skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Observed and simulated full-depth ocean heat-content changes for 1970–2005

Abstract

Greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80]  ×  10 22 J yr −1 (0.46 Wm −2) and 1.22 [1.16–1.29]  ×  10 22 J yr −1 (0.75 Wm −2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95 % confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some models are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82]  ×  10 22 J yr −1 (0.42 Wm −2) from 1970 to 2005 and 1.25 [1.10–1.41]  ×  10 22 J yr −1 (0.77 Wm −2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth's energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales).

Authors:
 [1];  [2];  [3];  [1];  [4]
  1. Chinese Academy of Sciences (CAS), Beijing (China)
  2. National Center for Atmospheric Research, Boulder, CO (United States)
  3. Met Office Hadley Centre, Exeter (United Kingdom)
  4. Univ. of St. Thomas, St. Paul, MN (United States)
Publication Date:
Research Org.:
Univ. Corp. for Atmospheric Research, Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1272636
Grant/Contract Number:
SC0012711
Resource Type:
Journal Article: Published Article
Journal Name:
Ocean Science
Additional Journal Information:
Journal Volume: 12; Journal Issue: 4; Journal ID: ISSN 1812-0792
Publisher:
Copernicus GmbH
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Cheng, Lijing, Trenberth, Kevin E., Palmer, Matthew D., Zhu, Jiang, and Abraham, John P.. Observed and simulated full-depth ocean heat-content changes for 1970–2005. United States: N. p., 2016. Web. doi:10.5194/os-12-925-2016.
Cheng, Lijing, Trenberth, Kevin E., Palmer, Matthew D., Zhu, Jiang, & Abraham, John P.. Observed and simulated full-depth ocean heat-content changes for 1970–2005. United States. doi:10.5194/os-12-925-2016.
Cheng, Lijing, Trenberth, Kevin E., Palmer, Matthew D., Zhu, Jiang, and Abraham, John P.. 2016. "Observed and simulated full-depth ocean heat-content changes for 1970–2005". United States. doi:10.5194/os-12-925-2016.
@article{osti_1272636,
title = {Observed and simulated full-depth ocean heat-content changes for 1970–2005},
author = {Cheng, Lijing and Trenberth, Kevin E. and Palmer, Matthew D. and Zhu, Jiang and Abraham, John P.},
abstractNote = {Greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80]  ×  1022 J yr−1 (0.46 Wm−2) and 1.22 [1.16–1.29]  ×  1022 J yr−1 (0.75 Wm−2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95 % confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some models are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82]  ×  1022 J yr−1 (0.42 Wm−2) from 1970 to 2005 and 1.25 [1.10–1.41]  ×  1022 J yr−1 (0.77 Wm−2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth's energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales).},
doi = {10.5194/os-12-925-2016},
journal = {Ocean Science},
number = 4,
volume = 12,
place = {United States},
year = 2016,
month = 7
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.5194/os-12-925-2016

