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

Gnanadesikan, Anand; Kim, Grace; Pradal, Marie-Aude

doi:10.1029/2018gl080695

Cited by 17 publications

(12 citation statements)

References 37 publications

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“…In contrast to the summertime surface warming, lower SSTs occur in winter (not shown here). These changes are accompanied by an amplified seasonal cycle of surface temperature (Figure 3b) implying changes in temperature extremes (Gnanadesikan et al, 2019) with potential ecological implications.…”

Section: Resultsmentioning

confidence: 99%

“…Previous modeling efforts focused on the effect of phytoplankton on ocean physics. The CDOM effect was either not considered or constant values of its absorption were used in the model's light attenuation scheme (Gnanadesikan et al, 2019; Kim et al, 2016, 2018). In a step forward, Kim et al (2018), by prescribing interannually averaged absorption estimates from a satellite data set, suggested that increased CDOM and suspended material may slow down the global warming effect on the ocean.…”

Section: Implications and Conclusionmentioning

confidence: 99%

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Amplified Arctic Surface Warming and Sea Ice Loss Due to Phytoplankton and Colored Dissolved Material

Pefanis

Losa

Lösch

et al. 2020

Geophysical Research Letters

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Optically active water constituents attenuate solar radiation and hence affect the vertical distribution of energy in the upper ocean. To understand their implications, we operate an ocean biogeochemical model coupled to a general circulation model with sea ice. Incorporating the effect of phytoplankton and colored dissolved organic matter (CDOM) on light attenuation in the model increases the sea surface temperature in summer and decreases sea ice concentration in the Arctic Ocean. Locally, the sea ice season is reduced by up to one month. CDOM drives a significant part of these changes, suggesting that an increase of this material will amplify the observed Arctic surface warming through its direct thermal effect. Indirectly, changing advective processes in the Nordic Seas may further intensify this effect. Our results emphasize the phytoplankton and CDOM feedbacks on the Arctic ocean and sea ice system and underline the need to consider these effects in future modeling studies to enhance their plausibility. Plain Language Summary The amount of microalgae and colored dissolved organic material in the ocean determines how much light is absorbed in the surface waters and how much can reach greater depths. The vertical distribution of energy affects the upper ocean temperature and general circulation. Here, we use a numerical ocean model with biogeochemistry and sea ice, in which the individual effects of microalgae and colored dissolved organic matter can be turned on and off separately. When both effects are turned on, the summertime surface temperatures in the Arctic are larger and consequently more sea ice melts, so that the sea ice season is shorter by up to one month. We find that, to a large extent, the colored dissolved material is responsible for these changes. An increase of this material due to climate change will amplify the observed Arctic surface warming. For better projections of climate change, new models should account for the effect of these light-absorbing water constituents. In numerical ocean general circulation models, the penetration of solar radiation needs to be parameterized. The choice of parameterization may affect the circulation significantly, as well as the upper ocean water masses (Cahill et al., 2008) and their transformation rates (Groeskamp & Iudicone, 2018). Compared RESEARCH LETTER

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Section: Resultsmentioning

confidence: 99%

Section: Implications and Conclusionmentioning

confidence: 99%

Amplified Arctic Surface Warming and Sea Ice Loss Due to Phytoplankton and Colored Dissolved Material

Pefanis

Losa

Lösch

et al. 2020

Geophysical Research Letters

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“…In this study, we present the absorption coefficient (m −1 ) at a wavelength of 350 nm: a CDOM (350). The wavelength was selected to make the results comparable with previous studies in Arctic waters (Granskog et al, 2012;Gonçalves-Araújo et al, 2015;Pavlov et al, 2016). The spectral slope of the absorption spectra in the wavelength range between 275 and 295 nm (S 275−295 ) and between 300 and 600 nm (S 300−600 ) was calculated by fitting with an exponential function a CDOM (λ) = a CDOM (λ0) × e − S(λ − λ0).…”

