Investigation of Atmospheric Chemistry in the Tropical UTLS with NASA’s Global Hawk UAS during ATTREX

Friday, 18 December 2015: 08:36
3004 (Moscone West)
Jochen Stutz1, Elliot L Atlas2, Ross Cheung1, Martyn Chipperfield3, Santo F Colosimo1, Tim Deutschmann4, Bruce C Daube5, Ru-Shan Gao6, James W Elkins6, David W Fahey7, Wuhu Feng3, Ryan Hossaini3, Maria A Navarro2, Jasna V Pittman5, Rasmus Raecke8, Lisa Scalone4, Max Spolaor9, Ugo Tricoli4, Troy D Thornberry6, Jui Yi Tsai1, Bodo Werner4, Steven C Wofsy5 and Klaus Pfeilsticker4, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)University of Miami, Miami, FL, United States, (3)University of Leeds, Leeds, United Kingdom, (4)University of Heidelberg, Institut fuer Umweltphysik, Heidelberg, Germany, (5)Harvard University, Cambridge, MA, United States, (6)NOAA/ESRL, Boulder, CO, United States, (7)NOAA ESRL, Boulder, CO, United States, (8)Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany, (9)UCLA, Los Angeles, CA, United States
Bromine species play an important role in ozone chemistry in the tropical upper troposphere / lower stratosphere (UTLS). The tropical UTLS also serves as a gate to the stratosphere, and the vertical transport of organic and inorganic bromine species is an important source of halogens that impact stratospheric ozone chemistry. An accurate quantification of the sources, sinks, and chemical transformation of bromine species is thus crucial to the understanding of the bromine and ozone budget in the UTLS and the stratosphere. However, the investigation of the composition of the tropical UTLS is challenging, as the altitude of this region of 15 - 20 km requires high-altitude aircraft, or balloons. In recent years a new aircraft has become available to penetrate into this region: NASA’s Global Hawk (GH) Unmanned Aircraft System (UAS). The GH has a ceiling altitude of 20 km and a 24h endurance with a full complement of scientific experiments. The GH provides a new and exciting platform that allows unique insights into atmospheric processes in the UTLS.

Here we present observations of CH4, BrO, NO2, and ozone made on-board the GH during the 2011, 2013, and 2014 Airborne Tropical TRopopause EXperiment (ATTREX) in the pacific tropical UTLS. We will discuss the details of UV-vis remote sensing measurements of BrO and NO2 by the UCLA/HD limb scanning Differential Optical Absorption Spectroscopy instrument. We also present observations of organic bromine species from the University of Miami’s Whole Air Sampler, in-situ ozone measurement by NOAA, and CH4 measurements by the Harvard Picarro instrument and the NOAA UCATS gas chromatograph. Methods to determine vertical trace gas profiles through aircraft maneuvers and by scanning the mini-DOAS telescope in viewing elevation will be discussed. The combination of the observations with calculations using the TOMCAT/SLIMCAT 3-D model allows quantification and interpretation of the bromine and ozone budget in the UTLS.