Performance of MODIS aerosol products at various timescales and in different pollution conditions over eastern Asia

High-quality aerosol optical depth(AOD)data derived from MODIS is widely used in studying spatiotemporal trends of fine particulate matter(PM2.5)concentrations in eastern Asia.However,the differences of MODIS-AOD(3/10 km DT;10 km DB)under four pollution situations(No-Po;Sl-Po;Mo-Po;Se-Po)are rarely considered.In this study,the MODIS-AOD and AODDifference spatial distributions from 2008 to 2017 are analyzed through annual/seasonal mean AOD maps generated at 0.1°×0.1°resolution.The MODIS-AOD performances are validated using AERONET AOD data for various pollution situations and aerosol types.Annual validations indicate that the 10-km DB algorithm provides the best performance,followed by 3-km DTand 10 km DT.The DB algorithm can provide spatially continuous AOD data for all seasons,whereas the DT algorithm often fails to yield valid data during winter.The validations under different pollution conditions illustrate that severe pollution significantly affects the validity of data obtained by the DB algorithm.However,the accuracy of DT-derived AOD data is robust against interference.Under the same pollution conditions,the correlation coefficient of the DB algorithm is smaller than that of the DT algorithm.The quantity of valid data in the DB product is higher than those in DT products for all pollution conditions,especially under Se-Po.

The Use of Imitation Models at Developing and Introducing Information-Control Systems

Imitation models for computing the environmental water pollution level depending on the intensity of pollution sources created by the author over the years are presented. For this purpose, an additive model of a non-stationary random process is considered. For the modeling of its components, models that consider only dilution and self-purification processes are proposed for waste water and three-dimensional turbulent diffusion equations for river waters, and multidimensional Gaussian Markov series are proposed for modeling the random component. The purpose, the capabilities and the peculiarities of such imitation models are discussed taking into account the peculiarities of the water objects. The modular principle of creating imitation models is proposed to facilitate their development and use.