10 April, 2001
Donald Perovich, Geophysicist, Ice Thermodynamics
Don Perovich is a sea ice geophysicist specializing in the optical properties of ice and ice thermodynamics at the Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire. Dr. Perovich's research addresses these questions: How does the ice interact with sunlight and how does ice grow in the winter and melt in summer? The expansive research required to investigate these questions takes Don to the remote Arctic regions for extended field campaigns. With this mix of fieldwork, numerical modeling and resulting lab work, Don Perovich believes that he has a nice combination of computer studies and fieldwork.
Project Surface Heat Budget of the Arctic Ocean (SHEBA) focusing on snow and ice studies has been central to Dr. Perovich's expertise requiring extensive time commitments over the past few years. The SHEBA experiment sent a Canadian Coast Guard icebreaker, Des Groseilliers, with scientific teams to the Beaufort Sea to become frozen into the ice and drift with the floes for one year. This frozen-in icebreaker served as an operations base for camps and scientific studies being conducted on the surrounding ice sheets from October 1997-October 1998.
Don performed investigations at this remote field site for a total of five months and as he says, "Going with the floe." The challenges facing this once in a lifetime yearlong experiment were taxing yet exhilarating. Polar bears were only one of the threats to personal safety. Testy scientific instruments were problems to be surmounted. The low Arctic temperatures coupled with high winds and the ice drift provided further dilemmas. Three of Dr. Perovich's Arctic field campaigns have been to Ice Station SHEBA.
What are the goals of Project SHEBA? The first goal has two parts. The first part is to understand the ice albedo (the fraction of the sunlight that is reflected) and quantitatively describe it or paint a picture with numbers. Albedo is further discussed at http://www.arcticice.org/albedo/htm.
The second part of this goal is to understand the cloud radiation feedback. Clouds have opposite effects on surface heat. On a sunny Arctic day when clouds move in, they act like an umbrella and cool the surface. But the long wave radiation is trapped between the surface and the clouds causing the surface to warm. The questions targeted in the SHEBA field study were how to treat clouds in the Arctic summer. What will happen? Will the clouds enhance the amount of ice melting in the summer or mitigate it?
Goal two of Project SHEBA is to use the understandings found in goal one for improving large-scale models. What is global warming? Is the earth warming? Is this a trend or is it a fluctuation? If it is a trend, is it a result of a natural cycle or a consequence of human activity? How can these questions be answered? Ice plays a crucial role in the response to these questions. Ice cores provide a window to the past because they document past climate changes.
What about the future? The General Circulation Model (GCM) is a way to simulate the global climate system on a computer. The Arctic is a place where climate changes should be first observed. It is also a place where there are feedbacks that are not well understood. These changes could possibly impact global climate.
The first phase of Project SHEBA was to compile and reduce the data for archiving. The second and present phase is data analysis and using the derived information for improving large-scale sea ice and climate models.
Besides the SHEBA project, Dr. Perovich is also involved in a study centered in Barrow, Alaska. The surface heat budget in this region is of parcticular interest because it contains all the ingredients to be investigated -snow, ice, ocean and land.
Of parcticular interest to teachers and students is the educational outreach component based on the Barrow research experiment. It is linking classes predominately in grades three and four in schools in New Hampshire, Vermont, and Alaska. Dr. Perovich's research team supports the technology facilitating these communications including the maintenance of a bulletin board. The students chat with each other and with the scientists with the focus being cross-cultural as well as scientific. Each class is developing a school and regional profile for their web page.
The CRREL research team for this Barrow project has enlisted the help of the four schools. Students collect snow depth and air temperatures in their areas and complete an on-line data form for submission to the scientists. Don Perovich then plots and posts this data as a general point of comparison for the student's regions. The scientists compare the data to their site in Barrow, Alaska. This year they have observed more snowfall in Hanover, New Hampshire than in Barrow, Alaska.
An outstanding website designed for student navigation and classroom use is http://www.arcticice.org. This website is based on the Barrow experiment and has informative and engaging links to other sites.
Be sure to navigate the Project SHEBA website at http://sheba.apl.washington.edu. An arcticle written for science teachers and students overviewing Project SHEBA, "Year on Ice Gives Climate Insights," by D.K. Perovich et al can be found in the December 1999 edition of Earth in Space, a magazine published by the American Geophysical Union. Dr. Perovich recommends THE TWO MILE TIME MACHINE by Richard Alley and published in 2000. This book is written for general audiences and describes how ice cores provide a window to the past and document past climate changes.
For further information, photos and Don Perovich's contact information at CRREL go to http://www.crrel.usace.army.mil/sid/personnel/perovich.html.
By Sandra Kolb, March 2001
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