ABSTRACT

Seasonal alpine snow contributes significantly to the water resource. It plays a crucial role in regulating the environmental feedback and from the perspective of socio-economic sustainability in the alpine regions. While most nations are pursuing renewable energy sources, hydropower generated from snowmelt runoff is one of the primary sources. Additionally, alpine regions with snow cover are major tourist destinations that are often affected by natural disasters such as avalanches. The snowmelt runoff and early avalanche warning require timely information on the spatio-temporal aspects of the snow geophysical parameters. In this regard, advances in remote sensing of snow have been observed to be significant. Recent developments in remote sensing technology in the visible, infrared, and microwave spectrum have significantly improved our understanding of snow geophysical processes. This paper provides a review concerning the qualitative and quantitative studies of alpine snow. The electromagnetic characteristics of the alpine snow are largely dependent upon its inherent geophysical structure and the properties of the snow. Snow behaves differently with respect to the wavelength of the incident radiation. In this paper, we provide a categorical review of the remote sensing techniques for estimating the snow geophysical properties, inclusive of permittivity, density, and wetness corresponding to the wavelength used in the remotely sensed data: (1) visible-infrared spectrum including multispectral/hyperspectral, (2) active and passive microwave spectrums. We also discuss the recent advancements in the remote sensing techniques for approximating the volumetric snowpack parameters such as the snow depth and the snow water equivalent based on active and passive microwave remote sensing. This review further discusses the limitations of the techniques reviewed and future prospects for the retrieval of snow geophysical parameters (SGP) corresponding to the recent progress in remote sensing technology. In summary, the recent advances have laid down a foundation for rigorous assessment of seasonal snow using spaceborne remote sensing, particularly at a regional scale. Yet, the scope for improvements in the methods and payload design exists.

摘要

季节性高山积雪对水资源的贡献很大。从高寒地区的社会经济可持续性的角度来看，它在调节环境反馈方面起着至关重要的作用。虽然大多数国家都在寻求可再生能源，但融雪径流产生的水力发电是主要来源之一。此外，积雪覆盖的高山地区是主要的旅游目的地，经常受到雪崩等自然灾害的影响。融雪径流和早期雪崩预警需要有关雪地球物理参数时空方面的及时信息。在这方面，已经观察到雪遥感方面的进展是显着的。可见光、红外、和微波频谱显着提高了我们对雪地球物理过程的理解。本文对高山积雪的定性和定量研究进行了综述。高山雪的电磁特性在很大程度上取决于其固有的地球物理结构和雪的特性。雪在入射辐射的波长方面表现不同。在本文中，我们对用于估计雪地球物理特性的遥感技术进行了分类回顾，包括与遥感数据中使用的波长相对应的介电常数、密度和湿度：(1) 可见红外光谱，包括多光谱/高光谱，（2）主动和被动微波光谱。我们还讨论了基于主动和被动微波遥感来近似体积积雪参数（如积雪深度和雪水当量）的遥感技术的最新进展。本综述进一步讨论了所审查技术的局限性以及与遥感技术的最新进展相对应的雪地球物理参数 (SGP) 反演的未来前景。总之，最近的进展为使用星载遥感对季节性降雪进行严格评估奠定了基础，特别是在区域范围内。然而，方法和有效载荷设计仍有改进的余地。本综述进一步讨论了所审查技术的局限性以及与遥感技术的最新进展相对应的雪地球物理参数 (SGP) 反演的未来前景。总之，最近的进展为使用星载遥感对季节性降雪进行严格评估奠定了基础，特别是在区域范围内。然而，方法和有效载荷设计仍有改进的余地。本综述进一步讨论了所审查技术的局限性以及与遥感技术的最新进展相对应的雪地球物理参数 (SGP) 反演的未来前景。总之，最近的进展为使用星载遥感对季节性降雪进行严格评估奠定了基础，特别是在区域范围内。然而，方法和有效载荷设计仍有改进的余地。