HIAPER, NSF's specially instrumented Gulfstream V airplane, flew on Monday from Anchorage toward the North Pole and back. Per the NCAR HIPPO Web site (http://hippo.ncar.edu/), a key goal of the flight was to sample high northern latitudes during daylight. The plane flew low, to avoid exposing HIAPER's instruments to moisture droplets from clouds. As it headed north, the plane flew toward a full moon, with the sun directly below the horizon behind.
As the HIPPO team makes its way south over the coming days and weeks, you can follow their progress via the HIPPO Facebook page. Sign up to be notified when the G-V launches on flights, and then follow the flight path via Google Earth (links available on the NCAR HIPPO Web site).
HIPPO stands for HIAPER Pole-to-Pole Observations ("HIAPER" stands for High-performance Instrumented Airborne Platform for Environmental Research; but we're going to follow the lead of project personnel and just call it the G-V). HIPPO will generate, from multiple sampling flights over a three-year period, a picture of the amounts of carbon dioxide and other greenhouse gases in the planet's atmosphere.