[1] We present version 4 of the Met Office Hadley Centre ''EN'' series of data sets of global quality controlled ocean temperature and salinity profiles and monthly objective analyses, which covers the period 1900 to present. We briefly describe the EN4 data sources, processing, quality control procedures, and the method of generating the analyses. In particular, we highlight improvements relative to previous versions, which include a new duplicate profile removal procedure and the inclusion of three new quality control checks. We discuss in detail a novel method for providing uncertainty estimates for the objective analyses and improving the background error variance estimates used by the analysis system. These were calculated using an iterative method that is relatively robust to initial misspecification of background error variances. We also show how the method can be used to identify issues with the analyses such as those caused by misspecification of error variances and demonstrate the impact of changes in the observing system on the uncertainty in the analyses.Citation: Good, S. A., M. J. Martin, and N. A. Rayner (2013), EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates,

[1] The evolution of ocean temperature measurement systems is presented with a focus on the development and accuracy of two critical devices in use today (expendable bathythermographs and conductivity-temperature-depth instruments used on Argo floats). A detailed discussion of the accuracy of these devices and a projection of the future of ocean temperature measurements are provided. The accuracy of ocean temperature measurements is discussed in detail in the context of ocean heat content, Earth's energy imbalance, and thermosteric sea level rise. Up-to-date estimates are provided for these three important quantities. The total energy imbalance at the top of atmosphere is best assessed by taking an inventory of changes in energy storage. The main storage is in the ocean, the latest values of which are presented. Furthermore, despite differences in measurement methods and analysis techniques, multiple studies show that there has been a multidecadal increase in the heat content of both the upper and deep ocean regions, which reflects the impact of anthropogenic warming. With respect to sea level rise, mutually reinforcing information from tide gauges and radar altimetry shows that presently, sea level is rising at approximately 3 mm yr À1 with contributions from both thermal expansion and mass accumulation from ice melt. The latest data for thermal expansion sea level rise are included here and analyzed.

A large ( approximately 10(23) J) multi-decadal globally averaged warming signal in the upper 300 m of the world's oceans was reported roughly a decade ago and is attributed to warming associated with anthropogenic greenhouse gases. The majority of the Earth's total energy uptake during recent decades has occurred in the upper ocean, but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sea-level budgets, the global radiation imbalance and climate models. For example, several teams have recently produced different multi-year estimates of the annually averaged global integral of upper-ocean heat content anomalies (hereafter OHCA curves) or, equivalently, the thermosteric sea-level rise. Patterns of interannual variability, in particular, differ among methods. Here we examine several sources of uncertainty that contribute to differences among OHCA curves from 1993 to 2008, focusing on the difficulties of correcting biases in expendable bathythermograph (XBT) data. XBT data constitute the majority of the in situ measurements of upper-ocean heat content from 1967 to 2002, and we find that the uncertainty due to choice of XBT bias correction dominates among-method variability in OHCA curves during our 1993-2008 study period. Accounting for multiple sources of uncertainty, a composite of several OHCA curves using different XBT bias corrections still yields a statistically significant linear warming trend for 1993-2008 of 0.64 W m(-2) (calculated for the Earth's entire surface area), with a 90-per-cent confidence interval of 0.53-0.75 W m(-2).

A climate data record of global sea surface temperature (SST) spanning 1981–2016 has been developed from 4 × 1012 satellite measurements of thermal infra-red radiance. The spatial area represented by pixel SST estimates is between 1 km2 and 45 km2. The mean density of good-quality observations is 13 km−2 yr−1. SST uncertainty is evaluated per datum, the median uncertainty for pixel SSTs being 0.18 K. Multi-annual observational stability relative to drifting buoy measurements is within 0.003 K yr−1 of zero with high confidence, despite maximal independence from in situ SSTs over the latter two decades of the record. Data are provided at native resolution, gridded at 0.05° latitude-longitude resolution (individual sensors), and aggregated and gap-filled on a daily 0.05° grid. Skin SSTs, depth-adjusted SSTs de-aliased with respect to the diurnal cycle, and SST anomalies are provided. Target applications of the dataset include: climate and ocean model evaluation; quantification of marine change and variability (including marine heatwaves); climate and ocean-atmosphere processes; and specific applications in ocean ecology, oceanography and geophysics.

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We present a series of systematic abundance measurements for 25 hot DA white dwarfs in the temperature range ∼20 000-110 000 K, based on far-ultraviolet spectroscopy with the Space Telescope Imaging Spectrograph (STIS)/Goddard High Resolution Spectrograph (GHRS) onboard Hubble Space Telescope, IUE and FUSE. Using our latest heavy-element blanketed non-local thermodynamic equilibrium (non-LTE) stellar atmosphere calculations we have addressed the heavy-element abundance patterns, making completely objective measurements of abundance values and upper limits using a χ 2 fitting technique to determine the uncertainties in the abundance measurements, which can be related to the formal upper limits in those stars where particular elements are not detected.We find that the presence or absence of heavy elements in the hot DA white dwarfs largely reflects what would be expected if radiative levitation is the supporting mechanism, although the measured abundances do not match the predicted values very well, as reported by other authors in the past. Almost all stars hotter than ∼50 000 K contain heavy elements. For most of these the spread in element abundances is quite narrow and similar to the abundances measured in G191-B2B. However, there is an unexplained dichotomy at lower temperatures with some stars having apparently pure H envelopes and others having detectable quantities of heavy elements. The heavy elements present in these cooler stars are often stratified, lying in the outermost layers of the envelope. A few strong temperature/evolutionary effects are seen in the abundance measurements. There is a decreasing Si abundance with temperature, the N abundance pattern splits into two groups at lower temperature and there is a sharp decline in Fe and Ni abundance to zero, below ∼50 000 K. When detected, the Fe and Ni abundances maintain an approximately constant ratio, close to the cosmic value of ∼20. For the hottest white dwarfs observed by STIS, the strongest determinant of abundance appears to be gravity.

Ocean warming accounts for the majority of the earth's recent energy imbalance. Historic ocean heat content (OHC) changes are important for understanding changing climate. Calculations of OHC anomalies (OHCA) from in situ measurements provide estimates of these changes. Uncertainties in OHCA estimates arise from calculating global fields from temporally and spatially irregular data (mapping method), instrument bias corrections, and the definitions of a baseline climatology from which anomalies are calculated. To investigate sensitivity of OHCA estimates for the upper 700 m to these different factors, the same qualitycontrolled dataset is used by seven groups and comparisons are made. Two time periods (1970-2008 and 1993-2008)