K. Ya. Kondratyev

Atmospheric greenhouse effect in the context of global climate change

SummaryGreat interest in the problem of the atmospheric greenhouse effect (not only in scientific publications, but also in mass media), on the one hand, and the undoubtfully overemphasised contribution of the greenhouse effect to the global climate change, on the other hand, motivate a necessity to analyse the role which the greenhouse effect plays as a factor of climate change. Significant progress in the analysis of existing observational data as well as succesful development of numerical climate modelling which have been achieved during the recent few years create a basis for a new survey of the atmospheric greenhouse effect in the context of global climate change. Such a survey is the principal purpose of this paper. After discussing a notion of the greenhouse effect, the detailed analysis of the present-day and paleoclimatic observational data has been conducted with subsequent consideration of numerical modelling results. A special attention has been paid to assessments of the greenhouse warmingvs. aerosol cooling. Then possibilities of the early detection of a greenhouse climate signal have been analysed and a few comments on the global climate observing system have been made with the general conclusion that more observations and further numerical modelling efforts are necessary to more reliably assess the contributions of various mechanisms to the observed global climate changes. It is only in the context of a coupled totality of significant climate forming factors and processes that the contribution of the greenhouse effect may be estimated.

On the seasonal variation of the surface ozone in Athens, Greece

Abstract An attempt has been made to examine the seasonal variation of the surface ozone mixing ratio in Athens, Greece during the periods 1901–1940 and 1987–1998. The first finding is that in July and August while the daytime surface ozone mixing ratio from the beginning until the end of the 20th century has increased by approximately 1.8 times, the nighttime surface ozone mixing ratio remained approximately at the same level. The second finding is that the increase in the mean daytime mixing ratio during the transition period from winter to summer is equal to the increase in the maximum daytime mixing ratios, whilst the enhancement of the nighttime surface ozone maxima is stronger than that of the nighttime mean surface ozone mixing ratio. Plausible explanation for this finding is given through mechanisms like long-range transport and photochemical processes occurring in the boundary layer, free troposphere and lower stratosphere.

On the altitude dependence of solar effective UV

Abstract Measurements of the solar biological effective UV radiation were carried out during the period from 7 to 14 June 1997 by using a radiometer flown on a Falcon aircraft, at several altitude levels, from sea level up to 13 Km. The results showed that an increase in the biological effective UV radiation of about 7% per kilometer occurs throughout the troposphere. This increase has been compared with the burden ozone content at each height level as it was derived from concurrent ozone measurements obtained from ozoneronde ascents. This comparison showed a strong anticorrelation between the biological effective UV radiation and the total ozone content above the UV measurement height level.

Volcanic eruptions and global ozone dynamics

It is well known that heterogeneous chemistry plays a very important role in global ozone dynamics. A survey of new observations and numerical modelling results has been made to analyse the potential impact of volcanic eruptions on the stratospheric ozone layer in the context of the heterogeneous chemical reactions on surfaces of volcanically produced stratospheric aerosol particles. An important aspect of the problem is that volcanically induced ozone changes may lead to a substantial impact on the radiative forcing for the surface-troposphere system and, subsequently, on climate.

Review article - Remote sensing and global tropospheric ozone observed dynamics

The development of remote sensing techniques to obtain measurements of ozone and its precursors from the Earths surface to the tropopause is considered, to present a review on the current achievements in measuring tropospheric ozone variability. Special attention is given to the surface ozone concentration observations, to the production and destruction mechanisms of ozone in both the atmospheric boundary layer and the free troposphere, and finally to ozone exchange through the tropopause.

Atmospheric ozone variability in the context of global change

A survey has been made of the role and place of atmospheric ozone dynamics in both the stratosphere and troposphere in the context of global change. Impacts on the ozone layer from solar activity (extraterrestrial solar ultraviolet irradiance variations), volcanic eruptions and high-flying aircraft have been discussed. Tropospheric ozone and surface ultraviolet irradiance changes have been considered, including relevant biological implications. Influences of the stratospheric ozone depletion on climate change have been discussed with emphasis on a coupled nature of ozone-climate interrelations. A necessity has been substantiated to develop a complex ozone studies programme in the context of the World Climate Research Programme and the International Geosphere-Biosphere Programme.

New evidence for ozone depletion over Athens, Greece

The seasonal total column ozone (TOZ) trends derived from satellite and ground-based instrumentation between June 1991-July 1999 at Athens, Greece, appear to be opposite to those of the period November 1978-May 1991. In the post-Pinatubo period large negative trends in TOZ during summertime combined with the large positive trends in TOZ during fall-winter period result in a decrease of the annual peak-to-trough differences from those of the pre-Pinatubo period.

An estimation of the surface solar ultraviolet irradiance during an extreme total ozone minimum

SummaryA simple theoretical algorithm has been employed to estimate the solar ultraviolet irradiance at Athens, Greece (38.7°N, 23.4°E) during, summertime 1993, a year of extreme total ozone minimum in the existing data record. This estimation has been performed by using total ozone measurements as derived by both ground-based and satellite instrumentation. The utilization of the present investigation will assist to the various assesments for the risk of human health from the biologically-effective doses of the solar ultraviolet radiation arrived at the earths surface during that time period.

On the relationship between total ozone and solar ultraviolet radiation at St. Petersburg, Russia

Daily total ozone observations made with the Total Ozone Mapping Spectrometer (TOMS) flown on the satellite Nimbus-7 during 1978–1992, have been used in order to investigate the increase in the daily broad-band and spectral solar ultraviolet radiation reaching the ground through a recently developed parametric model. Total ozone reductions of 3.0% during summer time and 11% during winter time per decade, at St. Petersburg (60°N, 30°E), Russia, cause an increase in erythematically active ultraviolet irradiance of at least 7% and 22%, respectively.

Total ozone amount trend at St Petersburg as deduced from Nimbus-7 TOMS observations

Abstract The observations of the Total Ozone Mapping Spectrometer (TOMS) flown on the Nimbus-7 satellite have been used in order to detect the monthly trend in total ozone concentration over St Petersburg (60°N, 30°E) during the period from November 1978 to January 1992. The trend analysis suggests that the total ozone depletion over the 13-year period shows strong variations from month to month reaching —13 per cent for December but with a slightly positive trend for September.