Total and tropospheric ozone changes: observations and numerical modelling

A survey has been made of total and tropospheric ozone dynamics in the context of its impacts on climate, human health and ecosystems. Observation data on total ozone content (TOZ) in the atmosphere and relevant numerical modelling results have been discussed as well as similar information for tropospheric ozone, whose formation and changes are being determined by quite different causes. A necessity has been emphasized to get more adequate global observational data on TOZ and tropospheric ozone (this is especially important in the latter case, because information on tropospheric ozone is far from being complete). Unsolved problems relevant to both total and tropospheric ozone have been briefly considered

Monthly sunspot number time series analysis and its modeling through autoregressive artificial neural network

This study reports a statistical analysis of monthly sunspot number time series and observes non homogeneity and asymmetry within it. Using Mann-Kendall test a linear trend is revealed. After identifying stationarity within the time series we generate autoregressive AR(p) and autoregressive moving average (ARMA(p,q)). Based on minimization of AIC we find 3 and 1 as the best values of p and q respectively. In the next phase, autoregressive neural network (AR-NN(3)) is generated by training a generalized feedforward neural network (GFNN). Assessing the model performances by means of Willmott's index of second order and coefficient of determination, the performance of AR-NN(3) is identified to be better than AR(3) and ARMA(3,1).Comment: 17 pages, 4 figure

The global signature of the ENSO and SST-like fields

The El Niño-Southern Oscillation (ENSO)-like variability of various parameters and indices (e.g. sea surface temperature (SST)) is explored, by employing the last six decades of data on a global scale. We found that the ENSO signal in the SST field extends over tropics and subtropics, becoming maximum around 30° N and 30° S. The pronounced ENSO signal in the SST is observed over the southern tropics and subtropics. Additionally, the investigation of regional links between the Pacific Decadal Oscillation and SST revealed a new regional link, which extends in the tropical southern Pacific Ocean, where the effects of a long-lived pattern of SST are taking place. Furthermore, very strong SST-like surface temperature behaviour is observed over the equatorial Indian Ocean, being a new input to the assessment of "dangerous anthropogenic interference". The above-mentioned findings could be employed to the advanced modelling development to improve climate change projections. © 2012 Springer-Verlag Wien

On the correction of the total ozone content over Athens, Greece as deduced from satellite observations

The observations with the Total Ozone Mapping Spectrometer (TOMS) mounted aboard the Nimbus-7 satellite have previously been used to determine the trends of the total ozone amount over Athens, Greece (38° N, 24° E), since 1979, for various months (Varotsos, C. A., and Cracknell, A. P., 1993, International Journal of Remote Sensing, 14, 2053-2059). The total ozone depletion over the 13-year time period showed a strong seasonal variation of the trend from more than 7 per cent in winter to about 2.5 per cent in summer. However, the TOMS instrument measures the back-scattered ultraviolet radiation in order to determine ozone content and is limited to observations above the cloud level. In the presence of thick cloud the column ozone content is generally underestimated. This underestimation of the total ozone amount is quantitatively examined, especially in the synoptic cases where ozone-rich air has been transported into the lower troposphere. The influence of this underestimation on the tolal ozone depletion over Athens, Greece, deduced from TOMS observations, is finally attempted. © 1995 Taylor & Francis Group, LLC

A new model for the spread of COVID-19 and the improvement of safety

COVID-19 has been spreading rapidly around the world since December 2019. The main goal of this study is to develop a more effective method for diagnosing and predicting the COVID-19 spread and to evaluate the effectiveness of control measures to reduce and stop the virus spread. To this end, the COVID-19 Decision-Making System (CDMS) was developed to study disease transmission. CDMS divides the population into groups as susceptible, infected, cured and dead. The trends of the people's number in these groups have deterministic and stochastic components. The deterministic components are described by a differential equations system with parameters determined by the data reported. The stochastic components are represented as an indicator of instability that characterizes the tendency of COVID-19 spread. The simulation experiments have shown a good agreement between the CDMS estimates and the data reported in Russia and Greece. The analysis performed showed that the newly-introduced instability indicator may be the precursor to the pandemic dynamics. In this context, our results showed three potential candidates for a second wave of COVID-19 disease: USA, Russia and Brazil. Although the proportion of infected individuals in countries with high temperatures is lower than in European countries and Russia, temperature and humidity are slowly affecting the effects of the pandemic. Finally, the results presented may contribute to the urgent need to reduce the risks associated with the second wave of the COVID-19, to improve public health intervention and safety measures to be taken by various countries. © 2020 Elsevier Lt

