Stochastic Resonance Observed in Aerosol Optical Depth Time Series

Mariarosaria Falanga,Salvatore De Martino,Enza De Lauro

doi:10.3390/atmos11050502

Mariarosaria Falanga, Salvatore De Martino + Show 1 more

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https://doi.org/10.3390/atmos11050502

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Journal: Atmosphere	Publication Date: May 13, 2020
Citations: 2	License type: CC BY 4.0

Affiliation: University of Salerno

Abstract

We analyzed the aerosol optical depth time series retrieved from daily satellite Moderate-Resolution Imaging Spectroradiometer measurements. The investigated geographic area includes Italy and the Mediterranean Sea. By performing second- and fourth-order statistics analyses, the dynamics can be decomposed into two sources, the main of which is the annual cycle. The residence time distribution is made of local maxima over an exponential behavior. The two successive peaks are located at about 200 and 600 days. This allows us to hypothesize a stochastic resonance phenomenon in the dynamics of aerosol optical depth. The characteristic periodicity of the resonance is on the annual timescale, and the asymmetric double-well potential is provided by two different regimes for the values of the aerosol optical depth in winter and summer time. This means that a simple, although stochastic, differential equation can represent the time evolution of the optical depth, at least concerning its component related to the annual cycle.

Highlights

Atmospheric aerosol particles influence the Earth’s radiation balance directly, by the scattering and the absorption of the incoming solar radiation and indirectly by changing the albedo, the clouds recovering, acting as condensation nuclei, and air quality, this playing a relevant role in the greenhouse effect [1,2,3]
Gaps in the regional coverage of MODIS retrievals, mostly due to the cloud coverage, to the difficulties with highly reflective arid and snow-covered land [5] are filled with a random extraction of missing data from a log-normal distribution parameterized by the statistical estimates of raw data
Notice that the black stars superimposed on the histogram represent the distribution of the aerosol optical depth (AOD) values calculated following Equation (1), showing quite a good accordance between simulated and raw data

Summary

Introduction

Atmospheric aerosol particles influence the Earth’s radiation balance directly, by the scattering and the absorption of the incoming solar radiation and indirectly by changing the albedo, the clouds recovering, acting as condensation nuclei, and air quality, this playing a relevant role in the greenhouse effect [1,2,3]. The understanding of the aerosol particles’ impact on the regional and global climate change is one of the most relevant problems in climate modeling. A well-defined physical quantity measuring these effects is aerosol optical depth (AOD). It is determined by subtracting the contributions of the total column ozone absorption, water vapor absorption and Rayleigh scattering from the total atmospheric optical depth as provided by the known

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