Revisiting the global mean ocean mass budget over 2005-202

Global mean sea level rose by 15 mm over June 2014 – May 2016. This rise is 7 mm larger than the 8 mm increase associated with the long‐term trend of 4 mm/yr estimated over 2006–2016. Using a combination of satellite gravimetry data and in situ measurements, we find that 20% of this rise is explained by ocean thermal expansion and 80% by an ocean mass increase, the latter being largely correlated with an equivalent terrestrial water storage (TWS) decrease. Half of the global ocean mass increase during that period can be attributed to the South American continent where we find a significant contribution of the TWS over the Amazon basin (5 mm). This TWS change between oceans and continents occurred during two El Nino events: one aborted in 2014–2015 and an extreme event in 2015–2016 which affected precipitation patterns, especially over the equatorial Pacific ocean and over South America.

Section: Resultssupporting

confidence: 92%

Cause of Substantial Global Mean Sea Level Rise Over 2014–2016

Llovel,

Balem,

Tajouri

et al. 2023

“…Recently, Barnoud et al. (2023) resolved this discrepancy using ocean reanalysis products to compute the thermosteric component of GMSL, suggesting that satellite gravity data have accurately estimated recent trends in barystatic sea level.…”

Section: Resultsmentioning

confidence: 99%

“…We analyzed the difference between barystatic and manometric sea level from the computed GRD values, estimated ocean mascons and steric‐corrected altimetry during the common data period (August 2002 to December 2020). We computed barystatic sea level using satellite gravity data by integrating our estimated ocean mascons and computed GRD values for all landmasses over the global ocean, excluding areas not well sampled by Argo data (i.e., polar oceans and marginal seas) and coastal areas poorly resolved by satellite altimetry (Barnoud et al., 2023; Legeais et al., 2021). We compared ice‐free manometric sea‐level changes of the computed GRD values with our ocean mascon estimates and steric‐corrected altimetry at particular locations where the rates of continental hydrology contributions were high.…”

Section: Ocean Mass From Satellite Altimetrymentioning

confidence: 99%

Significant Local Sea Level Variations Caused by Continental Hydrology Signals

McGirr,

Tregoning,

Purcell

et al. 2024

Space gravity missions have enabled the quantification of the mass component of sea‐level rise over the past two decades. Barystatic sea‐level rise is predominantly driven by melting polar ice sheets and mountain glaciers. However, continental hydrological processes also contribute to global sea level change at significant magnitudes. We show that for most coastal areas in low‐to‐mid latitudes, up to half of manometric sea‐level rise is due to changes in water storage in ice‐free continental regions. At other locations the direct attraction effect of anthropogenic pumping of groundwater over the duration of the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO) mission offsets sea‐level rise from ice sheet and glacier melt. If these trends in continental hydrological storage were to slow or stop, these regions would experience greatly accelerated sea‐level rise, posing a risk to coastal settlements and infrastructure, however, for most coastal communities current rates of sea‐level rise would be significantly reduced.

“…The steric component of GMSL can be derived from ocean reanalysis models (Storto & Yang, 2024; Storto et al., 2015) or in situ hydrographic measurements collected from global networks such as the Argo array (Johnson et al., 2022). For GMOM change, we can infer it indirectly by summing all land mass changes in polar ice sheets, mountain glaciers, and terrestrial water storage (TWS), known as the ocean mass budget approach (Barnoud et al., 2023; Chambers et al., 2016; Dieng et al., 2017; Horwath et al., 2022; Llovel et al., 2023; WCRP Global Sea Level Budget Group, 2018). Alternatively, direct quantification has been available since the launch of the Gravity Recovery and Climate Experiment (GRACE) mission in 2002 (Tapley et al., 2004), which routinely produces high‐precision, high‐resolution monthly gravity field models that are widely used for GMOM estimation (Chambers et al., 2004; Chen et al., 2013, 2018; Dobslaw et al., 2020; Jeon et al., 2021; Kim et al., 2019; Rietbroek et al., 2016; Uebbing et al., 2019; Yi et al., 2015, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…It is generally accepted that GMSL closure is achieved between 2005 and 2015, when the three complementary observational techniques (GRACE, Argo, and satellite altimetry) are all in nominal operation, providing data with sufficient accuracy and coverage (Chen et al., 2018; WCRP Global Sea Level Budget Group, 2018). There are notably large discrepancies between GRACE (plus GRACE Follow‐On (FO), launched in 2018) observed GMOM change and estimates from satellite altimetry and Argo, which were likely attributed to errors in Argo and GRACE/GRACE‐FO estimates (Barnoud et al., 2021, 2023; Chen et al., 2020; Horwath et al., 2022; Johnson et al., 2023).…”

Section: Introductionmentioning

confidence: 99%

Global Ocean Mass Change Estimation Using Low‐Degree Gravity Field From Satellite Laser Ranging

Nie,

Chen,

Peng

2024

Satellite laser ranging (SLR) is a well‐established geodetic technique for measuring the low‐degree time‐variable gravity field for decades. However, its application in mass change estimation is limited by low spatial resolution, even for global mean ocean mass (GMOM) change which represents one of the largest spatial scales. After successfully correcting for signal leakage, for the first time, we can infer realistic GMOM changes using SLR‐derived gravity fields up to only degree and order 5. Our leakage‐corrected SLR GMOM estimates are compared with those from the Gravity Recovery and Climate Experiment (GRACE) for the period 2005 to 2015. Our results show that the GMOM rate estimates from SLR are in remarkable agreement with those from GRACE, at 2.23 versus 2.28 mm/year, respectively. This proof‐of‐concept study opens the possibility of directly quantifying GMOM change using SLR data prior to the GRACE era.