NOAA and University of Washington scientists are using the heavily instrumented NOAA WP3 research aircraft

to monitor the oceanic and atmospheric processes that control the rate of Arctic sea ice freezeup in the Chukchi Sea,

a region of potential oil exploration.

This is part of a large scale experiment focused on the detailed physics of the marginal ice zone in the warming Arctic.

Sensors aboard the aircraft monitor hundreds of variables in the Marginal Ice Zone.

These measurements will be used to quantify the amount of heat moving out of the ocean and into the atmosphere during freezeup,

and the effects of the heat flux on the atmosphere.

Dropsonds are deployed from the aircraft from above the clouds, at twenty thousand feet, and measure temperature, humidity, pressure, and winds as they fall through the atmosphere.

Expendable ocean Instruments are deployed from lower altitudes

into leads of open water in the sea ice

to measure water temperature, salinity, and pressure.

Scientists on the first flight were surprised by the unexpectedly abrupt transition from 80 to 90 percent sea ice coverage to completely open water.

Four days later, more sea ice had formed and there was the more usual gradual transition through scattered floes or strips and streaks of new ice or pancake ice to open water.

Another surprise was the unexpectedly large changes seen in the wind speed and direction with height above a shallow layer of low-level winds from the Northeast.

It will be interesting to see if state of the art numerical weather prediction models are able to replicate this structure.

One motivation for making these intensive measurements in October is the warmer-than-usual surface temperatures that have been seen in the last 6-7 years during the Arctic freeze-up in autumn.

Monitoring atmospheric and ocean conditions will improve our understanding of the processes that control the rate of Arctic sea ice freezeup.