Abstract
Atmospheric aerosols can elicit variations in how much solar radiation reaches the ground surface due to scattering and absorption, which may affect plant photosynthesis and carbon uptake in terrestrial ecosystems. In this study, the spatio-temporal variations in aerosol optical depth (AOD) are compared with that in photosynthetically active radiation (PAR) and net primary productivity (NPP) during 2001–2017 in China using multiple remote sensing data. The correlations between them are analyzed at different scales. Overall, the AOD exhibited a northeast-to-southwest decreasing pattern in space. A national increasing trend of 0.004 year−1 and a declining trend of −0.007 year−1 of AOD are observed during 2001–2008 and 2009–2017. The direct PAR (PARdir) and diffuse PAR (PARdif) present consistent and opposite tendency with AOD during two periods, respectively. The total PAR (PARtotal) shows a similar variation pattern with PARdir. In terms of annual variation, the peaks of AOD coincide with the peaks of PARdif and the troughs of PARdir, indicating that aerosols have a significant positive impact on PARdir and a negative impact on PARdif. Furthermore, the PARdir has a stronger negative association with AOD than the positive correlation between PARdif and AOD at national and regional scales, indicating that PARdir is more sensitive to aerosol changes. The NPP has higher values in the east than in the west and exhibits a significant increasing trend of 0.035 gCm−2day−1 after 2008. The NPP has a negative correlation (−0.4–0) with AOD and PARdif and a positive correlation (0–0.4) with PARdir in most areas of China. The area covered by forests has the highest NPP-PAR correlation, indicating that NPP in forests is more sensitive to the PAR than is the NPP in grasslands and croplands. This study is beneficial for interpreting the aerosol-induced PAR impact on plant growth and for predicting plant production on haze days.
Highlights
Aerosols—solid or liquid particles suspended in the air with diameters ranging from 0.001 to 100 μm—are one of the main sources of air pollution and play an important role in the atmospheric environment [1]
In order to extend our understanding of how the plant production responds to the aerosol optical depth (AOD) and photosynthetically active radiation (PAR) change, this paper investigates the spatio-temporal characteristics of AOD and its correlations with PAR and net primary productivity (NPP) in China during 2001–2017 using multiple types of satellite data (MOD08, CERES, MOD17)
The spatio-temporal distribution, variation and trends of AOD was analyzed and compared with that of PAR and NPP from 2001 to 2017. We investigated their correlations at the pixel, regional and national scales
Summary
Aerosols—solid or liquid particles suspended in the air with diameters ranging from 0.001 to 100 μm—are one of the main sources of air pollution and play an important role in the atmospheric environment [1]. Results showed AOD has a trend of 0.002 decade−1 and is highly correlated with shortwave aerosol radiative effect (SWARE), which is the impact of aerosols on shortwave radiation Most of these studies focus on spatio-temporal variation in AOD and its correlations with NDVI, terrain, solar radiation, or population. The aerosol particles can lead to the decrease in direct PAR and increase in diffuse PAR, which may influence the plant photosynthesis and production indirectly. This was proved by some simulation studies based on the process-based models [3,9,10,11,12,13]. The correlations between AOD, PAR and NPP in reality have still not been comprehensively understood
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