By: Lauren McCarthy, Science Communications intern
Dr. Paty Matrai is a senior research scientist at Bigelow Laboratory who studies air quality and air-ocean interactions in the Arctic Ocean. One of Dr. Matrai’s many research topics involves how marine organic material is related to the formation of low-level clouds in the Arctic. Due to the pertinence of this research to the theme of “Changing Climate, Changing Ocean”, as well as my own academic interest in the atmospheric sciences, I decided to sit down with Dr. Matrai to learn more about this topic.
The Arctic (defined as all areas north of 65°N) is one of the most unique field sites in the world. Although the Arctic and Antarctic experience similar extreme weather conditions, the two Polar Regions have many differences. The Antarctic is a continent covered almost entirely with glaciers, whereas the Arctic is comprised mainly of frozen sea ice in addition to some land areas. This makes data collection from many Arctic regions difficult because measurements are easier to make from land. As a result, relatively little data exists from the higher latitudes of the Arctic. Additionally, the Arctic is particularly susceptible to increasing global temperatures due to its composition of ice and permafrost. Carbon dioxide is also more soluble at colder ocean temperatures, making ocean acidification rates more rapid in the Arctic. This will have drastic effects on calcareous organisms whose carbonate-based shells become more soluble in acidic waters.
Research in the Arctic often requires innovation on the technological front. In addition to designing a scientific study, Dr. Matrai and her team had to develop data collection devices that could withstand the extremely low temperatures in the Arctic. These came in the form of 16 buoys that have been deployed in the Arctic and return atmospheric data regularly, which include meteorological observations like temperature, pressure, wind speed, and precipitation, as well as ozone and carbon dioxide concentrations. The buoys are also equipped with a camera and can regulate their own internal conditions and communication devices.
A specific component of Dr. Matrai’s research involves the contribution of marine microgels to the initial stages of cloud formation. A microgel is an assembly of polymers (a large molecule comprised of several smaller, repeating units) that are derived from dissolved organic material in the ocean. Microgels are temporary in nature and their structure is influenced by the presence of metal ions in the water. The outer coating of the microgel commonly contains biogenic material, which can be broken down further into smaller particles by exposure to UV radiation. These smaller particles are good candidates for cloud condensation nuclei (CCN). In order for a cloud to form, water vapor needs to condense around a solid particle of very small (less than a micrometer) scale. These particles are referred to as CCNs. The research of Dr. Matrai has established that microgels definitely exist in the air and are good candidates for CCNs due to their size, charge, and hydrophilic nature. However, there is relatively little information available regarding the behavior of microgels once they enter the atmosphere.
In order for microscopic particles to become CCNs, they need to be transported into the atmosphere. A common method occurs through the aeration of the ocean through wave activity which releases bubbles coated with organic material. Another method of transport for potential CCNs is wind. Seasonal circulation patterns in the Arctic can provide clues as to where the particle originated. In the summer, Arctic circulation is more confined, meaning that winds do not transport particles from lower latitudes. Therefore, researchers can assume that CCNs are locally sourced and likely do not come from sources of pollution from the developed countries south of the Arctic. The concentration of soot particles, or black carbon, in the Arctic region increases in the winter seasons when regional circulation extends towards southern latitude. Winds associated with this change in circulation pick up black carbon particles from urban pollution, agricultural waste burning, and the logging industry activity in northern Europe, Asia, and North America. Most of these polluting particles are large and will fall out of suspension before they reach Arctic regions. Additionally, particles found at the surface or in the lower atmosphere are normally locally-sourced particles, whereas particles found in the higher atmosphere are normally from farther away.
Phytoplankton can also influence the production of aerosols in Arctic environments. The production of a sulfuric gas called dimethyl sulfide, or DMS, is produced by phytoplankton and can combine with sunlight to form particulates. Dr. Matrai also specializes in studying phytoplankton ecology and their role as producers and consumers of carbon dioxide.
In general, the effects of aerosols in the atmosphere are difficult to quantify. There are two hypotheses that express the potential relationship between climate and the formation of clouds: 1) Low-level clouds trap heat between the cloud layer and the Earth’s surface, or 2) Low-level clouds prevent sunlight from reaching the surface, resulting in a cooling effect. The magnitude of each of these effects will depend on other environmental factors, particularly changes in pH and UV radiation for microgels. Additionally, black carbon particles that accumulate on Arctic ice sheets have the ability to absorb heat from the sun and accelerate the melting process.
Dr. Matrai’s research of organic aerosols contributes to the scientific community’s understanding of climate patterns in the Arctic. Future studies will involve quantifying the effects of aerosols on cloud formation and local weather conditions, and how we can expect these factors to be influenced by climate change.
References
https://www.bigelow.org/about-bigelow-laboratory/research-topics/
Orellana, M. V., Matrai, P. A., Leck, C., Rauschenberg, C. D., Lee, A. M., and E. Coz, 2011: “Marine microgels as a source of cloud condensation nuclei in the high Arctic”, PNAS, 108.
Tjernström, M., C. Leck, C. E. Birch, J. W. Bottenheim, B. J. Brooks, I. M. Brooks, L. Bäcklin, R. Y.-W. Chang, E. Granath, M. Graus, A. Hansel, J. Heintzenberg, A. Held, A. Hind, S. de la Rosa, P. Johnston, J. Knulst, G. de Leuuw, L. di Liberto, M. Martin, P. A. Matrai, T. Mauritsen, M. Müller, S. J. Norris, M. V. Orellana, D. A. Orsini, J. Paatero, P. O. G. Persson, G. Qiuju, C. Rauschenberg, Z. Ristovski, J. Sedlar, M. D. Shupe, B. Sireau, A. Sirevaag, S. Sjogren, O. Stetzer, E. Swietlicki, M. Szczodrak, P. Vaattovaara, N. Wahlberg, M. Westberg, and C. R. Wheeler, 2014: “The Arctic Summer Cloud-Ocean Study (ASCOS): Overview and experimental design”. Atmospheric Chemistry and Physics, Arctic Summer Cloud Ocean Study (ASCOS), (ACP/OS/AMT Inter-Journal SI), Atmos. Chem. Phys., 14, 2823–2869.