Finnish researchers estimate snow amount in Northern Hemisphere

For the first time in the world, researchers from the Finnish Meteorological Institute (FMI) have reliably estimated the amount of annual snow mass and changes in snow cover in the Northern Hemisphere between 1980 and 2018, said a press release of FMI.

According to the study published in the Nature scientific journal, during the research period snow mass has remained the same in Eurasia and decreased in North America, although the extent of snow cover has decreased simultaneously in both continental regions.

The amount of snow and the changes in it are determined by satellite observations and measurements made from the ground. In the past, estimates of the amount of snow in the northern latitudes have varied so much that it has not been possible to obtain a coherent and reliable overall picture of the amount of snow.

"The method can be used to combine different observations and it provides more accurate information about the amount of snow than ever before. The previous considerable uncertainty of 33% in the amount of snow has decreased to 7.4%," said Jouni Pulliainen, the main contributor to the article and Research Professor of FMI.

The amount of snow cover and its changes affect the climate system and freshwater reserves. More detailed data will enable a better assessment of the role of seasonal snow in the carbon dioxide and methane cycles and water resources. The data can also be used to improve the quality of weather forecasts and provide more accurate information on flood risks.

In addition, a more accurate historical time series can be used to analyse and develop the reliability of climate models.

The researchers found that there has been little reduction in snow mass over the 40 years in the northern hemisphere when looking at the annual maximum amount of snow at the turn of February-March.

However, the extent of the snow cover has decreased significantly over the same period, especially in late spring. The change in the extent of snow cover is visible both on the entire northern hemisphere and in the Arctic.

"In the past, estimates of global and regional snowfall trends have only been indicative. The results show that the amount of rainfall has increased in the northern regions, especially in the northern parts of Asia," Pulliainen said.