An introduction to J-OFURO3, a third-generation Japanese ocean flux data set using remote-sensing observations

Hiroyuki Tomita,Kunio Kutsuwada,Shin’Ichiro Kako,Masahisa Kubota,Tsutomu Hihara

doi:10.1007/s10872-018-0493-x

Abstract

Accurate observational estimation of the ocean surface heat, momentum, and freshwater fluxes is crucial for studies of the global climate system. Estimating surface flux using satellite remote sensing techniques is one possible answer to this challenge. In this paper, we introduce J-OFURO3, a third-generation data set developed by the Japanese Ocean Flux Data Sets with Use of Remote-Sensing Observations (J-OFURO) research project, which represents a significant improvement from older data sets as the result of research and development conducted from several perspectives. J-OFURO3 offers data sets for surface heat, momentum, freshwater fluxes, and related parameters over the global oceans (except regions of sea ice) from 1988 to 2013. The surface flux data, based on a 0.25° grid system, have a higher spatial resolution and are more accurate than the previous efforts. This has been achieved through the adopting of the state-of-the-art algorithms that estimate the near-surface air specific humidity and the improvement of techniques using observations from multi-satellite sensors. Comparisons with in situ observations using a systematic system developed along with the J-OFURO3 data set confirmed these improvements in accuracy, as did comparisons with other data sets. J-OFURO3 data are of good quality, facilitating a clearer understanding of more fine-scale ocean–atmosphere features (such as ocean fronts, mesoscale eddies, and geographic features) and their effects on surface fluxes. The information contained in this long-term (26 year) data set is demonstrably beneficial to understanding climate change and its relationship to oceans and the atmosphere.

Highlights

The ocean surface fluxes of heat, momentum, and freshwater are fundamental physical quantities that are essential to understanding air-sea interactions and the nature of our climate system
The averages and standard deviations of the J-OFURO3 latent heat flux (LHF) are extremely similar to those of buoy observations; the bias is less than 1 W/m2 and the standard deviation is roughly the same
J-OFURO3 was developed and released by the J-OFURO research project as a third-generation product presenting air–sea heat, momentum, and freshwater flux data based on multi-satellite observations

Summary

Introduction

The ocean surface fluxes of heat, momentum, and freshwater are fundamental physical quantities that are essential to understanding air-sea interactions and the nature of our climate system. To understand the behavior of these fluctuations in the context of climate change, it is necessary to quantitatively and observationally evaluate surface fluxes over a broad area and long-term period. Since in situ observation platforms such as ships and surface buoys are remarkably limited in their temporal or spatial coverage, it is difficult to use only their data to evaluate surface fluxes at a global scale. Satellite remote sensing techniques are better able to cover large areas over longer time periods with higher temporal and spatial resolutions. Recent advancements in satellite remote sensing technology for earth observation are striking and continue to mature. The estimation of surface flux using satellitemounted microwave radiometers has continued since the late

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