资源环境科技发展态势分析平台

We estimate the cooling flux from snow melting in the ocean through CloudSat satellite snowfall retrievals and reanalysis data. For snowfall events with less than 0.01 mm/hr, this flux is inconsequential. Melting snow begins to compete with other ocean surface heat fluxes as snowfall rates increase beyond 0.1 mm/hr, and it may often become the dominant heat flux as snowfall rates approach and exceed 1 mm/hr. The largest monthly average values of the melting snow cooling flux occur in winter months, approaching -10 W/m(2) in both hemispheres. To determine the regional influence of melting snow on a seasonal basis, we calculate an impact metric that gauges the cooling flux of melting snow against the net flux in the ocean. This metric can be between 20% and 30% in the Northern Hemisphere during March, April, May; the Southern Ocean during March, April, May and September, October, November; and in high-latitude polar oceans during sea ice freeze up seasons.

Plain Language Summary Climate scientists are very interested in understanding how much heat is entering and leaving the ocean, as this heat budget has important connections to the weather, ocean, and ice patterns that are crucial to life as we know it. Melting snow cools the ocean surface, but this effect has not been studied as much as heat exchanges from wind or sunlight. Using satellites and weather models, we determine how much melting snow cools the ocean. The cooling from snowmelt is most often inconsequential, since most snowfall is light. During heavy snowstorms, however, the cooling from melting snow can become quite powerful, perhaps becoming the most powerful cooling source in the ocean at times. Melting snow also has a large impact on the ocean heat budget in polar oceans during sea ice freeze up seasons. This is an important result, as the loss of sea ice is one of the most visible and concerning signs of climate change today. Ultimately, we find that melting snow can be a powerful and influential cooling force in the ocean but only under appropriate circumstances.