Feature #4961

Updated by Twan van Noije almost 4 years ago

We have since long calculated the DMS emissions over the ocean based on a monthly climatology of surface ocean DMS concentrations from Kettle et al. (GBC, 1999), an expression of the transfer velocity as a function of wind speed and Schmidt number from Liss and Merlivat (1986), and a temperature dependence of the Schmidt number described by a (third-order) polynomial for which I do not have a reference.

I have now included a new parameterization based on the climatology of ocean concentrations from Lana et al. (GBC, 2011), which is an update of the climatology from Kettle et al., in combination with recent expressions for the transfer velocity and Schmidt number from Waninkhof et al. (Limnol. Oceanogr.: Methods, 2014). The (fourth-order polynomial) fit used for the Schmidt number is based on data presented by Saltzman et al. (JGR, 1993), but applies to a broader range of temperatures as the (third-order polynomial) fit presented there. The polynomial applied in the original TM5 code gives a quite different (and less reliable) dependence. I have also replaced the temperature criterion applied in the earlier implementation, to decide whether emissions are suppressed by the presence of sea ice. In the new scheme, the fractional sea ice cover is used directly.

For more information, see my comments in the code.

I will make some sensitivity simulations using ERA-Interim for the year 2010 to test the impact on the DMS source.