TY - JOUR
T1 - Observations of Air-Sea Momentum Flux Variability Across the Inner Shelf
AU - Ortiz-Suslow, David G.
AU - Haus, Brian K.
AU - Williams, Neil J.
AU - Graber, Hans C.
AU - MacMahan, Jamie H.
N1 - Funding Information:
This work was sponsored by the Office of Naval Research via grants N00014-17-1-2800 and N00014-16-1-2196. This study would not have been possible without the support of Qing Wang of the Naval Postgraduate School and her research group, especially the efforts of Ryan Yamaguchi. The authors would like to thank Paul Jensen and Keith Wyckoff, who were both instrumental in the success of the field measurement component of this study. Thank you for the efforts of Mike Caruso and CSTARS of the University of Miami for processing the satellite imagery presented here. Thank you to Nathan Laxague for helpful discussions in conceptualizing some of the findings presented here. The feedback of three anonymous reviewers was greatly appreciated and helped to improve the quality of this article. The data presented here are available from the University of Miami Scholarly Repository by following https://doi.org/10.17604/ab2d-rg72.
Funding Information:
This work was sponsored by the Office of Naval Research via grants N00014-17-1-2800 and N00014-16-1-2196. This study would not have been possible without the support of Qing Wang of the Naval Postgraduate School and her research group, especially the efforts of Ryan Yamaguchi. The authors would like to thank Paul Jensen and Keith Wyckoff, who were both instrumental in the success of the field measurement component of this study. Thank you for the efforts of Mike Caruso and CSTARS of the University of Miami for processing the satellite imagery presented here. Thank you to Nathan Laxague for helpful discussions in conceptualizing some of the findings presented here. The feedback of three anonymous reviewers was greatly appreciated and helped to improve the quality of this article. The data presented here are available from the University of Miami Scholarly Repository by following https://doi. org/10.17604/ab2d-rg72.
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/12
Y1 - 2018/12
N2 - Over the open ocean, the aerodynamic drag coefficient is typically well predicted; however, the impact depth-limited processes have on the drag remains underexplored. A case study is presented here where winds, waves, and currents were simultaneously observed from a mobile platform that repeatedly transected the inner shelf of Monterey Bay, CA. Eddy covariance-derived drag coefficients were compared to several bulk parameterizations, including all of the roughness variations of COARE 3.5 and two explicitly depth-limited models. The analysis demonstrated that the drag was underestimated by O(2–4) times and the variability with wind speed or cross-shore distance was not well predicted. The drag based on a recent depth-limited roughness length model performed substantially better than the rest of the bulk estimates, which were all within 15% of each other and effectively equivalent given typical operational uncertainties. The measured friction velocity was compared to a wave-dependent parameterization and generalizing the model to arbitrary water depth significantly improved the mean observation-model difference to within 30%. Latent variability in the observation-model comparison was associated with stability, wind direction, and wave steepness. The wind stress angle variability was also analyzed. Stress veering was correlated with the alongshore surface current within 2 km from shore (r 2 = 0.7–0.95, p < 0.05); offshore of this margin, consistent wind stress veering was observed and may be attributable to a secondary, low-frequency swell system. These results demonstrate that it remains a persistent challenge to accurately predict wind stress variability in the nearshore, especially at locations with complex wave and current fields.
AB - Over the open ocean, the aerodynamic drag coefficient is typically well predicted; however, the impact depth-limited processes have on the drag remains underexplored. A case study is presented here where winds, waves, and currents were simultaneously observed from a mobile platform that repeatedly transected the inner shelf of Monterey Bay, CA. Eddy covariance-derived drag coefficients were compared to several bulk parameterizations, including all of the roughness variations of COARE 3.5 and two explicitly depth-limited models. The analysis demonstrated that the drag was underestimated by O(2–4) times and the variability with wind speed or cross-shore distance was not well predicted. The drag based on a recent depth-limited roughness length model performed substantially better than the rest of the bulk estimates, which were all within 15% of each other and effectively equivalent given typical operational uncertainties. The measured friction velocity was compared to a wave-dependent parameterization and generalizing the model to arbitrary water depth significantly improved the mean observation-model difference to within 30%. Latent variability in the observation-model comparison was associated with stability, wind direction, and wave steepness. The wind stress angle variability was also analyzed. Stress veering was correlated with the alongshore surface current within 2 km from shore (r 2 = 0.7–0.95, p < 0.05); offshore of this margin, consistent wind stress veering was observed and may be attributable to a secondary, low-frequency swell system. These results demonstrate that it remains a persistent challenge to accurately predict wind stress variability in the nearshore, especially at locations with complex wave and current fields.
KW - Monterey Bay
KW - air-sea interaction
KW - field measurements
KW - inner shelf
KW - nearshore processes
KW - shoaling waves
UR - http://www.scopus.com/inward/record.url?scp=85058241820&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85058241820&partnerID=8YFLogxK
U2 - 10.1029/2018JC014348
DO - 10.1029/2018JC014348
M3 - Article
AN - SCOPUS:85058241820
VL - 123
SP - 8970
EP - 8993
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
SN - 2169-9291
IS - 12
ER -