# Presentation: 049346

## Purpose of “Climate Modeling” Breakout Session

**Present overview of the relevant parts of Chapters 4 and 12 in draft Plan**
**Opportunity for prepared comments by invited reviewers of the draft Plan**
**Opportunity for verbal questions, comments, and discussion from workshop attendees**

- IMPORTANT Reminder:
- To be effective in improving the Strategic Plan, comments should be submitted electronically according to instructions on the website
- (_[www.climatescience.gov](http://www.climatescience.gov/)__:  follow links to Strategic Plan)_

## Climate Modeling

**(**Strategic Plan: Chapters 4 & 12**)**
- Ants Leetmaa
- Geophysical Fluid Dynamics Laboratory
- OAR/NOAA/DOC
- Princeton, NJ 08542

## GOALS

- Provide a national high-end climate modeling capability for decision support (Chapter 4)
- Meet the modeling needs for CCSP Research (Chapter 12)
- SUB-GOALS
- Accelerate incorporation of research into improved models
- Provide capability for routine product generation
- Improved confidence in model results
- Link to global observing program

## Overview of Weather and Climate Modeling

- Mid

- -

- 1970s

- Atmosphere

- Mid

- -

- 1980s

- Atmosphere

- Land Surface

- Early 1990s

- Atmosphere

- Land Surface

- Ocean & Sea Ice

- Late 1990s

- Atmosphere

- Land Surface

- Ocean & Sea Ice

- Sulphate

- Aerosol

- Present Day

- Atmosphere

- Land Surface

- Ocean & Sea Ice

- Sulphate

- Aerosol

- Non

- -

- sulphate

- Aerosol

- Carbon Cycle

- Early 2000s?

- Atmosphere

- Land Surface

- Ocean & Sea Ice

- Sulphate

- Aerosol

- Non

- -

- sulphate

- Aerosol

- Carbon Cycle

- Dynamic

- Vegetation

- Atmospheric

- Chemistry

**Weather**

**Climate **

**Change**

**Climate**

**Variability**

**Overview of Weather and Climate Modeling**

## Meet Modeling Needs for CCSP Research

**The CCSP Research Program provides the science modules for an Earth System Model; close collaboration is needed between these and the modeling activities.**
- Atmospheric Composition
- Climate Variability and Change
- Water Cycle
- Land Use and Land Cover
- Carbon Cycle
- Ecosystems
- Human Contributions and Responses to Environmental Change

## Identify, Quantify, Reduce Uncertainty in Climate Model Projections

- Enhance Model Credibility through a Formal Program of Model Testing
- Testing against the climate record
- Testing against specialized data sets
- Sensitivity to unresolved ocean processes
- Ability to simulate major modes of climate variability
- Sensitivity comparisons
- Characterize and reduce key uncertainties

## Reduce Uncertainty in Climate Model Projections:  Sensitivity Comparisons

**State-of-art climate models can differ. Systematic intercomparisons are key to understanding and resolving the differences and pointing towards required observations**.

**Notes:**
All models use “identical” forcing.  Newer, more “sophisticated” models not necessarily converging (eg, NCAR and GFDL).

## Reduce Uncertainty in Climate Model Projections: Characterize and Reduce Key Uncertainties

**What are the major feedbacks in other U.S. models? Comparisons to observations and a focused research activities will be needed to reduce the key uncertainties**.

## Reducing the Uncertainty in Climate Model Projections:  Testing against specialized (benchmark) data sets

- Sea-level altimetry
- Solar irradiance
- GPS index of refraction
- CO2 mole fraction in the atmosphere
- Spectrally resolved, absolute radiance to space

- CO2

- Spectral Radiance

## Reducing the Uncertainty in Climate Projections: Sensitivity to Unresolved Ocean Processes

**What is the role of oceanic eddies in modulating the transports and uptakes of heat, fresh water, and carbon?**

- Reduce Uncertainty in Climate Model Projections:
- Ability to Simulate Modes of Climate Variability

**El Nino oscillations are an intrinsic feature of the coupled ocean-atmosphere system.**
**Better understanding and simulation of these modes will lead to improved seasonal forecasting skill**.

## Reduce Uncertainty in Climate Model Projections: Testing Against the Climate Record

**Simulation of 20****th**** Century Climate**

**Simulation of Ice Age**
**Climate**

**A program for systematic detection and attribution needs to be established**

**Notes:**
The overall sensitivity of a model can be tested by comparing climate simulations to observed climate history. Instrumental period: good obs, weak forcing. Ice age: Strong forcing, more observational uncertainty.

## STRENGTHENING U.S. APPLIED MODEL CAPABILITY

**Two Center Strategy**
- Community Climate System Model (NCAR): integrates basic knowledge from the broad, multi-disciplinary basic research community
- Geophysical Fluid Dynamics Laboratory (NOAA): benefits from CCSM and provides model product generation for research, assessments, and policy applications
- Success depends on collaborations with other modeling activities in US Laboratories or Universities
**Common Modeling Infrastructure**
**Access to Computational Capability**

## Strengthening U.S. Applied Climate Modeling:

- Two Center Strategy

**CCSM**

**GFDL**

- Understand major differences
- Overcome common shortcomings
- Support community standards
- Build community capacity for decision support

**Other Modeling Activities**

- Operational seasonal forecasts - NWS

- Product generation for decision support

- Broad research community

## PRODUCTS AND PAYOFFS

- Sets of ensemble global simulations, from several models, projecting possible climate change at continental and regional scales from various emissions scenarios (results in 3 years)
- North American scenarios for short-lived species: tropospheric ozone, sulfur-based and black carbon aerosols, and methane (results in 4 years)
- Better understanding of differences between: i) major U.S. high-end climate models; ii) models and observations (results yearly)

## Strengthening U.S. Applied Modelling Capabilities: Common Modeling Infrastructure

- Build on NASA funded Earth Science Modeling Framework

- Scientists implement all components

**Notes:**
Model Development Risks 
Proliferation of models and redundant model development activities
Model complexity growing rapidly
Developers need to combine efforts
Shortage of support for conversion to new architectures
Absence of programming standards

Model Development Solutions
Single lab-wide modeling framework, the Flexible Modeling System (FMS) 
Promotes code sharing, both within GFDL and with outside collaborators
Streamlines conversion efforts
Creates common standards and tools

## Strengthening U.S. Applied Climate Modeling Capabilities: Access to Computational Capabilities

- US needs substantial increase in computational capability for:
- If ..then scenario support
- Regional impacts of climate variability and change
- Exploring predictability on seasonal to centennial timescales
- High resolution modeling to explore fundamental processes associated with feedbacks

**Notes:**
1. We currently have an e-folding time of about three years, so we can afford to double the horizontal resolution every 6 years or so.