The NOAA CPO Modeling, Analysis, Prediction, and Projections (MAPP) program will host a webinar on the topic of model development on Tuesday, January 14. This webinar will discuss plans at NCEP and GFDL for next-generation model development as well as three new Climate Process Teams funded by the MAPP program and focused on improving the representation of clouds in NOAA’s climate models and advanced representations of sea ice processes in GFDL climate and Earth system models. The announcement is provided below; you are invited to remotely join the session.
Chris Bretherton (University of Washington) -- The NCEP/U. Washington/JPL/GFDL Cloud and Boundary Layer CPT -- Planned activities for this CPT will be reviewed, focusing on ongoing testing of a GFS eddy-diffusion mass-flux boundary-layer parameterization and the upcoming implementation of a moist version of this scheme, as well as related activities at GFDL.
Isaac Held (GFDL) -- The development strategy for a new climate/earth system model at GFDL - CM4/ESM4. -- I will describe our strategy for the development of a next-generation climate model at GFDL, which we are planning as a 4-5 year process of which we are currently finishing the first year. This is not meant to subsume all of the development efforts at GFDL, but it is an opportunity for the lab as a whole to get together to construct a new "trunk" model that builds on past efforts and provides coherence to the variety of future branches to our model tree that we expect will evolve from this effort. Available results are necessarily preliminary, but I will mention one or two from the atmospheric working group. The oceanic working group is currently focused on finalizing the new MOM6 code for CM4 development. I will focus in this talk on our overall goals and our vision for what this model will probably look like, and on some of the issues that we are discussing intensively.
Steven Krueger (Utah State University) -- A CPT for Improving Turbulence and Cloud Processes in the NCEP Global Models -- Global models parameterize the effects of processes that occur on scales near or below the horizontal grid spacing, including turbulence, convection, and associated cloud and radiation processes. Current global forecast models use grid spacings of a few tens of kilometers; in the next few years the mesh size is expect to be less than ten kilometers. Conventional parameterizations of deep convection rely on assumptions that are fundamentally inconsistent with such high-resolution models. Smaller clouds such as shallow cumuli, however, will not be even partially resolved in the foreseeable future. Developing parameterizations that work well across a range of parameterized and explicit phenomena is a significant challenge.
Our hypothesis is that the NCEP global models can be improved by installing an integrated, self-consistent description of turbulence, clouds, deep convection, and the interactions between clouds and radiative and microphysical processes. We therefore proposed a CPT to unify the representation of turbulence and SGS cloud processes and to unify the represen- tation of SGS deep convective precipitation and grid-scale precipitation as the horizontal resolution decreases. Both of these unifications are physically based and both have been extensively tested against LES and CRM results.
We hope to improve the representation of small-scale phenomena by implementing a PDF-based subgrid-scale turbulence and cloudiness scheme that would replace the boundary layer turbulence scheme, the shallow convection scheme, and the cloud fraction schemes in the GFS and CFS. We hope to improve the treatment of deep convection by introducing a unified parameterization that scales continuously between the simulation of individual clouds when and where the grid spacing is sufficiently fine and the behavior of a conventional parameterization of deep convection when and where the grid spacing is coarse. We hope to improve the representation of the interactions of clouds, radiation, and microphysics in the GFS/CFS by using the additional information provided by the PDF-based SGS cloud scheme.
The team will evaluate the impacts of the model upgrades with metrics used by the NCEP short-range and seasonal forecast operations.
Olga Sergienko (GFDL) -- Representing calving and iceberg dynamics in climate models -- Iceberg calving is a major mode of mass loss from the Greenland and Antarctic Ice Sheets (the other one is sub-ice-shelf melting). This process affects ice-shelf and ice-sheet flow, in some circumstances triggering additional discharge of ice from the grounded parts to the surrounding ocean. Once calved, icebergs drift in the open ocean, sometimes traveling large distances to mid-latitudes. During their lifetime, they melt causing redistribution of freshwater in the ocean and changes in the properties of water masses.
Despite significance of both, the calving process and iceberg-ocean interaction, there is no consistent representation of them in the continental-scale ice-sheet models and global ocean models. To fill this gap, we will (1) develop parameterizations of calving processes suitable for the continental scale ice sheet models, (2) include realistic representation of dimensional icebergs into the GFDL climate model, and (3) compile available observations to test and validate the developed parameterizations and the iceberg model component.