The Role of Melting Snow in the Ocean Surface Heat Budget

Abstract

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 À10 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 ; 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.

Using CloudSat‐CPR Retrievals to Estimate Snow Accumulation in the Canadian Arctic

“…Estimates of snowfall rate from individual profiles have been shown to include uncertainties of up to 150–250% from a combination of features of CloudSat's retrieved precipitation state, particle model parameters, fallspeed model, and assumptions about cloud particle distributions (Duffy & Bennartz, ; Wood & L'Ecuyer, ). However, previous work by Hiley et al () and Palerme et al () has shown that by aggregating a representative sample of discrete CloudSat profiles along the track into an “overpass average” snowfall rate, the uncertainty is considerably reduced, and the signal‐to‐noise ratio is increased.…”

Parsing Synthetic Aperture Radar Measurements of Snow in Complex Terrain: Scaling Behaviour and Sensitivity to Snow Wetness and Landcover

“…Seasonal snow-covered area (SCA) plays an important role in the Earth's water cycle. SCA inter-annual variability is tied to the Earth's climate because its high surface albedo governs the energy exchange between the land surface and the atmosphere in the cold regions of the world [1][2][3][4], where seasonal snowpacks represent the most important freshwater resource (quantified as snow water equivalent SWE). Natural hazards in regions of complex terrain such as avalanches and spring flash-floods often occur during the transition from snow-on to snow-free conditions [5][6][7].…”

Satellite Remote Sensing of Precipitation and the Terrestrial Water Cycle in a Changing Climate

“…A better quantification of snowfall at high latitudes [184] and on a global scale [176] will also contribute to unravelling the controversy around the impact of Arctic warming on increased rainfall/snowfall [185] and, more generally, to explaining the differences in model projections between the southern and northern hemispheres and wet and dry regions [186]. It will also help examine the impact of excluding precipitating ice on atmospheric radiative fluxes and heating rates in climate models [187] and estimate the cooling flux from snow melting in the ocean [188].…”