Synergy of In Situ and Satellite Ocean Observations in Determining Meridional Heat Transport in the Atlantic Ocean. Issue 4 (1st April 2021)

• Record Type: Journal Article
• Authors: Dong, Shenfu; Goni, Gustavo; Domingues, Ricardo; Bringas, Francis; Goes, Marlos; Christophersen, Jonathan; Baringer, Molly
• Is Part Of: Journal of geophysical research. Volume 126:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-01
• Subjects: Atlantic Ocean -- in situ and satellite observations -- meridional heat transport -- meridional overturning circulation; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2020JC017073
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: The meridional overturning circulation (MOC) is a major driver in global redistribution of heat, which modulates global climate and weather. Altimeter sea surface height measurements and in situ hydrographic data are combined in this work to derive monthly synthetic temperature and salinity (T/S) profiles along zonal transbasin sections in both the North (26.5°N) and South (20°S, 25°S, 30°S, and 35°S) Atlantic Ocean since 1993, which are then used to estimate the MOC and meridional heat transport (MHT). Consistent with previous studies, the results indicate that the MHT is highly correlated with the MOC at all five latitudes. At 26.5°N the mean MHT from synthetic profiles (1.09 ± 0.21 PW) is slightly lower than that from the RAPID‐MOCHA‐WBTS array (1.20 ± 0.28 PW), but their interannual variabilities show good agreements. Both the geostrophic and Ekman components contribute significantly to the MHT variability, with the geostrophic component dominating during 1993–2004 and the Ekman component dominating during 2005–2014. In the South Atlantic, the MHT seasonal cycle strengthens southward from 20°S to 34.5°S. On interannual time scale, the MHT at 20°S and 25°S experiences larger variations than that at 30°S and 34.5°S, in part due to the fact that the geostrophic and Ekman components work together to strengthen the MHT changes, while they tend to work against each other at 30°S and 34.5°S. Results shown here suggest that integrating data from different observing platforms provides better means to estimate the MOC and MHT in near real time. Plain Language Summary: The Atlantic meridional overturning circulation (AMOC) is an oceanic conveyor belt that transports large amounts of heat northwards throughout the Atlantic Ocean. Variations in the heat carried by the AMOC have pronounced impacts on regional and global extreme weather (hurricanes, heat waves, monsoons, etc.), climate, and sea level. Because of its importance, several efforts from the international community are underway to monitor the AMOC at a few latitudes based on in situ oceanographic instruments. The majority of these estimates, however, only span over relatively short and recent time periods. This study presents 28‐year long (1993–2020) estimates of the AMOC volume and heat transports at multiple latitudes (26.5°N, 20°S, 25°S, 30°S, and 34.5°S) by merging in situ oceanographic and satellite observations. These 28‐yearlong records indicate that the dominant mechanism causing changes in the strength of this conveyor belt varies between wind forcing and internal ocean dynamics. Therefore, it is important to monitor both fields to fully capture changes in the AMOC system. The methodology presented here provides a means to estimate the AMOC volume and heat transports in near real time, and can be used to validate ocean models, to detect climate variability, and to investigate their impact on extreme weather events. Key Points: Interannual variations in altimeter‐derived meridional heat transport (MHT) at 26.5°N show good agreement with mooring‐based MHT ( r = 0.78) Geostrophic and Ekman transports dominate MHT changes during different time periods MHT is highly correlated with the strength of the meridional overturning circulation in both the North and South Atlantic Ocean