Postdoctoral Research Associate openings

The Jaffe Research Group has openings for 1–2 postdoctoral fellows who will focus on understanding gas and aerosol chemistry from global and regional sources.

  • One position will focus on collecting and interpreting observations from the Mt. Bachelor Observatory (MBO), an NSF-funded observatory that we have operated since 2004. MBO measures a suite of key gases and aerosol components (e.g.,O3, CO, CO2, σscat, σabs) year round. During spring and summer intensives, additional measurements (NOx, NOy, VOCs, aerosol chemistry, and physics) are added to focus on specific research questions.
  • The second position will study O3, NOx, and VOC chemistry in wildfire plumes as part of the NOAA FIREX campaign.

The primary responsibilities for these positions include:

  • Making high quality observations of atmospheric constituents.
  • Interpretation of the data with other observations, such as meteorology, regional air quality, satellite data, and air quality models.
  • Publishing the results in top scientific journals.

Qualifications include:

  • PhD in Chemistry, Atmospheric Sciences, Geosciences, or a closely related field.
  • Strong expertise in one or more of the following areas: instrumentation for gas and aerosol measurements (especially VOCs by GCMS), data interpretation, integration of satellite data, and modeling of transport and chemistry.
  • Good communication skills and experience publishing in scientific journals.

Appointments will be for one year with possible extensions. Compensation is competitive and post docs receive a full benefits package.

To apply and to see the full position description, see For more information, contact Dan Jaffe at

The positions are available immediately and will remain open until filled.

US particulate matter air quality improves except in wildfire-prone areas—See our new group paper!

A new paper authored by Crystal McClure and Dan Jaffe describes the increasing  particulate matter (PM2.5) pollution over the last few decades in the Northwest. This research, published Monday in Proceedings of the National Academy of Sciences, analyzed PM2.5 data from rural monitoring (IMPROVE) sites across the contiguous US for 1988–2016. They found a decreasing trend  in PM2.5, and cleaner air, around the country except for in the Northwest, where there is a positive trend in PM2.5. This positive trend is associated with total carbon, a marker for wildfires.

The figure below shows trends in PM2.5 for 1988–2016 for the 98th quantile, that is, the seven highest days. In most of the Northwest (red and orange areas), these days are getting worse, while most of the country has improving air quality trends (purple, blue, and green areas).

Figure 1 in PNAS paper US particulate matter air quality improves except in wildfire-prone areas

The 98th Quantile Regression of PM2.5 trends. Observed PM trends for 1988–2016 (calculated using QR methods) from IMPROVE sites are shown by black dots with corresponding values in µg·m−3·y−1. Krige-interpolated values (calculated from observed data) are shown by the color ramp. Solid black lines with arrows (indicating direction) show the boundary where the Krige-interpolated PM2.5 trends within have a 90% probability of being positive or negative. Of the 157 sites, 92 show statistical significance (8 positive/84 negative).

Read the abstract on the PNAS website

This new research has been garnering a lot of press since its publication:

Purple reigns for new PhDs

Let me introduce you to our newest graduates, Dr. Crystal McClure and Dr. Pao Baylon! A few raindrops didn’t diminish their sunny smiles and the cheering crowd as they marched at the University of Washington’s graduation on June 9, 2018. We celebrate your success and are so excited for both of you!

Pao is employed at the Idaho Department of Environmental Quality in Boise. Crystal will begin a post-doctoral fellowship at UC Davis in August.

Congrats to Dr. Crystal McClure, newest PhD graduate in the Jaffe Group

Best wishes to Crystal McClure for the successful defense of her PhD dissertation on May 7, 2018! Her dissertation—titled Impacts of Biomass Burning on Ozone, Particulate Matter, and Carbon Dioxide in the Northwest U.S.—capped 7 years of solid work in the Jaffe Group.

Dan Jaffe and Crystal McClure celebrate her PhD defense

Dan Jaffe and Crystal McClure celebrate her PhD defense

Crystal is the first author on 2 published papers, 1 recently accepted paper, and 1 paper currently in review. (See her papers on the Publications page.) Later this summer, she will begin a post-doctoral fellowship at UC Davis with Chris Cappa that focuses on the optical properties of black carbon from wildfires.

Crystal offered some sage advice for students, and all of us: “Setbacks are part of the journey. Learn to embrace them and you’ll find that you learn and benefit more from your failures than your successes.” We are so excited for you, Crystal, and will miss you!

2018 begins with 3 new group papers

The Jaffe Group has kicked off 2018 with 3 new publications.

  • Xi Gong, et al., Ozone in China: Spatial distribution and leading meteorological factors controlling O3 in 16 Chinese cities. Gong and her coauthors examined ozone (O3) concentrations in 16 Chinese cities and developed a statistical model to estimate the maximum daily 8-hour (MDA8) O3 during 2014–2016. They found that the Generalized Additive Model (GAM) captured 43-90% of daily O3 variations. They also identified the leading meteorological factors that affect O3 for each city. Read the full paper here.
Average 8-hour MDA8 (ug/m3) ozone concentrations for 16 Chinese cities, 2014-2016

Average maximum daily 8-hour (MDA8, ug/m3) ozone concentrations for 16 Chinese cities, 2014-2016.

  • Pao Baylon, et al., Impact of biomass burning plumes on photolysis rates and ozone formation at the Mount Bachelor Observatory. Baylon and his coauthors examined biomass burning (BB) events at Mt. Bachelor Observatory (MBO) during the summer of 2015. Biomass burning can emit large amounts of aerosols and gases into the atmosphere. These plumes contain compounds that react with sunlight to produce ozone, a health hazard to sensitive individuals. The photochemistry in BB plumes is poorly understand. Baylon and his coauthors addressed this knowledge gap by using MBO data to calculate ozone production rates and comparing these values with modeled values. Read the full paper here.
  • Lei Zhang, et al., A quantification method for peroxyacetyl nitrate (PAN) using gas chromatography (GC) with a non-radioactive pulsed discharge detector (PDD). Zhang and his coauthors developed a method for continuous peroxyacetyl nitrate (PAN) measurements using gas chromatography with a non-radioactive detector. PAN is a known precursor of ozone. Their method has high accuracy and is more readily deployable in field campaigns than the traditional gas chromatography method that utilizes a radioactive detector.  Read the full paper here.