On the Increasing Importance of Air-Sea Exchanges in a Thawing Arctic: A Review

Abstract

Forty years ago, climate scientists predicted the Arctic to be one of Earth's most sensitive climate regions and thus extremely vulnerable to increased CO 2 . The rapid and unprecedented changes observed in the Arctic confirm this prediction. Especially significant, observed sea ice loss is altering the exchange of mass, energy, and momentum between the Arctic Ocean and atmosphere.As an important component of air-sea exchange, surface turbulent fluxes are controlled by vertical gradients of temperature and humidity between the surface and atmosphere, wind speed, and surface roughness, indicating that they respond to other forcing mechanisms such as atmospheric advection, ocean mixing, and radiative flux changes. The exchange of energy between the atmosphere and surface via surface turbulent fluxes in turn feeds back on the Arctic surface energy budget, sea ice, clouds, boundary layer temperature and humidity, and atmospheric and oceanic circulations. Understanding and attributing variability and trends in surface turbulent fluxes is important because they influence the magnitude of Arctic climate change, sea ice cover variability, and the atmospheric circulation response to increased CO 2 . This paper reviews current knowledge of Arctic Ocean surface turbulent fluxes and their effects on climate. We conclude that Arctic Ocean surface turbulent fluxes are having an increasingly consequential influence on Arctic climate variability in response to strong regional trends in the air-surface temperature contrast related to the changing character of the Arctic sea ice cover. Arctic Ocean surface turbulent energy exchanges are not smooth and steady but rather irregular and episodic, and consideration of the episodic nature of surface turbulent fluxes is essential for improving Arctic climate projections.

Cloud Response to Arctic Sea Ice Loss and Implications for Future Feedback in the CESM1 Climate Model

“…When the Sun sets in the fall, the atmosphere cools down faster than the ocean. As a result, more latent and sensible heat is released from the open ocean to the cooling fall atmosphere (as has been shown in many studies including Deser et al (2010), Manabe & Stouffer (1980), and Taylor et al (2018)). Increasing latent and sensible heat fluxes promote fall cloud formation over open water.…”

Resolving Future Arctic/Midlatitude Weather Connections

“…Three regions stand out: the Chukchi Sea northwest of Alaska, Baffin Bay/northern Hudson Bay, and the Barents/Kara Seas north of western Russia, with sea-ice concentration reductions of over 40% over the period of the satellite record. These regions represent new extended periods of open water, increased regional temperatures (Taylor et al, 2018), and reduced vertical stratification in the atmosphere (Jaiser et al, 2012). We concentrate on early winter North American potential connections.…”

Space‐Based Observations for Understanding Changes in the Arctic‐Boreal Zone

“…However, all indications are that significant changes are occurring during fall and winter in the regions of the Arctic Ocean that are experiencing delayed sea ice freeze onset (Barents‐Kara Sea and Beaufort Chukchi Sea regions). These trends are supported by both satellite retrievals of surface turbulent fluxes (Boisvert et al, ; Taylor et al, ) and from meteorological reanalysis (Screen & Simmonds, ). The significance of ABZ energy budget changes and their central role in understanding and credibly predicting ABZ climate change warrants long‐term, high quality observations of these variables.…”

“…Since permanent surface sites are confined to land, periodic suborbital observations over the Arctic Ocean are needed to constrain the ABZ surface energy budget. These periodic suborbital missions take the shape of airborne campaigns, ice camps, drifting stations, and buoys (e.g., Rigor et al, ; Taylor et al, ). More than 20 suborbital field campaigns have provided surface energy budget observations across the ABZ since 1975.…”

“…More recently, the Arctic Radiation IceBridge Sea ice Experiment (ARISE; Smith et al, ) took place in September 2014 as a radiation‐focused mission designed to evaluate CERES radiative fluxes and provide data to understand how cloud radiative effects are influencing the ABZ surface energy budget over sea ice. Readers are referred to Taylor et al () for a more complete list of ABZ field missions gathering surface energy budget data. More campaigns like ARISE and SHEBA are needed to accumulate the statistics required to reduce uncertainty in our understanding and our ABZ surface energy budget data sets.…”