Frozen Cheese

Friday, August 17, 2007

At the moment the sun rises at about the time of the daily weather balloon launch (11am). Shame it won't last long; the sunrise gets earlier by twenty minutes every day at the moment!

Here we are putting up a giant tent that will be used to inflate and store a 'blimp' (helium airship). Part of spring science campaign here at Halley involves flying the Blimp with ozone and meteorological sensors attached through the lower atmosphere to find out all about mysterious spring time 'ozone depletion events' that could have important consequences for climate change, at least at a regional scale. Here's a quick guide:

What is an Ozone Depletion Event?

A short-term reduction in the amount of ozone gas in the air near the ground.

Why are Ozone Depletion events important?

Ozone gas absorbs the sun’s radiation so surface level ozone has an influence on how much heat is reflected back out to space and how much is trapped causing warming. We are fairly sure that ozone depletion events have an impact on regional climate but as the extent of the events is not yet known, the wider impacts are not fully understood (the blimp work should help with this).

The changing climate in the polar regions will likely have an effect on how often these events occur, which in turn will affect the climate . Climate change science is full of feedbacks like this one, which is one of the main reasons it's so complex and hard to predict.

How does the ozone depletion take place?

There is very strong evidence that the ozone depletion occurs when the air comes into contact with newly forming sea ice. Satellites measurements have been used to trace the trajectories of ozone depleted air and confirm that it has passed over new sea-ice zones. Chemical reactions take place between the ozone in the air and naturally occuring molecules on the surface of the new sea ice that destroy the ozone. Sea ice formation takes place throughout winter and spring, however ozone depletion events occur predominantly in spring, as sunlight is an essential ingredient of the ozone destroying reactions.

What does the Blimp do?

We attach an ozone sensor and a set of meteorological sensors (wind, temperature, pressure and humidity) underneath the blimp and slowly raise it up to around 400m. This provides a profile of the conditions and ozone concentrations throughout the near surface air, which can help determine how far up the ozone depleted air stretches and how the level of ozone varies with height and meteorological conditions. The more we find out about what is going on within the ODE, the more we will understand about its origins and likely impacts.

The afternoon we put up the blimp tent it was freezing (-42 or so, see mine and Alex's faces below to prove it) but gorgeous with glowing skies and patches of lingering mist.