Scaling properties and multifractal dynamic of greenhouses gases

Abstract

This work presents an extensive analysis of scaling properties of the intra-day components that constitute the temporal behaviour of GHG tracers (CO2, CH4 and CO), recorded during the period from 2015 to 2017 at Monte Curcio Observatory. Through the application of Empirical Mode Decomposition and Mutual Information methods, fast and slow components have been highlighted, which characterize the dynamics of GHG tracers at small and large scales, respectively. From analyses of these two components, it was possible to investigate the scaling properties related to the Hurst coe cient. The results highlight di erent local properties that characterize the uctuations of the two components, particularly according to the scale and time period under investigation. The discrepancy of scaling exponents suggests that the dynamics of slow components are related to di erent phenomena that contribute more energy (force) to the process, while fast components are governed by small-scale turbulent processes. The Hurst coe cient of slow component for CO2 exhibits a large-scale temporal modulation, which may be related to the main environmental drivers responsible for dynamics of CO2 concentrations. In this context, the photosynthesis-respiration process has been considered, through the analysis of the vegetation indexes EVI and NDVI, and the variation of the Planetary Boundary Layer (PBL) height. The high correlation value measured between the monthly variations of these two indexes and the variation of Hs coe cient suggests that these phenomena played a primary role in de ning the intra-day fractal properties of the CO2. The results obtained are useful to the parametrization of sub-grid processes in atmosphericclimatic models, while providing a temporal evolution of the emission maps of the analyzed GHG tracers.