季节性积雪中吸收性粒子含量及其光学特性的观测与数值模拟研究

Black carbon (BC) and mineral dust (MD) deposited on snow have been found to shorten the snow cover season by decreasing the snow albedo and accelerating snow melt, thereafter change the hydrological cycle. Several snow surveys will be carried out to collect snow samples across northeastern China since 2018. A spectrophotometer combined with chemical analysis was used to quantify snow particulate absorption by insoluble light-absorbing particles (ILAPs, e.g., black carbon, BC; mineral dust, MD; and organic carbon, OC) in snow. The individual ILAPs and the mixing state analyses in snow samples were examined by using the transmission electron microscopy (TEM) and electron microscope (TEM). Snow albedo was measured using a field spectroradiometer. A new radiative transfer model (Spectral Albedo Model for Dirty Snow, or SAMDS) and the SNICAR model were then used to simulate the spectral albedo of snow based on the asymptotic radiative transfer theory. Compared with the surface measurements of the snow albedo, This funding try to reduce the uncertainties of the snow albedo simulation based on the mixing state of ILAPs in snow, and the snow grain size. This research could contribute the climate models, which could be better simulated the climate effects of the ILAPs in seasonal snow, especially including heavy loadings of mineral dust in snow over northern China.

大气中黑碳、沙尘等吸收性气溶胶经过干、湿沉降到冰雪表面，可显著降低积雪反照率，从而影响辐射收支平衡，加速冰雪融化，进而改变水循环。本项目拟对我国北方地区冬季季节性积雪进行大范围的现场观测与样品采集，基于地物光谱仪实地测量表层积雪反照率，利用带能谱的投射、扫描电子显微镜、黑碳光谱仪等仪器对积雪中黑碳、有机碳以及沙尘粒子的含量、光学吸收、单颗粒物貌及其混合状态进行定量甄别与测定，同时结合不同类型冰雪辐射传输模式模拟表层积雪反照率，基于试验观测与数值模拟结果的对比分析，筛选导致积雪反照率模拟结果不确定性的主导因子，优化冰雪辐射传输模式，进而降低积雪反照率数值模拟的不确定性，该项目的开展有助于揭示积雪中吸收性粒子对积雪消融进而影响气候变化提供科学参考与理论依据。

大气中黑碳、沙尘等吸收性气溶胶经过干、湿沉降到冰雪表面，可显著降低积雪反照率，从而影响辐射收支平衡，加速冰雪融化，进而改变水循环。在该项目的资助下，项目负责人及其团队成员对我国北方地区冬季季节性积雪进行多次大范围的现场观测与样品采集，取得的主要成果包括：（1）在青藏高原冰川及北方地区开展季节性积雪中黑碳等污染物含量及来源解析工作；（2）揭示了季节性积雪中棕碳等污染物的三维荧光特性；（3）研发可精确测量冰雪中的黑碳及有机碳含量的双光腔黑碳光谱仪；发展了高效甄别积雪中黑碳和沙尘形貌与混合态的探测方法；（4）发展了新的冰雪辐射传输模型，定量计算了有机碳对积雪反照率及其辐射强迫效应；（5）共发表相关SCI论文13篇，核心论文2篇，该项目圆满完成了项目制定之初的研究目标，正式申请结题。