Section: Sample Preparation and Analytical Methodsmentioning

confidence: 99%

The impact of the freeze–melt cycle of land-fast ice on the distribution of dissolved organic matter in the Laptev and East Siberian seas (Siberian Arctic)

et al. 2021

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Abstract. Permafrost degradation in the catchment of major Siberian rivers, combined with higher precipitation in a warming climate, could increase the flux of terrestrially derived dissolved organic matter (tDOM) into the Arctic Ocean (AO). Each year, ∼ 7.9 Tg of dissolved organic carbon (DOC) is discharged into the AO via the three largest rivers that flow into the Laptev Sea (LS) and East Siberian Sea (ESS). A significant proportion of this tDOM-rich river water undergoes at least one freeze–melt cycle in the land-fast ice that forms along the coast of the Laptev and East Siberian seas in winter. To better understand how growth and melting of land-fast ice affect dissolved organic matter (DOM) dynamics in the LS and ESS, we determined DOC concentrations and the optical properties of coloured dissolved organic matter (CDOM) in sea ice, river water and seawater. The data set, covering different seasons over a 9-year period (2010–2019), was complemented by oceanographic measurements (T, S) and determination of the oxygen isotope composition of the seawater. Although removal of tDOM cannot be ruled out, our study suggests that conservative mixing of high-tDOM river water and sea-ice meltwater with low-tDOM seawater is the major factor controlling the surface distribution of tDOM in the LS and ESS. A case study based on data from winter 2012 and spring 2014 reveals that the mixing of about 273 km3 of low-tDOM land-fast-ice meltwater (containing ∼ 0.3 Tg DOC) with more than 200 km3 of high-tDOM Lena River water discharged during the spring freshet (∼ 2.8 Tg DOC yr−1) plays a dominant role in this respect. The mixing of the two low-salinity surface water masses is possible because the meltwater and the river water of the spring freshet flow into the southeastern LS at the same time every year (May–July). In addition, budget calculations indicate that in the course of the growth of land-fast ice in the southeastern LS, ∼ 1.2 Tg DOC yr−1 (± 0.54 Tg) can be expelled from the growing ice in winter, together with brines. These DOC-rich brines can then be transported across the shelves into the Arctic halocline and the Transpolar Drift Current flowing from the Siberian Shelf towards Greenland. The study of dissolved organic matter dynamics in the AO is important not only to decipher the Arctic carbon cycle but also because CDOM regulates physical processes such as radiative forcing in the upper ocean, which has important effects on sea surface temperature, water column stratification, biological productivity and UV penetration.

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“…Jerlov (1976) developed a classification for different water masses based on specific optical properties. This classification is widely used in numerical ocean models (e.g., Griffies, 2004). For global models, this parametrization works reasonably well.…”

Section: Introductionmentioning

confidence: 87%

“…For model testing, we have used a similar model system to that in Neumann et al (2015). The circulation model is MOM5.1 (Griffies, 2004) adapted for the Baltic Sea. The horizontal resolution is 3 nautical miles.…”

Section: Circulation and Biogeochemical Modelmentioning

confidence: 99%

Optical model for the Baltic Sea with an explicit CDOM state variable: a case study with Model ERGOM (version 1.2)

et al. 2021

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Abstract. Colored dissolved organic matter (CDOM) in marine environments impacts primary production due to its absorption effect on the photosynthetically active radiation. In coastal seas, CDOM originates from terrestrial sources predominantly and causes spatial and temporal changing patterns of light absorption which should be considered in marine biogeochemical models. We propose a model approach in which Earth Observation (EO) products are used to define boundary conditions of CDOM concentrations in an ecosystem model of the Baltic Sea. CDOM concentrations in riverine water derived from EO products serve as forcing for the ecosystem model. For this reason, we introduced an explicit CDOM state variable in the model. We show that the light absorption by CDOM in the model can be improved considerably in comparison to approaches where CDOM is estimated from salinity. The model performance increases especially with respect to spatial CDOM patterns due to the consideration of single river properties. A prerequisite is high-quality CDOM data with sufficiently high spatial resolution which can be provided by the new generation of ESA satellite sensor systems (Sentinel 2 MSI and Sentinel 3 OLCI). Such data are essential, especially when local differences in riverine CDOM concentrations exist.

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

Cited by 17 publications

References 37 publications

Amplified Arctic Surface Warming and Sea Ice Loss Due to Phytoplankton and Colored Dissolved Material

Amplified Arctic Surface Warming and Sea Ice Loss Due to Phytoplankton and Colored Dissolved Material

The impact of the freeze–melt cycle of land-fast ice on the distribution of dissolved organic matter in the Laptev and East Siberian seas (Siberian Arctic)

Optical model for the Baltic Sea with an explicit CDOM state variable: a case study with Model ERGOM (version 1.2)

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