In Situ Data Biases and Recent Ocean Heat Content Variability*

2009 ◽  
Vol 26 (4) ◽  
pp. 846-852 ◽  
Author(s):  
Josh K. Willis ◽  
John M. Lyman ◽  
Gregory C. Johnson ◽  
John Gilson
Keyword(s):  
Heat Content ◽  
Ocean Heat Content ◽  
Rate Equations ◽  
Upper Ocean ◽  
Cold Bias ◽  
Sampling Errors ◽  
Upper Ocean Heat Content ◽  
Data Errors ◽  
In Situ Data

Abstract Two significant instrument biases have been identified in the in situ profile data used to estimate globally integrated upper-ocean heat content. A large cold bias was discovered in a small fraction of Argo floats along with a smaller but more prevalent warm bias in expendable bathythermograph (XBT) data. These biases appear to have caused the bulk of the upper-ocean cooling signal reported by Lyman et al. between 2003 and 2005. These systematic data errors are significantly larger than sampling errors in recent years and are the dominant sources of error in recent estimates of globally integrated upper-ocean heat content variability. The bias in the XBT data is found to be consistent with errors in the fall-rate equations, suggesting a physical explanation for that bias. With biased profiles discarded, no significant warming or cooling is observed in upper-ocean heat content between 2003 and 2006.

Estimating Annual Global Upper-Ocean Heat Content Anomalies despite Irregular In Situ Ocean Sampling*

2008 ◽  
Vol 21 (21) ◽  
pp. 5629-5641 ◽  
Author(s):  
John M. Lyman ◽  
Gregory C. Johnson
Keyword(s):  
Heat Content ◽  
Effective Area ◽  
Ocean Heat Content ◽  
Upper Ocean ◽  
Confidence Limits ◽  
Upper Ocean Heat Content ◽  
Argo Data ◽  
Ocean Sampling ◽  
Sampling Pattern

Abstract The effects of irregular in situ ocean sampling on estimates of annual globally integrated upper ocean heat content anomalies (OHCA) are investigated for sampling patterns from 1955 to 2006. An analytical method is presented for computing the effective area covered by an objective map for any given in situ sampling distribution. To evaluate the method, appropriately scaled sea surface height (SSH) anomaly maps from Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO) are used as a proxy for OHCA from 1993 to 2006. Use of these proxy data demonstrates that the simple area integral (SI) of such an objective map for sparse datasets does not agree as well with the actual integral as the weighted integral (WI), defined as the simple integral weighted by the ratio of the total area over the “observed” area. From 1955 to 1966, in situ ocean sampling is inadequate to estimate accurately annual global integrals of the proxy upper OHCA. During this period, the SI for the sampling pattern of any given year underestimates the 13-yr trend in proxy OHCA from 1993 to 2006 by around 70%, and confidence limits for the WI are often very large. From 1967 to 2003 there appear to be sufficient data to estimate annual global integrals. Limited by the constraints of this analysis, the SI for any given year’s sampling pattern still underestimates the 1993–2006 13-yr trend in the proxy by around 30%, but the WI matches the trend well with small confidence limits. For 2004 through 2006 in situ sampling, with near-global in situ Argo data coverage, the 1993–2006 13-yr trend in the proxy is equally well represented by the SI or WI.

Oceanic processes of upper ocean heat content associated with two types of ENSO

2017 ◽  
Vol 74 (2) ◽  
pp. 219-238 ◽  
Author(s):  
Junqiao Feng ◽  
Fei-fei Jin ◽  
Dunxin Hu ◽  
Shoude Guan
Keyword(s):  
Heat Content ◽  
Ocean Heat Content ◽  
Upper Ocean ◽  
Upper Ocean Heat Content

How Well Do Climate Models Reproduce North Atlantic Subtropical Mode Water?

2013 ◽  
Vol 43 (10) ◽  
pp. 2230-2244 ◽  
Author(s):  
Shenfu Dong ◽  
Kathryn A. Kelly
Keyword(s):  
Heat Flux ◽  
Data Assimilation ◽  
North Atlantic ◽  
Climate Models ◽  
Formation Rate ◽  
Heat Content ◽  
Ocean Heat Content ◽  
Upper Ocean ◽  
Upper Ocean Heat Content ◽  
Mode Water

Abstract Formation and the subsequent evolution of the subtropical mode water (STMW) involve various dynamic and thermodynamic processes. Proper representation of mode water variability and contributions from various processes in climate models is important in order to predict future climate change under changing forcings. The North Atlantic STMW, often referred to as Eighteen Degree Water (EDW), in three coupled models, both with data assimilation [GFDL coupled data assimilation (GFDL CDA)] and without data assimilation [GFDL Climate Model, version 2.1 (GFDL CM2.1), and NCAR Community Climate System Model, version 3 (CCSM3)], is analyzed to evaluate how well EDW processes are simulated in those models and to examine whether data assimilation alters the model response to forcing. In comparison with estimates from observations, the data-assimilating model gives a better representation of the formation rate, the spatial distribution of EDW, and its thickness, with the largest EDW variability along the Gulf Stream (GS) path. The EDW formation rate in GFDL CM2.1 is very weak because of weak heat loss from the ocean in the model. Unlike the observed dominant southward movement of the EDW, the EDW in GFDL CM2.1 and CCSM3 moves eastward after formation in the excessively wide GS in the models. However, the GFDL CDA does not capture the observed thermal response of the overlying atmosphere to the ocean. Observations show a robust anticorrelation between the upper-ocean heat content and air–sea heat flux, with upper-ocean heat content leading air–sea heat flux by a few months. This anticorrelation is well captured by GFDL CM2.1 and CCSM3 but not by GFDL CDA. Only GFDL CM2.1 captures the observed anticorrelation between the upper-ocean heat content and EDW volume. This suggests that, although data assimilation corrects the readily observed variables, it degrades the model thermodynamic response to forcing.

scholarly journals Processes controlling upper-ocean heat content in Drake Passage

2013 ◽  
Vol 118 (9) ◽  
pp. 4409-4423 ◽  
Author(s):  
Gordon R. Stephenson ◽  
Sarah T. Gille ◽  
Janet Sprintall
Keyword(s):  
Heat Content ◽  
Drake Passage ◽  
Ocean Heat Content ◽  
Upper Ocean ◽  
Upper Ocean Heat Content
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