Abstract
Abstract. 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 power-law fashion. The exponent of this dependence is larger in the tropics than in the middle and high latitudes in both hemispheres. Greater persistence is observed in the tropopause of the Northern than in the Southern Hemisphere. A plausible physical explanation of the fact that long-range correlations in tropopause variability decreases with increasing latitude is that the column ozone fluctuations (that are closely related with the tropopause ones) exhibit long range correlations, which are larger in tropics than in the middle and high latitudes at long time scales. This finding for the tropopause height variability should reduce the existing uncertainties in assessing the climatic characteristics. More specifically the reliably modelled values of a climatic variable (i.e. past and future simulations) must exhibit the same scaling behaviour with that possibly existing in the real observations of the variable under consideration. An effort has been made to this end by applying the detrended fluctuation analysis to the global mean monthly land and sea surface temperature anomalies during the period January 1850–August 2008. The result obtained supports the findings presented above, notably: the correlations between the fluctuations in the global mean monthly land and sea surface temperature display scaling behaviour which must characterizes any projection.
Highlights
IntroductionThe location of the tropopause – the boundary between the troposphere and stratosphere – can be defined in a variety of ways, according to dynamic, thermal, and physico-chemical properties of the atmosphere (Hoinka, 1998; 1999; Reichler et al, 2003)
The location of the tropopause – the boundary between the troposphere and stratosphere – can be defined in a variety of ways, according to dynamic, thermal, and physico-chemical properties of the atmosphere (Hoinka, 1998; 1999; Reichler et al, 2003).Conventionally, the tropopause is a thin layer separating the turbulently mixed troposphere from the stably stratified stratosphere
Anomaly time series were computed by subtracting the mean seasonal cycle from the monthly means
Summary
The location of the tropopause – the boundary between the troposphere and stratosphere – can be defined in a variety of ways, according to dynamic, thermal, and physico-chemical properties of the atmosphere (Hoinka, 1998; 1999; Reichler et al, 2003). The tropopause is a thin layer separating the turbulently mixed troposphere (where temperature decreases with height) from the stably stratified stratosphere (with temperatures constant or increasing with height). Precise knowledge of the temporal and spatial structure of this transition zone is necessary in order to evaluate the exchange of mass, water, and chemical constituents between the troposphere and the stratosphere (Allen et al, 2008; Varotsos et al, 1995, 2004). Under the physicochemical conditions prevailed in the upper troposphere-lower stratosphere, several gas-solid reactions involving chlorine and bromine can directly or indirectly cause ozone destruction, depending on the variability of the solid particle properties (e.g. the conductivity, dielectric constant) with air temperature and pressure (Kostopoulos et al 1975; Varotsos, 1978, 1981)
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