The rapid changes in the pattern of atmospheric warming as well as the degradation of glaciers in the Himalayas point to the inevitability of accurate source characterization and quantification of the impact of aerosols. In this regard, optical and chemical properties of aerosols, and their role in radiative effects are examined over a remote high-altitude site Lachung (27.4°N, 88.4°E, 2700 m a.s.l.) in the eastern Himalayas during August-2018 to February-2020. It is found that the sulphate (SO₄²⁻) and carbonaceous aerosols (both organic carbon - OC and elemental carbon - EC) significantly contribute to the total aerosol mass loading in winter (DJF) and spring (MAM), resulting in high values of scattering and absorption coefficients. Aerosol single scattering albedo (SSA) is relatively higher in winter (> 0.85) due to a significantly higher amount of OC (OC/EC > 8). However, SSA ~ 0.8 in spring despite of higher SO₄²⁻ concentrations (SO₄²⁻/EC > 4.0 and SO₄²⁻/OC ~ 1.0) than winter. A reverse pattern is seen in summer-monsoon (JJAS) having lower SO₄²⁻/EC < 2 and SO₄²⁻/OC < 0.5, resulting in SSA as low as ~0.64. The seasonal values of aerosol direct radiative forcing in the top of the atmosphere (DRF_TOA) are as high as −2.9 ± 1.2 Wm⁻² during the period of abundant OC in winter and −2.8 ± 0.5 Wm⁻² during the period of abundant SO₄²⁻ in spring. The combined effect of carbonaceous and SO₄²⁻ aerosols on the surface cooling is highest in spring (−16.7 ± 4.9 Wm⁻²). DRF in the atmosphere is also ~ 34% higher in spring (13.8 ± 4.5 Wm⁻², which translates to an atmospheric heating rate of ~ 0.39 K day^-1), than in winter. The seasonal pattern of forcing influenced by the heterogeneous sources and chemical composition of aerosols over the eastern Himalayan site is significantly influenced by the transport of aerosols from the Indo-Gangetic Plains of India.

大气变暖模式的快速变化以及喜马拉雅山冰川的退化表明准确源表征和量化气溶胶影响的必然性。在这方面，在 2018 年 8 月至 2 月期间，在喜马拉雅山脉东部的偏远高海拔站点 Lachung（北纬 27.4°，东经 2700 米）上检查了气溶胶的光学和化学性质及其在辐射效应中的作用-2020。发现硫酸盐 (SO ₄ ^2-) 和含碳气溶胶（有机碳 - OC 和元素碳 - EC）对冬季 (DJF) 和春季 (MAM) 的总气溶胶质量负荷有显着贡献，导致散射和吸收系数值较高。由于 OC 量显着增加 (OC/EC > 8)，冬季气溶胶单次散射反照率 (SSA) 相对较高 (> 0.85)。然而，尽管 SO ₄ ²⁻浓度（SO ₄ ²⁻ /EC > 4.0 和 SO ₄ ²⁻ /OC ~ 1.0）比冬季高，但春季 SSA ~ 0.8 。在具有较低 SO ₄ ^2- /EC < 2 和 SO ₄ ^{2- 的}夏季季风 (JJAS) 中可以看到相反的模式/OC < 0.5，导致 SSA 低至 ~0.64。气溶胶直接辐射在大气中（DRF的顶部迫使季节性值_TOA）都高达-2.9±1.2了Wm ^-2期间丰富OC冬季期间和-2.8±0.5了Wm ^-2期间的丰富的周期SO ₄ ²⁻在春天。碳质和 SO ₄ ^2-气溶胶对地表冷却的综合影响在春季最高 (-16.7 ± 4.9 Wm ^-2 )。春季大气中的 DRF 也高出约 34%（13.8 ± 4.5 Wm ^-2，这意味着大气加热率为约 0.39 K 天^-1)，比冬天。受喜马拉雅东部地区气溶胶的异质来源和化学成分影响的季节性强迫模式受到来自印度-恒河平原的气溶胶传输的显着影响。