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Will HPC Ever Meet the Demand of Weather and Climate Forecasting. REACH-2010 IIT-Kanpur. P Goswami Centre for Mathematical Modelling and Computer Simulation Bengaluru. Why doubt the power of computing?!. By 2050 the cost of computing comparable to 1 Billion Human brains will be US$ 1000. - PowerPoint PPT Presentation
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P GoswamiCentre for Mathematical Modelling and Computer Simulation
Bengaluru
Will HPC Ever Meet the Demand of Weather and Climate Forecasting
REACH-2010IIT-Kanpur
Why doubt the power of computing?!
By 2050 the cost of computing comparable to 1 Billion Human brains will be US$ 1000
By 2050 each human being will want customized personal forecast!
What will such demand mean for computing?
Atmosphere: A thermally active (water in three phases, with phase transition) mechanical system with interacting and dynamic boundary conditions
External Persistent Forcing: Solar Radiation, Lower Boundary
Random Forcing: Volcanoes, Forest Fire etc.
Anthropogenic Forcing: Emissions, Land Use
The Grandest Challenge in Computing
Sl No System Cahracteristics Scales Extreme Scales
(km)
Resolution Reqd
Spatial
(Kms)
Temporal
(hours)
Largest Smallest Spatial
(Km)
Temporal
(minutes)
1. Extreme Weather 10 0.25 Global <1 <1 <1
2. Tropical Cyclone 1000 1 Global <1 <1 <1
3. Monsoon 10,000 1 ≥Global <1 <1 <1
4. Regional Climate 10,000 1 ≥Global <1 <1 <1
5. Global Climate 10,000 1 ≥Global <1 <1 <1
6. Geo-Dynamics 105 ? ≥Global ? ? <1
7. Solar systems and Space weather
1010 ? 1010 ? ? ?
8. Stellar Evolution ? ? 1015 ? ? ?
9. Cluster Dynamics ? ? 1018 ? ? ?
10. Galactic Evolution ? ? 1020 ? ? ?
These are Interacting Scales
Forecast of Weather and Climate: The Wish List
On-Demand Forecast (Location, time, variable, resolution)
Projections Backward and Forward in time: Paleo-climate and climate forecast
Reliability: 90%, No False Positive, No False Negative
Forecast (Hindcast) Period: Hour to decades
Range of Forecast: Hours to decades and beyond
Spatial Coverage: Station to global, and beyond
The Measure of our Understanding is our Ability to Forecast
Forecasting Weather and Climate
The ability to forecast depends on power to compute
The Route to Forecasting
Forecasting Weather and Climate
Mathematical RepresentationsVariables and
Relations
Numerical RepresentationParameterization Schemes
Post Processing Initial and Boundary Data
Simplifying Assumptions
Code development
Computing Platform
Error Management
Simulation
Mapping of small scales to large scales
Identification of Scales
The Technology: A Generic Structure of Dynamical Forecasting
Tropical Precip forecast made: 1Apr2006
India
The Promise of Weather Forecasting
NOAA NCEP CPC CAMS_OPI V0208 ANOMALY PRCP JUN-AUG 2007
Model JJA Rainfall Anomaly
Vector wind (m/s) over the Bay of Bengal region on 27 Oct 1999, 00 hour. The left panels represent ECMWF Analysis while the right panels represent model forecasts.The panels represent data for 925mb, 850mb and 200mb, respectively.
Surface Pressure (hPa) over the Bay of Bengal region on 27 Oct 1999. The left panels represent ECMWF Analysis while the right panels represent model forecasts.
The Orissa Super Cyclone: A Case Study
ic: 26 OctWind Vector and Surface Pressure on 27th Oct
Track Forecast Error Bay of Bengal (15 cases: 1980-2000)
Lead -1
Lead 0Forecast Time (hour)
Forecast Time (hour)
Lead +1
Multi-scale Forecasting: Heavy Rainfall Events
Forecast GCM (40km Resolution) (Satellite Observation, 10 km resolution)
Mumbai Heavy Rainfall on 26th July 2005
BANGALOREHeavy Rainfall on 24th October 2005
CHENNAIHeavy Rainfall on 27th October 2005
Multi-scale Forecasting: Heavy Rainfall Events
The circled areas indicate observed locations of heavy rainfall
Satellite observations at 10 Km resolution
Satellite observations at 10 Km resolution
Compromise with Computing
• Are we doing it right?
