To investigate the relationship between the interannual. They further indicate that deeper ocean heat content variability on multidecadal and longer timescales may be important in the global energy budget. Global decadal upperocean heat content as viewed in nine. Chu department of oceanography, naval postgraduate school, monterey, ca 93943, usa, email. Ocean heat content is measured in joules, a unit of energy, and compared against the 19712000 average, which is set at zero for reference. Decadal variability of upper ocean heat content in the. To understand past and present global warming trends, and so to provide data for improvement of predictions of future changes, it is necessary to refine estimates of global upper ocean heat content anomalies ohca and their uncertainties. Among the analyses are two that are independent of any numerical model, six that rely on sequential data assimilation, including an ocean general circulation model, and one that uses fourdimensional variational data assimilation 4dvar. Composite were used to get gridded data of ohc seasonal variability and anomaly. Global map showing where 2017 heat content in the top 700 meters 2,300 feet of the ocean was higher orange or lower blue than the 19932017 average. Contribution of surface waveinduced vertical mixing to heat content in global upper ocean. Global ocean tripole and climate variability peter c. Global change research program climate science special report key findings 1.
Explanation of differences in heat content between published work and online values is outlined in the notes pdf, 4. Possible global surface warming hiatus and regional. This paper reports improved estimates of nearglobal ocean heat content and thermal expansion for the upper ocean from 19502003, applying corrections to. It is with high confidence that ocean warming accounts for 90% of the energy accumulation from global warming between 1971 and 2010. Measuring global ocean heat content to estimate the. For this reason the global ocean heat content ohc places a strong. Estimating annual global upperocean heat content anomalies. Earths energy imbalance eei drives the ongoing global warming and can best be assessed across the historical record that is, since 1960 from ocean heat content ohc changes. Xbt bias, mapping, climatology, climate change, global warming. Future improvement upper ocean heat content should not be calculated to a.
Choosing a different baseline period would not change the shape of the data over time. Using simulations of 20th century climate performed. This paper examines nine analyses of global ocean 0700m temperature and heat content during the 43yr period of warming, 19602002. Similarly, the same gtspp data is used here to identify the freshwater.
The elusive nature of the post2004 upper ocean warming has exposed uncertainties in the oceans role in the earths energy budget and transient climate sensitivity. Heat content variability in the north atlantic ocean in. Three reanalyses and two observational data sets are compared. May 20, 2010 the upper ocean acts as a giant heat sink and has absorbed the majority of excess energy generated by anthropogenic greenhouse gasses. Recent observations also show substantial warming of the deeper ocean between depths of 700 and. Global average temperature has increased, as have atmospheric water vapour and ocean heat content. The redistribution of ohc in upper layer explains not only the global warming hiatus, but also the multidecadal climate variability. Ummenhofer, and hyodae seo department of physical oceanography, woods hole oceanographic institution, woods hole. The majority of the earths total energy uptake during recent decades has occurred in the upper ocean 3, but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sealevel budgets 4,5,6,7, the global radiation imbalance 8 and climate models 5.
A trend for increasing heat content in the upper ocean has become evident since the 1950s. Upper ocean heat content and climate variability peter c. Ocean reanalysis data are used to evaluate relationships with changes in ocean heat content ohc and oxygen solubility o 2,sat. Improved estimates of upperocean warming and multidecadal. Maps of these quantities from mid1993 through mid2003 were calculated using the technique presented by willis et al. The global upper ocean o 2 inventory 0 m changed at. These data are available for the top 700 meters of the ocean nearly 2,300 feet, which accounts for just under 20 percent of the total volume of water in the worlds oceans. Distinctive climate signals in reanalysis of global ocean. Chu naval postgraduate school eaps, mit june 2, 2010. An accurate assessment of ohc is a challenge, mainly because of insufficient and irregular data coverage. Global warming seems to have paused over the past 15 years while the deep ocean takes the heat instead.
