I notice that there has been interest recently in the question of the difference between (shortwave) solar radiation and (longwave) infrared radiation as it affects ocean heating. Water is essentially opaque to infrared radiation, while shortwave radiation (especially in the blue wavelengths) can penetrate to substantial depths. realclimate takes the position that this doesn’t matter. I get the impression that GCMs, used in IPCC climate modeling, treat both shortwave and longwave radiation identically. I don’t propose to comment on these matters, but I happen to have read some interesting specialist articles on the topic, which are web available. It doesn’t look to me like the realclimate position on this matter is a gimme. There are some interesting connections between biological (phytoplankton) activity and penetration. Anyway here are a few articles that I’ve seen – no representations as to completeness – and which are available on the Internet. First, a really nice survey: Bissett et al. (2001), Resolving the Impacts and Feedback of Ocean Optics on Upper Ocean Ecology, Oceanography, 14(4) URL Manizza et al. (2004). Modelling the impact of phytoplankton on upper ocean physics on global scale, GRL. URL1 URL2
Marine phytoplankton partly regulate Earth’s temperature and climate through feedbacks whose full understanding is still under investigation [Gildor and Follows, 2002; Boyd and Doney, 2003]. They alter the cycle of elements such carbon and sulphur [Watson and Liss, 1998] which in turn modifies the radiative forcing of the atmosphere.
Sweeney et al., Impacts of shortwave penetration depth on large-scale ocean circulation and heat transport URL
While many one-dimensional studies of the mixed layer have considered the importance of heating due to VIS at depth (i.e. Denman, 1973; Simpson and Dickey, 1981; Dickey and Simpson, 1983; Lewis et al., 1983; Woods and Onken, 1982; Woods et al., 1984; Martin, 1985; Siegel et al., 1999; Siegel et al., 1995; Ohlmann et al., 1996; Ohlmann et al., 1998), the climate modeling community has been slow to implement these parameterizations in OGCMs. As a first step, most models assume that all of the solar irradiance is absorbed at the surface in the same way that latent and sensible heat are passed across the air-sea interface.
Thus, some of the systematic deficiencies in the present-day climate models, such as the colder than observed cold tongue in the equatorial Pacific may simply be related to inaccurate representation of the penetrative radiation and can be improved by the formulation presented here.
There are many references to articles by Murtugudde. Here is one reference: Should Climate Models Account for Biological Feedbacks? URL A little googling or following the references turns up more. The topic is rather a large one and the specialist literature doesn’t seem to support the realclimate view that it doesn’t matter, but that’s just an impression.