Article: Kravitz, B; MacMartin, DG; Rasch, PJ; Wang, HL; “Technical note: Simultaneous fully dynamic characterization of multiple input-output relationships in climate models”, Atmospheric Chemistry and Physics, 17 (4): 2525-2541
Abstract: We introduce system identification techniques to climate science wherein multiple dynamic input-output relationships can be simultaneously characterized in a single simulation. This method, involving multiple small perturbations (in space and time) of an input field while monitoring output fields to quantify responses, allows for identification of different timescales of climate response to forcing without substantially pushing the climate far away from a steady state.
We use this technique to determine the steady-state responses of low cloud fraction and latent heat flux to heating perturbations over 22 regions spanning Earth’s oceans. We show that the response characteristics are similar to those of step-change simulations, but in this new method the responses for 22 regions can be characterized simultaneously. Furthermore, we can estimate the timescale over which the steady-state response emerges. The proposed methodology could be useful for a wide variety of purposes in climate science, including characterization of teleconnections and uncertainty quantification to identify the effects of climate model tuning parameters.
Funding Acknowledgement: U.S. Department of Energy by Battelle Memorial Institute [DE-AC05-76RL01830]; NOAA Award [NA13OAR4310129]; Regional and Global Climate Modeling Program of the Office of Biological and Environmental Research in the United States Department of Energy’s Office of Science
Funding Text: We thank Daniel Kirk-Davidoff and one anonymous reviewer for their helpful suggestions in improving this manuscript. We thank Stephen Salter for bringing this concept to our attention and for his generosity in making time for repeated discussions. We also thank Hansi K. A. Singh, Susannah M. Burrows, and Jin-Ho Yoon for helpful discussions. This work was supported in part by the Regional and Global Climate Modeling Program of the Office of Biological and Environmental Research in the United States Department of Energy’s Office of Science as a contribution to the HiLAT project. The Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle Memorial Institute under contract DE-AC05-76RL01830. Douglas G. MacMartin was supported by NOAA Award NA13OAR4310129.