Impact of Ocean Domain Definition on Sea Level Budget

Total sea level changes from space radar altimetry are mainly decomposed into two contributions of mass addition and volume expansion of oceans, measured by GRACE space gravimeter and Argo float array, respectively. However, the averages of altimetry, mass, and steric sea level changes have been usually examined over the respective data domains, which are different to one another. Errors arise from this area inconsistency is rarely discussed in the previous studies. Here in this study, an alternative definition of ocean domain is applied for examining sea level budgets, and the results are compared with estimates from different ocean areas. It shows that the impact of area inconsistency is estimated by about 0.3 mm/yr of global trend difference, and averages based on a consistent ocean area yield a closer agreement between altimetry and mass + steric in trend. This contribution would explain some discordances of past sea level budget studies.

Automated summary

Total sea level changes from different methods can be affected by area inconsistency, leading to a global trend difference of approximately 0.3 mm/yr. Applying a consistent ocean area for averaging can improve the agreement between altimetry and mass + steric in trend. This finding may help explain discrepancies in past sea level budget studies.