Arctic Cloud Experiment Objectives

The overall objective of the FIRE Arctic Cloud Experiment is to produce an integrated data set that:

• supports the analysis and interpretation of physical processes that couple clouds, radiation, chemistry and the atmospheric boundary layer;
• provides in situ data for testing satellite, aircraft and surface-based remote sensing analyses; and
• provides initial data, boundary conditions, forcing functions, and test data to support Arctic FIRE cloud modeling efforts.

The scientific payoff from FIRE does not come merely from collecting a set of measurements, even if the set is comprehensive and some of it has been analyzed to retrieve key quantities. Rather the real payoff comes from using the retrieved results to answer questions about what is going on in the Arctic. The key overarching question for FIRE is:

How do the radiative feedback processes occurring between the clouds and the sea ice surface influence the Arctic energy balance?

The subsidiary questions are:

• What are the properties of Arctic clouds, including their synoptic and annual variations?
• How do Arctic clouds alter radiative exchanges between the surface, atmosphere and space?
• Why are these particular clouds produced in the Arctic?

To answer these questions from observations requires, first, the reduction of the measurements of the most important quantities that are associated with the controlling cloud and radiative processes, with particular emphasis on characterizing the variations of these quantities over the relevant space and time scales that are indicative of the processes at work. To cover these scales requires employing many remote sensing observations which need to be validated for the difficult Arctic conditions.