01 August 2013

Novel Analysis of Cloud Observations Helps Pave the Way Toward a New Class of High-resolution Climate Models

Science

Variable-resolution climate models provide a promising and efficient way to produce high-resolution projections of climate change. An emerging theme in the climate model community is the development of 'scale aware' models, which focus on making models that improve as their resolution increases; ‘scale-awareness’ is a key criterion for variable-resolution climate modeling. A recent study by DOE researchers used satellite-based observations of clouds and precipitation to develop a theory that describes how resolved clouds and precipitation should increase as resolution increases in climate models. An examination of modeled clouds and precipitation shows excellent agreement with the satellite observations, but that models resolve fewer clouds and less precipitation as resolution increases; this behavior is ‘scale-incognizant’ rather than ‘scale-aware’. This work points to a specific, precipitation-related, model component as a cause of scale-incognizance in the DOE-supported climate model, the Community Earth System Model (CESM). Developers are now targeting this model component to improve the scale-aware behavior of the CESM. This study provides a framework for using observations of scale-dependent behavior in the earth system to derive constraints on the resolution dependence of climate models. It is an early step that paves the way toward enabling variable-resolution climate simulations with the CESM.

Summary

Variable-resolution climate models provide a promising and efficient way to produce high-resolution projections of climate change. An emerging theme in the climate model community is the development of 'scale aware' models, which focus on making models that improve as their resolution increases; ‘scale-awareness’ is a key criterion for variable-resolution climate modeling. A recent study by DOE researchers used satellite-based observations of clouds and precipitation to develop a theory that describes how resolved clouds and precipitation should increase as resolution increases in climate models. An examination of modeled clouds and precipitation shows excellent agreement with the satellite observations, but that models resolve fewer clouds and less precipitation as resolution increases; this behavior is ‘scale-incognizant’ rather than ‘scale-aware’. This work points to a specific, precipitation-related, model component as a cause of scale-incognizance in the DOE-supported climate model, the Community Earth System Model (CESM). Developers are now targeting this model component to improve the scale-aware behavior of the CESM. This study provides a framework for using observations of scale-dependent behavior in the earth system to derive constraints on the resolution dependence of climate models. It is an early step that paves the way toward enabling variable-resolution climate simulations with the CESM.

Contact
Siyu Chen
Acknowledgments

This research was supported by the Director, Office of Science, Office of Biological and Environmental Research of the U.S. Department of Energy Regional and Global Climate Modeling Program (RGCM) and used resources of the National Energy Research Scientific Computing Center (NERSC), also supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.