National Science FoundationRain on Snow (ROS) events occur when rain falls onto an existing snowpack and freezes, forming an ice crust that can have severe consequences to wildlife, infrastructure, and communities. The Arctic Rain on Snow Study (AROSS) at NSIDC seeks to better observe and understand rain-on-snow (ROS) events. AROSS is funded by the National Science Foundation and will run from 2019 to 2024. The project team will develop a database of all known rain on snow events across the Arctic since 1979, and incorporate data from surface observations, satellite, and output from modeling.

Explore our interactive Rain on Snow Observations Map

Rain on snow observations map image

Why Rain on Snow Matters

Impacts from ROS events range from mild inconveniences, such an inability to travel to work or school, to severe consequences that result in the starvation of tens of thousands of animals, damage to infrastructure, and harm to communities. After a ROS event in 2013, more than 26,000 square kilometers (10,000 square miles) of ice blanketed parts of the Yamal Peninsula in Siberia, leading to the starvation of 61,000 reindeer. Some Nenets herders were stranded on the tundra. Others had to turn to full-time fishing and borrow breeding stock to rebuild their herds, a multiyear process.​ For communities that depend on the environment for their livelihoods and cultural identity, shifts to unpredictable and unseasonable weather events can have lasting effects that stretch across generations.

Indigenous hunters and community members provide key insights to the project through interviews, group discussions, and the Local Environmental Observer (LEO) Network to assess effects of ROS events on livelihoods and ecosystems. By gathering quantitative data, photos and videos, and first-hand accounts from individuals, the LEO Network collects reports of ROS and other notable environmental events.

Rain on snow event
This photograph shows ice crust layers after a massive dual-rain-on-snow event in November 2007 on the Yamal Penisula, Siberia, Russia. Credit: Florian Stammler

ROS events occur most often across the Arctic’s coastal regions. However, as climate change continues to raise Arctic temperatures, precipitation is projected to increase, with more falling as rain. There is also growing evidence that ROS events will stretch farther across the entire Arctic region.

AROSS gathers information on where and how these ROS and melt-refreeze events occur, noting their severity, frequency, and impacts. Detailed and comprehensive data can assist Arctic peoples and decisionmakers in mitigating the challenges that often accompany ROS events.

AROSS is a collaboration between NSIDC, the Cooperative Institute for Research in Environmental Sciences, the University of Colorado Boulder, the University of Winnipeg, the Alaska Pacific University, and the University of Lapland. The project also relies on observations and input from local Arctic communities and the LEO Network. It is funded for five years by the National Science Foundation’s Navigating the New Arctic program, which funds interdisciplinary research that informs our understanding of Arctic change and its local and global effects. While NSF funding of the project only lasts for five years, those involved anticipate AROSS being a “living project” that will extend far beyond this initial funding. Award number 1928230.

Collaborating Organizations

NSIDC CIRES CU Boulder Arctic Centre University of Lapland Alaska Pacific University LEO Network