Adequacy of the Ocean Observation System for Quantifying Regional Heat and Freshwater Storage and Change

Abstract

Considerable advances in the global ocean observing system over the last two decades offers an opportunity to provide more quantitative information on changes in heat and freshwater storage. Variations in these storage terms can arise through internal variability and also the response of the ocean to anthropogenic climate change. Disentangling these competing influences on the regional patterns of change and elucidating their governing processes remains an outstanding scientific challenge. This challenge is compounded by instrumental and sampling uncertainties. The combined use of ocean observations and model simulations is the most viable method to assess the forced signal from noise and ascertain the primary drivers of variability and change. Moreover, this approach offers the potential for improved seasonal-to-decadal predictions and the possibility to develop powerful multi-variate constraints on climate model future projections. Regional heat storage changes dominate the steric contribution to sea level rise over most of the ocean and are vital to understanding both global and regional heat budgets. Variations in regional freshwater storage are particularly relevant to our understanding of changes in the hydrological cycle and can potentially be used to verify local ocean mass addition from terrestrial and cryospheric systems associated with contemporary sea level rise. This White Paper will examine the ability of the current ocean observing system to quantify changes in regional heat and freshwater storage. In particular we will seek to answer the question: What time and space scales are currently Frontiers in Marine Science | www.frontiersin.org 1 August 2019 | Volume 6 | Article 416Palmer et al.Regional Heat and Freshwater Observations resolved in different regions of the global oceans? In light of some of the key scientific questions, we will discuss the requirements for measurement accuracy, sampling, and coverage as well as the synergies that can be leveraged by more comprehensively analyzing the multi-variable arrays provided by the integrated observing system.

Measuring Global Ocean Heat Content to Estimate the Earth Energy Imbalance

“…This paper does not address any scientific questions associated with OHC other than the estimation of EEI. Other scientific questions associated with OHC are addressed by the Oceanobs'19 community white paper from Palmer et al (2019).…”

Observing the Oceans Acoustically

“…Observing the ocean acoustically creates strong synergies with other observing programs, as reflected in the white papers in this Special Issue for OceanObs'19. Closing the sealevel budget (Leuliette, 2015;WCRP Global Sea Level Budget Group, 2018) requires accurate knowledge of ocean bathymetry (Woelfl et al, 2019), ocean sea level (Ponte et al, 2019), barystatic changes (mass of freshwater added or removed; Palmer et al, 2019), and thermostatic changes (e.g., changes in heat content; Meyssignac et al, 2019). Multipurpose acoustic observing systems will contribute to improved monitoring of volume, freshwater, and long-term heat fluxes, as well as monitoring long-term heat content changes at basin-scale, as well as in specific regions of global importance (e.g., Indonesian throughflow; Ravichandran, 2011;Sprintall et al, 2019).…”

Ocean Climate Observing Requirements in Support of Climate Research and Climate Information

“…They are also essential to climate-quality satellite data for calibration and inter-calibration purposes. The combination of in situ and space measurements is indispensable in regional and global process studies and estimates of anthropogenic heat and carbon uptake, among others (e.g., Palmer et al, 2019;Wannikhov et al, 2019).…”

“…The scientific community is moving toward a better rationalization of the Atlantic Observing System as a whole (AtlantOS, deYoung et al, 2019). Being the ocean that receives a large portion of the oceanic excess heat uptake, and that hosts major modes of climate variability, the Atlantic should be observed adequately to accompany the society in adaptation to sea level rise (Ponte et al, 2019), ocean warming (Palmer et al, 2019), ocean acidification (Tilbrook et al, 2019), and the increased intensity of extreme events, including hurricanes (Goni et al, 2019). It is necessary to improve process understanding (in particular, ocean interactions between the meso-and submeso-scales and the large-scale circulation, air-sea interactions at the meso-and submeso-scales, and heat, freshwater, oxygen and carbon uptake, transport and release to the atmosphere), monitor changes, and feed robustly model developments (Fox-Kemper et al, 2019;Subramanian et al, 2019) and predictions (Penny et al, 2019).…”