Guest Editorial: Special Issue on Oceanography, Hydrology and Glaciology from Space

Abstract

Observations made from space comprise a fundamental component of the global observing system, contributing to a better understanding of the Earth system as a whole and its evolution, including climate and global environmental changes, under both natural and anthropogenic forcing factors. They are also essential to understand how human societies are impacted by these changes which occur from global to local scales. This Special Issue focuses on the use of space observations to monitor the oceans (their physics and biology on global, regional and coastal scales), inland waters (lakes and river water levels, river discharge, and total water storage), the mass balances of large ice sheets, and sea ice extent and thickness. It provides an overview of how remote sensing techniques, available now for more than three decades, have revolutionized our understanding of the surface fluid envelopes of the Earth-the oceans, inland waters, land ice and sea ice. It provides upto-date information about space-based observations and their applications to monitor the dynamical and biological changes occurring in the oceans, hydrology on land and its water resources, as well as changes affecting land ice and sea ice, and their roles in global climate change. A collection of eleven overview articles is presented in this Special Issue.The paper by Morrow et al. (2023) reviews the recent progress made in measuring, with multiple nadir radar altimeter missions, the dynamic topography of the oceans and in deriving surface geostrophic currents. It reports recent advances in observing the largescale and mesoscale ocean circulation from space, and the challenges and opportunities for new observations in the polar regions. It also presents current research on ocean barotropic tides and internal tidal circulation. The paper finally discusses how the global multisatellite and in situ observations are being combined and assimilated in ocean circulation models to characterize the 4D ocean circulation, for climate research and ocean forecasting applications.Visible spectral radiometric measurements from space, known as ocean color measurements, yield extensive information on ocean biota and biological/ecosystem processes.