scholarly journals A framework to evaluate and elucidate the driving mechanisms of coastal sea surface <i>p</i>CO<sub>2</sub> seasonality using an ocean general circulation model (MOM6-COBALT)

Ocean Science ◽  
2022 ◽  
Vol 18 (1) ◽  
pp. 67-88
Author(s):  
Alizée Roobaert ◽  
Laure Resplandy ◽  
Goulven G. Laruelle ◽  
Enhui Liao ◽  
Pierre Regnier
Keyword(s):  
Biological Activity ◽  
Surface Temperature ◽  
Ocean Circulation ◽  
East Coast ◽  
Coastal Ocean ◽  
Sea Surface ◽  
Coastal Environments ◽  
Coastal Regions ◽  
Thermal Changes ◽  
Us East Coast

Abstract. The temporal variability of the sea surface partial pressure of CO2 (pCO2) and the underlying processes driving this variability are poorly understood in the coastal ocean. In this study, we tailor an existing method that quantifies the effects of thermal changes, biological activity, ocean circulation and freshwater fluxes to examine seasonal pCO2 changes in highly variable coastal environments. We first use the Modular Ocean Model version 6 (MOM6) and biogeochemical module Carbon Ocean Biogeochemistry And Lower Trophics version 2 (COBALTv2) at a half-degree resolution to simulate coastal CO2 dynamics and evaluate them against pCO2 from the Surface Ocean CO2 Atlas database (SOCAT) and from the continuous coastal pCO2 product generated from SOCAT by a two-step neuronal network interpolation method (coastal Self-Organizing Map Feed-Forward neural Network SOM-FFN, Laruelle et al., 2017). The MOM6-COBALT model reproduces the observed spatiotemporal variability not only in pCO2 but also in sea surface temperature, salinity and nutrients in most coastal environments, except in a few specific regions such as marginal seas. Based on this evaluation, we identify coastal regions of “high” and “medium” agreement between model and coastal SOM-FFN where the drivers of coastal pCO2 seasonal changes can be examined with reasonable confidence. Second, we apply our decomposition method in three contrasted coastal regions: an eastern (US East Coast) and a western (the Californian Current) boundary current and a polar coastal region (the Norwegian Basin). Results show that differences in pCO2 seasonality in the three regions are controlled by the balance between ocean circulation and biological and thermal changes. Circulation controls the pCO2 seasonality in the Californian Current; biological activity controls pCO2 in the Norwegian Basin; and the interplay between biological processes and thermal and circulation changes is key on the US East Coast. The refined approach presented here allows the attribution of pCO2 changes with small residual biases in the coastal ocean, allowing for future work on the mechanisms controlling coastal air–sea CO2 exchanges and how they are likely to be affected by future changes in sea surface temperature, hydrodynamics and biological dynamics.

scholarly journals A framework to evaluate and elucidate the driving mechanisms of coastal sea surface pCO<sub>2</sub> seasonality using an ocean general circulation model (MOM6-COBALT)

2021 ◽  
Author(s):  
Alizée Roobaert ◽  
Laure Resplandy ◽  
Goulven Gildas Laruelle ◽  
Enhui Liao ◽  
Pierre Regnier
Keyword(s):  
Biological Activity ◽  
Ocean Circulation ◽  
Temporal Variability ◽  
East Coast ◽  
Coastal Ocean ◽  
Sea Surface ◽  
Coastal Environments ◽  
Coastal Regions ◽  
Thermal Changes ◽  
The U.S

Abstract. The temporal variability of the sea surface partial pressure of CO2 (pCO2) and the underlying processes driving this variability are poorly understood in the coastal ocean. In this study, we tailor an existing method that quantifies the effects of thermal changes, biological activity, ocean circulation and fresh water fluxes to examine seasonal pCO2 changes in highly-variable coastal environments. We first use the Modular Ocean Model version 6 (MOM6) and biogeochemical module Carbon Ocean Biogeochemistry And Lower Trophics version 2 (COBALTv2) at a half degree resolution to simulate the coastal CO2 dynamics and evaluate it against pCO2 from the Surface Ocean CO2 Atlas database (SOCAT) and from the continuous coastal pCO2 product generated from SOCAT by a two-step neuronal network interpolation method (coastal-SOM-FFN, Laruelle et al., 2017). The MOM6-COBALT model not only reproduces the observed spatio-temporal variability in pCO2 but also in sea surface temperature, salinity, nutrients, in most coastal environments except in a few specific regions such as marginal seas. Based on this evaluation, we identify coastal regions of ‘high’ and ‘medium’ model skill where the drivers of coastal pCO2 seasonal changes can be examined with reasonable confidence. Second, we apply our decomposition method in three contrasted coastal regions: an Eastern (East coast of the U.S) and a Western (the Californian Current) boundary current and a polar coastal region (the Norwegian Basin). Results show that differences in pCO2 seasonality in the three regions are controlled by the balance between ocean circulation, biological and thermal changes. Circulation controls the pCO2 seasonality in the Californian Current, biological activity controls pCO2 in the Norwegian Basin, while the interplay between biology, thermal and circulation changes is key in the East coast of the U.S. The refined approach presented here allows the attribution of pCO2 changes with small residual biases in the coastal ocean, allowing future work on the mechanisms controlling coastal air-sea CO2 exchanges and how they are likely to be affected by future changes in sea surface temperature, hydrodynamics and biological dynamics.

scholarly journals Long-Term Sea Surface Temperature Variability along the U.S. East Coast

2010 ◽  
Vol 40 (5) ◽  
pp. 1004-1017 ◽  
Author(s):  
R. Kipp Shearman ◽  
Steven J. Lentz
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
East Coast ◽  
Atmospheric Temperature ◽  
Coastal Ocean ◽  
Temperature Trend ◽  
Sea Surface ◽  
Temperature Trends ◽  
Cape Hatteras

