Call for FICUS Research Proposals with ARM and EMSL, FY 2025

EMSL Balloon-Borne Instruments

EMSL has developed an automated Size and Time-resolved Aerosol Collector (STAC), a Time-Resolved Bulk Aerosol Collector (TBAC), and a new Time-Resolved Automated Volatile organic compounds Sampling (TRAVIS) system to fly as guest instruments on ARM’s Tethered Balloon System (TBS). These instruments will enable researchers to capture aerosols and VOCs in situ during upcoming ARM campaigns for subsequent “offline” analyses of the physical, chemical, optical, and microphysical properties of aerosol particles using multimodal microscopy, spectroscopy, and advanced mass spectrometry techniques at EMSL. For questions about the STAC, TBAC, and TRAVIS systems, please direct questions to Swarup China.

For the offline analysis of VOCs, EMSL recently acquired a high-throughput Thermal Desorption Gas Chromatography coupled to Quadrupole Time-of-Flight Mass Spectrometry (TD-GC-QTOFMS) instrument. In addition, EMSL will support the offline analysis of the vertical profiles of VOCs collected onto sorbent tubes using the TRAVIS system.

STAC is an automated sampler that collects aerosol particles in the size range of 0.07–2.3 µm. STAC carries 20 filters and is able to switch from one filter to the next in a few seconds but typically integrates over periods on the order of 30 minutes for each filter to obtain a sufficient particle loading for analysis. The STAC platform is integrated with a temperature and relative humidity sensor and a pressure sensor to monitor ambient conditions and may be operated with an optical particle counter to measure the aerosol size distribution and a micro-aethalometer to measure the black carbon mass concentration. The sampler can be programmed with a measurement delay (start time), the number of samples, and the time at each point of sampling. STAC has four stages where size-resolved particles will be collected on multiple substrates for microscopy, spectroscopy, and substrate-based mass spectrometry analysis. The current version of STAC can sample up to 20 different altitudes per flight. STAC has three substrate holders in each stage and can accommodate transmission electron microscopy grids, silicon nitride substrates, or quartz substrates. Typically, two TEM grids (B-film and lacey film) and silicon nitride substrates are placed on each stage.

TBAC collects total aerosols on either quartz or Teflon filters for various bulk chemical analyses.

TRAVIS collects VOC samples at up to six different altitudes for offline analysis at EMSL; the sampling onset time and collection duration are programmed prior to flight.

Tethered Balloon Mission Opportunities

During calendar year (CY) 2022/23, ARM deployed TBS at its Southern Great Plains (SGP) site, in support of the Surface Atmosphere Integrated Field Laboratory (SAIL) field campaign in the Rocky Mountains in central Colorado, and during the Tracking Aerosol Convection Interactions Experiment (TRACER) mobile facility deployment to Houston, Texas, during the summer deep convective season. These deployments provided a combination of flights with periods at fixed altitudes and flights that sampled profiles through the boundary layer to altitudes of up to 1.5 km above ground level (AGL).

Applicants may propose to analyze samples from past missions or from the three missions already planned for fiscal year (FY) 2024 at the SGP site in association with a study of organosulfates and organonitrates. These missions will include samples obtained by STAC and TBAC spanning several seasons at SGP.

Applicants may propose new FY 2025 missions for the SGP site, a new observatory deployment in the Bankhead National Forest (BNF) in northwest Alabama, or for a site on Kent Island in the Chesapeake Bay. The Kent Island site is part of the Coast–Urban–Rural Atmospheric Gradient Experiment (CoURAGE) campaign, which includes several measurement sites in the Baltimore, Maryland, region. ARM is already committed to flying two TBS missions at the Kent Island site in FY 2025 (one in winter and one in summer) with baseline ARM instruments and several guest instruments that are part of the CoURAGE campaign. EMSL particle samplers may be requested for any of the FY 2025 missions. There may also be capacity to host additional guest instruments on the already-planned CoURAGE missions.

Missions are typically up to 14 days in length, and ARM is planning to fly approximately six to eight total TBS missions during FY 2025. A standard mission involves a single tethered balloon carrying baseline ARM instruments in addition to the STAC, TBAC, and TRAVIS capabilities. Investigators are asked to propose no more than three missions, and requests for multiple missions should be well justified. The balloon must remain in clear air and below the base of nearby clouds. TBS flights are generally restricted to a maximum altitude limit of 1.5 km AGL, and an individual flight typically lasts from a few hours to approximately eight hours with varying flight styles. ARM is seeking permissions for FY 2025 operations at the SGP and BNF sites and for the CoURAGE campaign and will revisit the feasibility of operations at these locations at the full proposal stage. Only daytime operations may be proposed for BNF and CoURAGE. Daytime or nighttime operations may be proposed at the SGP site.

Proposals for new TBS missions in FY 2025 should provide details regarding mission expectations including needed instrumentation, the flight location (SGP, BNF, CoURAGE), desired season or seasons and time of day, desired altitude, the number and duration of flights required, desired meteorological conditions during the flight, whether fixed-altitude flights or profiles would be more appropriate for the applicant’s science goals, and where these factors are important for achieving the applicant’s science goals. Proposals for flights of nonbaseline ARM instruments (including those listed on the ARM TBS webpage) or guest instruments will also be considered but will need to be reviewed in consideration of payload constraints.