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  • Author or Editor: Albert Plueddemann x
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Robert A. Weller
,
Roger Lukas
,
James Potemra
,
Albert J. Plueddemann
,
Chris Fairall
, and
Sebastien Bigorre

Abstract

There is great interest in improving our understanding of the respective roles of the ocean and atmosphere in variability and change in weather and climate. Due to the sparsity of sustained observing sites in the open ocean, information about the air–sea exchanges of heat, freshwater, and momentum is often drawn from models. In this paper observations from three long-term surface moorings deployed in the trade wind regions of the Pacific and Atlantic Oceans are used to compare observed means and low-passed air–sea fluxes from the moorings with coincident records from three atmospheric reanalyses (ERA5, NCEP-2, and MERRA-2) and from CMIP6 coupled models. To set the stage for the comparison, the methodologies of maintaining the long-term surface moorings, known as ocean reference stations (ORS), and assessing the accuracies of their air–sea fluxes are described first. Biases in the reanalyses’ means and low-passed wind stresses and net air–sea heat fluxes are significantly larger than the observational uncertainties and in some case show variability in time. These reanalyses and most CMIP6 models fail to provide as much heat into the ocean as observed. In the discussion and conclusions section, long-term observing sites in the open ocean are seen as essential, independent benchmarks not only to document the coupling between the atmosphere and ocean but also to promote collaborative efforts to assess and improve the ability of models to simulate air–sea fluxes.

Full access
James Edson
,
Timothy Crawford
,
Jerry Crescenti
,
Tom Farrar
,
Nelson Frew
,
Greg Gerbi
,
Costas Helmis
,
Tihomir Hristov
,
Djamal Khelif
,
Andrew Jessup
,
Haf Jonsson
,
Ming Li
,
Larry Mahrt
,
Wade McGillis
,
Albert Plueddemann
,
Lian Shen
,
Eric Skyllingstad
,
Tim Stanton
,
Peter Sullivan
,
Jielun Sun
,
John Trowbridge
,
Dean Vickers
,
Shouping Wang
,
Qing Wang
,
Robert Weller
,
John Wilkin
,
Albert J. Williams III
,
D. K. P. Yue
, and
Chris Zappa

The Office of Naval Research's Coupled Boundary Layers and Air–Sea Transfer (CBLAST) program is being conducted to investigate the processes that couple the marine boundary layers and govern the exchange of heat, mass, and momentum across the air–sea interface. CBLAST-LOW was designed to investigate these processes at the low-wind extreme where the processes are often driven or strongly modulated by buoyant forcing. The focus was on conditions ranging from negligible wind stress, where buoyant forcing dominates, up to wind speeds where wave breaking and Langmuir circulations play a significant role in the exchange processes. The field program provided observations from a suite of platforms deployed in the coastal ocean south of Martha's Vineyard. Highlights from the measurement campaigns include direct measurement of the momentum and heat fluxes on both sides of the air–sea interface using a specially constructed Air–Sea Interaction Tower (ASIT), and quantification of regional oceanic variability over scales of O(1–104 mm) using a mesoscale mooring array, aircraft-borne remote sensors, drifters, and ship surveys. To our knowledge, the former represents the first successful attempt to directly and simultaneously measure the heat and momentum exchange on both sides of the air–sea interface. The latter provided a 3D picture of the oceanic boundary layer during the month-long main experiment. These observations have been combined with numerical models and direct numerical and large-eddy simulations to investigate the processes that couple the atmosphere and ocean under these conditions. For example, the oceanic measurements have been used in the Regional Ocean Modeling System (ROMS) to investigate the 3D evolution of regional ocean thermal stratification. The ultimate goal of these investigations is to incorporate improved parameterizations of these processes in coupled models such as the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) to improve marine forecasts of wind, waves, and currents.

Full access
Tim Boyer
,
Huai-Min Zhang
,
Kevin O’Brien
,
James Reagan
,
Stephen Diggs
,
Eric Freeman
,
Hernan Garcia
,
Emma Heslop
,
Patrick Hogan
,
Boyin Huang
,
Li-Qing Jiang
,
Alex Kozyr
,
Chunying Liu
,
Ricardo Locarnini
,
Alexey V. Mishonov
,
Christopher Paver
,
Zhankun Wang
,
Melissa Zweng
,
Simone Alin
,
Leticia Barbero
,
John A. Barth
,
Mathieu Belbeoch
,
Just Cebrian
,
Kenneth J. Connell
,
Rebecca Cowley
,
Dmitry Dukhovskoy
,
Nancy R. Galbraith
,
Gustavo Goni
,
Fred Katz
,
Martin Kramp
,
Arun Kumar
,
David M. Legler
,
Rick Lumpkin
,
Clive R. McMahon
,
Denis Pierrot
,
Albert J. Plueddemann
,
Emily A. Smith
,
Adrienne Sutton
,
Victor Turpin
,
Long Jiang
,
V. Suneel
,
Rik Wanninkhof
,
Robert A. Weller
, and
Annie P. S. Wong

Abstract

The years since 2000 have been a golden age in in situ ocean observing with the proliferation and organization of autonomous platforms such as surface drogued buoys and subsurface Argo profiling floats augmenting ship-based observations. Global time series of mean sea surface temperature and ocean heat content are routinely calculated based on data from these platforms, enhancing our understanding of the ocean’s role in Earth’s climate system. Individual measurements of meteorological, sea surface, and subsurface variables directly improve our understanding of the Earth system, weather forecasting, and climate projections. They also provide the data necessary for validating and calibrating satellite observations. Maintaining this ocean observing system has been a technological, logistical, and funding challenge. The global COVID-19 pandemic, which took hold in 2020, added strain to the maintenance of the observing system. A survey of the contributing components of the observing system illustrates the impacts of the pandemic from January 2020 through December 2021. The pandemic did not reduce the short-term geographic coverage (days to months) capabilities mainly due to the continuation of autonomous platform observations. In contrast, the pandemic caused critical loss to longer-term (years to decades) observations, greatly impairing the monitoring of such crucial variables as ocean carbon and the state of the deep ocean. So, while the observing system has held under the stress of the pandemic, work must be done to restore the interrupted replenishment of the autonomous components and plan for more resilient methods to support components of the system that rely on cruise-based measurements.

Open access