Accuracy of Global Upper Ocean Heat Content Estimation Expected from Present Observational Data Sets

Abstract

The simplest global mapping method and dense data coverage for the global oceans by the latest observation network ensure an estimate of global ocean heat content (OHC) within a satisfactory uncertainty for the last 60 years. The observational database conditionally presented a level high enough for practical use for the global OHC estimation when applying bias corrections of expendable bathythermograph, assuming that the other severe observational biases are not included in the database. Uncertainties in annual global mean temperatures averaged vertically from the surface to 1,500 m are within 0.01 K for the period from 1955 onward, when only sampling errors are taken into account. Those in annual mean global OHC of an improved objective analysis for 0−1,500 m depth is 16ZJ on average throughout the period. Compared to previous studies, the new objective analysis provides a higher estimation of the global 0−1,500 m OHC trend for a longer period from 1955 to 2015, which is an increase of 350 ± 57ZJ with a 95% confidence interval.(Citation: Ishii, M., Y. Fukuda, H. Hirahara, S. Yasui, T. Suzuki, and K. Sato, 2017: Accuracy of global upper ocean heat content estimation expected from present observational data sets.

Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition

“…6 (PMEL), ref. 5 (MRI, climate.mri-jma.go.jp/pub/ocean/ts/v7.2/), an updated version of ref. 47 (NCEI, www.nodc.…”

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A Drift-Free Decadal Climate Prediction System for the Community Earth System Model

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“…To assess the predictive skills in our newly developed drift-free prediction system, we evaluate the anomaly correlation coefficient (ACC) of surface air temperature (SAT), ocean heat content from the surface to 300 m (OHC300), and SSH between the observations and the ensemble mean of initialized/uninitialized runs . Observation-based datasets for SAT, OHC300, and SSH are obtained from NASA GISTEMP version 3 (Hansen et al 2010), an ocean objective analysis named ProjD version 7.2 (Ishii et al 2017), and ORA-S4 (Balmaseda et al 2013), respectively. Anomalies are defined as deviation from the climatological mean for 1960-2014 in both observations and the uninitialized run, whereas for the initialized run, the climatological mean is calculated based on a function of lead time.…”

Ocean Climate Observing Requirements in Support of Climate Research and Climate Information

“…Climate monitoring requires long, sustained and high-quality measurements of essential and process-oriented climate parameters in the ocean, including surface fluxes of heat, freshwater, and momentum. For climate purposes, the FIGURE 5 | Observational ocean heat content changes for the upper 2000 m from in situ observations in Domingues et al (2008), Cheng et al (2017), and Ishii et al (2017), compared with the ensemble means of the CMIP5 models for historical simulations pre-2005 and projections after 2005. Model calculations performed for emissions projections RCP2.6, RCP4.5 and RCP8.5 (Taylor et al, 2012).…”