In Their Own Words

5Q4 : Five Questions For...
12.17.09
 
5Q4 : Marty Mlynczak
SABER Associate Principal Investigator
Senior Research Scientist at NASA's Langley Research Center

A silent solar "season" will find a voice at the Fall Meeting of the American Geophysical Union in San Francisco from Dec. 14 to 18, 2009. NASA Langley's Marty Mlynczak will present new measurements from a NASA satellite that shows how a "Quiet Sun Means Cooling of Earth's Upper Atmosphere." Researchers are taking the first steps in climate change predictions between the Sun and the "heat" sphere or thermosphere, the largest layer of the Earth's atmosphere over 56 miles (90 km) above the surface.



1. Why is the climate of the upper atmosphere important?
"The climate of the upper atmosphere is important because a fundamental prediction of climate change theory is that the upper atmosphere will cool as the greenhouse gas concentration increases in the atmosphere. And so we like to observe and understand the upper atmosphere to give ourselves an understanding of climate change throughout the entire atmosphere not just down here at the surface."

2. What is SABER on TIMED?
"SABER is an instrument, which the name stands for Sounding of the Atmosphere using Broadband Emission Radiometry, and it's one of four instruments on the NASA TIMED satellite. TIMED stands for Thermosphere Ionosphere Mesosphere Energetics and Dynamics. And the goal of SABER really is to quantify the energy balance in the upper atmosphere. It measures both the radiative heating of the atmosphere that is the energy deposited into the atmosphere from the sun and how that heats the atmosphere, and it also measures how the atmosphere is cooled by infrared emission. And from the measurements from SABER, we can get an idea of the fundamental elements of climate in the upper atmosphere."

3. What kind of measurements has SABER been collecting?
"SABER has been collecting a variety of measurements for the past eight years now -- measurements of temperature in the upper atmosphere, ozone, water vapor, carbon dioxide abundance. And also from these measurements we're able to make determinations of the amount of infrared radiation being emitted by the upper atmosphere that cools the atmosphere, so we have a clear picture of the energy balance of the upper atmosphere now from SABER."

4. How much cooling is happening in the upper atmosphere?
"Well, what we're seeing with SABER is not only how much cooling, but how it's changing over time. And one of the interesting things we've seen in the last eight years, we've gone from the maximum in the 11-year solar cycles to the minimum here and rather a deep minimum. One of the interesting effects we've seen is the way in which the radiative cooling of the upper atmosphere has decreased as the atmosphere has cooled off because the sun has gone into its minimum cycle. So just like your stove when it's hot, it glows. And as it gets cooler, it doesn't glow. The same sort of phenomenon in the upper atmosphere is that when it's hot, it emits more infrared radiation -- as it gets cool, it emits less. So we've seen in the particular case of one emitter, one molecule -- the nitric oxide molecule -- emitting in the upper atmosphere, its emission has gone down by nearly a factor of ten in the last eight years, which to us is a very dramatic response to the decrease in solar energy.

5. Will the SABER data allow us to predict climate changes in the upper atmosphere?
"The SABER data will help us to improve our models of the prediction of climate changes in the upper atmosphere. It gives us for the first time, a real constraint on the radiative cooling -- basically half of the energy balance that hasn't been measured before. We've measured the solar inputs before; we've never had the infrared outputs. So now that we have this, we'll be able to test our climate models against the SABER data and then use that data to improve our models, improve the parameters of the models so that they match the SABER data, and then have a much better prediction going forward of climate change in the upper atmosphere."