Research Summaries

Back Quantifying the Role of Atmospheric Forcing in Ice Edge Retreat and Advance Including Wind-Wave Coupling

Fiscal Year 2013
Division Graduate School of Engineering & Applied Science
Department Meteorology
Investigator(s) Guest, Peter S.
Sponsor Office of Naval Research (Navy)
Summary The fluxes of momentum (wind stress), sensible heat (turbulence and radiation) and latent heat (moisture and salinity), between the atmosphere and ocean have strong effects on sea state and oceanic boundary layer (OBL) physics in the Beaufort and Chukchi seas (BCS), and throughout the world ocean. Any attempt to understand sea state and the OBL needs to consider these air-ocean interactions, which include the poorly-understood pressure momentum transport over waves. A critical process needing predictive capability is how the sea ice in the BCS will behave on short time scales (for operational predictions) and in the future (for planning Navy and societal needs); understanding the role of surface fluxes is crucial for this. This proposal addresses that need with a plan to deploy state-of-the-art flux and related parameter sensors on a vessel with researchers who will be simultaneously performing oceanographic measurements. The proposed measurements include (1) direct measurements of all these important fluxes, including the pressure terms, (2) direct measurements of the sea state using laser altimetry and (3) supporting measurements of atmospheric boundary layer and cloud parameters. Similar measurements have been performed in the past, what makes these so important for the success of the current BAA?
(1) Studies of sea state and OBL physics need the context of the mechanisms driving these processes; the interactions with the atmosphere are arguably the most significant of these driving mechanisms. Only by performing the atmospheric measurements on the same ship as the oceanographic measurements resulting from this BAA can this context be fully realized.
(2) Despite previous measurements, there are considerable uncertainties on the role of atmospheric fluxes for sea state and OBL physics in the BCS and, in particular, the associated effects on the sea ice cover. For example, with respect to ice freeze-up and ice retreat, the relative importance of longwave cooling vs. air turbulent fluxes vs. ocean heat flux from below is not known. Researchers also don't fully understand the role of sea state and clouds in these processes.
(3) Only recently have fast response pressure sensors been available to quantify the effect of pressure transport on wind stress, and hence, sea state and OBL momentum. There are no published studies of open ocean observations of wave-pressure effects, including the spectral behavior. Other flux sensors and also inertial systems have been recently improved for shipboard use, allowing more accurate quantifications than have been available in the past.
Why does this work need to be performed by multiple PIs and institutions?
Performing experiments in the Arctic is logistically challenging and inherently expensive. By pooling equipment, and technical and scientific expertise, the proposed effort represents the most cost-effective way to address the critical issues associated with understanding and predicting the role of atmospheric fluxes on sea state, OBL physics and ice conditions in the BCS. The PIs and their technical support staffs have a long history of participating in field programs from open ocean ships, in polar regions (ship, ice camp and aircraft) and being at the forefront of relevant published studies.
Finally, by enabling US Navy officer/students at the Naval Postgraduate School to participate in this research, the proposed effort will be a make an investment in the Navy's intellectual capital as Arctic surface operations likely become more common in the expected reduced-ice conditions of the future.
Publications Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal
Data Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal