Solar radiative forcing of mixed-phase boundary layer clouds in the Arctic

该项目是研究北极气溶胶和云层对气候影响的国际努力（VALHALA）的一部分。这里建议的该项目的具体目标是评估北极边界层混合相云的冰相对其辐射特性的影响，并量化这类云的光谱太阳辐射强迫。虽然这些主题对气候系统的重要性已得到充分认识，但过去对它们的研究很少。为了实现这些目标，建议将航空辐射测量与复杂的单散射和1-D/3-D辐射传输计算相结合，两者都与VALHALA的合作伙伴密切合作。测量包括用一种独特的仪器——所谓的反射率计——测量向下和向上的光谱辐照度。为了解释这些数据，将在混合相云微物理特性和北极冰/雪或海面上确定的光谱表面反照率的基础上进行辐射计算。根据实测辐射和计算辐射之间的闭合，将计算混合相云的辐射强迫。

This project is embebbed in an international effort to study climate effects of aerosols and clouds in the Arctic (VALHALA). The specific goals of the project suggested here are to evaluate the influence on the ice phase of Arctic boundary layer mixed-phase clouds on their radiative properties, and to quantify the spectral solar radiative forcing of this type of clouds. These topics have only poorly been studied in the past, although their importance for the climate system is well recognized. To reach these goals a combination of airborne radiation measurements and sophisticated single scattering an 1-D/3-D radiative transfer calculations is suggested, both in close collaboration with the partners of VALHALA. The measurements include down- and upwelling spectral irradiances with a unique instrument - the so-called albedometer. To interpret the data radiation calculations will be performed on the basis of the mixed-phase cloud microphysical properties and the spectral surface albedo determined over the Arctis ice/snow or sea surfaces. On the basis of closure between measured and calculated radiation the radiative forcing of mixed-phase clouds will be calculated.