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Overview Some slides about resolution Short video: build a climate model Hands-on activity: resolution vs. computing time A few more slides: why we need supercomputers

Resolution: What Does It Mean?

Improving Resolution of Climate Models Grid Cell Sizes 1990s (T42) 200 x 300 km 120 x 180 miles 2000s (T85) 100 x 150 km 60 x 90 miles Resolution – temporal and spatial – relationship to computing power or resources needed – differences in Wx vs. Climate models Credit: Warren Washington, NCAR

Improving Resolution of Climate Models Around the time of the First Assessment Report (FAR) in 1990, many climate models used a grid with cells of about 500 km (311 miles) on a side (upper left image). By the time of the the Second Assessment Report (SAR) in 1996, resolution had improved by a factor of two, producing grid cells 250 km (155 miles) on a side. Models references in the Third Assessment Report (TAR) in 2001 generally had reduced grid cells sizes to about 180 km (112 miles), while Fourth Assessment Report (AR4) models typically used a 110 km (68 mile) wide grid cell, further improving resolution. Notice how elements of topography, such as the Alps Mountains, are shown in much greater detail in higher-resolution models. This allows such models to begin to make reasonable forecasts of regional climate in the future, a currently emerging capability. Credit: Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4): Working Group 1: Chapter 1, page 113, Fig. 1.4

Vertical Resolution of Climate Models Vertical Layers 1990s 10 layer atmosphere 1 layer “slab” ocean 2000s 30 layer atmosphere 30 layer ocean Credit: UCAR

Horizontal and Vertical Grid

Horizontal and Vertical Grid

Building a Climate Model Movie gcm_model_grid_very_hi_res.mov

One-dimensional Model 40 km resolution each square on checkerboard represents 10 km cards are every fourth square 4 x 10 km = 40 km

One Dimensional Data - Altitude

One-dimensional Model 40 km resolution 2 calculations

One-dimensional Model 20 km resolution 4 calculations

One-dimensional Model 10 km resolution 8 calculations

80 km x 80 km square – how big?

Two-dimensional Model 40 km resolution 4 calculations

Two-dimensional Model 20 km resolution 16 calculations

Two-dimensional Model 10 km resolution 64 calculations

Two-dimensional Model 10 km resolution 64 calculations

Resolution and Computing Power Double resolution – increase number of nodes – more calculations! One Dimension 2 times as many nodes relationship between resolution and computing power or resources needed show simple math of need for 16x computing power if temporal and spatial (x, y and z) resolution double supercomputing – movies at end Two Dimensions 4 times as many nodes

Three Dimensions

Fourth Dimension – Time!

Double Resolution – in 4 Dimensions What happens to number of calculations if we double the resolution in four dimensions (3 space + time)? relationship between resolution and computing power or resources needed show simple math of need for 16x computing power if temporal and spatial (x, y and z) resolution double supercomputing – movies at end

Double Resolution – in 4 Dimensions 16 times as many nodes – 16x computing power required! This is why we need supercomputers!

Activity Data and Graph

Extras? Extra

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Hexagonal Grid and Sub-grids TitleTitle Lorem ipsum Grids – hexagonal vs. rectangular Credit: UCAR (Lisa Gardiner)

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Evolution of Climate Models TitleTitle Lorem ipsum Credit: Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4): Working Group 1: Chapter 1, page 99, Fig. 1.2