High frequency fluctuations in the heat content of an ocean general  circulation model

Huerta-Casas, Adriana; Webb, D. J.

doi:10.5194/os-8-813-2012

Cited by 2 publications

(6 citation statements)

References 21 publications

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“…Furthermore, the 5-day averaging of output variables in the OCCAM model leads to inexact heat budget closure (Huerta-Casas and Webb, 2012). The averaging leads to underestimating the eddy correlation and any variable varying significantly within the 5-day window.…”

Section: Discussionmentioning

confidence: 99%

“…For the period covered by the RAPID observations, we will also make use of observation-based OHC estimates calculated directly from Argo float data and from EN3 (Ingleby et al, 2007). EN3 was produced in the framework of the EU projects ENSEMBLES and ENACT and combine Argo data with other hydrographic data available during that period.…”

Section: Gcm and Observational Datamentioning

confidence: 99%

“…4 models, we do not include diffusion or an eddy correlation term as described in Huerta-Casas and Webb (2012). Figure 4 shows that the full AV and FV box models largely reproduce the OHC variability retrieved from the OCCAM model.…”

Section: Validating the Box Modelmentioning

confidence: 99%

“…In a next step, we use the FV box model to interpret the recent OHC variability between 26 • and 36 • N as observed by Argo floats and in the EN3 data set (Ingleby et al, 2007). Figure 9a illustrates that the OHC evolution after mid-2007 is of particular interest.…”

Section: Partitioning Ohc Variabilitymentioning

confidence: 99%

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Atlantic meridional ocean heat transport at 26° N: impact on subtropical ocean heat content variability

et al. 2013

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Abstract. Local climate is significantly affected by changes in the oceanic heat content on a range of timescales. This variability is driven by heat fluxes from both the atmosphere and the ocean. In the Atlantic the meridional overturning circulation is the main contributor to the oceanic meridional heat transport for latitudes south of about 50 • N. The RAPID project has been successfully monitoring the Atlantic meridional overturning at 26 • N since 2004. This study demonstrates how these data can be used to estimate the variability of the basin-wide ocean heat content in the upper 800 m between 26 and 36 • N. Traditionally the atmosphere is seen to dominate the ocean heat content variability. However, previous studies have looked at smaller areas in the Gulf Stream region, finding that the ocean dominates deseasoned fluctuations of ocean heat content, while studies of the whole North Atlantic region suggest that the atmosphere may be dominant. In our study we use a box model to investigate fluctuations of the ocean heat content in the subtropical North Atlantic between 26 • and 36 • N. The box model approach is validated using 19 yr of high-resolution general circulation model (GCM) data. We find that in both the GCM-and RAPID-based data the ocean heat transport dominates the deseasoned heat content variability, while the atmosphere's impact on the ocean heat content evolution stabilizes after 6 months. We demonstrate that the utility of the RAPID data goes beyond monitoring the overturning circulation at 26 • N, and that it can be used to better understand the causes of ocean heat content variability in the North Atlantic. We illustrate this for a recent decrease in ocean heat content which was observed in the North Atlantic in 2009 and 2010. Our results suggest that most of this ocean heat content reduction can be explained by a reduction of the meridional ocean heat transport during this period.

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Section: Discussionmentioning

confidence: 99%

Section: Gcm and Observational Datamentioning

confidence: 99%

Section: Validating the Box Modelmentioning

confidence: 99%

Section: Partitioning Ohc Variabilitymentioning

confidence: 99%

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Atlantic meridional ocean heat transport at 26° N: impact on subtropical ocean heat content variability

et al. 2013

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“…A strong relationship between MOC and MHT is also found in OCCAM where the correlation is 0.994. For the period covered by the RAPID observations, we will also make use of observation-based OHC estimates calculated directly from Argo float data and from EN3 (Ingleby et al, 2007). EN3 was produced in the framework of the EU projects ENSEMBLES and ENACT and combine Argo data with other hydrographic data available during that period.…”

Section: Gcm and Observational Datamentioning

confidence: 99%

Oceanic dominance of interannual subtropical North Atlantic heat content variability

Sonnewald¹,

Hirschi²,

Marsh³

2013

Preprint

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Ocean heat content varies on a range of timescales. Traditionally the atmosphere is seen to dominate the oceanic heat content variability. However, this variability can be driven either by oceanic or atmospheric heat fluxes. To diagnose the relative contributions and respective timescales, this study uses a box model forced with output from an ocean general circulation model (OGCM) to investigate the heat content variability of the upper 800 m of the subtropical North Atlantic from 26° N to 36° N. The ocean and air-sea heat flux data needed to force the box model is taken from a 19 yr (1988 to 2006) simulation performed with the 1/12° version of the OCCAM OGCM. The box model heat content is compared to the corresponding heat content in OCCAM for verification. The main goal of the study is to identify to what extent the seasonal to interannual ocean heat content variability is of atmospheric or oceanic origin. To this end, the box model is subjected to a range of scenarios forced either with the full (detrended) ocean and air-sea fluxes, or their deseasoned counterparts. Results show that in all cases, the seasonal variability is dominated by the seasonal component of the air-sea fluxes, which produce a seasonal range in mean temperature of the upper 800 m of ~ 0.42 °C. However, on longer timescales oceanic heat transport dominates, with changes of up to ~ 0.30 °C over 4 yr. <br><br> The technique is subsequently applied to observational data. For the ocean heat fluxes, we use data from the RAPID program at 26° N from April 2004 to January 2011. At 36° N heat transport is inferred using a linear regression model based on the oceanic low-frequency transport in OCCAM. The air-sea flux from OCCAM is used for the period 2004 to 2006 when the RAPID timeseries and the OCCAM simulation overlap, and a climatology is used for the air-sea flux from 2006 onwards. The results confirm that on longer (> 2 yr) timescales the ocean dominates the ocean heat content variability, which is further verified using data from the ARGO project. This work illustrates that oceanic divergence significantly impacts the ocean heat content variability on timescales relevant for applications such as seasonal hurricane forecasts

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High frequency fluctuations in the heat content of an ocean general circulation model

Cited by 2 publications

References 21 publications

Atlantic meridional ocean heat transport at 26° N: impact on subtropical ocean heat content variability

Atlantic meridional ocean heat transport at 26° N: impact on subtropical ocean heat content variability

Oceanic dominance of interannual subtropical North Atlantic heat content variability

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