Atmospheric response to solar radiation absorbed by phytoplankton

Abstract

[1] Phytoplankton alter the absorption of solar radiation, affecting upper ocean temperature and circulation. These changes, in turn, influence the atmosphere through modification of the sea surface temperature (SST). To investigate the effects of the present-day phytoplankton concentration on the atmosphere, an atmospheric general circulation model was forced by SST changes due to phytoplankton. The modified SST was obtained from ocean general circulation model runs with space-and time-varying phytoplankton abundances from Coastal Zone Color Scanner data. The atmospheric simulations indicate that phytoplankton amplify the seasonal cycle of the lowest atmospheric layer temperature. This amplification has an average magnitude of 0.3°K but may reach over 1°K locally. The surface warming in the summer is marginally larger than the cooling in the winter, so that on average annually and globally, phytoplankton warm the lowest layer by about 0.05°K. Over the ocean the surface air temperature changes closely follow the SST changes. Significant, often amplified, temperature changes also occur over land. The climatic effect of phytoplankton extends throughout the troposphere, especially in middle latitudes where increased subsidence during summer traps heat. The amplification of the seasonal cycle of air temperature strengthens tropical convection in the summer hemisphere. In the eastern tropical Pacific Ocean a decreased SST strengthens the Walker circulation and weakens the Hadley circulation. These significant atmospheric changes indicate that the radiative effects of phytoplankton should not be overlooked in studies of climate change.

Causes of the Regional Variability in Observed Sea Level, Sea Surface Temperature and Ocean Colour Over the Period 1993–2011

“…Zhai et al (2011) demonstrated increased heat loss from the ocean to the air associated with bio-optical heating of the upper ocean caused by the presence of phytoplankton in the Gulf of St. Lawrence. Atmospheric heat gain induced by the presence of phytoplankton has been further examined in coupled ocean-atmosphere models, which show an amplification of the seasonal cycle of temperature in the troposphere, modulating the tropical convection patterns and atmospheric circulation (Shell et al 2003) and affecting large patterns of climate variability such as ENSO (Zhang 2015).…”

Regional impacts of ocean color on tropical Pacific variability

“…Not surprisingly, since visible light inhabits a substantial portion of the shortwave spectrum, Correspondence to: W. Anderson (whit.anderson@noaa.gov) these constituents are important in determining the characteristic hue of seawater, often termed ocean color. Several bodies of work have investigated or suggested the importance of ocean color on the circulation of the ocean and the climate system (Rosati and Miyakoda, 1988;Lewis et al, 1990;Stramska and Dickey, 1993;Schneider and Zhu, 1998;Nakamoto et al, 2001;Murtugudde et al, 2002;Timmerman and Jin, 2002;Shell et al, 2003;Sweeney et al, 2005;Manizza et al, 2005;Lengaigne et al, 2007). Changes in shortwave absorption have also been found to impact interannual tropical variability, both in hybrid coupled models (Marzeion et al, 2005;Ballabrera-Poy et al, 2007) and fully coupled climate models (Lengaigne et al, 2007;Anderson et al, 2007).…”

Effects of Ocean Biology on the Penetrative Radiation in a Coupled Climate Model

“…A global ocean GCM is applied by Manizza et al (2005) to look at the bio-optical feedbacks between phytoplankton, ocean dynamics and sea ice. Possible atmospheric responses are discussed in Shell et al (2003). They first run an ocean GCM to obtain the biologically induced modifications of the sea surface temperature (SST) and then run a global atmospheric simulation using the modified SST.…”