U.C. San Diego Team Tracks Atmospheric Aerosols in the Arctic

D uring International Polar Year (www.ipy.org), UCSD researchers with an international team of scientists will be studying climate change in the Arctic as part of the Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport (POLARCAT, www.polarcat.no). 

Specifically, the aerosol time-of-flight mass spectrometer (ATOFMS), a unique tool developed in the laboratory of Professor Kimberly Prather in UCSD’s Department of Chemistry and Biochemistry, will be used to study the Arctic haze over the polar regions of the Greenland, Norwegian, and Barents Seas. With Arctic snow cover, sea ice extent, and permafrost thickness declining considerably and surface air temperatures increasing at twice the rate of the rest of the world, the sensitivity of the Arctic to climate change is becoming an ever increasing area of worldwide concern.  

To help derive a better understanding of the sources of particulate matter (or aerosols) contributing to the springtime haze in the Arctic, the ATOFMS will be used to perform state-of-the-art measurements of the size, chemical composition, and optical properties of individual atmospheric particles. ATOFMS can measure virtually all species present including dust, metals, elemental carbon, sea salt, organic carbon and their associations with secondary species, such as nitrate and sulfate.  In particular, ATOFMS provides unique insights into the sources of these particles by measuring the chemical “fingerprint” of each particle.  By comparing these fingerprints with their library of different sources, researchers can tell whether the major pollution is from fires, vehicles, ships, or industry, for example, as well as the region from which they were transported.

This research is very important because the Arctic is where the most rapid climate change is taking place globally,” explains Kerri Denkenberger, a fourth year analytical environmental chemistry graduate student of Professor Prather. “The spring is the most polluted time of year in the Arctic when aerosol and gas pollutants from the mid-latitude regions of the U.S., Canada and Asia react at polar sunrise, forming a photochemical haze, somewhat like what you see in Los Angeles on a sunny day,” says Denkenberger.

"This research is very important because the Arctic is where the most rapid climate change is taking place globally. The spring is the most polluted time of year in the Arctic when aerosol and gas pollutants from the mid-latitude regions of the U.S., Canada and Asia react at polar sunrise, forming a photochemical haze, somewhat like what you see in Los Angeles on a sunny day.”

Denkenberger will conduct continuous (24 hours/day) ATOFMS measurements aboard a research ship on a 50-day research cruise, as part of the International Chemistry Experiment in the Arctic Lower Troposphere (ICEALOT), a shipboard field campaign with the National Oceanic & Atmospheric Administration (NOAA) that is part of POLARCAT. The ship will transit from Woods Hole Oceanographic Institution (WHOI) in Massachusetts to Tromso, Norway to Reykjavik, Iceland through the ice-free region of the Arctic during March and April of 2008.

ICEALOT 2008 NOAA Cruise Expedition.

The POLARCAT field campaign encompasses multiple countries, investigators, planes, ships, and ground stations in a joint effort over the course of six months to understand air pollution and climate change in the Arctic. “The person who is head of ICEALOT at NOAA really wants the ATOFMS on this research cruise, as it will provide real-time information to help us understand the sources and transport pathways of aerosols to the Arctic,” states Denkenberger.  "The ATOFMS results from ICEALOT will allow for better predictions of future climate change.  Our biggest concern, however, is keeping the ATOFMS working continuously and flawlessly on this long research cruise, so we need back-up equipment,” explains Denkenberger.

"The ATOFMS results from ICEALOT will allow for better predictions of future climate change.  Our biggest concern, however, is keeping the ATOFMS working continuously and flawlessly on this long research cruise, so we will need back-up equipment,” explains Denkenberger.

Kerri Denkenberger beside the NCAR C130 aircraft.

Awarded both the National Science Foundation Graduate Research Fellowship and the EPA STAR Graduate Fellowship in 2005, Denkenberger has dedicated her graduate work to the development and field testing of the aircraft (A)-ATOFMS, the newest version of the ATOFMS, which is smaller and faster. Adapting it to fly on the National Center for Atmospheric Research (C130) aircraft “has not been a trivial endeavor,” she admits.

Currently, she is flying the A-ATOFMS during the Ice in Clouds Experiment – Layer Clouds (ICE-L) national airborne field campaign in Colorado to study how particles form cloud droplets.  These are the first dual-polarity single particle mass spectrometry measurements that will be collected aboard an aircraft.  “I love the fact that my atmospheric research is directly related to understanding how aerosols impact air pollution and climate change.  Fieldwork and the data acquired is like a puzzle where you’re not sure of the picture.  To me this is challenging, exciting, and very rewarding. A good day consists of working on the instrument and doing data analysis,” states Denkenberger. Her career goal is to become a professor studying air pollution and climate change in the Arctic.

Kerri Denkenberger working on the A-ATOFMS instrument on the NCAR C130.

Funds are yet to be raised for backup equipment and travel costs for this work. Those interested in supporting the project may contact:

Melanie Cruz Walsh
University of California, San Diego
Division of Physical Sciences
Phone: (858) 822-3258.