This requires the closure of regional and global oceanic heat budgets. Abstractocean heat content ohc change contributes substantially to global sea level rise, so it is a vital task for the climate research community to estimate. Interannual variability in upper ocean heat content. The warming of the oceans has accounted for approximately 93 % of the warming of the earth since the 1950s. Observational data from the global temperature and salinity profile program were used to calculate the upper ocean heat content ohc anomaly. Between 0600 gmt and 1800 gmt feb 14 2019, data and figures for all ocean heat, salt, and steric sea level variables had erroneous values for year 2018, all four quarters of 2018, and pentad 20142018. Read global decadal upperocean heat content as viewed in nine analyses, journal of climate on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. The timemean gfs are derived from the estimating the circulation and climate of the ocean eccoglobal ocean data assimilation experiment godae. Understanding the variability of upper ocean thermal conditions is key to regional climate prediction. The thickness of the upper layer is taken as 300 m for the pacificatlantic ocean and 150 m for the indian ocean since the indian ocean has shallower thermoclines. Oceanography and climatology are the science branches which study ocean heat content. Understanding climate variability and climate change. Warming of the upper 0700 m ocean accounted for about 64 % of the total heat uptake.
As a result, upper ocean heat content has increased significantly. Northern north atlantic sea surface height and ocean heat content variability. Module 1 understanding climate variability and climate change. A trend for increasing heat content in the upper ocean has become evident since the. Although climate models are able to simulate overall changes in ohc, they are generally thought to underestimate the amplitude of ohc variability. The shaded area indicates the socalled golden period of earth system measurements for global ocean heat content estimates, which starts circa 2005 and is characterized by initially sparse but steadily improving global coverage of in situ temperature measurements through the argo program. Because heat content is one component of these budgets, analysis of its variability is vital. Varying planetary heat sink led to globalwarming slowdown. It was confirmed that ocean heat content ohc plays a critical role in the earths heat balance for the climatological annual cycle ellis et al. We find that the siod is associated with a prominent southwestnortheast sea level anomaly sla dipole over the westerncentral south indian ocean, with the north pole located in the seychelleschagos thermocline ridge sctr and the south pole at southeast. Simulated and observed variability in ocean temperature.
Here we present the time evolution of the global ocean heat content for 1958 through 2009 from a new observation. Global reconstruction of historical ocean heat storage and. In this study, the indian ocean upperocean variability associated with the subtropical indian ocean dipole siod is investigated. The climate system exchanges energy with outer space at the top of the. Contrasting changes in the sea surface temperature and upper. Chen and tung used observational data to trace the pathways of recent ocean. Variability of sea level and upperocean heat content in. Trends in globally averaged temperature, sea level rise, upperocean heat content, landbased ice melt, arctic sea ice, depth of seasonal permafrost thaw. This makes ocean heat content, potentially, a key indicator. The global climate continues to change rapidly compared to the pace of the natural variations in climate that have occurred throughout earths history. Worldwide, most ocean basins had higherthanaverage heat content in 2018, consistent with the longterm trend of ocean heat uptake due to global warming. Pacific ocean heat content during the past 10,000 years.
A synthesis of atmospheric and oceanic analysis yan xue, boyin huang, arun kumar, wanqui wang climate prediction center, noaanational weather service 1. Pdf global upper ocean heat content and climate variability. Lyman joint institute for marine and atmospheric research, university of hawaii at manoa, honolulu, hawaii, and noaapacific marine. In recent decades, the sea surface temperature and upper ocean heat content in the south china sea scs sst and scs ohc have exhibited contrasting changes. Statistics show the global mean surface temperature increased by 0. Upper ocean heat content anomaly analyzing the heat content of the worlds oceans shown above is the 25year trend in 0700 m global ocean heat content anomaly ohca estimated from in situ data lyman et al. Global ohc, global mean sea surface temperature sst. Heat energy in the top 2,300 feet 700 meters, or slightly less than half a mile of the ocean in 2014 compared to the average from 19932014.
Trenberth,2 and erland kallen1 received february 20. Distinctive climate signals in reanalysis of global ocean heat content magdalena a. Observed increases in ocean heat content ohc and temperature are robust indicators of global warming during the past several decades. Recent observations also show substantial warming of the deeper ocean between depths of 700 and 2 000 m. Here we present the time evolution of the global ocean heat content for 1958 through 2009 from a. It seeks to develop and maintain a global ocean temperaturesalinity fig.
