EOL and climate research - Jorgen Jensen

1. EOL and climate research - Jorgen Jensen 3 ways that EOL directly or indirectly serves the climate community: (1) General understanding of processes (2) Data for validation of models (3) Data used for developing new physics/chem parameterizations

2. 3 ways that EOL directly or indirectly serves the climate community: (1) General understanding of processes: EOL has a good understanding of many processes, in some cases better than the community due to EOL staff being frequently deployed to take measurements in a wide variety of environments. Yet, there is almost no direct contact between EOL staff and climate model developers. (Witha few exceptions.) Suggested action: EOL must push to increase the 2-way interaction; take the initiative. EOL must improve its understanding of what climate modelers want. EOL scientists must think of ways that their knowledge is of use to climate model developers. EOL and climate research - Jorgen Jensen

3. 3 ways that EOL directly or indirectly serves the climate community: (2) Data for validation of models: EOL has excellent data for model validation. This can be as direct comparisons or as validation of the physics assumptions. When did each of us last do such a comparison and publish the results? Suggested action: Understand the model physics. See e.g.http://www.cesm.ucar.edu/working_groups/Atmosphere/development/#Projects http://journals.ametsoc.org/doi/pdf/10.1175/2011JCLI4083.1 Think of statistics based on EOL data that may help the climate modelers; ask them what is most relevant. Focus onthe BIG PROBLEMS! EOL and climate research - Jorgen Jensen

4. 3 ways that EOL directly or indirectly serves the climate community: (3) Data used for developing new parameterizations: Most scientists are climate model users. Relatively few (?) are serious climate model developers. If the model developers are too busy to use EOL data in a serious way, then EOL scientists must think about developments of parameterizations. When did each of us last do a model parameterization?? Suggested action: Again, understand the model physics. Not all of it, but the part relevant to each of us. Think of statistics based on EOL data that may help the climate modelers. Again, focus onthe BIG PROBLEMS! EOL and climate research - Jorgen Jensen

5. Firstexample of a big problem: VERTICAL MIXING Climate models do not resolve inversions well. That leads to too high vertical mixing, less shear than observed, etc. Sometimes the climate models do not even predict the presence of marine stratus in areas where the worlds largest stratus decks exists! (E.g. VOCALS and the ECHAM model.) This is not just a resolution problem; it is also a physics problem. Suggestion: EOL has excellent knowledge of stable surface layers. Use the same expertise to examine the stable inversion at the top of the marine boundary layer. - Let ISF and RAF staff work together (which we very rarely do on science questions) on this problem. Let EOL staff do the vertical mixing calculation based on EOL data. Get the model codes. EOL and climate research - Jorgen Jensen

6. Second example of a big problem: Warm rain initiation Early autoconversion schemes parameterized the initiation of warm rain by moving liquid water from the cloud droplet category to the precipitation category – once the liquid water content exceeded at threshold value (Kessler, 1969). Subsequently Manton and Cotton (1977) suggested that autoconversion depends on the mean cloud droplet size exceeding some threshold value, e.g. r = 10 μm. Similar schemes are used in virtually all climate and weather forecast models. The implication is that these models predict warm rain formation based on “small” aerosol properties (r ~ 0.1 μm; these give rise to the majority of drops, and thus to the mean cloud droplet radius). If instead “giant” aerosol particles (r > 1 μm) form the nuclei for warm rain drops, then the action of drops formed on giant aerosol particles must be treated properly. Suggestion: Implement autoconversion based on the sizes and concentrations of giant aerosol particles. Re-evaluate impact on the indirect aerosol effect. EOL and climate research - Jorgen Jensen