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Jan. 16, 2009
CIRES Successfully Tracks Earth's Most Abundant Greenhouse Gas In Real-Time
Fifty years after the first continuous CO2 measurements were launched, scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) are experimenting with tracking another, and equally important, greenhouse gas at Mauna Loa Observatory (MLO). In October 2008, CIRES scientist David Noone, with MLO's technical staff and scientists from the University of New Mexico and NASA's Jet Propulsion Laboratory, set up the first tests to measure the concentration of water vapor isotopologues (molecules differing only in their isotopic composition) in real-time. By analyzing the isotopic fingerprint of moisture passing over Mauna Loa, the researchers can gauge the types of water cycle processes that affect free tropospheric air and, over time, estimate the water cycle's response to climate. When combined with an analysis of weather trajectories, the isotope analysis helps them understand where subtropical moisture likely originated, an important clue for predicting how atmospheric humidity and, in turn, global temperature, may change with future climate states.
Background
Noone and his collaborators employed a trio of new laser-based, continuous analyzers to track isotopes of hydrogen and oxygen in real-time. Since heavy isotopes—atoms with extra neutrons—preferentially condense, the researchers can use the isotopic ratios of elements in water vapor to estimate which kinds of dehydrating processes have affected air arriving at MLO. They will compare data from the analyzers with traditional flask and cryogenic trap measurements, and with isotopologue retrievals from satellite.
Significance
By unraveling how moist and dry air masses traverse the globe, bringing precipitation and heat to some regions while drying and cooling others, the CIRES experiments at MLO will provide important clues about how changes in the water cycle will influence atmospheric circulation and global temperature. Specifically, the experiments will help scientists understand the processes that dehydrate the subtropics, influencing the amount of net radiation lost to space. This should help them quantify the water vapor feedback and more accurately model future climate states. This research supports NOAA Mission Goal 2—Understand Climate Variability and Change to Enhance Society's Ability to Plan and Respond.
Contact information
Name: Adriana Bailey
Tel: (303) 492-6289
adriana.bailey@colorado.edu
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For more information, see Tracking Earth's Most Abundant Greenhouse Gas.
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