Congratulations to Wes (first author), Dr. Shepson, and former group members Kerri Pratt, Travis Knepp, and Chelsea Thompson, whose paper “Temporal and spatial characteristics of ozone depletion events from measurements in the Arctic” was published in Atmospheric Chemistry and Physics today!  Way to go! Click here to read it. Abstract below:

“Following polar sunrise in the Arctic springtime, tropospheric ozone episodically decreases rapidly to near-zero levels during ozone depletion events (ODEs). Many uncertainties remain in our understanding of ODE characteristics, including the temporal and spatial scales, as well as environmental drivers. Measurements of ozone, bromine monoxide (BrO), and meteorology were obtained during several deployments of autonomous, ice-tethered buoys (O-Buoys) from both coastal sites and over the Arctic Ocean; these data were used to characterize observed ODEs. Detected decreases in surface ozone levels during the onset of ODEs corresponded to a median estimated apparent ozone depletion timescale (based on both chemistry and the advection of O₃-depleted air) of 11 h. If assumed to be dominated by chemical mechanisms, these timescales would correspond to larger-than-observed BrO mole fractions based on known chemistry and assumed other radical levels. Using backward air mass trajectories and an assumption that transport mechanisms dominate observations, the spatial scales for ODEs (defined by time periods in which ozone levels ≤15 nmol mol⁻¹) were estimated to be 877 km (median), while areas estimated to represent major ozone depletions (<10 nmol mol⁻¹) had dimensions of 282 km (median). These observations point to a heterogeneous boundary layer with localized regions of active, ozone-destroying halogen chemistry, interspersed among larger regions of previously depleted air that retain reduced ozone levels through hindered atmospheric mixing. Based on the estimated size distribution, Monte Carlo simulations showed it was statistically possible that all ODEs observed could have originated upwind, followed by transport to the measurement site. Local wind speed averages were low during most ODEs (median of ~3.6 m s⁻¹), and there was no apparent dependence on local temperature.”

The observational science performed by the Shepson Group has been greatly facilitated, enhanced and enabled through help from the Jonathan Amy Facility for Chemical Instrumentation. The facility was built by Dr. Jonathan Amy, who was awarded an honorary doctorate from Purdue University in May 2014. The Amy Facility has been an integral partner in many Shepson Group projects, including the construction of BOB for chamber studies, building instrumentation for forest and Arctic measurements, the success of ALAR, and much more. The group owes much to the Amy Facility and its great staff and was happy to honor him at a reception for his degree last week. We thank you, Dr. Amy, for providing a legacy that enables us to perform our science.

The Shepson Group would like to welcome its newest Postdoctoral Research Associate, Alexie Heimburger! Welcome Alexie!

Congratulations to Dana (first author), Dr. Shepson, and Dr. Obie, whose paper “Toward a better understanding and quantification of methane emissions from shale gas development” was published in PNAS today!  Way to go! Click here to read it , and here to read the Purdue news press release.  Abstract below:

“The identification and quantification of methane emissions from natural gas production has become increasingly important owing to the increase in the natural gas component of the energy sector. An instrumented aircraft platform was used to identify large sources of methane and quantify emission rates in southwestern PA in June 2012. A large regional flux, 2.0–14 g CH₄ s⁻¹ km⁻², was quantified for a ∼2,800-km² area, which did not differ statistically from a bottom-up inventory, 2.3–4.6 g CH₄ s⁻¹ km⁻². Large emissions averaging 34 g CH₄/s per well were observed from seven well pads determined to be in the drilling phase, 2 to 3 orders of magnitude greater than US Environmental Protection Agency estimates for this operational phase. The emissions from these well pads, representing ∼1% of the total number of wells, account for 4–30% of the observed regional flux. More work is needed to determine all of the sources of methane emissions from natural gas production, to ascertain why these emissions occur and to evaluate their climate and atmospheric chemistry impacts.”

Gan has set up an ozone monitor at West Lafayette High School, and it automatically uploads these data to the Global Ozone Project.  Check it out here!

During the BROMEX campaign in 2012, filmmaker Derek Hallquist tagged along to learn about the science.  The film, Young Ice, was produced by Green River Pictures will premier soon.  Check out an extended seen featuring Dr. Shepson below:

You can view the trailer here.

During a field study this spring, Kyle was interviewed by a local TV station in Anchorage, AK.  You can check out the video and news article here.

We would like to extend a warm welcome to the two newest Shepson Group members, Tegan Lavoie and Olivia Salmon!

Kerri will be leaving the Shepson Group to start her new faculty position at the University of Michigan on July 1. We wish her all the best! Thanks for everything, and don’t be a stranger!

Congrats to Kerri, Prof. Shepson, and former group member Marc Fiddler, whose paper titled “Organosulfates in cloud water above the Ozarks’ isoprene source region” was published in Atmospheric Enivornment! You can find it here: https://doi.org/10.1016/j.atmosenv.2013.05.011. Abstract below!

“Secondary organic aerosol formation via aqueous processing, particularly from the oxidation of biogenic volatile organic compounds, is hypothesized to contribute significantly to the global aerosol burden. In this study, electrospray ionization coupled with mass spectrometry (ESI-MS) was utilized to detect organosulfates and oligomers in cloud water collected in July above the Missouri Ozarks, an environment significantly influenced by isoprene oxidation. Community Multiscale Air Quality (CMAQ) modeling suggested that the aerosol at cloud height was characterized by high water, sulfate, and biogenic secondary organic aerosol content, conducive to aqueous-phase processing and organosulfate formation. CMAQ modeling also suggested the presence of gas-phase organic peroxides and nitrates, which can partition into the particle-phase and form organosulfates. Several potential organosulfates from isoprene, monoterpene, and sesquiterpene oxidation were detected in the cloud water. In particular, the ubiquitous organosulfate C₅H₁₂O₇S (detected by ESI-MS at m/z −215), derived from isoprene epoxydiols, was detected. These results highlight the role of aqueous-phase reactions in biogenic SOA formation and cloud processes in isoprene oxidation-influenced regions.”