Maria Efstathiou

A substantial weakness of several climate studies on long-range dependence is the conclusion of long-term memory of the climate conditions, without considering it necessary to establish the power-law scaling and to reject a simple exponential decay of the autocorrelation function. We herewith show one paradigmatic case, where a strong long-range de...

In the present analysis, we study the North Atlantic hurricanes and the tropical cyclones over the Atlantic, attempting to statistically contribute to the study of the recently observed rapid shifts of sea surface temperature anomalies (SSTa) and hurricane activity. Indeed, the annual values of hurricane count (HC), during 1900-2012, seem to show t...

In the present study, the investigation of the levels of the local and regional oxidants concentration at Athens, Greece, is attempted by analyzing the observations obtained at an urban and a rural station, during 2001-2011 and 2007-2011, respectively. A progressive increase of the daytime and nighttime average of [NO2]/[Ox] versus [NOx] is observe...

[1] We hereby attempt to detect plausible reasons for the discrepancies between the measured and modeled tropospheric temperature anomalies in the tropics. For this purpose, we calculate the trends of the upper-minus-lower tropospheric temperature anomaly differences (TAD) for both the measured and modeled time series during 1979–2010. The modeled...

We have recently suggested that the warming in the sea surface temperature (SST) since 1900, did not occur smoothly and slowly, but with two rapid shifts in 1925/1926 and 1987/1988, which are more obvious over the tropics and the northern midlatitudes. Apart from these shifts, most of the remaining SST variability can be explained by the El Niño So...

The investigation of the intrinsic properties of the annual tropical cyclone count over Atlantic, during 1870–2006, is herewith attempted. The motivation behind this exploration is to contribute to the current understanding about the dynamics of these disastrous events, as tropical cyclones create destructive impacts for people living around tropic...

The main aim of the present study is to investigate further the association between total ozone (TOZ) and the 11 year solar cycle (SC) during the period 1979–2010, by employing satellite observations of TOZ made by Nimbus‐7, Meteor‐3, Earth Probe Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) instrumentation. A statis...

Changes in solar ultraviolet radiation (SUVR) have many different effects on global biogeochemistry. Nowadays, there is an increasing interest in the interactions and feedbacks between climate change and surface UV radiation. The amount of the UV radiation reaching the ground depends on a number of atmospheric and surface parameters such as the atm...

The estimation of the future projected precipitation and rainfall on short- and long-term basis is crucial because their substantial changes are closely associated with severe socioeconomic and ecological consequences. For this reason, the detrended fluctuation analysis is applied on the Sahel precipitation and standardized rainfall anomalies in or...

The annual and the monthly mean values of the land-surface air temperature anomalies from 1880-2011, over both hemispheres, are used to investigate the existence of long-range correlations in their temporal evolution. The analytical tool employed is the detrended fluctuation analysis, which eliminates the noise of the non-stationarities that charac...

Recent studies have suggested that variation of the total ozone content may be a precursor tool for earthquake forecasts. The main aim of this analysis is to examine whether the total ozone variability before and after the eight large earthquakes (Mw ≥ 6.0) of the decade 2001–2010 in Greece could be related with these earthquake events. The results...

The main aim of this study is to investigate whether the main components of the photochemical smog episodes over megacities obey the Gaussian distribution or do they follow the distribution of the Gutenberg-Richter law. To this end, a case study has been implemented for Athens, Greece, which is among the most densely populated capitals in the middl...

The investigation of the intrinsic properties of the solar spectral irradiance as a function of the ultraviolet (UV) wavelength is attempted by exploiting rare observations performed at the Villard St. Pancrace station of the Lille University of Sciences and Technology ranging from 278 to 400 nm with a step of 0.05 nm every half an hour from nearly...

The aim of this study is to investigate the potential effects of increased urbanization in the Athens city, Greece on the intrinsic features of the temporal fluctuations of the surface ozone concentration (SOC). The detrended fluctuation analysis was applied to the mean monthly values of SOC derived from ground-based observations collected at the c...

Global mean land and sea surface temperature (LSST) anomalies were analysed statistically with detrended fluctuation analysis (DFA), for the period from January 1850 to August 2008, for both hemispheres, individually. Persistent long-range power-law correlations were revealed within the time series of the LSST anomalies, for all time lags between 4...

