This product is a collection of time series and anomalies for several ocean climate variables that are critical to understanding the Earth’s radiation budget, sea level, global freshwater budget, ocean subsurface temperature and salinity. Understanding changes in Ocean Heat Content (OHC) is a prerequisite to understanding global energy imbalance. The ocean’s thermal expansion due to OHC change directly affects sea level. Calculating OHC from in situ ocean subsurface temperature changes allows researchers to create a corresponding time series, but this data is limited by the uncertainty of temperature measurements and the geographic and temporal distribution of subsurface temperature measurements.
Monthly OHC gridded one-degree latitude/longitude fields are needed as input for climate models, as are the temperature anomaly (change from mean) fields which are used to calculate OHC. The fields and time series presented here are calculated using in situ temperature data from the World Ocean Database. Calculations are performed as detailed in Levitus et al. (2012) using the World Ocean Atlas 2009 mean climatological fields for years 1955-2006 as a basis for anomaly calculations. It should be noted that the uncertainty of the monthly fields (standard error of the mean of the objectively analyzed fields) is an uncertainty on the analysis method only. Further, the initial assumption of mean conditions as a baseline for the analysis calculation is known to be a conservative condition which results in underestimation of anomalies in low data density regions and this assumption is particularly relevant at the monthly time frequency.