The Hot Zone

WE ONLY KNOW WHAT WE CAN MEASURE

Posted by Alison Hawkes on November 11, 2009
Category : Climate Science and Scientists

by Erica Rex

Last week, I wrote about how ethics comes into play in our thinking – or not thinking – about climate change.

Even more importantly, though, we have to have facts – proven facts – to back up any claims we make about climate.  Dr. Marty Mlynczak, a senior research scientist based at NASA’s Langley, Virginia research centre is all about finding out the facts.  Technology he developed gives us even greater access to data about the atmosphere.

When we think of climate change we tend to think only of near-earth phenomenon: changes in average temperature, diminishing polar ice, changes in weather patterns, variations in El Niño effects, and measurements of atmospheric C02.  Most of these data are collected either at the Earth’s surface or else they are viewed from afar, by satellites.

After I spoke with Dr. Marty Mlynczak, I realized that often there were limitations to what technology on hand could measure.  And some of what isn’t – or wasn’t – being measured is very important indeed for our understanding of climate change.

Radiative emissions of water vapour at the far infrared part of the electromagnetic spectrum, for instance – that is, wavelengths between 15 and 100 micrometers – could not be measured directly until very recently.  The lack of accurate measurement of radiation at this wave length, it turns out, really matters:  based on the results yielded by climate models, scientists studying the atmosphere hypothesized that half of all of the cooling emissions into the outer parts of the atmosphere were in the far infra-red part of the spectrum.

The far infrared relative to other parts of the electromagnetic spectrum

The far infrared relative to other parts of the electromagnetic spectrum

Dr. Mlynczak is very interested in the far-infrared part of the electromagnetic spectrum.  “All infrared energy relevant to the Earth’s climate occurs at the shorter wavelenths,” he wrote in a 2006 paper.*  He believes being able to measure radiative emissions in the upper troposphere at far-infrared wavelengths is crucial to our understanding of how the Earth’s atmosphere cools.  The trouble was, said Dr. Mlynczak, “There wasn’t an instrument available that could measure this part of the spectrum.”

So he and his colleagues built one.

Dr. Mlynczak’s team launched a prototype of the the Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument during a high-altitude balloon flight from Fort Sumner, New Mexico in June of 2005.  It was a success.

“FIRST opens a new window on the spectrum that can be used for studying atmospheric radiation and climate, cirrus clouds, and water vapor in the upper troposphere,” wrote Dr. Mlynczak.*

In October of this year, Dr. Mlynczak and his colleagues traveled to a location high up in the Andes mountains of Chile, the Atacama desert, an altitude of 17,600.  Because it’s one of the driest regions on Earth, the Atacama desert offers an ideal environment for measuring water vapor.

At this altitude, said Dr. Mlynczak, there’s nothing getting in the way of accurate measurement.  “We’re above everything.  We’re above the pollution.  It’s the ideal location for atmospheric observation.”

Next time: precise measurement tells us a great deal about how glacial melting is affecting both agriculture and sea level rise.

*Source: Martin Mlynczak et al, “First light from the Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument,” GEOPHYSICAL RESEARCH LETTERS, VOL. 33, 4 April, 2006.

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