1. What is a Climate Model?

2. Computer Model of Earth System
A mathematical formulation applied to a grid of how the system works implemented in a computer program.
Scientists incorporate into these models their current knowledge of how parts of the Earth system interact – taking into account what they want to study.
Using data that describes the present as a starting point, models simulate the weather or climate of the Earth

3. Example Weather Model Resolution
35 vertical levels
8 km horizontal resolution
Calculations for each 30 min
Model run 4 times per day: twice out 24 hours and twice out 18 hours
Some models run out as long as 16 days

4. Weather Model Horizontal Grid Example
Greater Boston area with 8km grid overlaid

5. GISS (Goddard Institute for Space Studies) Atmospheric Global Climate Model (AGCM)
7-9 vertical levels
8o x 10o horizontal resolution
Calculations for each hour
>400 variables
Run out at years.

6. One Latitude Zone of Simple Energy Balance Climate Model
vertical levels: 1 atmosphere, 1 ocean, 1 land, and sea ice
10o latitude zone
one land grid square & one ocean grid square in each latitude zone
Calculations 1 week – 1 month
Run out 240,000 years.