The impact of aerosol spatio-temporal variability on the Arctic radiative budget is not fully constrained. This case study focuses on the intra-Arctic modification of long-range transported aerosol and its direct aerosol radiative effect (ARE). Different types of air-borne and ground-based remote sensing observations (from Lidar and sun-photometer) revealed a high tropospheric aerosol transport episode over two parts of the European Arctic in April 2018. By incorporating the derived aerosol optical and microphysical properties into a radiative transfer model, we assessed the ARE over the two locations. Our study displayed that even in neighboring Arctic upper tropospheric levels, aged aerosol was transformed due to the interplay of removal processes (nucleation scavenging and dry deposition) and alteration of the aerosol source regions (northeast Asia and north Europe). Along the intra-Arctic transport, the coarse aerosol mode was depleted and the visible wavelength Lidar ratio (LR) increased significantly (from 15 to 64-82 sr). However, the aerosol modifications were not reflected on the ARE. More specifically, the short-wave (SW) atmospheric column ARE amounted to +4.4 - +4.9 W m^-2 over the ice-covered Fram Strait and +4.5 W m^-2 over the snow-covered Ny-Ålesund. Over both locations, top-of-atmosphere (TOA) warming was accompanied by surface cooling. These similarities can be attributed to the predominant accumulation mode, which drives the SW radiative budget, as well as to the similar layer altitude, solar geometry, and surface albedo conditions over both locations. However, in the context of retreating sea ice, the ARE may change even along individual transport episodes due to the ice albedo feedback.

中文翻译：

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远程运输的气溶胶在北极的内部变化是否会影响当地的辐射预算？（案例研究）

气溶胶时空变化对北极辐射预算的影响并未得到完全限制。该案例研究的重点是远程运输气溶胶在北极内部的变型及其直接气溶胶辐射效应（ARE）。不同类型的机载和地面遥感观测（来自激光雷达和太阳光度计）显示，在2018年4月，欧洲北极地区的对流层气溶胶运输量很高。辐射传输模型，我们评估了两个位置的ARE。我们的研究表明，即使在邻近的北极对流层高空，由于去除过程（成核清除和干沉降）和气溶胶来源区域（东北亚和北欧）之间的相互作用，使老化的气溶胶发生了转化。沿北极内部的运输，粗气溶胶模式被耗尽，可见光波长激光雷达比（LR）显着增加（从15增至64-82 sr）。但是，气雾剂的修改未反映在ARE上。更具体地说，短波（SW）大气柱面积为+4.4-+4.9 W m^-2在冰雪覆盖的弗拉姆海峡和+4.5脉冲W M ^-2在冰雪覆盖的新奥尔松。在这两个地点，大气顶（TOA）变暖都伴随着表面冷却。这些相似之处可归因于主要的累积模式，该模式驱动了西南部的辐射预算，以及这两个位置的相似的层高，太阳几何形状和表面反照率条件。但是，在退回海冰的情况下，由于冰的反照率反馈，即使在个别运输过程中，ARE也可能发生变化。