AOSC Seminar
November 17, 2016

Two decades of ground-based microwave measurements of the middle atmosphere

Gerald Nedoluha
Middle Atmospheric Physics Section, Naval Research Lab

We have been making microwave measurements of changes in H2O, O3, and ClO in the middle atmosphere for 20+ years from several ground-based stations as part of the Network for the Detection of Atmospheric Composition Change. ClO is the molecule most directly involved in the depletion of the Earth’s ozone layer due to the input of CFCs. Measurements of O3 are important not just for understanding the recovery of the ozone layer, but also because they can provide data on hemispheric scale changes in transport. Changes in H2O in the stratosphere not only affect O3, but have been implicated in decadal scale global surface temperature variations. We will first discuss some of the basic techniques used in making these measurements and retrieving from them middle atmospheric profile information. Then, by comparing ground-based and satellite data, we’ll talk about how effective a few ground-based instruments are at tracking long-term hemispheric and even global changes in the middle atmosphere. Finally, we’ll talk about the variations in these three species in the middle atmosphere that have been observed both from the ground and from satellites over the past 20 years, and what these measurements tell us about physical changes in the middle atmosphere.