Upper Ocean Cooling in a Coupled Climate Model Due to Light Attenuation by Yellowing Materials

Abstract

Colored detrital matter consists of dissolved organic molecules and detrital materials that impart a yellow shift to the ocean's color. These materials reduce light penetration, concentrating heating by sunlight closer to the surface. We ran two climate model simulations: one of an ocean including colored detrital matter (Yellow Ocean) and one without (Green Ocean). Due to the decreased water clarity in the Yellow Ocean, upper ocean heat content was lower and temperatures were colder compared to the Green Ocean. The difference between these simulations is opposite to the ocean warming that has been observed in recent decades. Increasing precipitation in high‐latitude regions has also been observed, with greater inputs of terrestrial organic materials to the ocean. We suggest that an increase in these yellowing materials behaves as a buffer that mitigates some effects of a warming climate. Future studies should investigate this link between the atmosphere, land, and ocean systems.

Small Phytoplankton Shapes Colored Dissolved Organic Matter Dynamics in the North Atlantic Subtropical Gyre

“…CDOM thus attenuates the penetration of UV and blue light with depth and modifies the color of the ocean (Morel & Prieur, 1977). Modifications in CDOM light absorption track climate change signals (Dutkiewicz et al, 2019), and ultimately may affect the ocean's heat budget (Kim et al, 2018). Because of ocean warming due to climate change, NASTG is expanding and thus represents how the future ocean will look like (Polovina et al, 2008).…”

Impact of Colored Dissolved Materials on the Annual Cycle of Sea Surface Temperature: Potential Implications for Extreme Ocean Temperatures

“…As seen in Figure 2a, the SST during the warmest month over the year does rise in regions such as the Pacific west coast, Baltic Sea, and NE Atlantic. However, noted in previous work (Kim et al, 2016(Kim et al, , 2018, absorbing more heat near the surface means that less heat is absorbed at depth. As a result subsurface waters are cooler and, when exposed in the wintertime, drive a seasonal cooling (Figure 2c).…”

“…Both simulations were then run out for 900 years. While there are some drifts in the deep ocean, surface temperatures come to equilibrium after about 100 years (Kim et al, )—though in order to be cautious we look only at the last 700 years of the simulation. Differences between the CDM + Chl and Chl‐only simulations thus show the total impact of adding CDM to the Earth System Model.…”

A Positive Feedback Onto ENSO Due to Tropical Instability Wave (TIW)‐Induced Chlorophyll Effects in the Pacific

“…• Supporting Information S1 atmosphere interaction (Gnanadesikan et al, 2010;Jochum et al, 2010;Kim et al, 2018;Lengaigne et al, 2007;Murtugudde et al, 2002;Nakamoto et al, 2001;Park, Kug, Seo, et al, 2014;Sweeney et al, 2005;Timmermann & Jin, 2002;Wetzel et al, 2006;). On interannual timescale, for example, Zhang et al (2018a) argued that interannual variability of chlorophyll can induce a negative feedback onto ENSO; that is, interannually varying chlorophyll effect acts to reduce ENSO amplitudes.…”

“…Ocean chlorophyll and other materials (e.g., colored dissolved organic matter) can absorb solar radiation and consequently modulate the penetrative radiation in the upper ocean due to their spatiotemporal variability. The modulation of penetrative solar radiation alters the stratification and vertical mixing in the upper ocean, which further modulates sea surface temperature (SST) and ENSO characteristics through ocean‐atmosphere interaction (Gnanadesikan et al, ; Jochum et al, ; Kim et al, ; Lengaigne et al, ; Murtugudde et al, ; Nakamoto et al, ; Park, Kug, Seo, et al, ; Sweeney et al, ; Timmermann & Jin, ; Wetzel et al, ; Zhang et al, ). On interannual timescale, for example, Zhang et al () argued that interannual variability of chlorophyll can induce a negative feedback onto ENSO; that is, interannually varying chlorophyll effect acts to reduce ENSO amplitudes.…”