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Compared to recent years, the development of the Antarctic ozone hole in 2002 showed very unusual dynamical features. The midwinter polar vortex was one of the smallest observed during the past decade. Driven by planetary waves, the vortex showed a strong asymmetry in early spring. A large air mass separated in late September, leaving what was previously a small vortex even smaller. Furthermore, stratospheric temperatures exceeded the polar stratospheric cloud (PSC) threshold earlier than in previous years, leading to a decrease in halogen activation by heterogeneous surface reactions. Ground-based observation of stratospheric trace gases in austral spring of 2001 and 2002 using passive Differential Optical Absorption Spectroscopy (DOAS) observations of zenith-scattered sunlight in the UV and visible wavelength region (320–650 nm) are presented. Using DOAS measurements of ozone, NO2, BrO, and OClO at two different Antarctic sites, Neumayer Station (70°S, 8°W) and Arrival Heights (78°S, 167°E), the chemical composition of the stratosphere is investigated under the unusual conditions of the 2002 ozone hole period and compared to the more typical observations of the previous year (2001). [ABSTRACT FROM AUTHOR]

An algorithm has been developed to retrieve altitude information at different diurnal stages for trace gas species by combining direct-sun and zenith-sky UV-visible differential slant column density (DSCD) measurements. DSCDs are derived here using differential optical absorption spectroscopy. Combining the complementary zenith-sky measurements (sensitive to the stratosphere) with direct-sun measurements (sensitive to the troposphere) allows this vertical distinction. Trace gas species such as BrO and NO2 have vertical profiles with strong diurnal dependence. Information about the diurnal variation is simultaneously retrieved with the altitude distribution of the trace gas. The retrieval is a formal optimal estimation profile retrieval, allowing a complete assessment of information content and errors. [Copyright &y& Elsevier]

The consistency of BrO column amounts derived from GOME spectra and from correlative ground-based and balloon measurements performed in 1998-1999 during the Third European Stratospheric Experiment on Ozone (THESEO) has been investigated. The study relies on UV-visible observations at several mid- and high latitude ground-based stations in both hemispheres, complemented by balloon-borne solar occultation profile measurements and 3D chemical transport model simulations. Previous investigations have reported GOME BrO columns systematically larger than those deduced from balloon, suggesting BrO being present, possibly ubiquitously, in the free troposphere. The robustness of this hypothesis has been further tested based on the presently available correlative data set. It is shown that when accounting for the BrO diurnal variation and the solar zenith angle dependency of the sensitivity of correlative data to the troposphere, measurements from all platforms are consistent with the presence of a tropospheric BrO background of 1–3 ×1013 molec/cm2 extending over mid- and high latitudes. [Copyright &y& Elsevier]

For several years NO2 and OClO, two species important to understanding ozone destruction in the Antarctic stratosphere, have been measured at Arrival Heights, Antarctica by two groups: New Zealand's National Institute of Water and Atmospheric Research (NIWA) and the NOAA Aeronomy Laboratory in Boulder, Colorado. Using data independently collected by these two groups during the Austral spring of 1996, it is shown that the two data sets are in extremely close agreement. Besides offering validation of the instrumentation and analysis techniques of both groups, this result provides confidence in the more complete history of these species gained by combining the two data sets. [ABSTRACT FROM AUTHOR]

Abstract. Large-area pulsed laser deposition (PLD) producing high-quality YBa[sub 2]Cu[sub 3]O[sub 7-x] (YBCO) thin films on both sides of R-plane sapphire substrates with CeO[sub 2] buffer layer is used routinely to optimize planar microwave stripline filters for satellite and mobile communication systems. A relatively simple PLD arrangement with fixed laser plume and rotating substrate, with an offset between the laser plume and the center of the substrate is employed to deposit laterally homogeneous 3-inch-diameter Ag-doped YBCO thin films. The YBCO:Ag films are about 250 nm thick and have laterally homogeneous critical current densities of mom than 3.5 MA/cm[sup 2] at 77 K and homogeneous maps of microwave surface resistance R[sub s] of about 40 m OMEGA at 145 GHz and 77 K. The R[sub s] at 8.5 GHz and 77 K, determined in the center position of the YBCO:Ag films, remains constant at about 370 micro OMEGA up to a microwave surface magnetic field of about 10 mT. After experience with more than 700 double-sided 3-inch-diameter films, a high degree of homogeneity and reproducibility of j[sub c] and R[sub s] is reached. The PLD-YBCO:Ag films are suitable for microwave applications envisaged for future communication systems. [ABSTRACT FROM AUTHOR]

Pulsed laser deposition (PLD) of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films on both sides of 3-inch diameter sapphire wafers and LaAlO/sub 3/ (LAO) cylinder substrates, respectively, is a basic and flexible technique in order to optimize microwave bandpass filters for wireless communication systems. The large-area and double-side PLD technique allows homogeneous and reproducible YBCO deposition on both substrate sides with inductively measured critical current densities j/sub c/ of 3/spl times/10/sup 6/ to 5/spl times/10/sup 6/ A/cm/sup 2/ at 77 K with a YBCO thickness of 350 nm to 600 nm. Selected results of compositional, structural, electrical, and microwave characterization of the PLD-YBCO films are reported. [ABSTRACT FROM PUBLISHER]

Examines the pulsed laser deposition of YBa[sub 2]Cu[sub 3]O[sub 7-x] thin films on sapphire wafers. Formation of microwave C-band strip-line filters; Measurement of the critical current densities; Application of planar high-temperature superconducting strip line filters.