Abstract Sea surface temperature variations along the entire U.S. East Coast from 1875 to 2007 are characterized using a collection of historical observations from lighthouses and lightships combined with recent buoy and shore-based measurements. Long-term coastal temperature trends are warming in the Gulf of Maine [1.0° ± 0.3°C (100 yr)−1] and Middle Atlantic Bight [0.7° ± 0.3°C (100 yr)−1], whereas trends are weakly cooling or not significant in the South Atlantic Bight [−0.1° ± 0.3°C (100 yr)−1] and off Florida [−0.3° ± 0.2°C (100 yr)−1]. Over the last century, temperatures along the northeastern U.S. coast have warmed at a rate 1.8–2.5 times the regional atmospheric temperature trend but are comparable to warming rates for the Arctic and Labrador, the source of coastal ocean waters north of Cape Hatteras (36°N). South of Cape Hatteras, coastal ocean temperature trends match the regional atmospheric temperature trend. The observations and a simple model show that along-shelf transport, associated with the mean coastal current system running from Labrador to Cape Hatteras, is the mechanism controlling long-term temperature changes for this region and not the local air–sea exchange of heat.

Long-Term Variations of the Sea Surface Temperature in the East Coast of Korea

2014 ◽  
Vol 20 (6) ◽  
pp. 601-608 ◽  
Author(s):  
Sang-Woo Kim ◽  
◽  
Jin-Wook Im ◽  
Byung-Sun Yoon ◽  
Hee-Dong Jeong ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
East Coast ◽  
Sea Surface ◽  
Long Term Variations

Local and remote causes of the equatorial Pacific cold sea surface temperature bias in the Kiel Climate Model

2020 ◽  
Author(s):  
Yuming Zhang ◽  
Tobias Bayr ◽  
Mojib Latif ◽  
Zhaoyang Song ◽  
Wonsun Park ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Ocean Circulation ◽  
Climate Model ◽  
Coupled Model ◽  
Equatorial Pacific ◽  
Ocean Dynamics ◽  
Sea Surface ◽  
Sst Bias ◽  
Atmosphere Model

&lt;p&gt;We investigate the origin of the equatorial Pacific cold sea surface temperature (SST) bias and its link to wind biases, local and remote, in the Kiel Climate Model (KCM) with dedicated coupled and stand-alone atmosphere model experiments. In the coupled experiments, the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP/CFSR) wind stress is prescribed over four different spatial domains: globally, over the equatorial Pacific (EP), the northern Pacific (NP) and southern Pacific (SP). The corresponding cold SST bias over the equatorial Pacific is reduced by 94%, 48%, 11%&amp;#160;and 22%, respectively. Thus, the equatorial Pacific SST bias is mainly attributed to the wind bias over the EP&amp;#160;region, with small but not negligible contributions from the SP and NP&amp;#160;regions. Biases in the ocean dynamics cause the EP SST bias, while the atmospheric thermodynamics counteract it.&lt;/p&gt;&lt;p&gt;To examine the origin of wind biases, we force the atmospheric component of&amp;#160;the&amp;#160;KCM in stand-alone mode by observed SSTs and simulated SSTs from the coupled experiments with the KCM. The results show that wind biases over the EP, NP and SP regions are initially generated in the atmosphere model and further enhanced by the biased SST in the coupled model.&lt;/p&gt;&lt;p&gt;We conclude that the cold SST bias over the equatorial Pacific originates from biases in the ocean circulation that are forced by the biased surface winds over the EP, NP and SP regions. On the other hand, the cold equatorial Pacific SST bias amplifies the wind biases over the EP, NP and SP regions, which in turn enhances the cold SST bias by ocean-atmosphere coupling.&lt;/p&gt;

scholarly journals Improving the Altimeter-Derived Surface Currents Using High-Resolution Sea Surface Temperature Data: A Feasability Study Based on Model Outputs

2016 ◽  
Vol 33 (12) ◽  
pp. 2769-2784 ◽  
Author(s):  
M.-H. Rio ◽  
R. Santoleri ◽  
R. Bourdalle-Badie ◽  
A. Griffa ◽  
L. Piterbarg ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Ocean Circulation ◽  
Large Scale ◽  
Spatial Scales ◽  
Ocean Surface ◽  
Sea Surface ◽  
High Temporal Resolution ◽  
Surface Currents ◽  
Ocean Surface Currents

AbstractAccurate knowledge of ocean surface currents at high spatial and temporal resolutions is crucial for a gamut of applications. The altimeter observing system, by providing repeated global measurements of the sea surface height, has been by far the most exploited system to estimate ocean surface currents over the past 20 years. However, it neither permits the observation of currents moving away from the geostrophic balance nor is it capable of resolving the shortest spatial and temporal scales of the currents. Therefore, to overcome these limitations, in this study the ways in which the high-spatial-resolution and high-temporal-resolution information from sea surface temperature (SST) images can improve the altimeter current estimates are investigated. The method involves inverting the SST evolution equation for the velocity by prescribing the source and sink terms and employing the altimeter currents as the large-scale background flow. The method feasibility is tested using modeled data from the Mercator Ocean system. This study shows that the methodology may improve the altimeter velocities at spatial scales not resolved by the altimeter system (i.e., below 150 km) but also at larger scales, where the geostrophic equilibrium might not be the unique or dominant process of the ocean circulation. In particular, the major improvements (more than 30% on the meridional component) are obtained in the equatorial band, where the geostrophic assumption is not valid. Finally, the main issues anticipated when this method is applied using real datasets are investigated and discussed.

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