المؤلفون: Pazmiño, Andrea, Godin-Beekmann, Sophie, Hauchecorne, Alain, Claud, Chantal, Khaykin, Sergey, Goutail, Florence, Wolfram, Elian, Salvador, Jacobo, Quel, Eduardo

المصدر: Atmospheric Chemistry & Physics; 2018, Vol. 18 Issue 10, p7557-7572, 16p, 4 Charts, 13 Graphs

مصطلحات موضوعية: ATMOSPHERIC ozone, POLAR vortex, OZONE layer depletion, ANTARCTIC environmental conditions, REGRESSION analysis

مستخلص: The long-term evolution of total ozone column inside the Antarctic polar vortex is investigated over the 1980-2017 period. Trend analyses are performed using a multilinear regression (MLR) model based on various proxies for the evaluation of ozone interannual variability (heat flux, quasi-biennial oscillation, solar flux, Antarctic oscillation and aerosols). Annual total ozone column measurements corresponding to the mean monthly values inside the vortex in September and during the period of maximum ozone depletion from 15 September to 15 October are used. Total ozone columns from the Multi-Sensor Reanalysis version 2 (MSR-2) dataset and from a combined record based on TOMS and OMI satellite datasets with gaps filled by MSR-2 (1993-1995) are considered in the study. Ozone trends are computed by a piece-wise trend (PWT) proxy that includes two linear functions before and after the turnaround year in 2001 and a parabolic function to account for the saturation of the polar ozone destruction. In order to evaluate average total ozone within the vortex, two classification methods are used, based on the potential vorticity gradient as a function of equivalent latitude. The first standard one considers this gradient at a single isentropic level (475 or 550 K), while the second one uses a range of isentropic levels between 400 and 600 K. The regression model includes a new proxy (GRAD) linked to the gradient of potential vorticity as a function of equivalent latitude and representing the stability of the vortex during the studied month. The determination coefficient (R²) between observations and modelled values increases by *** 0.05 when this proxy is included in the MLR model. Highest R² (0.92-0.95) and minimum residuals are obtained for the second classification method for both datasets and months. Trends in September over the 2001-2017 period are statistically significant at 2σ level with values ranging between 1.84±1.03 and 2.83±1.48 DU yr^-1 depending on the methods and considered proxies. This result confirms the recent studies of Antarctic ozone healing during that month. Trends from 2001 are 2 to 3 times smaller than before the turnaround year, as expected from the response to the slowly ozonedepleting substances decrease in polar regions. For the first time, significant trends are found for the period of maximum ozone depletion. Estimated trends from 2001 for the 15 September-15 October period over 2001± 2017 vary from 1.21±0.83 to 1.96DU±0.99 yr^-1 and are significant at 2σ level. MLR analysis is also applied to the ozone mass deficit (OMD) metric for both periods, considering a threshold at 220DU and total ozone columns south of 60° S. Significant trend values are observed for all cases and periods. A decrease of OMD of 0.86±0.36 and 0.65±0.33 Mt yr^-1 since 2001 is observed in September and 15 September-15 October, respectively. Ozone recovery is also confirmed by a steady decrease of the relative area of total ozone values lower than 175DU within the vortex in the 15 September-15 October period since 2010 and a delay in the occurrence of ozone levels below 125DU since 2005. [ABSTRACT FROM AUTHOR]

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المؤلفون: Salvador, Jacobo¹ jsalvador@citedef.gob.ar, Wolfram, Elian², Orte, Facundo³, D'Elia, Raul², Bulnes, Daniela², Quel, Eduardo²

المصدر: AIP Conference Proceedings. May2013, Vol. 1531 Issue 1, p364-367. 4p.

مصطلحات موضوعية: *METEOROLOGICAL observations, *ULTRAVIOLET radiation, *ATMOSPHERIC ozone, *ATMOSPHERIC effects on remote sensing, *SOLAR radiation

مصطلحات جغرافية: SOUTHERN Hemisphere, ARGENTINA

الشركة/الكيان: KOKUSAI Kyoryoku Jigyodan

مستخلص: As a part of environmental studies in the southern hemisphere, the CEILAP Lidar Division with the financial support of JICA (Japan International Cooperation Agency) and the collaboration of IPSL France, mounted a ground based remote sensing site at Río Gallegos city (51° 36'S, 69° 19'W), at southern part of South America for the measurements of stratospheric ozone, with lidar remote sensing techniques and passive sensors to measure solar UV irradiance. The Patagonian region is characterized by high cloud cover during day changing strongly the distribution of UV radiation that reaches the ground surface. During the spring season some overpasses of ozone hole are masked by cloud cover avoiding the increase in UVB radiation. Solar UV radiation measured with multiband filter radiometer GUV-541 and Biometer manufactured by Biospherial Inc. San Diego and the Yankee Environmental Systems (YES) companies respectively. We present nine study days in the period 2007-2011 where total ozone column was below 250 DU focusing the impact that cloud cover had on the temporal evolution of these events. [ABSTRACT FROM AUTHOR]

المؤلفون: Wolfram, Elian A.¹, Salvador, Jacobo², Orte, Facundo³, Bulnes, Daniela¹, D'Elia, Raul¹, Antón, Manuel⁴, Alados-Arboledas, Lucas⁴, Quel, Eduardo¹

المصدر: AIP Conference Proceedings. May2013, Vol. 1531 Issue 1, p907-910. 4p.

مصطلحات موضوعية: *ATMOSPHERIC ozone, *CLOUDS, *ULTRAVIOLET radiation, *CLIMATE change, *REMOTE sensing, *RADIOMETERS, *METEOROLOGICAL observations

مصطلحات جغرافية: PATAGONIA (Argentina & Chile), ARGENTINA

مستخلص: Ozone and ultraviolet (UV) radiation are two important issues in the study of Earth's atmosphere. The anthropogenic perturbation of the ozone layer has induced change in the amount of UV radiation that reaches the Earth's surface, mainly through the Antarctic ozone hole. Also clouds have been identified as the main modulator of UV amount over short time scales. While clouds can decrease direct radiation, they can produce an increase in the diffuse component, and as a consequence the surface UV radiation may be higher than during an equivalent clear sky scenario. In particular this situation can be important when a low ozone column and partially cloud coverered skies occur simultaneously. These situations happen frequently in southern Patagonia, where the CEILAP Lidar Division has established the Atmospheric Observatory of Southern Patagonia, an atmospheric remote sensing site near the city of Río Gallegos (51°55'S, 69°14'W). In this paper, the impact of clouds on UV radiation is investigated by the use of ground based measurements from the passive remote sensing instruments operating at this site, mainly broad and moderate narrow band filter radiometers. Cloud modification factors (CMF, ratio between the measured UV radiation in a cloudy sky and the simulated radiation under cloud-free conditions) are evaluated for the study site. CMFs higher than 1 are found during spring and summer time, when lower total ozone columns, higher solar elevations and high cloud cover occur simultaneously, producing extreme erythemal irradiance at the ground surface. Enhancements as high as 25% were registered. The maximum duration of the enhancement was around 30 minutes. This produces dangerous sunbathing conditions for the Río Gallegos citizen. [ABSTRACT FROM AUTHOR]

المؤلفون: Wolfram, Elian A.¹, Salvador, Jacobo², D'Elia, Raul¹, Pazmiño, Andrea³, Godin-Beeckmann, Sophie³, Nakane, Hideki⁴, Quel, Eduardo¹

المصدر: AIP Conference Proceedings. 4/15/2008, Vol. 992 Issue 1, p589-593. 5p. 1 Diagram, 1 Chart, 2 Graphs.

مصطلحات موضوعية: *OZONE layer, *OPTICAL radar, *TELECOMMUNICATION satellites, *PHOTOMULTIPLIERS, *ATMOSPHERIC ozone, *OZONESONDES

مستخلص: As part of environmental studies concerning with measurements of the stratospheric ozone layer, the CEILAP developed a new Differential Absorption Lidar (DIAL) instrument. Since the early construction of the first DIAL instrument, Lidar Division has been made important financial and scientific investments to improve this initial prototype. The new version has a bigger reception system formed by 4 newtonian telescopes of 50 cm diameter each one and a higher number of detection channels: four different wavelengths are detected simultaneously and six digital channels record the Rayleigh and Raman backscattered photons emitted by an ClXe Excimer laser at 308 nm and third harmonic of Nd-YAG laser at 355 nm. A number of different changes have been made to increase the dynamical range of this lidar: a mechanical chopper was installed together with gated photomultiplier in the high energy detection channels to avoid strong signals from lower atmospheric layers. This new version was installed inside a shelter given the possibility to make field campaigns outside CEILAP laboratories as SOLAR Campaign made in Argentine Patagonian region during 2005–2006 springs. In this paper a full description of instrument update is given. Intercomparisons with ozonesonde and satellite platform instrument are presented. The results show agreement better than 10% in 16–38 km range when same airmasses are sampled. [ABSTRACT FROM AUTHOR]