Comunicación presentada en: Symposium on Atmospheric Chemistry and Physics at Mountain Sites celebrado del 8 al 10 de junio de 2010 en Interlaken, Suiza

Alonso-Pérez, Silvia

Baldasano, José María

Cuevas Agulló, Emilio

González Ramos, Yenny

Guerra García, Juan Carlos

Rodríguez González, Sergio

English

Alonso Pérez, Silvia

Agencia Estatal de Meteorología

Long Term Ozone Observations at Izaña Atmospheric Observatory (1988-2009)  Y. González1,2,5*, S. Alonso-Pérez1,3,5, E. Cuevas1,5, S. Rodríguez1,4,5 , J.C. Guerra5, J.M. Baldasano2 1 Izaña Atmospheric Research Centre, AEMET, Associated Unit CSIC “Studies on Atmospheric Pollution”, C/ La Marina 20, planta 6, E38071, Santa Cruz de Tenerife, Canary Islands, Spain. *email: ygonzalez@inm.es 2 Barcelona Supercomputing Centre, Torre Girona, C/ Jordi Girona, 31, E08034, Barcelona, Spain. 3 Institute of Environmental Assessment and Water Research, IDAEA, CSIC. C/ Jordi Girona, 18, E08034, Barcelona, Spain 4 University of Huelva, Associate Unit CSIC “Air Pollution”, Campus El Carmen, E21071, Huelva, Spain 5 University of La Laguna, Hidrometeorology Research Group, San Cristóbal de La Laguna, S/C de Tenerife, Spain   Keywords: surface ozone, daily cycle, trends, meteorological processes.   The distribution of ozone in the troposphere is highly variable in time and space because of the numerous sources and sinks, as well as the several production/destruction reactions with other atmospherics constituents. It is also affected by downward transport from the upper troposphere-lower stratosphere (Rodríguez et al., 2004) and regional photochemistry (Crutzen, 1995; Lelieveld and Dentener, 2000). All these features make difficult to asses ozone trends in the free troposphere, in fact, different patterns of long-term changes are found in N.H. (Oltmans et al., 2008).  Daily cycle of surface ozone at Izaña Observatory (IZO; 2370 m a.s.l.) shows a minimum during daylight caused by upslope flow from lower levels by the coasts of the Tenerife Island. This local influence is eliminated using only night period data. Yearly mean ozone values at Izana during in the period 1988-2008 show three different tendency periods. A slight negative trend until 1995 was followed by a large positive trend until 1998. After that a significant decrease in growth rate is observed (figure 1). A slight positive trend in the annual mean data, as well as a statistically significant jump (at α <0.01) in 1996 is observed, being mean ozone value smaller in the first period than in the second one. Taking into account the three tendencies found during the 20 years of recording data, a less difference between mean night and mean day values is found during the last period 1999-2008, that is, more intensive daily cycles were observed during the two first trends (1988-1995 and 1996-1998). However, no significant changes have been observed on the annual seasonality for the different trends, with a maximum and a large variability in spring (Apr-Jun) and summer (Jul-Sep), and a less fluctuating minimum in autumn (Oct-Dec) and winter (Jan-Mar, figure 2).  Ozone levels at Izaña is also influenced by the large-scale subsidence, an important meteorological feature in this region, which is driven by the descending branch of the Hadley cell and the proximity of the Azores high, associated with fair weather. Above the inversion layer, in the free troposphere, the atmospheric circulation consists of subsiding air masses which are typically originated on the North Atlantic mid latitudes which are related to increasing ozone levels at Izaña (Rodríguez et al., 2004). During the night, the measurements at IZO are representative of pure middle free troposphere. Long range transport also varies levels concentrations. Transport from Europe (at IZO) is infrequent except by way of North Africa. Such events are characterized by hazy (dust-laden) air masses which also contain relatively high concentrations of pollutant aerosols (e.g., sulphate, nitrate) and low levels of ozone (Prospero et al., 1995). As a consequence, air masses with different physical and chemical properties impact Izaña, depending on its original geographical region. In other to assess the atmospheric transport in modulating tropospheric ozone in this region, an air mass back trajectory analysis for the period 1988-2008 is presented in this study. This long-term record provides unique insights into the several processes that affect ozone concentrations in the subtropical free troposphere. yearAnnualstandarddeviation(%)Annualozone mean (ppvb)-10-50510151987 1991 1995 1999 2003 200730405060Annualstandarddeviation(%)Annualstandarddeviation(%)Annualozone mean (ppvb)Annualozone mean (ppvb) Figure 1. Ozone annual means and corresponding annual standard deviation with regard to the ozone mean value in 1987.  O3(ppbv)O3(ppbv)Years Years2550751986 1990 1994 1998 2002 2006 2010Spring Mean Percentile_10thPercentile_90th2550751986 1990 1994 1998 2002 2006 2010Summer Mean Percentile 10thPercentile 90th2550751986 1990 1994 1998 2002 2006 2010Autumn Mean Percentile 10thPercentile 90th2550751986 1990 1994 1998 2002 2006 2010Winter Mean Percentile 10thPercentile 90thO3(ppbv)O3(ppbv) Figure 2. Long term ozone records for the period 1987-2009: spring (Apr-Jun), summer (Jul-Sep), autumn (Oct-Dec) and winter (Jan-Mar).  This work has been supported by AEMET (Ministry of Environment and of Rural and Marine Affairs of Spain).  Crutzen, P. J.: Ozone in the troposphere, in: Composition, Chemistry and Climate of Atmosphere, edited by: Singh, H. B., Van Nostrand Reinhold, New York, pp. 349–393, 1995. Oltmans, S., Lefohn, A., Scheel, H.-E., Brunke, E.-G., Claude, H., Galbally, I. and Meyer, C., Bodeker, G., Cuevas, E. and Redondas, A., Simmonds, P., Schmidlin, F., Koide, T., Johnson, B. and Harris, J., Shadwick, D., American Geophysical Union Fall Meeting, December 2008. Prospero, J.M., R. Schmitt, E. Cuevas, D. Savoie, W. Graustein, K. Turekian, A. Volz-Thomas, A. Díaz, S. Oltmans, H. Levy, Temporal Variability of Ozone and Aerosols in the Free Troposphere Over the Eastern North Atlantic; Geophys. Res. Letts., 22, 21, 2925-2928, 1995. Rodríguez, S., Torres, C., Guerra, J-C, Cuevas, E., Transport pathways of ozone to marine and free-troposphere sites in Tenerife, Canary Islands, Atmospheric environment, 38, 4733-4747, 2004. 

Long Term Ozone Observations at Izaña Atmospheric Observatory (1988-2009)

https://repositorio.aemet.es/bitstream/20.500.11765/7728/1/Abstract_Long_term_ozone.pdf

Long Term Ozone Observations at Izaña Atmospheric Observatory (1988-2009)

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