Detrended fluctuation analysis is applied to the mean monthly temperature values, over different heights of the global troposphere, during 1980–2004, to search for self-similarity properties. The results show that the tropospheric temperature anomalies obey persistent long-range power-law correlations for time-scales longer than about four months a...

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) an...

The recently constructed retrospective time-series of total ozone content at Arosa (46.47°N, 9.40°E) and Poluy River (66.1°N, 68.3°E) are used to detect the existence of long-range correlations. The multifractal detrended fluctuation analysis applied to the mean yearly values of the reconstructed total ozone content over both locations showed that...

Measurements of the solar ultraviolet radiation in the wavelength region 295-385 nm were carried out at the Athens basin in summer 2007 and 2008 to study the influence of the air pollution, aerosols and forest fires on the UV doses reaching the ground. For comparison reasons, a recently developed theoretical algorithm for the calculation of the UV...

Detrended fluctuation analysis is applied to the time series of the global tropopause height derived from the 1980–2004 daily radiosonde data, in order to detect long-range correlations in its time evolution. Global tropopause height fluctuations in small time-intervals are found to be positively correlated to those in larger time intervals in a...

Detrended fluctuation analysis is applied to the time series of the global tropopause height derived from the 1980–2004 daily radiosonde data, in order to detect long-range correlations in its time evolution. Global tropopause height fluctuations in small time-intervals are found to be positively correlated to those in larger time intervals in a po...

Detrended fluctuation analysis (DFA) was applied to the total ozone planetary waves 1 and 2 at the middle and high latitudes of the southern hemisphere that had been acquired by daily Total Ozone Mapping Spectrometer (TOMS) total ozone observations since 1979. The main aim of the analysis was to examine the ozone layer as a system invariant in a wi...

The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, USA during 1958–2004 (the longest continuous record available in the world) are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result...

The monthly mean values of the atmospheric carbon dioxide concentration derived from in-situ air samples collected at Mauna Loa Observatory, Hawaii, during 1958-2004 (the longest continuous record available in the world) are analyzed by employing the detrended fluctuation analysis to detect scaling behavior in this time series. The main result is t...

Detrended fluctuation analysis (DFA) was applied to zonal mean daily Aerosol Index (AI) values derived from satellite observations during 1979–2003 to search for self‐similarity properties. The results show that the detrended and deseasonalized AI fluctuations in both hemispheres and globally obey persistent long‐range power‐law correlations for ti...

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, obse...

An investigation was made into the characteristic features of the signature of the quasi‐stationary planetary waves in ozone over Antarctica during recent years, where the Antarctic ozone hole exhibits peculiar behaviour. To this end, mean monthly ozone data, collected by the Total Ozone Mapping Spectrometer (TOMS) flown on the Earth‐Probe satellit...

Detrended fluctuation analysis is applied to the Athens air-pollution time-series consisting of hourly observations of ozone, nitrogen oxides, and particulate matter obtained at five air-pollution monitoring stations during 1987–2003.Persistent power-law correlations in the fluctuations of daytime and nighttime ozone concentrations with lag times r...

It has recently been observed that the total ozone trends derived from certain geographical regions such as the Mediterranean and Athens (Greece) show similar values to those derived from the 40degreesN zonal averaged column ozone data. In this Letter, the total ozone concentration, collected by the Total Ozone Mapping Spectrometer (TOMS) flown on...

Photochemical pollution is a very complex process involving meteorological, topographic, emission and chemical parameters. The most important chemical mechanisms involved in the atmospheric process have already been identified and studied. However, many unknown parameters still exist because of the large number of participating chemical reactions....

Intention, Goal, Scope, Background.Photochemical pollution is a very complex process involving meteorological, topographic, emission and chemical parameters. The most important chemical mechanisms involved in the atmospheric process have already been identified and studied. However, many unknown parameters still exist because of the large number of...

The increase in solar ultraviolet radiation can have various direct and indirect effects on human health, like the incidence of ocular damage. Data of eye damage in residents of three suburban regions in Greece and in two groups of monks/nuns and fishermen are examined here. The statistics performed on these data provides new information about the...

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 nightt...

The enhanced UVB radiation causes adverse effects on human health such as eye abnormalities. According to relevant studies, although the risk for eye damage can be estimated fairly reliably, many uncertainties still remain. In the present study the existing archive of a research centre in Greece has been used to examine relationships between the fr...

A simple theoretical algorithm has been employed to estimate the solar ultraviolet irradiance at Athens, Greece (38.7N, 23.4E) 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....