GHG/CO/SO2PicarroTeresa CamposNCAR ACOM
Individual particle composition, including sea saltATOF-MSKerri PrattU Michigan
SOA compositionAMSDelphine FarmerCSU
Aerosol impaction collectorTRACDaniel KnopfStony Brook
Aerosol size distributionsUHSAS, cloud proben/aNCAR EOL
J-valuesHARP actinic fluxSamuel HallNCAR ACOM

All measurements are in situ. Gas-phase observations include speciated VOC, speciated and total reactive nitrogen, radicals (OH, HO2, RO2), greenhouse gases, sulfur and halogen-containing compounds, and more. Aerosol measurements include single-particle and bulk chemical composition, physical properties, and size distributions.

Mission Execution

With 150 flight hours, GOTHAAM will generate a high-resolution 4-D portrait of atmospheric composition and processes in the NYMA during the peak ozone season. Flights will include a combination of Lagrangian and Eulerian strategies and focus on the same domain as the NEC-AQ-GHG Cessna research aircraft. Missed approaches at designated airports will provide full vertical profiles of short-lived reactive species and improve connections to ground monitoring networks. Flights will also exploit natural variability in near-surface wind patterns to probe the various chemical regimes both independently and in combination (e.g., urban plume outflow over land vs. over water). Multi-scale models, including F0AM, CMAQ, and GEOS-Chem, will support forecasting and analysis

Anticipated Outcomes

The next-generation instrumentation on GOTHAAM will provide an unprecedented dataset detailing NYMA atmospheric composition. Analyses will reveal the controls on O3 and PM formation, informing air quality stakeholders in both NY and other megacities. Regional and global models struggle in coastal regions, and GOTHAAM observations can serve as a benchmark constraint for pinpointing model shortfalls and testing new parameterizations. Finally, with potential concurrent sampling under TEMPO, GOTHAAM data will serve as a ground-truth resource for validation of satellite retrievals and applications of satellite data to studies of emissions and chemistry.