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Despite its low concentration, stratospheric water vapor has large impacts on the earth’s energy budget and climate. Recent studies suggest that even small changes in stratospheric humidity may have climate impacts that are significant compared to those of decadal increases in greenhouse gases. Future changes in stratospheric humidity and ozone concentration in response to changing climate are significant climate feedbacks.

While the tropospheric water vapor climate feedback is well represented in global models, predictions of future changes in stratospheric humidity are highly uncertain because of gaps in our understanding of physical processes occurring in the Tropical Tropopause Layer (TTL, ~13-18 km), the region of the atmosphere that controls the composition of the stratosphere. Uncertainties in the TTL chemical composition also limit our ability to predict future changes in stratospheric ozone.

Airborne Tropical TRopopause EXperiment (ATTREX) will perform a series of measurement campaigns using the long-range NASA Global Hawk (GH) unmanned aircraft system (UAS) to directly address these problems.

See one of our ATTREX videos which explain our mission and its objectives: