A prominent maximum in surface ozone concentration during winter months at Pune (India)

ABSTRACT. Concentration of ozone near the ground has been recorded at Pune (India) since 1972 with the help of a continuous surface ozone recorder using electro-chemical sensor. The analysis of the records of winter season indicates a sharp rise in ozone amount in the forenoon around 1000 to 1200 LST. Prior to 1985 this forenoon: higher value in surface ozone concentration was followed by another maximum in the afternoon hours coinciding with the maximum temperature epoch of the day. After 1985 the surface ozone data indicates that the forenoon peak value has become invariably higher than the afternoon value. Due to increasing concentration of anthropogenic gases in the atmosphere there is a possibility of photochemical production of ozone in the troposphere which may give rise to higher surface ozone values, when the meteorological conditions are favourable for the accumulation of such gases which are involved in ozone production.

Removal of SOC Hard Mask for Patterning of Work Function Metal by Thermally Activated Ozone Gas

Thermally activated ozone gas (TAO) was demonstrated as an alternative technology to conventional spin-on carbon (SOC) stripping. The SOC stripping rate with ozone gas was found to be a function of substrate temperature and actual ozone amount calculated from the ozone flow rate and concentration. Furthermore, work function metal (WFM) stripping rate showed a high selectivity to SOC films, and the amount of oxidation TiN, which is a WFM metal, was also equivalent to conventional technology of SOC stripping. This TAO gas process can be used in clean tools, making it a promising integrated solution for SOC stripping followed by post clean.

UV measurements at Marambio and Ushuaia during 2000–2010

Solar ultraviolet (UV) irradiances were measured with NILU-UV multichannel radiometers at Ushuaia (54∘ S) and Marambio (64∘ S) between 2000 and 2013. The measurements were part of the Antarctic NILU-UV network, which was started in cooperation between Spain, Argentina and Finland. The erythemally weighted UV irradiance time series of both stations were analysed for the first time. The quality assurance procedures included a travelling reference instrument to transfer the irradiance scale to the stations. The time series were homogenized and high quality measurements were available for the period 2000–2010. During this period UV indices of 11 or more were measured on 5 and 35 days at Marambio and Ushuaia, respectively. At Marambio, the peak daily maximum UV index of 12 and daily doses of around 7 kJ m−2 were measured in November 2007. The highest UV daily doses at both stations were typically around 6 kJ m−2 and occurred when the stations were inside the polar vortex, resulting in very low total ozone amount. At both stations, daily doses in late November could even exceed those in the summer. At Marambio, in some years, also daily doses in October can be as high as those during the summer. At Ushuaia, the peak daily maximum UV index of 13 was measured twice: in November 2003 and 2009. Also during those days, the station of Ushuaia was inside the polar vortex.

UV measurements at Marambio and Ushuaia during 2000–2010

Solar ultraviolet (UV) irradiances were measured with NILU-UV multichannel radiometers at Ushuaia (54° S) and Marambio (64° S) between 2000 and 2013. The measurements were part of the Antarctic NILU-UV network, which was started in cooperation between Spain, Argentina and Finland. The erythemally weighted UV irradiance time series of both stations were analyzed for the first time in this study. The quality assurance procedures included a traveling refence instrument to transfer the irradiance scale to the stations. The time series were homogenized and high quality measurements were available for the period 2000–2010. During this period UV indices of 11 or more were measured on 5 and 35 days at Marambio and Ushuaia, correspondingly. At Marambio, the peak daily maximum UV index of 12 and dailydoses of around 7 kJ/m2 were measured in November 2007. Typically the highest UV daily doses were at both stations around 6 kJ/m2, and they occurred on time periods, when the station was inside the polar vortex with very low total ozone amount. At both stations, dailydoses of late November could even exceed those of summer. At Marambio, in some years, also dailydoses in October can be as high as those during the summer. At Ushuaia, the peak daily maximum UV index of 13 was measured twice: in November 2003 and 2009. Also during those days, the station of Ushuaia was inside the polar vortex.

Influence of transport and mixing in autumn on stratospheric ozone variability over the Arctic in early winter

Early winter ozone mixing ratios in the Arctic middle stratosphere show an interannual variability of about 10%. We show that ozone variability in early January is caused by dynamical processes during Arctic polar vortex formation in autumn (September to December). Observational data from satellites and ozone sondes are used in conjunction with simulations of the chemistry and transport model ATLAS to examine the relationship between the meridional and vertical origin of air enclosed in the polar vortex and its ozone amount. For this, we use a set of artificial model tracers to deduce the origin of the air masses in the vortex in January in latitude and altitude in September. High vortex mean ozone mixing ratios are correlated with a high fraction of air from low latitudes enclosed in the vortex and a high fraction of air that experienced small net subsidence (in a Lagrangian sense). As a measure for the strength of the Brewer-Dobson circulation and meridional mixing in autumn, we use the Eliassen-Palm flux through the mid-latitude tropopause averaged from September to November. In the lower stratosphere, this quantity correlates well with the origin of air enclosed in the vortex and reasonably well with the ozone amount in early winter.

Influence of transport and mixing in autumn on stratospheric ozone variability over the Arctic in early winter

Early winter ozone mixing ratios in the Arctic middle stratosphere show a fair amount of interannual variability. We show that ozone variability in early January is caused by dynamical processes during Arctic polar vortex formation in autumn (September to December). Observational data from satellites and ozone sondes are used in conjunction with simulations of the Chemistry and Transport Model ATLAS to examine the relationship between the meridional and vertical origin of air enclosed in the polar vortex and its ozone amount. For this, we use a set of artificial model tracers to deduce the origin of the air masses in the vortex in January in latitude and altitude in September. High vortex mean ozone mixing ratios are related to a high fraction of air from low latitudes enclosed in the vortex and a high fraction of air that experienced small net subsidence. As a measure for the strength of the Brewer-Dobson circulation and meridional mixing in autumn, we use the Eliassen-Palm flux through the mid-latitude tropopause averaged from August to November. In the lower stratosphere, this quantity correlates well with both the ozone amount in early winter and the origin of air enclosed in the vortex.

THE TOTAL OZONE AMOUNT CHANGES OVER LITHUANIA AND NEIGHBOURING COUNTRIES / BENDROJO OZONO KIEKIO POKYČIAI VIRŠ LIETUVOS IR KAIMYNINIŲ ŠALIŲ

Changes in the total ozone amount (TOA) above Lithuania and neighbouring countries during the period 1993–2008 have been analysed. The present study focuses on the TOA seasonal variations over the aforementioned area. The statistical data of measurements were analysed. The detailed information of TOA was presented by the Lithuanian Hydrometeorological Service and the World Ozone and Ultraviolet Radiation Data Centre (WOUDC). The net of stations measuring the TOA changes was set; it consisted of 16 meteorological stations. The coefficients of correlation of TOA changes between various stations were calculated basing upon the Pearson's Correlation Coefficient. It was established that the seasonal TOA variation tendencies were coincident between the stations and most linear correlation coefficients between Lithuania and neighbouring countries were 0.9 and 1.0. During the analysis of TOA data, it was established that the results of measurements performed in Lithuania from May 1999 to February 2000 and from May 2000 to January 2001 were insufficiently precise. To estimate TOA in Lithuania (at Kaunas Meteorological Station) without performing direct measurements, the linear function was calculated using the least squares method and the data obtained from the investigated net of meteorological stations. The difference between calculated and measured TOA results was up to 8%. Santrauka Remiantis 1993–2008 m. duomenimis, nagrinėjami bendrojo ozono kiekio (BOK) pokyčiai virš Lietuvos ir kaimyninių šalių. Įvertintos sezoninių šių BOK pokyčių sąsajos. Išsamiõs informacijos apie BOK pateikė Lietuvos hidrometeorologijos tarnyba bei Pasaulio ozono ir ultravioletinės spinduliuotės duomenų centras. Sudarytas bendrojo ozono kiekio matavimo stočių tinklas iš 16 meteorologinių stočių. Analizuojant BOK pokyčių tarp skirtingų stočių tiesinės sąsajos stiprumą taikyti Pirsono koreliacijos koeficientai. Nustatyta, kad BOK sezoninių pokyčių tendencijos tarp šių stočių sutampa, ir dauguma koreliacijos koeficientų (tarp Lietuvos ir kaimyninių šalių) yra 0,9–1,0. Analizuojant BOK duomenis, nustatyta, kad nuo 1999 m. gegužės iki 2000 m. vasario ir nuo 2000 m. gegužės iki 2001 m. sausio Lietuvoje atliktų matavimų rezultatai nėra pakankamai tikslūs. Mažiausiųjų kvadratų metodu apskaičiuota tiesinė funkcija BOK nustatyti Lietuvoje (Kauno meteorologijos stotyje) neatliekant tiesioginių matavimų. BOK skaičiavimo ir matavimo rezultatų skirtumas siekia iki 8%.