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CLIM 101 - Fall 2008 What are the Roles of Satellites & Supercomputers in Studying Weather and Climate? CLIM 101 Slide 2 CLIM 101 - Fall 2008 Satellites and Supercomputers Satellites Observing the weather Observing the climate and planetary ecosystems Provide global coverage Provide nearly continuous observations Supercomputers Modeling the atmosphere Numerical weather prediction Modeling the physical climate system Modeling the Earth system Simulating the current and future climate Slide 3 CLIM 101 - Fall 2008 Slide 4 Slide 5 Geostationary Satellite SMS-A, 1974: 1st geostationary Slide 6 CLIM 101 - Fall 2008 GOES-8 - Geostationary Earth Orbiting Satellite Slide 7 CLIM 101 - Fall 2008 GOES East - Full Disk View Slide 8 CLIM 101 - Fall 2008 GOES West - Zoomed View Slide 9 CLIM 101 - Fall 2008 Mosaic of Multiple Geostationary Satellite Images (infrared band) Slide 10 CLIM 101 - Fall 2008 Geostationary Satellite Polar Orbiting Satellite SMS-A, 1974: 1st geostationary TIROS-1, 1960: 1st polar orbiter Slide 11 CLIM 101 - Fall 2008 Slide 12 Slide 13 Slide 14 How are weather forecasts made? by Wiley Miller Slide 15 CLIM 101 - Fall 2008 Numerical Weather Prediction 1.Determine (continuous) equations to be solved Equation of state or Ideal Gas Law (Boyles Law relates P V, Charles Law relates V T, Gay-Lussacs Law relates T P) Conservation of mass (dry air, water) Conservation of energy Conservation of angular momentum Result: set of coupled, nonlinear, partial differential equations 2.Discretize the equations for numerical solution (typically requires computer) 3.Measure current state of global atmosphere to obtain initial conditions 4.Solve the initial value problem to produce a forecast 5.Take into account uncertainty in measured atmospheric state by repeating step 4 over an ensemble of slightly different initial conditions Slide 16 CLIM 101 - Fall 2008 (approximation) Mass conservation Energy conservation Newtons law = p / p s Slide 17 CLIM 101 - Fall 2008 Using the secant approach, we can approximate the temperature equation: By reducing t, we can obtain an increasingly accurate solution. Slide 18 CLIM 101 - Fall 2008 Discretization Atmosphere and ocean are continuous fluids but computers can only represent discrete objects Slide 19 CLIM 101 - Fall 2008 Discretization Atmosphere and ocean are continuous fluids but computers can only represent discrete objects Slide 20 CLIM 101 - Fall 2008 John von Neumann Seymour Cray & Cray-1 ENIAC IBM 360 Cray-2 Columbia NASA Slide 21 CLIM 101 - Fall 2008 Computing Capability & Global Model Grid Size (km) Peak Rate:10 TFLOPS100 TFLOPS1 PFLOPS10 PFLOPS100 PFLOPS Cores (1 st year available) 1,400 (2006) 12,000 (2008) 80-100,000 (2009) 300-800,000 (2011) 6,000,000? (20xx?) Global NWP 0 : 5-10 days/hr 18 - 298.5 - 14 4.0 - 6.3 (~20X10 6 points) 1.8 - 2.90.85 - 1.4 Seasonal 1 : 50-100 days/day 17 - 288.0 - 13 3.7 - 5.9 (~20X10 6 points) 1.7 - 2.80.80 - 1.3 Decadal 1 : 5-10 yrs/day 57 - 9127 - 42 12 - 20 (~2X10 6 points) 5.7 - 9.12.7 - 4.2 Climate Change 2 : 20-50 yrs/day 120 - 20057 - 91 27 - 42 (~0.5X10 6 points) 12 - 205.7 - 9.1 Range: Assumed efficiency of 10-40% 0 - Atmospheric General Circulation Model (AGCM; 100 levels) 1 - Coupled Ocean-Atmosphere-Land Model (CGCM; ~ 2X AGCM computation with 100-level OGCM) 2 - Earth System Model (ESM; ~ 2X CGCM computation) * Core counts above O(10 4 ) are unprecedented for weather or climate codes, so the last 3 columns require getting 3 orders of magnitude in scalable parallelization (scalar processors assumed; vector processors would have lower processor counts) Thanks to Jim Abeles (IBM) Slide 22 CLIM 101 - Fall 2008 Numerical Weather Prediction: Data Assimilation Cycle Slide 23 CLIM 101 - Fall 2008 Slide 24 Slide 25 Slide 26 Slide 27 NCEP Forecast Ensembles: 850 hPa Geopotential Height Contours: 126 and 147 gpm Valid 03Oct08 Target1-day forecast3-day forecast4-day forecast2-day forecast Slide 28 CLIM 101 - Fall 2008 Slide 29 Mobile Radar Hurricane Katrina Intensity at Landfall 29 Aug 2005 14 Z 4 km WRF, 62 h forecast Courtesy of P. Fox (NCAR) Slide 30 CLIM 101 - Fall 2008