Making Forecasts Better-Community Infrastructure for Facilitating Improvement and Testing of Physical Parameterizations

"Making Forecasts Better" is the vision of the Global Systems Division (GSD) of NOAA's Earth System Research Laboratory. It is also a central goal of operational modeling centers and climate prediction centers, who are always on the lookout for opportunities to improve their numerical weather prediction products, seasonal predictions and climate change projections. One way to achieve this goal is to improve the physical parameterizations in the numerical model components of nowadays increasingly complex forecasting systems.

The Common Community Physics Package (CCPP) is a collaborative effort of GSD and the Joint Numerical Testbed (JNT) at the National Center for Atmospheric Research (NCAR) with the goal to develop a collection of physical parameterizations and a software infrastructure that facilitate the addition of physics innovations to earth system model components. The CCPP infrastructure is designed in a model-agnostic approach and allows for an easy integration with models of the atmosphere, land, ocean or hydrology. The CCPP is a well-documented, freely-available community-supported code that students and scientists can obtain for development and testing, and for contributing back promising innovations to the pool of parameterizations.

The communication between the host model and the physical parameterizations through the CCPP infrastructure makes use of auto-generated caps at both ends, which lowers the bar for adding new parameterizations to the pool. In order to be considered as CCPP-compliant, a parameterization must adopt certain standards such as a well-described interface and modern Fortran/C coding styles. The initial development of CCPP is centered around the GMTB single-column model and the Finite-Volume Cubed-Sphere dynamical core (FV3), planned for use in upcoming operational implementations of the U.S. Global Forecast System (GFS). However, GMTB’s long-term vision is to embrace other weather- and climate modeling groups to leverage the brain power of scientists worldwide and translate it into model improvements accessible to all.

In this contribution, we will discuss the technical design and the requirements for physical parameterizations to be considered as CCPP-compliant. We will also describe the connection and integration of the CCPP with the host model and demonstrate its application with the atmospheric core FV3. We will present a summary of the current pool of physical parameterizations and an outlook on future developments. We explicitly invite model and parameterization developers to engage in further discussions to help improve the CCPP and enable a broad usage of our system.