Welcome to the Pratt Lab blog! Dr. Kerri Pratt is an assistant professor in the Departments of Chemistry and Earth & Environmental Sciences and faculty associate of the Program in the Environment at the University of Michigan. We study atmospheric trace gases, particles, snow, and clouds and their interactions with the biosphere (forests) and cryosphere (snow and sea ice). Our interdisciplinary research has relevance to climate change, air quality, and human health. As an analytical chemistry lab, we primarily use novel mass spectrometry techniques during our field research. We invite you to follow our adventures in (and outside!) the lab!

Tuesday, May 31, 2016

Arctic ozone paper published in Elementa!

Congratulations to post-doc Peter Peterson!  His first-author paper titled "The Role of Open Lead Interactions in Atmospheric Ozone Variability between Arctic Coastal and Inland Sites" was published in the Biogeochemical Exchange Processes at Sea-Ice Interfaces (BEPSII) special issue of Elementa: Science of the Anthropocene.  Thank you to our co-authors from the University of Alaska, Fairbanks, Jet Propulsion Laboratory, University of Heidelberg, and Purdue University for their contributions!

Melting Barrow!

The spring is a special time of year for any place. Usually, the leaves start to come out, the flowers begin to bloom, the bees are buzzing about.

Well since Barrow has none of those things, spring is a bit different experience:
THE SUN. ALL. THE. TIME.
May 20th, 11:30 pm, out at the shed
One of the fruits of the Barrow spring transition is the eternal sunlight. The sun stopped officially setting on May 10th, but it's been twilight in the really late hours for weeks prior. That night we decided to catch the last sunset and sunrise.
Sunset, 2:01 am...
Sunrise, 2:41 am.
Unfortunately, it's usually cloudy, but occasionally you get some more direct sunlight and things look really pretty! Here are some better pictures:
Watching the sunset around 12:30 am, a few days prior.
Midnight sun, was a little chilly!
A rare, sunny morning out on the tundra

All of this sunlight starts to warm things up. And when things warm up, some things, like all of the snow and ice, melt! Probably the most surprising parts of Barrow was how FAST the snow melted. It doesn't take long at all.
May 6
May 7
May 8
May 9

May 11
May 12
May 13


















































Above is my attempt at a time lapse from May 6th to May 13th. Temps started rising on May 9th, and we had record warm temperatures on May 11th (41 F was an all-time record for the first half of May). As you can see, it didn't take long for everything to melt!


Unfortunately, with all the melt water, the roads become filled with potholes! They are absolutely everywhere. A little reminder of our roads at home...
Our poor truck took some serious abuse


Tuesday, May 24, 2016

Spring fieldwork in Barrow

At the end of April, I (Stephen) traveled up to Barrow on the northern Arctic coast of Alaska to finish out a season-long, NSF-funded atmospheric study in collaboration with Penn State and Purdue Universities. For the next month, I would be manning the chemical ionization mass spectrometer, or CIMS, that was measuring the extremely interesting chemical interactions between the boundary level air and snowpack, right during the melt season! Being focused on mid-latitude, urban atmospheric chemistry, this was definitely a change of pace!

At the iconic "Welcome to Barrow" sign on the beach!

Just as the weather was finally starting to warm up in Ann Arbor, naturally it was time to head thousands of miles north, back to the snow and ice. In a snow chemistry lab, it's not a successful summer unless it's snowing out.

At the end of April, the weather was actually quite nice for Barrow standards- temps right around freezing, occasional flurries, low winds, the works. Basically paradise. But also very above average for that time of year. In fact, on May 11th, Barrow broke a high temperature record for the single warmest day ever in the first half of May (41F). More on that later!


When I arrived, there was still a significant snowpack on the tundra that had been quite hardened and wind-blown over the course of the winter, so it was pretty easy to walk on. On this tundra was our shed packed full of instrumentation and supplies, as well as a couple of people to keep track of it all. With the weather getting warm, it actually got quite hot in the shed with everything running, even with all of holes drilled in the walls over the years of past field studies.
The world famous sled shed, 154 Cake Eater Road, where all the magic happens.
The sled shed out in the distance (it was actually quite brighter out than the picture suggests)
Sunglasses were absolutely necessary
So, what are we doing again? I mentioned the snowpack before, and that's an important part to our work in the Arctic. The snow in the area gets "contaminated" by sea spray from the Arctic Ocean nearby, depositing halide salts all over the snowpack. With a little sunlight and the right pH of the snowpack, we can have trace amounts of highly reactive halogen gases emitted, which are then measured by the CIMS. The process of converting the halides (eg Br-) into something more reactive like bromine (Br2) is called halogen activation. These reactive halogen gases can then quickly deplete ozone. What nobody really knows is how much halogens are actually emitted from the snowpack! This is very important for models that want to predict how this chemistry will change as the Arctic warms up. Open ocean is becoming more common, which could potentially bring more sea spray to the snowpack.
Using Angela Raso's specialized twirl-in-place technique to wind up a sampling line for the CIMS! I promise we weren't screwing around on the tundra all day...
Open ocean on the horizon, May 2, 2016.

Monday, May 2, 2016

May is Commuter Month!

Put on your walking shoes, dust off your bus pass, or get working on that jet pack because May is the Commuter Challenge in Ann Arbor! The Pratt Lab is participating in this event which is aimed at promoting alternative modes of transportation (pretty much anything other than driving yourself in a car). All of the Pratt Lab members either rode their bike, walked, carpooled or took the bus to work today. We were all a little tired and needed to sit down for this picture. Here's to a good start to the Commuter Challenge!