Desktop To Grids

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Desktop To Grids

• Environmental Science

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Environmental Science

• Environmental Science corresponds to the
  scientific principles, concepts, and
  methodologies required to understand the
  interrelationships of the natural world, to
  identify and analyze environmental problems both
  natural and human-made, to evaluate the relative
  risks associated with these problems, and to
  examine alternative solutions for resolving
  and/or preventing them.

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Why Environmental Science Matters

• The environment drives a lot of our news, our
  culture, our society, and especially our energy
  use, our politics.
• Environmental problems are hard
• Energy conversions
• Variables are extremely interconnected
• Environmental problems have social and cultural
  ramifications
• Time scales are on the orders of lifetimes

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Types of Environmental Science Computing

• The most natural example is weather forecasting
• Then there's the trendy aspirations of climate
  modeling
• GIS Geographic Information System
• a system for capturing, storing, analyzing and
  managing data and associated attributes which are
  spatially referenced to the Earth.

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Desktop Computing. Feasible?

• Weather tools
• The Beaufort Wind Scale
• developed in 1805 by Sir Francis Beaufort of the
  Royal Navy. He wanted a consistent way to measure
  wind force on fighting ships. Today's version
  states the wind's effects on land as well as sea.
• Doppler Radar
• a type of radar that sees rain and snow and
  measures wind speed and direction. It is most
  useful for short-range forecasts on the day of
  the weather event.
• Infrared Radiation
• an invisible form of radiation given off by all
  objects both day and night. Satellites equipped
  with infrared sensors take images of clouds and
  of the Earth's surface.

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Weather Models

• NAM Models
• The NAM model is a regional mesoscale model using
  enhanced terrain and improved parameterization of
  surface and precipitation processes. It produces
  forecasts out to 84 hours at 00, 06, 12 and
  18UTC.
• Grid resolution is 40km, run over CONUS (which
  is the Continental US).

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Weather Models

• NGM Models
• The Nested Grid model (NGM) - Its name comes from
  the technique of using a finer grid over North
  America and coarser grid over the oceans.
• The NGM provides guidance out to 48 hours at 00
  and 12UTC.

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Weather Models

• GFS Models
• The Global Forecast System (GFS) - The GFS is a
  global spectral model used primarily for aviation
  weather forecasts.
• The GFS provides guidance out to 384 hours at 00,
  06, 12 and 18UTC.

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Weather Models

• RUC Models
• The Rapid Update Cycle (RUC) -
• The RUC provides guidance out to 12 hours at 23,
  00, 01 and 02UTC.

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Weather Models

• ADAS
• ADAS is the AWOS (Automated Weather Observation
  System) Data Acquisition System
• ADAS uses NAM data along with other data from
  radars, satellites, mesonets, wind profilers,
  aircrafts, and other surface data to a 10km grid
  (as opposed to a 40km grid in NAM).

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Napkin-back calculations

• What type of weather can you reasonably simulate?
• Let's try ADAS over CONUS...
• 10km spacing
• Area of US is approximately 9,600,000
• Say... 8x1M, or 8 x 220
• Atmosphere 10 miles at the equator
• Say 20 km, or two cells high
• How many cells?
• (8 x 220) x 2 224 cells

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Napkin-back calculations

• What type of weather can you reasonably simulate?
• 224 cells. But how much data is being gathered
  at each cell?
• Temp
• Pressure
• Wind speed
• Wind vector
• any others? (yes! quite a few!)
• Say 8 variables per cell. That makes 227 total
  variables to keep track of
• Each variable might be a double, which is 64
  bites or 8 bytes.
• An even 230 bytes.

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Napkin-back calculations

• What type of weather can you reasonably simulate?
• 230 bytes, or an even Gigabyte just to initialize
  the data.
• That's certainly reasonable to do on a single
  computer these days.
• Now, let's run the simulation
• Forecasts out to 84 hours, dumping every 6
  hours.
• 15 snapshots...15 GB.
• Sounds rather do-able.

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Simulations on a workstation

• You can download the WRF model from NCAR (WRF
  Weather Research Forecast, NCAR National
  Center for Atmospheric Research).
• Compiling the code is a pain.
• Running the code is an exercise in patience and
  sacrifice.
• Code runs, task complete.

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Simulations on a Cluster

• A lot of things happens in six hours.
• Weather forecasters say that weather changes at
  minute resolutions.
• Over 84 hours, that's 5041 data sets! 5 TB of
  data.
• Still looking at regional resolutions, and
  non-decorated simulations

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Simulations on a Grid

• Larger resolution or more decorations require
  moving to a Grid
• Even moving of the data around to visualize would
  require a high-performance filesystem
• http//portal.leadproject.org
• A TeraGrid Science Gateway.

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Links

• Lead Portal
• https//portal.leadproject.org
• Earth Systems Grid
• http//www.earthsystemgrid.org/
• Weather Forecasting Code
• NCAR
• http//www.ncar.ucar.edu/
• Weather Research and Forecasting Code
• http//www.mmm.ucar.edu/wrf/users/download/get_sou
  rce2.html