Middle atmospheric O₃, CO, N₂O, HNO₃, and temperature profiles during the warm Arctic winter 2001–2002

Abstract

Ground‐based measurements of stratospheric constituents were carried out from Thule Air Base, Greenland (76.5°N, 68.7°W), during the winters of 2001–2002 and 2002–2003, involving operation of a millimeter‐wave spectrometer (GBMS) and a lidar system. This work focuses on the GBMS retrievals of stratospheric O3, CO, N2O, and HNO3, and on lidar stratospheric temperature data obtained during the first of the two winter campaigns, from mid‐January to early March 2002. For the Arctic lower stratosphere, the winter 2001–2002 is one of the warmest winters on record. During a large fraction of the winter, the vortex was weakened by the influence of the Aleutian high, with low ozone concentrations and high temperatures observed by GBMS and lidar above ∼27 km during the second half of February and in early March. At 900 K (∼32 km altitude), the low ozone concentrations observed by GBMS in the Aleutian high are shown to be well correlated to low solar exposure. Throughout the winter, PSCs were rarely observed by POAM III, and the last detection was recorded on 17 January. During the lidar and GBMS observing period that followed, stratospheric temperatures remained above the threshold for PSCs formation throughout the vortex. Nonetheless, using correlations between GBMS O3 and N2O mixing ratios, in early February a large ozone deficiency owing to local ozone loss is noted inside the vortex. GBMS O3‐N2O correlations suggest that isentropic transport brought a O3 deficit also to regions near the vortex edge, where transport most likely mimicked local ozone loss.

Measurements of low amounts of precipitable water vapor by millimeter wave spectroscopy: An intercomparison with radiosonde, Raman lidar, and Fourier transform infrared data

“…Therefore, by means of the observed line shape together with pressure and temperature vertical profiles, a mathematical deconvolution process allows finding the emitting molecule's concentration as a function of altitude. The overall spectral band pass and resolution of the GBMS are key elements to determine the 17–75 km altitude range where trace gases concentration can be measured [e.g., see Muscari et al , 2007, and references therein]. For water vapor, we do not observe an H 2 O emission line (e.g., at 183 or 325 GHz) but rather the emission from the H 2 O continuum existing between emission lines.…”

The vegetative arctic freshwater green alga Zygnema is insensitive to experimental UV exposure

“…Whereas seasonal ozone depletion is regularly observed in the Antarctic since more than 30 years, significant depletion of the Arctic ozone layer sporadically occurred in some years (e.g. 1999-2000, 2001-2002, and 2004-2005) during late winter/spring period (January-April) (Dahlback, 2002;Hessen, 2002;Fahey, 2003;Jin et al, 2006;Muscari et al, 2007). Even under non-depleted ozone conditions, UV-B still presents potential negative impacts to photosynthetic organisms.…”

Ground-based stratospheric O<sub>3</sub> and HNO<sub>3</sub> measurements at Thule, Greenland: an intercomparison with Aura MLS observations

“…Starting in 1993, observations of stratospheric O 3 and HNO 3 have been carried out by means of a Ground-Based Millimeter-wave Spectrometer (GBMS) at different sites in both hemispheres, at polar and mid-latitudes (e.g., de Zafra et al, 1997;Muscari et al, 2007;Santee et al, 2007). GBMS data have contributed to shed light on processes related to the global ozone decline and to the dramatic ozone loss occurring over the Antarctic continent every spring.…”