Simulation of the Ecosystem Productivity Responses to Aerosol Diffuse Radiation Fertilization Effects over the Pan-Arctic during 2001–19

Abstract

The pan-Arctic is confronted with air pollution transported from lower latitudes. Observations have shown that aerosols help increase plant photosynthesis through the diffuse radiation fertilization effects (DRFEs). While such DRFEs have been explored at low to middle latitudes, the aerosol impacts on pan-Arctic ecosystems and the contributions by anthropogenic and natural emission sources remain less quantified. Here, we perform regional simulations at 0.2°×0.2° using a well-validated vegetation model (Yale Interactive terrestrial Biosphere, YIBs) in combination with multi-source of observations to quantify the impacts of aerosol DRFEs on the net primary productivity (NPP) in the pan-Arctic during 2001–19. Results show that aerosol DRFEs increase pan-Arctic NPP by 2.19 Pg C (12.8%) yr⁻¹ under clear-sky conditions, in which natural and anthropogenic sources contribute to 8.9% and 3.9%, respectively. Under all-sky conditions, such DRFEs are largely dampened by cloud to only 0.26 Pg C (1.24%) yr⁻¹, with contributions of 0.65% by natural and 0.59% by anthropogenic species. Natural aerosols cause a positive NPP trend of 0.022% yr⁻¹ following the increased fire activities in the pan-Arctic. In contrast, anthropogenic aerosols induce a negative trend of ⁻0.01% yr⁻¹ due to reduced emissions from the middle latitudes. Such trends in aerosol DRFEs show a turning point in the year of 2007 with more positive NPP trends by natural aerosols but negative NPP trends by anthropogenic aerosols thereafter. Though affected by modeling uncertainties, this study suggests a likely increasing impact of aerosols on terrestrial ecosystems in the pan-Arctic under global warming.

摘 要

泛北极地区面临着从低纬度传输而来的空气污染的影响. 观测表明气溶胶能够通过散射辐射施肥效应(DRFEs)促进植被的光合作用. 尽管DRFEs在中低纬度地区已有相关研究, 气溶胶对泛北极生态系统的影响以及对人为和自然气溶胶的相对贡献尚不明确. 在本研究中我们使用一个充分验证的植被模式(耶鲁互动生物圈模式, YIBs)和多源观测数据, 量化了气溶胶的DRFEs对2001–19年期间泛北极地区净初级生产力(NPP)的影响. 结果表明, 晴空条件下气溶胶DRFEs使泛北极地区NPP增加了2.19 Pg C(12.8%)yr⁻¹, 其中自然和人为气溶胶的贡献分别为8.9%和3.9%. 在全天空条件下, 气溶胶的 DRFEs在很大程度上被云层削弱, 仅有0.26 Pg C(1.24%)yr⁻¹的促进效应, 其中自然气溶胶贡献0.65%而人为气溶胶贡献0.59%. 随着泛北极地区野火活动的增加, 自然气溶胶导致NPP呈0.022%yr⁻¹的增长趋势. 相比之下, 由于中纬度地区的排放量减少, 人为气溶胶产生了−0.01%yr⁻¹的NPP降低趋势. 气溶胶DRFEs的趋势转折点出现在2007年, 在此之后自然气溶胶导致的NPP增长趋势更强, 而人为气溶胶导致的NPP增长趋势开始减弱. 尽管受到模型不确定性的影响, 本研究表明在全球变暖背景下, 气溶胶对泛北极地区陆地生态系统的影响可能会越来越大.

Electronic Supplementary Material to

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Simulation of the Ecosystem Productivity Responses to Aerosol Diffuse Radiation Fertilization Effects over the Pan-Arctic during 2001–19