Anomalous mesospheric ozone variability is not a precursor to earthquakes: A case study in Greece

Very recently, it has been found that intense anomalies of the mesospheric ozone occur a few days before major earthquakes. This paper explores the credibility of this finding in the case of the last two major earthquakes in Greece. Indeed, the study of the mesospheric ozone vertical distribution showed that unusual anomalies occurred a few days before these two earthquakes. However, at time periods with no significant seismicity the same unusual changes in the mesospheric ozone vertical distribution were observed. Consequently, significant temporal changes of the mesospheric ozone can not be considered as precursors for upcoming significant seismic activity. © 2018 Elsevier Lt

On the 11 year solar cycle signature in global total ozone dynamics

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 statistically significant correlation between the annual mean TOZ over both hemispheres and sunspot number (SN) is found. On the contrary, focusing on the January and February mean monthly TOZ fluctuations from the equator to the high latitudes of the Northern Hemisphere, no association between TOZ and SN is derived. This is attributed to the existence of the quasi-biennial-oscillation (QBO) and the El Niño-Southern oscillation (ENSO) in the TOZ time series. The latter oscillation is herewith expressed by the recently introduced Ozone ENSO Index (OEI). However, when considering the TOZ zonal means centred at 17.5 and 27.5°N during the east phase years of the QBO in the equatorial zonal wind at 50 hPa, a statistically significant correlation between TOZ and SN is revealed. It is an indication that the quasi-periodic fluctuations (i.e. QBO, ENSO) strongly contaminate the relationship between TOZ and solar activity. Plausible mechanisms are discussed, exploring the momentum flux (MF) measurements between 45 and 75°N, in the periods of increased dynamical variability. The findings obtained point to the conclusion that the 11 year solar cycle response in TOZ is caused by dynamical changes which are caused by solar activity. These are of crucial importance because solar radiation is a major driving force of the climate system. © 2012 Royal Meteorological Society

Symmetric scaling properties in global surface air temperature anomalies

We have recently suggested “long-term memory” or internal long-range correlation within the time-series of land-surface air temperature (LSAT) anomalies in both hemispheres. For example, an increasing trend in the LSAT anomalies is followed by another one at a different time in a power-law fashion. However, our previous research was mainly focused on the overall long-term persistence, while in the present study, the upward and downward scaling dynamics of the LSAT anomalies are analysed, separately. Our results show that no significant fluctuation differences were found between the increments and decrements in LSAT anomalies, over the whole Earth and over each hemisphere, individually. On the contrary, the combination of land-surface air and sea-surface water temperature anomalies seemed to cause a departure from symmetry and the increments in the land and sea surface temperature anomalies appear to be more persistent than the decrements. © 2014, Springer-Verlag Wien

Modelling the CO2 atmosphere-ocean flux in the upwelling zones using radiative transfer tools

An advanced mathematical model of the radiation forcing on the ocean surface is proposed for the assessment of the CO2 fluxes between atmosphere and ocean boundary in the upwelling zones. Two types of the upwelling are considered: coastal and local in the open ocean that are closely associated with changes in solar irradiance. The proposed model takes into account the maximal number of the carbon fluxes in the upwelling ecosystem considering that in the latter the only original source of energy and matter for all forms of life is the energy of the solar radiation. The vertical structure of the upwelling zone is represented by four levels: the upper mixed layer above the thermocline, the intermediate photic layer below the thermocline, the deep ocean and the near-bottom layer. Peruvian upwelling and typical local upwelling of tropical pelagic region are considered as examples for the model calculations. © 2016 Elsevier Lt