Monitoring the ocean heat content change and the Earth energy imbalance from space altimetry and space gravimetry

[摘要] The Earth energy imbalance (EEI) at the top of theatmosphere is responsible for the accumulation of heat in the climatesystem. Monitoring the EEI is therefore necessary to better understand theEarth's warming climate. Measuring the EEI is challenging as it is aglobally integrated variable whose variations are small (0.5–1  W m −2 )compared to the amount of energy entering and leaving the climate system( ∼340   W m −2 ). Since the ocean absorbs more than 90 %of the excess energy stored by the Earth system, estimating the ocean heatcontent (OHC) change provides an accurate proxy of the EEI. This studyprovides a space geodetic estimation of the OHC changes at global andregional scales based on the combination of space altimetry and spacegravimetry measurements. From this estimate, the global variations in theEEI are derived with realistic estimates of its uncertainty. The mean EEIvalue is estimated at + 0.74 ± 0.22   W m −2 (90 % confidencelevel) between August 2002 and August 2016. Comparisons against estimatesbased on Argo data and on CERES measurements show good agreement within theerror bars of the global mean and the time variations in EEI. Furtherimprovements are needed to reduce uncertainties and to improve the timeseries, especially at interannual timescales. The space geodetic OHC-EEIproduct (version 2.1) is freely available at https://doi.org/10.24400/527896/a01-2020.003 (Magellium/LEGOS, 2020).

[学科分类] 眼科学