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

Abstract

The influence of phytoplankton on the seasonal cycle and the mean global climate is investigated in a fully coupled climate model. The control experiment uses a fixed attenuation depth for shortwave radiation, while the attenuation depth in the experiment with biology is derived from phytoplankton concentrations simulated with a marine biogeochemical model coupled online to the ocean model. Some of the changes in the upper ocean are similar to the results from previous studies that did not use interactive atmospheres, for example, amplification of the seasonal cycle; warming in upwelling regions, such as the equatorial Pacific and the Arabian Sea; and reduction in sea ice cover in the high latitudes. In addition, positive feedbacks within the climate system cause a global shift of the seasonal cycle. The onset of spring is about 2 weeks earlier, which results in a more realistic representation of the seasons. Feedback mechanisms, such as increased wind stress and changes in the shortwave radiation, lead to significant warming in the midlatitudes in summer and to seasonal modifications of the overall warming in the equatorial Pacific. Temperature changes also occur over land where they are sometimes even larger than over the ocean. In the equatorial Pacific, the strength of interannual SST variability is reduced by about 10%-15% and phase locking to the annual cycle is improved. The ENSO spectral peak is broader than in the experiment without biology and the dominant ENSO period is increased to around 5 yr. Also the skewness of ENSO variability is slightly improved. All of these changes lead to the conclusion that the influence of marine biology on the radiative budget of the upper ocean should be considered in detailed simulations of the earth's climate.

Evidence of the return of past pollution in the ocean: A model study

“…The Hamburg Ocean Carbon Cycle Model (HAMOCC5) includes nutrient, phytoplankton, zooplankton, and detritus cycles [Wetzel et al, 2006]. The chemical cycles and trophic levels represented in the model are linked through the nutrient uptake and remineralization of organic matter.…”

Temperature variability in China in an ensemble simulation for the last 1,200 years

“…The model includes the atmospheric model ECHAM5 (Roeckner et al 2003), the ocean model MPIOM (Marsland et al 2003), and modules for land vegetation (JSBACH; Raddatz et al 2007) and ocean biogeochemistry (HAMOCC; Wetzel et al 2006), which are coupled via the OASIS3 coupler. The carbon cycle is interactively simulated.…”

Impact of bio-physical feedbacks on the tropical climate in coupled and uncoupled GCMs

“…So far, there have been multiple attempts to access the biological impacts on the physical fields (Sathyendranath et al 1991;Nakamoto et al 2000;Murtugudde et al 2002;Timmermann and Jin 2002;Ohlmann 2003;Strutton and Chavez 2004;Wetzel et al 2006;Lin et al 2008;Gnanadesikan and Anderson 2009;Jochum et al 2010;Turner et al 2011). In particular, because the biological feedback can induce significant physical perturbations in the equatorial Pacific, this region has been an active research area for these studies.…”

“…The atmosphere-ocean coupled global circulation models (CGCMs) incorporating marine biology have also shown that biological feedback can significantly change the modeled climatology and variability (Marzeion et al 2005;Wetzel et al 2006;Anderson et al 2007;Ballabrera-Poy et al 2007;Lengaigne et al 2007;Jochum et al 2010;Lin et al 2011;Patara et al 2012). For example, Marzeion et al (2005) showed that the presence of chlorophyll leads to a deepening of the mixed layer in the eastern equatorial Pacific due to the biologically enhanced subsurface warming.…”

“…For example, some studies reported that the presence of chlorophyll derives an increased mean SST in the eastern equatorial Pacific due to enhanced absorption of shortwave radiation and/or deepening of the mixed layer that leads to reduced upwelling (Murtugudde et al 2002;Marzeion et al 2005;Wetzel et al 2006). On the other hand, surface cooling caused by an indirect dynamical response to the biologically enhanced heating has been also reported (Nakamoto et al 2001;Manizza et al 2005;Loptien et al 2009;Jochum et al 2010).…”