A new global ocean hydrographic climatology

Viktor Gouretski

doi:10.1080/16742834.2019.1588066

Abstract

ABSTRACTThis report describes the main features of the recently published World Ocean Experiment–Argo Global Hydrographic Climatology. This climatology is based on profile data from ships, Argo floats, and sensors attached to marine mammals. As an important deviation from the widely used climatologies produced previously by the National Oceanographic Data Center, the spatial interpolation was performed on local potential density surfaces, so that no ‘artificial water masses’ were created. In addition to monthly fields of temperature and salinity, gridded maps of the upper mixed layer depth are now provided.

Highlights

The beginning of oceanographic observations in the 19th century was linked to the expedition of HMS Challenger (1875–77) (Roemmich, Gould, and Gilson 2012), whose data for the first time revealed the thermal structure of the global ocean at depth
The establishment of World Oceanographic Data Centers in several countries during the International Geophysical Year 1957–58 facilitated the accumulation of data and resulted in the first digital Climatological Atlas of the World Ocean (Levitus 1982) — a logical response to the needs of the rapidly developing ocean modeling community
Several updates of this climatological atlas have been published by the National Center for Environmental Information, like WOA2009 (Locarnini et al 2010) and WOA13 (Locarnini et al 2013), to mention only the most recent

Summary

Introduction

The beginning of oceanographic observations in the 19th century was linked to the expedition of HMS Challenger (1875–77) (Roemmich, Gould, and Gilson 2012), whose data for the first time revealed the thermal structure of the global ocean at depth. Other scientific expeditions that followed resulted in the compilation of new maps and sections showing additional details of the ocean thermohaline structure. Most of these studies just produced snapshots of the areas surveyed by different ships in different years. It was not until the late 1950s that the amount of accumulated data was sufficient to produce the first handdrawn climatological atlases of the World Ocean, or parts of it, showing the average distributions of temperature, salinity, and other parameters. Presenting the main characteristics of a new global ocean hydrographic climatology —the World Ocean Experiment—Argo Global Hydrographic Climatology (WAGHC) —this report provides examples not available in the original paper (Gouretski 2018a), such as differences between the WAGHC and WOA13 temperature and salinity fields in the Kuroshio region, and maps of the upper mixed layer depth

Isobaric versus isopycnal averaging of hydrographic data

Comparison between WAGHC and WOA13

Conclusions