The evolving SST record from ICOADS

Abstract

Sea surface temperature (SST) is a key oceanic variable – widely used for research, including global climate change assessments and atmospheric reanalyses. This paper reviews the evolution of the SST data and products available from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS), since that project’s inception in 1981. Climate-scale SST products based on ICOADS (or related in situ data) are also reviewed. Measurements of SST have been made since around the early 1800s from ships, augmented in recent decades by in situ measurements from buoys and other automated Ocean Data Acquisition Systems (ODAS). SST, unlike some other ICOADS variables such as surface air temperature or humidity, is observed from space with reasonable accuracy. However, without reference to in situ measurements most satellite-based SST products will contain large-scale biases due to varying atmospheric composition and imperfect instrumental calibration. ICOADS is vital to the removal of such biases, which are especially large following volcanic eruptions. We describe products combining in situ and satellite SSTs that exploit the strengths of each type of measurement, to yield both high resolution and high accuracy. Finally, we discuss future developments anticipated for ICOADS and SST products, such as further blending of metadata and enhanced product uncertainty assessments.