Physical properties of stratospheric clouds during the Antarctic winter of 1995

Gobbi, Gian Paolo; Donfrancesco, G. Di; Adriani, A.

doi:10.1029/98jd00280

Cited by 39 publications

(29 citation statements)

References 31 publications

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“…Hofmann and Deshler, 1991), but the physical state and temperature histories are uncertain here. Lidar measurements from Antarctica have also been interpreted as mixed phase clouds (Gobbi et al, 1998). A large mode in liquid particle size distributions have been noted in previous measurements from Kiruna Deshler et al, 2003), but the formation mechanism could be different in these cases under the influence of mountain leewaves.…”

Section: Discussionmentioning

confidence: 91%

Formation of solid particles in synoptic-scale Arctic PSCs in early winter 2002/2003

et al. 2004

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Abstract. Polar stratospheric clouds (PSC) have been observed in early winter (December 2002) during the SOLVE II/Vintersol campaign, both from balloons carrying comprehensive instrumentation for measurements of chemical composition, size distributions, and optical properties of the particles, as well as from individual backscatter soundings from Esrange and Sodankylä. The observations are unique in the sense that the PSC particles seem to have formed in the early winter under synoptic temperature conditions and not being influenced by mountain lee waves. A sequence of measurements during a 5-days period shows a gradual change between liquid and solid type PSCs with the development of a well-known sandwich structure. It appears that all PSC observations show the presence of a background population of solid particles, occasionally mixed in with more optically dominating liquid particles. The measurements have been compared with results from a detailed microphysical and optical simulation of the formation processes. Calculated extinctions are in good agreement with SAGE-III measurements from the same period. Apparently the solid particles are controlled by the synoptic temperature history while the presence of liquid particles is controlled by the local temperatures at the time of observation. The temperature histories indicate that the solid particles are nucleated above the ice frost point, and a surface freezing mechanism for this is included in the model. Reducing the calculated freezing ratesCorrespondence to: N. Larsen (nl@dmi.dk) by a factor 10-20, the model is able to simulate the observed particle size distributions and reproduce observed HNO 3 gas phase concentrations.

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Section: Discussionmentioning

confidence: 91%

Formation of solid particles in synoptic-scale Arctic PSCs in early winter 2002/2003

et al. 2004

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“…For the stable Antarctic conditions, the seasonal chronology of different PSC types is well documented from long-term lidar observations (Gobbi et al, 1998;Santacesaria et al, 2001;Adriani et al, 2004), but the relative occurrence frequency of solid and liquid clouds has not been determined so far.…”

Section: Introductionmentioning

confidence: 99%

“…As the droplets are assumed to be spherical, depolarisation lidar measurements allow to identify liquid clouds by their low depolarisation (Gobbi et al, 1998). They typically have a moderate backscatter ratio of R 532 nm ≈2-8.…”

Section: Introductionmentioning

confidence: 99%

Differences in Arctic and Antarctic PSC occurrence as observed by lidar in Ny-Ålesund (79° N, 12° E) and McMurdo (78° S, 167° E)

Maturilli

Neuber²,

Massoli³

et al. 2005

Atmos. Chem. Phys.

