BLC

Investigators from Pacific Northwest National Laboratory, in collaboration with scientists from a number of other institutions, carried out a month of intensive measurements at the ARM Climate Research Facility on the North Slope of Alaska in the summer of 2005. The purpose of these measurements was to determine how much the arctic land surface modifies the way low clouds reflect, absorb, and transmit solar and infrared radiation. This is an important problem because arctic clouds play a prominent role in modulating the earth’s radiation balance and, hence, in controlling climate. Preliminary research has shown, somewhat surprisingly, that summertime arctic clouds contain more water inland from the coast than over the tundra adjacent to the Arctic Ocean. We hypothesized that this is because solar heating of the tundra after the snow melts allows more water to evaporate from the multitude of lakes and ponds that are typical of arctic land masses.

In order to determine how the interaction with the surface controls the liquid water, droplet size, and physical dimensions of summertime arctic clouds, scientists launched rawinsondes every four hours at Barrow and Atqasuk, Alaska. Rawinsondes are balloon-borne instrument packages that measure the vertical changes in temperature and humidity from the surface to a height of about 10 km. Other instruments measured the heat and water vapor exchange between the surface and the atmosphere, and the exchange of solar and infrared radiation between the clouds and the surface. The data allows us to better understand the physical processes that couple clouds to the surface but also allows collaborating scientists to test how well their climate models represent the behavior of summertime arctic clouds.

Timeline

Campaign Data Sets