Air Resources Lab collects data during planned natural gas release

April 16, 2026

A natural gas facility in Accident, MD, planned a scheduled gas release, known as a blowdown, on April 11, 2026. These blowdowns are necessary to depressurize the pipelines for routine maintenance.

Over one million cubic feet of natural gas, about the amount as five Good Year Blimps, was released into the air. Because the amount of gas being discharged was known, it created a chance to collect data from the ground, air and space.

a pressure gauge is in the front left, there are silver pipes from off the bottom of the image running to the middle of the image. Each pipe has a raised knob with a red handle. There is a bright sky with the sun in the background.
Gas pressure gauge on gas pipeline. Credit: Maksym Yemelyanov - stock.adobe.com

ARL deployed the newly upgraded Air Resources Car (ARC) downwind to measure methane, the main component of natural gas, and collect air samples for later testing in another lab. The Civil Air Patrol and the University of Maryland worked together to fly an airplane to take the same measurements from the air. Finally, NOAA’s National Environmental Satellite Data, and Information Service arranged for the satellite GHGSat, which measures greenhouse gases like methane, to observe the event from space.

Side view of a black panel van, with the side and back doors open.
The new Air Resources Car stopped to collect data during the blowdown. The sensors mounted to the roof collect measurements which feed into the instruments mounted inside the van. Credit: NOAA/ARL
Computer screen displays six plots in two rows of three. Starting at the top left, there is a dark blob stretching to the bottom right corner. The first four show the plume growing longer and wider. The fifth is about the same size as the fourth and you start to see yellow-green and blue colors in the center. In the last image, the blob is smaller, a little more circular and a large part of it is yellow, green and blue. It is also significantly further from the center point the others all are touching.
The team has a laptop in the van they used to look at the HYSPLIT model plumes showing both the direction the methane is traveling from the source point and the concentrations of it in the air. The top left image is at 8 AM with forecasts every hour to 1 PM. Credit: NOAA/ARL

The ARL HYSPLIT modeling team was crucial during the blowdown, running HYSPLIT forecasts to predict where the gas would travel. This ensured the ARC and the airplane were consistently positioned in the gas plume as it moved. The HYSPLIT model, developed and improved for nearly 30 years by ARL, is one of the most extensively used atmospheric transport and dispersion models in the atmospheric sciences community.

By comparing the data collected from the ground and air, researchers can check how accurate the satellite data and HYSPLIT model predictions were. This work confirms the scientific value of these tools and provides a chance to make them even better.