Sensitivity of global upperocean heat content estimates to mapping methods. Variability of sea level and upperocean heat content in the. This figure shows changes in ocean heat content between 1955 and 2015. Interannual variability in upperocean heat content. The map shows locations with belowaverage ocean heat content blue and aboveaverage ocean heat content orange in 2014. The thermal capacity of the oceans far exceeds that of the atmosphere, so the oceans can store up to 90% of the heat buildup caused by increased concentrations of greenhouse gases such as carbon dioxide. Changes in the ocean heat content play an important role in the sea level rise, because of thermal expansion. Aug 20, 2019 for this reason the global ocean heat content ohc places a strong constraint on the absolute magnitude of eei and its uncertainty. Heat content variability in the north atlantic ocean in ocean.
The mechanism for solar activity to drive climate variability is still under debate. We find that the siod is associated with a prominent southwestnortheast sea level anomaly sla dipole over the westerncentral south indian ocean, with the north pole located in the seychelleschagos thermocline ridge sctr and the south pole at. Studies of ocean heat content ohc show warming of the global oceans over the last 60 years. The temporal and spatial variability of the global upper ocean heat content has been identified using the gtspp data 14. Recent progress and the remaining challenges cheng lijing1, zhu jiang1, and john abraham2 1 international center for climate and environment sciences icces, institute of atmospheric physics, chinese academy of sciences, beijing 29, china 2 university of st. Indian ocean was found to be the accelerator for the global surface warming hiatus through supplying heat to the southern atlantic ocean. Global o 2 decline is evident after the 1980s, accompanied by an increase in global ohc. Pdf contribution of surface waveinduced vertical mixing. Converting the temperatures to joules a standard unit of energy allows them to compare heat in the ocean to heat in other parts of earths climate system. Improved estimates of ocean heat content from 1960 to 2015. Frontiers measuring global ocean heat content to estimate. The ohc variability is significant globally and thought to represent some 93% of the heating of the earth over the past 60 years levitus et al. Trends in globally averaged temperature, sea level. Jun 19, 2008 this paper reports improved estimates of nearglobal ocean heat content and thermal expansion for the upper ocean from 19502003, applying corrections to reduce systematic biases in the most.
Estimating annual global upper ocean heat content anomalies despite irregular in situ ocean sampling john m. Global upper ocean heat content and climate variability. Likewise, the accuracy of the eei estimate through the inventory method essentially relies on the accuracy of the estimated change in global mean ohc. The upper ocean acts as a giant heat sink and has absorbed the majority of excess energy generated by anthropogenic greenhouse gasses. Nov 29, 2016 the warming of the oceans has accounted for approximately 93 % of the warming of the earth since the 1950s.
This indicator shows trends in global ocean heat content from 1955 to 2015. Atmosphere is the blanket of air that surrounds the earth, moving both. We used highresolution proxy records from sediment cores to extend these observations in the pacific 10,000 years beyond the instrumental record. Pdf contribution of surface waveinduced vertical mixing to. Improved estimates of upperocean warming and multi. Feb 19, 2008 read global decadal upper ocean heat content as viewed in nine analyses, journal of climate on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Annual time series of global and hemispheric ohc change for 0700 m show. Time series of global ocean heat content at different depths. Among the analyses are two that are independent of any numerical model, six that rely on sequential data assimilation, including an ocean general circulation model, and one that uses fourdimensional variational data assimilation 4dvar, including an ocean. Observed changes in the global climate system warming of the climate system during the industrial era is unequivocal, based on robust evidence from a suite of indicators. The model of stochastic climate variability developed by hasselmann 1976, in its simplest form, represents the climate by the heat content of a wellmixed box representing all or part of the oceans that is perturbed by random airsea heat. Ocean heat content variability and change in an ensemble of ocean. Through its transport of heat, carbon, plankton, nutrients, and oxygen around the world, ocean circulation regulates global climate and maintains primary productivity and marine ecosystems, with widespread implications for global fisheries, tourism, and the shipping industry. Observations show both a pronounced increase in ocean heat content ohc over the second half of the 20th century and substantial ohc variability on interannualtodecadal time scales.
Industrialera global ocean heat uptake doubles in recent. Upper ocean heat content ohc is dominated in most regions by heat transport convergence without widespread changes in the potential temperaturesalinity relation. Chu department of oceanography naval postgraduate school monterey, ca 93943. Influences of pacific climate variability on decadal. Maps of these quantities from mid1993 through mid2003 were calculated using the technique developed by willis et al. Pdf ocean heat content ohc change contributes substantially to global sea level rise, so it is a vital task for the climate research community. Insitu observations and reanalysis data reveal a linear warming trend in scs sst during 19752010 but a regime shift of scs ohc.