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Abstract. The extent of springtime Arctic ozone loss does not reach Antarctic "ozone hole" dimensions because of the generally higher temperatures in the northern hemisphere vortex and consequent less polar stratospheric cloud (PSC) particle surface for heterogeneous chlorine activation. Yet, with increasing greenhouse gases stratospheric temperatures are expected to further decrease. To infer if present Antarctic PSC occurrence can be applied to predict future Arctic PSC occurrence, lidar observations from McMurdo station (78 • S, 167 • E) and NyÅlesund (79 • N, 12 • E) have been analysed for the 9 winters between 1995 (1995/1996) and 2003 (2003/2004). Although the statistics may not completely cover the overall hemispheric PSC occurrence, the observations are considered to represent the main synoptic cloud features as both stations are mostly situated in the centre or at the inner edge of the vortex. Since the focus is set on the occurrence frequency of solid and liquid particles, the analysis has been restricted to volcanic aerosol free conditions. In McMurdo, by far the largest part of PSC observations is associated with NAT PSCs. The observed persistent background of NAT particles and their potential ability to cause denoxification and irreversible denitrification is presumably more important to Antarctic ozone chemistry than the scarcely observed ice PSCs. Meanwhile in Ny-Ålesund, ice PSCs have never been observed, while solid NAT and liquid STS clouds both occur in large fraction. Although they are also found solely, the majority of observations reveals solid and liquid particle layers in the same profile. For the Ny-Ålesund measurements, the frequent occurrence of liquid PSC particles yields major significance in terms of ozone chemistry, as their chlorine activation rates are more efficient.Correspondence to: M. Maturilli (mmaturilli@awi-potsdam.de) The relationship between temperature, PSC formation, and denitrification is nonlinear and the McMurdo and NyAlesund PSC observations imply that for predicted stratospheric cooling it is not possible to directly apply current Antarctic PSC occurrence to the Arctic stratosphere. Future Arctic PSC occurrence, and thus ozone loss, is likely to depend on the shape and barotropy of the vortex rather than on minimum temperature alone.

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“…Gobbi et al, 1998;Stein et al, 1999;Toon et al, 2000;Biele et al, 2001). In this case, the interpretation of the PSC data in terms of the two coexisting particle classes can be improved if backscatter coefficients (or backscatter ratios) are studied separately for both states of polarization, since droplet scattering adds to the parallel-polarized lidar signal alone (single scattering assumed) whereas the light backscattered from nonspherical solid particles has both parallel-and perpendicular-polarized components.…”

Section: Polarization-sensitive Backscatter Ratiosmentioning

confidence: 99%

Mountain wave PSC dynamics and microphysics from ground-based lidar measurements and meteorological modeling

Reichardt

Dörnbrack²,

Reichardt

et al. 2004

Atmos. Chem. Phys.

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Abstract. The day-long observation of a polar stratospheric cloud (PSC) by two co-located ground-based lidars at the Swedish research facility Esrange (67.9 • N, 21.1 • E) on 16 January 1997 is analyzed in terms of PSC dynamics and microphysics. Mesoscale modeling is utilized to simulate the meteorological setting of the lidar measurements. Microphysical properties of the PSC particles are retrieved by comparing the measured particle depolarization ratio and the PSC-averaged lidar ratio with theoretical optical data derived for different particle shapes. In the morning, nitric acid trihydrate (NAT) particles and then increasingly coexisting liquid ternary aerosol (LTA) were detected as outflow from a mountain wave-induced ice PSC upwind Esrange. The NAT PSC is in good agreement with simulations for irregularshaped particles with length-to-diameter ratios between 0.75 and 1.25, maximum dimensions from 0.7 to 0.9 µm, and a number density from 8 to 12 cm −3 and the coexisting LTA droplets had diameters from 0.7 to 0.9 µm, a refractive index of 1.39 and a number density from 7 to 11 cm −3 . The total amount of condensed HNO 3 was in the range of 8-12 ppbv. The data provide further observational evidence that NAT forms via deposition nucleation on ice particles as a number of recently published papers suggest. By early afternoon the mountain-wave ice PSC expanded above the lidar site. Its optical data indicate a decrease in minimum particle size from 3 to 1.9 µm with time. Later on, following the weakening of the mountain wave, wave-induced LTA was observed only. Our study demonstrates that ground-based lidar measurements of PSCs can be comprehensively interpreted if combined with mesoscale meteorological data.

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Physical properties of stratospheric clouds during the Antarctic winter of 1995

Cited by 39 publications

References 31 publications

Formation of solid particles in synoptic-scale Arctic PSCs in early winter 2002/2003

Formation of solid particles in synoptic-scale Arctic PSCs in early winter 2002/2003

Differences in Arctic and Antarctic PSC occurrence as observed by lidar in Ny-Ålesund (79° N, 12° E) and McMurdo (78° S, 167° E)

Mountain wave PSC dynamics and microphysics from ground-based lidar measurements and meteorological modeling

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