Intercomparison between Aura MLS and ground-based millimeter-wave observations of stratospheric O3 and HNO3 from Thule (76.5° N, 68.7° W)

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Fiorucci, I., Muscari, G., Froidevaux, L., Santee, M., Manney, G. L.
• Other Authors: Fiorucci, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Muscari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Froidevaux, L.; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA, Santee, M.; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA, Manney, G. L.; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA, Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
• Format: Other/Unknown Material
• Language: English
• Published: 2011
• Subjects: millimeter wave spectroscopy; stratospheric trace gases; satellite validation; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques; Arctic; Greenland; Thule Air Base; Thule Air; Thule
• Online Access: http://hdl.handle.net/2122/7410

The Ground-Based Millimeter-wave Spectrometer (GBMS) measures rotational emission spectra of middle atmospheric trace gases, with a spectral window of 600 MHz tunable between approximately 230 and 280 GHz and a resolution of up to 65 kHz. It was designed and built at the State University of New York at Stony Brook in the early 90’s and since then has been regularly upgraded and operated at a variety of sites in both hemispheres, at polar and mid-latitudes. In view of a growing need for long-term data sets of stratospheric constituents, in January 2009 we resolved to establish a long-term GBMS observation site at the Arctic station of Thule Air Base (76.5°N, 68.8°W), Greenland, in order to track the long- and short-term interactions between the changing climate and the seasonal processes tied to the ozone depletion phenomenon. Since then three winter campaigns were carried out from Thule during the period January-March 2009, 2010 and 2011. Observations of O3, HNO3, CO and N2O were performed, mostly on a daily basis, except during periods characterized by poor weather conditions. In this study we compare GBMS stratospheric O3 and HNO3 measurements obtained during these three winter periods at Thule with colocated satellite observations from the Aura Microwave Limb Sounder (MLS) experiment. The Version 3.3 Aura MLS O3 and HNO3 data sets have a resolution of about 2.5 km and 3-4 km, respectively, in the stratosphere. The MLS precisions range from 0.1 to 0.6 ppmv for O3 and about 0.6-0.7 ppbv for HNO3 throughout the stratosphere. Based on preliminary comparisons with correlative data sets and on results obtained for v2.2, systematic uncertainties are estimated to lead to HNO3 measurements biases that vary between ±0.5 and ±2 ppbv and multiplicative errors of ±5 –15% throughout most of the stratosphere. Similarly, a systematic uncertainty of the order of 5-10% has been assessed for O3 data. As for the GBMS, the O3 pure rotational transition line at 276.923 GHz is observed with a ~1.5-hour integration, while the weaker ...