Multidecadal-scale adjustment of the ocean mixed layer heat budget in the tropics: examining ocean reanalyses

Examining multidecadal trends in the surface heat balance over the tropical and subtropical oceans in atmospheric reanalyses

“…The goal is not to understand how the observed trends are forced, since that is not possible when examining mutually adjusted fields. The focus is the exchange of heat between the atmosphere and the ocean surface; changes internal to the ocean mixed layer associated with this heat exchange and with air/sea momentum fluxes are addressed in a previous study (Cook et al, 2018). Confidence in the linear trends in the reanalysis products is evaluated by intercomparison, statistical significance, and physical realism.…”

“…In particular, the surface heat balance calculation is only partially constrained by observations, and most terms depend on physical parameterizations. Nonetheless, an examination of heat budget trends reanalyses have proven to be useful for diagnosing surface temperature trends (e.g., Loeb et al ., , Tillinger and Gordon, , Johnston and Gabric, , Yang et al ., , Hakkinen et al ., , Cook and Vizy, , Cook et al ., , Cook et al ., .…”

“…In particular, the surface heat balance calculation is only partially constrained by observations, and most terms depend on physical parameterizations. Nonetheless, an examination of heat budget trends reanalyses have proven to be useful for diagnosing surface temperature trends (e.g., Loeb et al, 2012, Tillinger and Gordon, 2009, Johnston and Gabric, 2010, Yang et al, 2014, Hakkinen et al, 2015, Cook et al, 2018, Cook et al, 2018 Surface heat budget components in reanalyses are compared with more direct observations in many studies (e.g., Bosilovich et al, 2011;Brunke et al, 2011;Masina et al, 2011;Decker et al, 2012;Bosilovich et al, 2013;Chaudhuri et al, 2013;Dee et al, 2014;Pinker et al, 2014;Dolinar et al, 2015;Valdivieso et al, 2017). For example, Brunke et al (2011) compare ocean surface turbulent heat fluxes from six reanalyses with satellite-derived products and direct measurements and find that climatological biases are small for wind speeds below 10 mÁs -1 , but become larger at high wind speeds.…”

“…Here, we examine adjustments in the surface heat balance to SST trends over the tropical and subtropical oceans (30 S-30 N) for 1979-2018 in three atmospheric reanalyses. The purpose is to understand how the reanalyses represent the adjustment of the surface heat balance to prescribed SST trends; changes internal to the ocean mixed layer are addressed in a separate study (Cook et al, 2018). In reality and in coupled climate models, trends in SSTs and the components of the surface heat budget are tightly coupled and co-dependent.…”

Physical drivers of the summer 2019 North Pacific marine heatwave

“…3 may suffer from uncertainty as a result of using GODAS ocean reanalysis, which includes data assimilation of in situ ocean measurements, but may also include nonphysical heat sources and sinks to match the model to observations. While GODAS has been successfully implemented in the past when considering large-scale climate variability 2,46 , calculating the heat budget offline across long-term average fields may cloud interpretation of the results (particularly the mechanisms that drive variability in the residual) and/or introduce errors into the calculations. Despite these concerns, the spatial consistency of atmospheric circulation and low-cloud fraction anomalies (Figs.…”