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You-Soon Chang 《Ocean Dynamics》2014,64(6):823-832
A previous study (Lyman et al., Nature 465:334–337, 2010) showed a robust warming signal of the global upper ocean (0–700 m). They examined several sources of uncertainty that contribute to differences among heat content estimations. However, their focus was limited to globally averaged estimation. This study presents the spatial pattern of the global heat content change based on observed gridded datasets (Levitus et al., Geophys Res Lett 36:L07608, 2009). The western Pacific, Atlantic, and Indian Oceans showed significant warming trends, whereas eastern Pacific and some areas of the Gulf Stream experienced negative trends during 1993–2009. Steady warming trend was obtained from the first EOF mode when El Nino and Southern Oscillation (ENSO)-related signals were removed. This result implies that the rapid increase in heat content of the upper ocean around 2000–2005 is not related to a sampling transition from XBT to Argo observations but is associated with a natural variability dominated by strong ENSO-related signals. 相似文献
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You-Soon Chang Shaoqing Zhang Anthony Rosati Gabriel A. Vecchi Xiaosong Yang 《Ocean Science Journal》2018,53(2):179-189
An observing system simulation experiment (OSSE) using an ensemble coupled data assimilation system was designed to investigate the impact of deep ocean Argo profile assimilation in a biased numerical climate system. Based on the modern Argo observational array and an artificial extension to full depth, “observations” drawn from one coupled general circulation model (CM2.0) were assimilated into another model (CM2.1). Our results showed that coupled data assimilation with simultaneous atmospheric and oceanic constraints plays a significant role in preventing deep ocean drift. However, the extension of the Argo array to full depth did not significantly improve the quality of the oceanic climate estimation within the bias magnitude in the twin experiment. Even in the “identical” twin experiment for the deep Argo array from the same model (CM2.1) with the assimilation model, no significant changes were shown in the deep ocean, such as in the Atlantic meridional overturning circulation and the Antarctic bottom water cell. The small ensemble spread and corresponding weak constraints by the deep Argo profiles with medium spatial and temporal resolution may explain why the deep Argo profiles did not improve the deep ocean features in the assimilation system. Additional studies using different assimilation methods with improved spatial and temporal resolution of the deep Argo array are necessary in order to more thoroughly understand the impact of the deep Argo array on the assimilation system. 相似文献
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You-Soon Chang Shaoqing Zhang Anthony Rosati Thomas L. Delworth William F. Stern 《Climate Dynamics》2013,40(3-4):775-803
The Geophysical Fluid Dynamics Laboratory has developed an ensemble coupled data assimilation (ECDA) system based on the fully coupled climate model, CM2.1, in order to provide reanalyzed coupled initial conditions that are balanced with the climate prediction model. Here, we conduct a comprehensive assessment for the oceanic variability from the latest version of the ECDA analyzed for 51 years, 1960–2010. Meridional oceanic heat transport, net ocean surface heat flux, wind stress, sea surface height, top 300 m heat content, tropical temperature, salinity and currents are compared with various in situ observations and reanalyses by employing similar configurations with the assessment of the NCEP’s climate forecast system reanalysis (Xue et al. in Clim Dyn 37(11):2511–2539, 2011). Results show that the ECDA agrees well with observations in both climatology and variability for 51 years. For the simulation of the Tropical Atlantic Ocean and global salinity variability, the ECDA shows a good performance compared to existing reanalyses. The ECDA also shows no significant drift in the deep ocean temperature and salinity. While systematic model biases are mostly corrected with the coupled data assimilation, some biases (e.g., strong trade winds, weak westerly winds and warm SST in the southern oceans, subsurface temperature and salinity biases along the equatorial western Pacific boundary, overestimating the mixed layer depth around the subpolar Atlantic and high-latitude southern oceans in the winter seasons) are not completely eliminated. Mean biases such as strong South Equatorial Current, weak Equatorial Under Current, and weak Atlantic overturning transport are generated during the assimilation procedure, but their variabilities are well simulated. In terms of climate variability, the ECDA provides good simulations of the dominant oceanic signals associated with El Nino and Southern Oscillation, Indian Ocean Dipole, Pacific Decadal Oscillation, and Atlantic Meridional Overturning Circulation during the whole analyzed period, 1960–2010. 相似文献
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Pak Gyundo Park Jae-Hyoung Lee Seok-Joon Park Young-Gyu Chang You-Soon 《Ocean Science Journal》2020,55(4):477-493
Ocean Science Journal - This study focuses on the intercomparisons of 22 net heat flux (NHF) data sets in terms of mean, linear trend, and interannual variability during 1993–2007 over the... 相似文献
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Toyoda Takahiro Fujii Yosuke Kuragano Tsurane Kosugi Naohiro Sasano Daisuke Kamachi Masafumi Ishikawa Yoichi Masuda Shuhei Sato Kanako Awaji Toshiyuki Hernandez Fabrice Ferry Nicolas Guinehut Stéphanie Martin Matthew Andrew Peterson K. Good Simon A. Valdivieso Maria Haines Keith Storto Andrea Masina Simona Köhl Armin Yin Yonghong Shi Li Alves Oscar Smith Gregory Chang You-Soon Vernieres Guillaume Wang Xiaochun Forget Gael Heimbach Patrick Wang Ou Fukumori Ichiro Lee Tong Zuo Hao Balmaseda Magdalena 《Climate Dynamics》2017,49(3):891-907
Climate Dynamics - The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an... 相似文献
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