In the present paper, the climate cooling potential of technical snow making on ski slopes is investigated with regard to radiative forcing. It is well-known, that snow shows a higher degree of reflection compared to other ground surfaces. During snow-poor winters, guaranteeing snow covered ski slopes by using snow making may therefore lead to an increase in the albedo of a mountainous region. Since increasing albedo engenders a negative radiative forcing, the cooling potential of snow production on ski slopes is of particular relevance in the context of the current climate debate. Investigations were however generally performed for flat surfaces. Several studies nevertheless demonstrated that the topography leads to a substantial decrease in the mean albedo of a given region. This is attributable to shading effects and to slope inclinations.

The present study was therefore dedicated to the accurate simulation of the impact of the albedo increase of ski slopes on the mean albedo and on the resulting change in shortwave radiative budget of a chosen mountainous region. We used therefore a state of the art 3-dimensional radiative transfer model. The investigations were carried out for the skiing area Saalbach-Hinterglemm in Austria. Broadband snow albedo values between 0.61 and 0.62 in cloudless conditions and 0.64 and 0.65 in cloudy conditions for solar zenith angle (sza) between 30 and 80 degrees were used for the simulations. An uncertainty of ±0.17 was taken into account. First a sensitivity study was performed, that showed a substantial decrease in the mean albedo of the ski slopes as a function of slope inclination. A strong impact of topography and of surrounding trees on the mean albedo of the ski slopes of up to 40% and 14% respectively was found at high sza under clear sky conditions. Compared to snow free conditions an increase in albedo between 0.18 and 0.36 was observed, the higher values for smaller sza and assuming no trees in the surroundings. Only related to the ski slopes a radiative forcing between −7 and −35 W/m² was obtained. If the long-term snow cover conditions were taken into account, snow making lead to a change in albedo, only, in March and April. The increase in albedo was just below 0.10 in April and 0.02 in March, resulting in a radiative forcing around −12 W/m² and around −1.5 W/m² respectively. Though, in order to analyze an eventual cooling effect on climate the whole carbon footprint related to the production of technical snow making shall be determined.

在本文中，就辐射强迫研究了滑雪场技术造雪的气候降温潜力。众所周知，与其他地面相比，雪具有更高的反射度。因此，在积雪不足的冬季，通过造雪确保积雪覆盖的滑雪场可能会导致山区反照率增加。由于反照率的增加会产生负的辐射强迫，因此在当前气候辩论的背景下，滑雪场积雪的降温潜力尤为重要。然而，通常对平坦的表面进行研究。尽管如此，一些研究表明，地形导致给定区域的平均反照率大大降低。这归因于阴影效应和倾斜度。

因此，本研究致力于精确模拟滑雪坡度的反照率增加对平均反照率的影响以及所选山区短波辐射收支的最终变化。因此，我们使用了最先进的3维辐射传递模型。调查是针对奥地利Saalbach-Hinterglemm滑雪场进行的。对于30至80度之间的太阳天顶角（sza），在无云条件下的宽带雪反照率值在0.61至0.62之间，在阴天条件下的宽带雪反照率值在0.64至0.65之间。考虑了±0.17的不确定度。首先进行了敏感性研究，结果表明，滑雪坡的平均反照率随坡度的变化而显着降低。在晴朗的天空条件下，在高海拔地区，地形和周围树木对分别高达40％和14％的滑雪坡平均反照率的影响很大。与无雪条件相比，观察到反照率增加了0.18至0.36，较小的sza值较高，并且假设周围没有树木，则反照率较高。仅与滑雪坡有关，辐射强迫在-7和-35 W / m之间获得²。如果考虑到长期的积雪条件，则造雪只会导致三月和四月反照率发生变化。4月的反照率增加刚好低于0.10，3月的反照率增加仅为0.02，导致辐射强迫分别约为-12 W / m ²和-1.5 W / m ²。但是，为了分析最终的降温对气候的影响，应确定与技术造雪生产有关的全部碳足迹。