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Arctic Methane: Mr Blue Sky

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By Sam Illingworth.

“Hey there mister blue, we're so pleased to be with you. Look around see what you do, everybody smiles at you”

During the (all too rapidly) approaching August and September MAMM flight campaigns I’ll be working as a mission scientist, a fascinating role that involves flight planning, communicating between the pilots and the instrument scientists, and evaluating meteorological forecasts. Depending on the type of science that is being conducted, the weather can play a great part in deciding which particular flight patterns are able to be conducted on which particular days, and as such it is imperative that we are provided with not only up-to-the-minute weather maps, but also with accurate medium to long range forecasts of what the atmospheric conditions will be like throughout the duration of the campaign.

Speaking with my ‘mission scientist’ hat on it would be great if we got lots of dry and cloud-free days, as these are perfect flying conditions that would allow us to fly near to the surface, where most of the interesting methane related chemistry is taking place. Speaking with my ‘dramatic postdoctoral researcher’ hat on it would be disastrous if we didn’t get lots of dry and cloud-free days, as these are the only conditions in which the data from the instrument that I do most of my work with, the Airborne Research Interferometer Evaluation System (ARIES), is useable in my research.

ARIES makes measurements of the upwelling radiance (heat) detected at the FAAM aircraft, which is a combination of the radiance emitted by the Earth and that emitted by the atmosphere, as well as a small amount that comes directly from the sun and is reflected (without absorption) at the Earth’s surface. My research is concerned with converting that measured radiance signal into a number of quantities which tell us about the composition of the atmosphere directly below the aircraft, primarily information relating to the temperature, water vapour, and greenhouse gas concentrations.

In the presence of clouds (between the aircraft and the ground) two things can happen to this upwelling radiation: the cloud can either be sufficiently thick so as to block it entirely, creating a new ‘surface’ at the cloud top height; or the cloud is thin enough so as to let the radiation through, but alters its properties (via absorption and scattering processes) before it is detected by the ARIES instrument, meaning that it is difficult to differentiate between what could be possible changes in the atmospheric quantities that we are interested in, and what is simply cloud. Either way for the research that I am conducting: cloud equals bad.

The medium range weather forecasts for the start of the campaign don’t look too promising, but this area of the world is notoriously difficult for the modellers to get right, and so I am still hopeful of sunny days. Fingers crossed though that this isn’t just blue-sky thinking.

-- Dr Sam Illingworth, The University of Manchester. Find me on twitter @samillingworth, and striving for the Booker Prize at: http://fablesforadamagedworld.wordpress.com/

Previously in this series:

Arctic Methane: Hello and welcome to the MAMM blog

Arctic methane: What’s the story?

Methane and Mosquitoes – Blogging Bogs

The views expressed are those of the author and are not necessarily those of Scientific American.

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