What is a Climate Model?

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

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

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

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 5-100 years.

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.