我国北方季节性积雪中沙尘和黑碳源分析及其辐射强迫的模拟研究

Mineral dust (MD) and black carbon (BC), as the most important light-absorbing aerosols in snow, can reduce the albedo relative to pure snow, absorb more solar radiation, then further change the surface energy budget and accelerate the snow aging process, and have profound impacts on the regional climate, the atmospheric general circulation and hydrologic cycle. There is a large amount of MD and BC in seasonal snow over northern China, which obviously affects the regional climate and ecological environment. Due to lack of the detailed and accurate data sets of MD and BC in snow, the studies of source analysis and radiative forcing of LAA in seasonal snow over northern China is insufficient. Thus, we will add the BC source partition by an explicit emission tagging technique (dust source partition has been finished) in the new coupled WRF-Chem model, and the model can well quantify the comprehensive source-region-resolved MD and BC characteristics (e.g., burden, transport, and deposition rate). The purpose of this proposal will investigate the MD and BC source contribution in seasonal snow over northern China, including the MD and BC mass concentration source contribution, its spatial and temporal distribution and the radiative forcing effect of different MD and BC source for the 30 years of 1988-2017. This research will help to better understand the regional climate change induced by the light-absorbing aerosols in seasonal snow over northern China.

沙尘和黑碳被认为是两种主要的吸收性气溶胶，其沉降在积雪中可明显降低积雪表面反照率，影响辐射收支平衡，加速积雪融化，进而改变水循环，是目前造成全球气候变暖的主要驱动因子之一。我国北方季节性积雪中存在大量的沙尘和黑碳，显著地影响区域气候和生态环境。然而由于缺乏长时间、高分辨率的相关数据，目前对这一地区积雪中沙尘和黑碳的来源及其辐射效应的认识还不足。本项目拟在新耦合了SNICAR模块的WRF-Chem模式中，利用源标签技术实现黑碳的源分区（前期已实现沙尘的源分区），使模式能够在线追踪各个源区沙尘和黑碳的排放、传输及沉降等过程；然后基于修改后的模式模拟1988-2017年我国北方季节性积雪中沙尘和黑碳的时空变化，得出不同源区对上述积雪中颗粒物的贡献，定量计算不同源区产生的沙尘和黑碳对我国北方地表积雪辐射强迫的贡献。本项目的实施可为进一步研究我国北方季节性积雪中吸收性颗粒物的气候效应提供坚实的基础。

吸收性气溶胶（黑碳和沙尘）通过远距离输送导致地表积雪加速消融，对东亚区域气候和水循环产生了重要的影响，探讨积雪中吸收性气溶胶的来源及其辐射影响具有十分重要的意义。本项目通过将源标签技术应用到耦合了SNICAR模块的WRF-Chem模式中，实现了模式对不同来源吸收性气溶胶在线追踪和模拟研究。利用地面观测和卫星资料定量评估新改进的模式对气溶胶及其辐射特性的模拟效果，指出模式可以很好地模拟吸收性气溶胶的时空分布。通过对东亚吸收性气溶胶来源、传输及其辐射特性的模拟，分析了不同来源沙尘对东亚气溶胶的贡献及其粒径和数浓度的分布，定量估算了东亚、北非及其中亚对青藏高原沙尘气溶胶的季节贡献率以及不同来源气溶胶对地表辐射强迫的贡献，厘清了吸收性气溶胶在东亚地区的传输机理及其时空分布特征，揭示了吸收性气溶胶对地表积雪辐射和温度的影响机制。该项目的实施加深了对季节性积雪中吸收性气溶胶气候效应的认识，对局地气候变化、成因解释甚至预测都有科学意义。