The 11-yr ozone modulation of extreme surface air temperatures

Summary The opposite effect of the total ozone on daily maximum and minimum air temperatures is one of the reasons for the failure of the correlation between solar activity and surface air temperature by means of mean daily values. The solar-related fluctuations in the atmospheric total ozone are found to be responsible for the observed correlations between solar activity and separately daily maximum and minimum air temperatures. The present evidence indicates that ozone serves as a stratospheric shutter modulating both the incoming daytime visible solar energy flux and the Earth's night-time upward infrared radiation transferred downward.

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Zusammenfassung Der umgekehrte Effekt des gesamten Ozons auf die Tagesmaxima und -minima der Lufttemperatur ist einer der Gründe für die mißglückte Korrelation zwischen Sonnenaktivität und Oberflächenlufttemperatur, wie sie bis jetzt aus Tagesmittelwerten ermittelt wurde. Die sonnenabhängige Fluktuation im atmosphärischen Gesamtozon erwies sich als Ursache der genannten Korrelation zwischen Sonnenaktivität und täglichen Maxima und Minima der Lufttemperaturen andererseits. Damit wird darauf hingewiesen, daß Ozon als stratosphärischer Absorber sowohl für die tagsüber einfallende sichtbare Sonnenstrahlung als auch für die nächtliche, rücktransferrierte Erdinfrarotabstrahlung wirkt.

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Quantifying the Multivariate ENSO Index (MEI) coupling to CO2 concentration and to the length of day variations

The El Niño Southern Oscillation (ENSO) is the Earth’s strongest climate fluctuation on inter-annual time scales and has global impacts although originating in the tropical Pacific. Many point indices have been developed to describe ENSO but the Multivariate ENSO Index (MEI) is considered as the most representative since it links six different meteorological parameters measured over the tropical Pacific. Extreme values of MEI are correlated to the extreme values of atmospheric CO₂ concentration rate variations and negatively correlated to equivalent scale extreme values of the length of day rate variation. We evaluate a first-order conversion function between MEI and the other two indexes using their annual rate of variation. The quantification of the strength of the coupling herein evaluated provides a quantitative measure to test the accuracy of theoretical model predictions. Our results further confirm the idea that the major local and global Earth–atmosphere system mechanisms are significantly coupled and synchronized to each other at multiple scales.     

The Time Clustering of Floodings in Venice and the Cantor Dust Method

Summary The catalogue of sea-floodings in Venice, accurately reconstructed for a period of 12 centuries (interval: 872–1996) has been analysed according to the Cantor Dust method. This provides a means of testing whether clustering in time is a scale-invariant process: if the fraction R of the intervals of length t containing flooding events is related to the time interval by: R∼t ^(1−D) , then the fractal clustering is occurring with fractal dimension D (0<D<1). The main result is the evidence for a gradual increase of the fractal clustering starting from 1914, when the soil subsidence of the lagoon basin determines an increase in its hydrodynamic response to the marine forcing with a gradual increase of flooding occurrences. Received October 1, 1996 Revised September 10, 1997     

An analysis of heat index over Naples (Southern Italy) in the context of European heat wave of 2003

Two strong heat waves in the summer of 2003 determined elevated heat discomfort conditions all across the Western Europe. In this context, the analysis of hourly Heat Index values in the city of Naples (Southern Italy) showed prolonged heat discomfort conditions during the second half of June 2003 and from the second half of July 2003 up to the first week of September 2003, resulting in highest mortality rate for persons 75 years or more.     

Fractal Characterisation of Geophysical Measuring Networks and its Implication for an Optimal Location of Additional Stations: An Application to a Rain-Gauge Network

Summary The locations of measuring stations are often inhomogeneously distributed in space, possibly because of both geophysical interests and access problems. The areal inhomogeneity of a network can be well characterised by its fractal dimension, that is an index ranging progressively from 0 (when all stations are distributed on a single point or on isolated points) to 2 (when all stations are uniformly distributed). Appreciating the scaling region, inside which the station-co-ordinates are fractally distributed, provides valuable information both on the minimum detectable scale and on the minimum resolvable dimension. The increase in the measuring capability of a network must occur through its strategic enlargement resulting in a compromise between the fractal dimension increase and local topographic necessities. An application to a rain-gauge network belonging to the Naples Section of the Italian Hydrographic Service is reported. Received March 30, 1999 Revised September 15, 1999     

Nowcasting and real-time monitoring of heavy rainfall events inducing flash-floods: an application to Phlegraean area (Central-Southern Italy)

Natural Hazards - Severe weather events cause considerable disruptions to social and economic activities. Thus, high-precision meteorological products and services should be provided in order to...     

The 60-year solar modulation of global air temperature: the Earth’s rotation and atmospheric circulation connection

Summary Spectral analysis of geomagnetic activity, global air temperature, Earth’s rotation rate and zonal circulation, when smoothed from secular trend and periods shorter than 23 years, shows a concentration of energy around the 60-year period explaining more than 80% of the entire variance. This information has enabled the set-up of a cascade physical model that integrates the Sun-atmosphere-Earth system as a single unit and ties solar corpuscular radiation to global warming through Earth’s rotation and atmospheric circulation. Our results suggest that changes in geomagnetic activity, and in the Earth’s rotation, could be used as long- and short-term indicators, respectively, of future changes in global air temperature.     

Solar Activity and Algal-bloom Occurrences in the Northern Adriatic Sea: Geomagnetic Connection

Summary The high-speed particle flux (solar wind) escaping from the Sun controls the geomagnetic activity at middle latitudes. The latter is found to be negatively correlated to the difference of atmospheric pressure between January and April averaged out in the area of the Northern Adriatic. This difference is again related to the water volume flowing from the South into the Northern Adriatic Sea and is a necessary (though not sufficient) condition for the occurrence of strong algal-blooms in summer. A physical model involving geomagnetic activity, mean atmospheric pressured difference between latitude 35 °N and 55 °N in the European area and atmospheric pressure difference from winter to spring in the Northern Adriatic basin is proposed. The possibility of predicting the long-term variations of geomagnetic activity allows one to obtain long-term predictions of winter minus spring pressure and therefore indications of the risk of strong summer-time algal-bloom episodes. Received March 29, 1996 Revised February 14, 1997     

Modeling IR spectral energy distributions: a?pilot study of?starburst parameters and silicate absorption curves for some GOALS galaxies

This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the Spitzer Space Telescope. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine ??astronomical silicate?? model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished (A _V??50 mag.) starbursts. We have derived an empirical fit to the ??starburst silicate?? absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AGN. This technique is simple and provides reasonably robust and uniform parameters for the starburst, especially as far as the star formation rate, population of old stars, compactness of the starburst region and total foreground extinction are concerned. However, the chemical abundances and the optical extinction cannot be reliably determined by this analysis, and optical SEDs will also be required to provide a complete characterization of the starburst region and of the surrounding galaxy.