Climatological Characteristics and Aerosol Loading Trends from 2001 to 2020 Based on MODIS MAIAC Data for Tianjin, North China Plain

Zhenling Wu,Jian Hao,Hujia Zhao,Guoliang Wu

doi:10.3390/su14031072

Abstract

The North China Plain (NCP) in East Asia has a severe air pollution problem. In this study, the long-term spatial distribution and interannual trends of aerosol optical depth (AOD) were investigated using the MODIS MAIAC (multiangle implementation of the atmospheric correction) dataset from 2001 to 2020 for Tianjin, a city on the NCP. The annual AOD in Tianjin was 0.59 from 2001 to 2020. The average AOD of Tianjin was the highest in summer (0.96), followed by spring (0.58) and autumn (0.51). The annual AOD in Tianjin increased significantly in 2008 (approximately 0.77), and the minimum annual AOD was observed in 2020 (0.41). In summer, AOD in the 11 districts of Tianjin significantly increased from 2001 to 2010 and gradually decreased from 2011 to 2020. The occurrence frequency of AOD in the range of 0.2–0.5 was high in Tianjin accounting for almost 40% of the total proportion. In Tianjin, AOD exhibited a positive trend from 2001 to 2008 and an obvious negative growth trend from 2009 to 2020 due to anthropogenic emission. The findings are valuable for analyzing the climatological characteristics of aerosol loading and their optical properties at the district level of cities on the NCP.

Highlights

Atmospheric aerosols can directly change the energy balance of the earth-atmosphere system by absorbing and scattering solar radiation [1,2,3]
The area near the Bohai Bay in the southeast has an average altitude of only 3.5 m, which is the lowest point on the North China Plain (NCP); Tianjin is the lowest major city in China
The lowest aerosol optical depth (AOD) value was observed in the northern mountainous district, and the annual average AOD was approximately 0.3

Summary

Introduction

Atmospheric aerosols can directly change the energy balance of the earth-atmosphere system by absorbing and scattering solar radiation [1,2,3]. The ground-based monitoring network of aerosol optical properties can obtain long-term national, regional, and global observation data, and is widely used to understand the impact of aerosols on the climate. These observation networks include the Aerosol Robotic Network Ground-based observations of the optical properties of aerosols are limited due to the lack of coverage of observation sites; satellite remote sensing can provide detailed information on spatial and temporal optical properties of aerosols [15,16,17,18,19]. The Moderate Resolution Imaging Spectroradiometer (MODIS) multiangle implementation of the atmospheric correction (MAIAC) algorithm was applied to provide MODIS aerosol optical depth (AOD) at 1-km-high spatial resolution

Methods

Results

Conclusion