What is a Climate Model?

Weather Model

Computer Model of Earth System A mathematical formulation 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.

Global Forecast System From Wikipedia, the free encyclopedia Jump to: navigation, search The Global Forecast System (GFS) is global numerical weather prediction model run by NOAA. This model is run four times a day and produces forecasts up 16 days in advance, but with decreasing spatial and temporal resolution over time (although it is widely accepted that beyond 7 days the forecast is little better than guesswork). The model is run in two parts: the first part has a higher resolution and goes out to 180 hours in the future, the second part runs from 180 to 384 hours. The resolution of the model varies in each part of the model: horizontally, it divides the surface of the earth into 35 or 70 kilometre grid squares; vertically, it divides the atmosphere into 64 layers and temporally, it produces a forecast for every 3rd hour for the first 180 hours, after that they are produced for every 12th hour. Incidentally, this is the only global NWP output available for free over the internet (as a result of U.S. law), and as such is the basis for many web based forecast services