Wet snow applications

The importance of snow wetness spans across several domains. Each of these domains can benefit significantly from accurate measurements and early warnings related to snow conditions. Some of most important are:

  • Avalanches: snow wetness is a critical factor in avalanche formation (wet snow avalanches being the most dangerous ones). Wet snow, often resulting from rising temperatures, can increase the likelihood of snow slides. Monitoring snow wetness can provide early warnings for potential avalanche conditions, thereby enhancing public safety in mountainous regions.
  • Floods: the melting of wet snow can contribute to flooding, particularly during the spring thaw in river basins. Timely information about snow wetness can aid in modelling/predicting flood risks, enabling better preparedness and response.
  • Agriculture/drought: in regions where agriculture relies on snowmelt for irrigation, the wetness of the snowpack indicates the potential water availability. Accurate monitoring can help predict water supply for irrigation, aiding in drought management and planning.
  • Ski industry: for the ski industry, snow conditions directly affect business. Knowledge of snow wetness helps in assessing the quality of the ski slopes and can inform snowmaking and grooming decisions.
  • Hydro power: hydroelectric power generation is often dependent on water from snowmelt. Understanding the snow wetness can assist in predicting the water flow available for power generation, optimizing resource management.
  • Meteorology: snow wetness has direct implications for weather forecasting. It affects local weather patterns, particularly in terms of temperature and humidity. Wet snow has different thermal properties compared to dry snow, influencing the local microclimate. Meteorologists use data about snow wetness to improve weather prediction models, which can be critical for preparing for extreme weather events, such as heavy snowfall, sudden thaws, and potential flooding.
  • Climate research: snow wetness is an important parameter in studying climate patterns and changes. The characteristics of snow, including its wetness, play a vital role in the Earth's energy balance. Snow reflects a significant amount of sunlight, and changes in snow wetness can affect this albedo effect, potentially leading to climate feedback loops. For example, wetter snow tends to have a lower albedo than dry snow, absorbing more heat and potentially contributing to faster melting and warming trends. Understanding these dynamics is very important for modeling and predicting climate change impacts.

Countries with significant mountains, or countries affected by mountains through rivers, are vulnerable to impacts from the seasonal snow cover. Larger parts of Europe is, therefore, vulnerable as they are affected from large amounts of snow falling in the Alps, the Carpathian and the Scandinavian Mountains.

Photo credit: unsplash.com.

Earth Observation (EO) data and Copernicus programe role

EO data, collected by satellites, provides comprehensive, real-time information about snow cover and conditions over large areas, which is difficult to achieve through ground-based observations alone.

The role of EO data in wet snow monitoring is pivotal. Satellites equipped with various sensors can detect changes in snow wetness, providing critical data that informs models and prediction systems. This data helps in making informed decisions in the aforementioned domains.

The Copernicus program, an EO initiative led by the European Union, plays a significant role in this context. It offers detailed and accurate EO data through its Sentinel satellites. These satellites are equipped with advanced sensors that can monitor Earth's surface, including snow-covered areas. The data from the Copernicus program is instrumental in understanding snow dynamics, including snow wetness. The program's consistent and freely available data is crucial for research, policy-making, and operational applications related to snow wetness in various sectors. WetSnow project is just one of the many evidences of the utility of Copernicus Sentinel data in real life situations.

Sentinel-2 image from 21.03.2023 depicting the snow cover in the Carpathian Mountains (Romania). Credit: Copernicus/Sentinel Hub.

WetSnow consortium approach

The algorithm used for generation the wet snow product uses the Sentinel-3 SLSTR (Sea and Land Surface Temperature Radiometer) instrument to retrieve information about snow grain size and snow surface temperature. The temporal development of these variables is also used. Melting snow drives the optical, effective grain size up significantly. The amount of liquid water in the snow surface is related to this observed grain size. The temperature measurements assures that there cannot be other processes, in particular surface hoar, that create the measured large snow grain size. Based on this, the algorithm infers five snow wetness categories: dry, moist, wet, very wet and soaked snow.

Example of snow wet evolution depicted with Sentinel-3 SLSTR data. Credit: NR.