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

Save / Share:
  • Here, greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80] × 10 22 J yr –1 (0.46 Wm –2) and 1.22 [1.16–1.29] × 10 22 J yr –1 (0.75 Wm –2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95 % confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some modelsmore » are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82] × 10 22 J yr –1 (0.42 Wm –2) from 1970 to 2005 and 1.25 [1.10–1.41] × 10 22 J yr –1 (0.77 Wm –2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth's energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales).« less
  • The study evaluated 1948-2004 summer (JJA) mean monthly air temperatures for two California air basins: SoCAB and SFBA. The study focuses on the more rapid post-1970 warming period, and its daily T{sub min} and T{sub max} values were used to produce average monthly values and spatial distributions of trends for each air basins. Additional analyses included T{sub D} values at two NWS sites, SSTs, NCEP reanalysis sea-level pressures, and GCM T{sub ave}-values. Results for all California COOP sites together showed increased JJA T{sub ave}-values; asymmetric warming, as T{sub min}-values increase faster than T{sub max}-values; and thus decreased DTR values. Themore » spatial distribution of observed SoCAB and SFBA T{sub max} values exhibited a complex pattern, with cooling in low-elevation coastal-areas open to marine air penetration and warming at inland areas. Results also showed that decreased DTR values in the valleys arose from small increases at 'inland' sites combined with large decreases at 'coastal' sites. Previous studies suggest that cooling JJA T{sub max}-values in coastal California were due to increased irrigation, coastal upwelling, or cloud cover, while the current hypothesis is that they arises from GHG-induced global-warming of 'inland' areas, which results in increased sea breeze flow activity. Sea level pressure trends showed increases in the oceanic Pacific High and decreases in the central-California Thermal Low. The corresponding gradient thus showed a trend of 0.02 hPa 100-km{sup -1} decade{sup -1}, supportive of the hypothesis of increased sea breeze activity. Trends in T{sub D} values showed a larger value at coastal SFO than at inland SEC, which indicative of increased sea breeze activity; calculated SST trends (0.15 C decade{sup -1}) could also have increase T{sub D}-values. GCM model Tave-values showed warming that decreases from 0.13 C decade{sup -1} at inland California to 0.08 C decade{sup -1} at coastal areas. Significant societal impacts may result from this observed 'reverse-reaction' to GHG-warming, i.e., the decreased JJA T{sub max}-values in coastal areas. Possible beneficial effects include decreased: maximum O{sub 3} levels, human thermal-stress, and energy requirements for cooling.« less
  • The life cycle and structure of dominant wintertime SST anomalies and associated atmospheric response in the extratropical North Pacific are examined using results from a 100-yr seasonal simulation of a low-resolution atmospheric model with realistic geography coupled to a simple mixed layer ocean. The study focuses on composited SST anomalies produced solely by ocean-atmosphere energy exchange. One key pattern shows a negative (positive) SST anomaly in the central Pacific, denoted CCP (WCP), flanked by opposite signed anomalies in the western and eastern Pacific. For the WCP case, the SST anomaly reaches about 1.0{degrees}C in the central Pacific, whereas for themore » CCP case it is -1.5{degrees}C. During the growth phase of the WCP (CCP) SST anomalies, anomalous highs (lows) occur over the western Pacific and over western North America, and an anomalous low (high) is over the east-central Pacific. To the rear of the anomalous low (high), a negative (positive) SST anomaly develops in response to anomalous cold, dry (warm, moist) air. The effect of anomalous wind also contributes but to a lesser extent. The composited SST anomalies primarily develop in 1-2 months. During the decay stage of the WCP SST anomaly, the atmospheric anomalies are essentially of opposite sign than during the growth stage and help to destroy the SST anomaly. In contrast, the atmospheric anomalies during the decay stage of the CCP SST anomaly are of the same sign but weaker than during the growth stage. For this case, a positive SST-atmosphere feedback involving ocean-atmosphere energy exchange helps maintain a more persistent SST anomaly than in the WCP composite case. Comparison of results with prescribed SST anomaly experiments indicate that the ocean is in part forcing the atmosphere during the decay stage of CCP SST anomalies. 40 refs., 10 figs.« less
  • Countermeasures to biofouling in simulated ocean thermal energy conversion heat exchangers have been studied in single-pass flow systems, using cold deep and warm surface ocean waters off the island of Hawaii. Manual brushing of the loops after free fouling periods removed most of the biofouling material. However, over a 2-year period a tenacious film formed. Daily free passage of sponge rubber balls through the tubing only removed the loose surface biofouling layer and was inadequate as a countermeasure in both titanium and aluminum alloys tubes. Chlorination at 0.05, 0.07, and 0.10 mg liter/sup -1/ for a h day/sup -1/ loweredmore » biofouling rates. Only at 0.10 mg liter/sup -1/ was chlorine adequate over a 1-year period to keep film formation and heat transfer resistance from rising above the maximum tolerated values. Lower chorination regimens led to the buildup of uneven or patchy films which produced increased flow turbulence. The result was lower heat transfer resistance values which did not correlate with the amount of biofouling. Surfaces which were let foul and then treated with intermittent or continuous chlorination at 0.10 mg of chlorine or less per liter were only partially or unevenly cleaned, although heat transfer measurements did not indicate that fact. It took continuous chlorination at 0.25 mg liter/sup -1/ to bring the heat transfer resistance to zero and eliminate the fouling layer. Biofouling in deep cold seawater was much slower than in the warm surface waters. Tubing in one stainless-steel loop had a barely detecting layer after 1 year in flow. With aluminum alloys sufficient corrosion and biofouling material accumulated to require that some fouling countermeasure be used in long-term operation of an ocean thermal energy conversion plant.« less
  • The OSU global atmospheric general circulation model (AGCM) has been coupled to a 60-m deep mixed-layer ocean model to simulate the equilibrium seasonal climatic changes induced by a doubling of the CO{sub 2} concentration. Simulations with CO{sub 2} concentrations of 326 ppmv (1{times}CO{sub 2}) and 652 ppmv (2{times}CO{sub 2}) were performed using an accelerated integration procedure for 45 solar cycles followed by the normal unaccelerated integration procedure for 24 and 16 solar cycles (years), respectively. Averages were then obtained over the last 10 yr of each simulation and were analyzed in terms of the annual-mean climate and the annual cyclemore » of climate, the latter defined as the departure of the monthly or seasonal mean from the corresponding annual mean.« less