A generalized tagging method

Abstract

Abstract. The understanding of causes of changes in climate-chemistry simulations is an important, but often challenging task. In atmospheric chemistry, one approach is to tag species according to their origin (e.g. emission categories) and to inherit these tags to other species during subsequent reactions. This concept was recently employed to calculate the contribution of atmospheric processes to temperature. Here a new concept for tagging any state variable is presented. This generalized tagging method results from a sensitivity analysis of the individual forcing terms of the right hand side of the governing differential equations. In a couple of examples, the consistency with previous approaches and the synergy by using different analysis techniques are shown. Since the method is based on a ratio describing relative sensitivities, singularities occur where the method is not applicable. For some applications, such as in atmospheric chemistry, these singularities can easily be removed. However, one theoretical example is given, where this method is not applicable at all.

A new method to diagnose the contribution of anthropogenic activities to temperature: temperature tagging

“…This facilitates the tagging concept, but is physically or mathematically not necessary. Tags can be viewed as contributions of a process to any regarded quantity (Grewe, 2013).…”

“…This would give a temperature sensitivity, whereas the tagging provides consistent temperature contributions. This is often confused but has to be distinguished, since both approaches differ significantly and address different questions (Grewe et al, 2010(Grewe et al, , 2012Grewe, 2013).…”

“…For the latter, the heating rates caused by individual components have to be determined. A companion paper (Grewe, 2013) describes a generalized tagging formula and provides a basis for how to treat more complex processes.…”

“…However, I like to give some ideas on possible implementations. A generalized tagging approach is presented in a companion paper (Grewe, 2013). Figure 10 gives an simplified overview on an arbitrary 3-D climate model (black) and necessary extensions for the tagging scheme (red).…”

“…During the physics and radiation calculation, all temperature tendencies have to be extracted and tagging tendencies calculated from these tendencies, which is basically the heart of the tagging scheme and refers to Sect. 2.3 in this paper and to Grewe (2013). Finally the temperature field and the tagged fields have to be integrated; i.e.…”