Models are metaphors; need to use them carefully
Irreducible Model Error and Predictability
Boundary data
Optimum Model Configuration
Reducible ErrorsResolution
Initial Data
Model Configuration
Intrinsic limits on predictabilityFalse limits on predictability
HPC
Nature is subtle; Reaching irreducible error configuration may require more computing than we can afford!
Lower Boundary Forcing may change depending on resolution
Weekly average time series of rainfall (red line) and number of ERE (blue line) >mm/day) both average over the region (70-85E; 5-30N). The CC between the weekly rainfall and ERE counts for each year is given in the respective panel. The blue dots represent distribution of daily counts of ERE. (Goswami and Ramesh, 2006)
Monsoon and Extreme Rainfall Events: Monsoon and Extreme Rainfall Events: A Case of Tail Wagging the Dog?A Case of Tail Wagging the Dog?
Daily Rainfall Daily Rainfall (Satellite) (Satellite)
at at 10 KM 10 KM
ResolutionResolution
Simulation of Weather and ClimateChallenges for Computing and Modelling
• Resolving small scales in a global environment: Resolution
• Removing Forecast uncertainties: Probabilistic Forecasts
• Utilization of Observations: Data Assimilation
• Customization: Sensitivity Experiments
• Industrialization: Location-specific Forecast
• Project with EID Parry: Forecast over sugar cane fields• Project with Govt. Karnataka: Hobli-level Forecast
Science and Cost of Customization
Customization An extremely computing-intensive proposition
Sensitivity of limited area simulations to model domains
Spatial distribution of 30 Hr Accumulated ensemble mean rainfall (cm) for different Domains of 90km resolution
Reducing and Managing Forecast Uncertainty
• The Problem of Forecast Dispersion
• Intra-model Multi-lead/Multi-grid Ensemble• Inter-model Multi-model Ensemble (MI-ERMP)
• Forecast dispersion may be addressed through ensemble forecasting => more computing
Ensemble Forecasting: Instead of classical initial point to final point, initial neighborhood to final neighborhood
An effective ensemble forecast may require hundreds of simulations for a given forecast!
What Type of Computing
Small-ensemble Long Runs
•Climate Simulations•Impact Assessment• ……………………….
Large-ensemble Short Runs
•Short-range Weather Forecasts•Probabilistic Forecasts•……………………….
Parallel Computing Simultaneous Multi-tasking
We may need more than one type of computing architecture to generate
the best forecast in an optimum configuration
Computational Requirement: An Example
• Creation of Monsoon Climatology
Integration Length: 6 months
Number of Time steps: 104
Resolution: 20 km
Number of Horizontal Grid Points: 105
Number of Vertical levels: 50
Ensemble Size: 100
Approximate Computing Time Required on ALTIX 3750 (SP):
100*6*10 = 6000 days !With 30 processor multi-tasking, it is still 200 days of dedicated computing.
Simulation of Weather and Climate
• A Cosmic Problem
Forecast Without Frontier
• Habitat Planning (Location for Sustainability and Health)
• Space Weather (Space Tourism and Freight Services)
• Solar Flares (Satellite and terrestrial blackout Warnings)
• Arctic Weather (Eco-Tourism and Habitat)
Martian Weather (For precision landings and future colonies)
Geo-Cosmological Computations
Beyond Earth Simulator: Cosmo Simulator
and beyond (Stars like Dust)
The Sky is not the limit!!
HPC in Weather and Climate ForecastingSummary
As HPC grows, demand grows:
•Higher Precision: Higher Resolution (larger grid)
•Higher Reliability: Ensemble Forecasts (larger number of forecasts)
• Customized Forecast: Larger Number of Simulations
• Coverage: Earth, Solar system and Beyond (domain size)
• Longer Outlook: Increase in integration time (days to centuries)
• Archival: Cumulative (New unit beyond petabytes!)
Light Years of Computing before we stop;
Happy Computing!
Looking aheadTo simulate the Galaxy at a resolution of cyclonic vortex!
Size: 1028
Number of Grid Points: 1028/103
Integration Time: Millions of years Time step: Decade