J. Christodoulakis

Observed association between air pollution and the biologically effective solar ultraviolet irradiance

The interplay between solar ultraviolet irradiance at the Earth’s surface and the air quality of the troposphere is explored. This attempt is focused mainly on the quantitative and qualitative dependence of the photochemical air pollution on the solar ultraviolet irradiance reaching different height levels and vice versa. To reach this target, observational data acquired in the greater Athens (Greece) area are employed. Special attention is paid to biologically effective solar ultraviolet radiation, focusing on the wavelengths that have an adverse impact on human eyes.

Comparison of the Athens Dobson spectrophotometer with World Standard Instruments

The results of the intercomparison between Dobson spectrophotometer No. 118 operating in Athens, Greece and the Reference Instruments Dobson No. 065 and No. 064 in the period 1990–2006 is presented. The Athens Dobson spectrophotometer participated in the Dobson intercomparison campaigns held at Arosa, Switzerland (1990), Kalavryta, Greece (1997) and Hohenpeißenberg, Germany (2006). The results obtained at Arosa showed a deviation of 0.03% in total ozone observations, whereas at Kalavryta and Hohenpeißenberg the highest deviations were –0.4% and 0.6%, respectively. Hence the Dobson spectrophotometer installed in Athens since 1989 can be regarded as a reliable ground-truth station that can be used for the validation of satellite ozone observations and the study of trends in total ozone content (TOC).

The deterioration of materials as a result of air pollution as derived from satellite and ground based observations

Abstract Dose Response Functions (DRFs) are widely used in estimating corrosion and/or soiling levels of materials used in building constructions and cultural monuments. These functions quantify the effects of air pollution and environmental parameters on different materials through ground based measurements of specific air pollutants and climatic parameters. Here, we propose a new approach where available satellite observations are used instead of ground-based data. Through this approach, the use of DRFs is expanded to cover situations where there are no in situ measurements, introducing also a totally new field where satellite data can be shown to be very helpful. In the present work satellite observations made by MODIS (MODerate resolution Imaging Spectroradiometer) on board Terra and Aqua, OMI (Ozone Monitoring Instrument) on board Aura and AIRS (Atmospheric Infrared Sounder) on board Aqua have been used.

Technical Report: Standardization of the Athens Dobson spectrophotometer versus Reference Dobson spectrophotometer 064

The comparison between Dobson spectrophotometer number 118 operating in Athens, Greece, and the Reference Instrument Dobson number 064 (Hohenpeissenberg, Germany) for column ozone observations, is discussed. The results obtained showed that the highest difference in total ozone observations derived from those instruments is almost 0.6% when the μ value ranges from 1.2 to 2.5, and hence no data reprocessing of historical data from Athens is necessary.

Comparison between the total ozone observations made by ground‐based and satellite‐borne instrumentation at Athens, Greece

The major, sudden stratospheric warming and the ozone hole split over Antarctica in September 2002 coincided with the beginning of Envisat activity. In the frame of this activity, the daily Dobson observations of the total ozone (TOZ) content over Athens, Greece, are compared with those performed by SCIAMACHY (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY), as Total Ozone Mapping Spectrometer (TOMS) and Global Ozone Monitoring Experiment (GOME) instruments during October 2002–June 2004. The results show that the Athens station may be used to provide ground data for satellite‐based TOZ measurements and also for providing reasonably accurate TOZ values.

Total Ozone Observations Made by Dobson Spectrophotometer at the Most SE Station in Europe the Last Twenty Years

Total ozone is closely connected with two crucial environmental problems: ozone depletion and global climate change. The Dobson spectrophotometer is the oldest measuring device (prototype) for total ozone observations in the atmosphere. The Dobson spectrophotometer No. 118 has been installed in Athens, Greece since 1989. We present a brief overview of the main activities of the instrument. According to the results of the intercomparison of the Athens Dobson spectrophotometer with World Standard Dobson Instruments, Dobson No. 118 is a reliable spectrophotometer and its measurements accurate and appropriate for further analysis. The comparison between Dobson measurements at Athens and all the available total ozone observations that have been performed using satellite-borne instrumentation revealed that it may be used as a ground-truth total ozone station for the validation of the satellite total ozone observations.