Computers and Weather

forecasting

Weather forecasting

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Weather forecasting

Explanation

Overview picture

Data collection

Sensors

Data logging

The Grid System

Weather station

Radiosonde

Satellites

Radar

Weather ships

Supercomputers

Parallel Processing

Software

Pressing Weather forecasting on any slide will bring you back to this menu

During the last two decades the Met Office hasused state-of-the-art supercomputersfor numerical weather prediction and morerecently, also for predictions of global climate.

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This is a picture of a supercomputer

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Weather forecasters are helped by several things. These include:-

The computer makes millions of calculations.

1. The computer’s advice2. Information from radar

3. Information from satellite pictures

The sums are called differential equations

Before the computer can do the calculations, data has to be collected first.

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Collecting data on the weather is very important.

Without the data, the computer could not do the calculations that enable it tomake weather predictions.

The next slide shows where the data comes from.

It also shows where the forecasts are sent.

Always remember that the forecasters are highlytrained people and they use their judgementand expertise to make their forecastbased on the information the computergives them and the information from the radarand the satellite pictures.

Supercomputer

Radio-sonde

Weather shipand weather buoys

Satellites

Radar

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Weatherstations

Forecaster

Supercomputer

Global forecast services

Aviation

ShippingNational and International

Forecast Services up to 7 days ahead.

Radio-sonde

Weather shipand weather buoys

Satellites

Radar

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Weatherstations

Forecaster

Supercomputer

Global forecast services

Aviation

ShippingNational and International

Forecast Services up to 7 days ahead.

Radio-sonde

Weather shipand weather buoys

Satellites

Radar

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Weatherstations

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Data is collected continuously for the computer from the following:-

1. Weather stations2. Automated weather

stations 3. Satellites 4. Radar 5. Radiosondes 6. Weather ships 7. Mini-radiosondes 8. Radar 9. Aeroplanes10. Drifting buoys

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The data measurements are made by sensors

A sensor is a transducer which responds to some physical property such as pressure, temperature, rate of flow.

A transducer is an electronic component which converts energy from one form to another.

We want the transducers to send signals to the computer in the Met. Office.

1. Temperature .. Air, surface and subsurface temp.

2. Atmospheric Pressure

3. Wind speed

4. Wind direction

5. Humidity

6. Rainfall

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7. Sunshine

The measurements needed include:-

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These are some of the sensors used to collect data.

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Data logging is the capture and storage of data for future use.

All the measurements from the sensors are stored because:-

So data logging is used in weather forecasting.

• The computer processes the data in batches

• People need to refer back to weather data for many reasons

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The next slides explain more about data collection.

To jump to the details of the computers, click on the computer.

Mountain effects

Formation of clouds

Formation of rain and snow

FrictionRadiation from the

earth

Radiation from the atmosphere

Radiation from the sun

Evaporation and

heat exchange

The atmosphere is split up into a 3-D grid.Each land based grid is about 60km.

Sea

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The vertical grid you just saw only had 5 levels.

The Met Office uses far more, some computer models work on 40 vertical levels.

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For UK forecasts the horizontal grid is 15km.

For the global forecasts the horizontal grid is 60km

Sea

We need to measure pressure, temperature,

wind speed and wind directions as well as rainfall, cloud cover,etc in as many grid spaces as possible

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Sea

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Weather stations are used here.

A weather station sends signals back to the Met Office computer.

The instruments measure pressure, temperature and humidity.

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Some weather stations are automated. These send their measurements back to the computerdirectly.

Picture thanks to Sparholt school who have a great web sitewww.hants.gov.uk/sparsholtschoolscentre

We need to measure pressure, temperature,

wind speed and wind directions as well as rainfall, cloud cover,etcRadiosonde

s are used up here.

20 km

Sea

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A radiosonde sends signals backto the Met Office computer. They are attached to a balloon carrying instruments.

The instruments measure pressure, temperature and humidity.

By measuring the track of the radiosonde, the wind direction and speed can be calculated.

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Photo courtesy of the British Atmospheric Data Centre

All over the world, radiosondes are released at midday and midnight UTC.

UTC = Universal Time Co-ordinated

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UTC = Universal Time Co-ordinated

Hawaii 2 amAtlantic Daylight

9 am

Baghdad3 pm

West Australian Standard 7 pm

UTC is also known as GMTGreenwich Mean Time

Here are some of the times when the radiosondesare released to correspond with the ones in Britain at midday.

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Sea

We need to measure pressure, temperature,

wind speed and wind directions as well as rainfall, cloud cover,etc

Minisondes are used

here.

5 km

Everest is 8.85 Kms high. So we have shown you a very high mountain!

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A minisonde system takes measurements at 5Km above sea level.

Both radiosondes and minisondes use radio waves to transmit the data readings to the computers

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Sea

We need to measure pressure, temperature,

wind speed and wind directions as well as rainfall, cloud cover,etc

Aeroplanes send

data too. 10 km

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Sea

We need to measure pressure, temperature,

wind speed and wind directions as well as rainfall, cloud cover,etc

Satellites send

data too.

36,000km

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The Geostationary satellites are 36,000 Km above earth.

There are two types of satellites.

• Geostationary. These stay in the same spot. They orbit the earth at exactly the same speed as the earth rotates. They are very high above earth - 36,000 km.5 geostationary satellites are enough to give

global coverage.

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• Polar orbiting. These orbit the earth about 14 times a day. They orbit at 1000 km above the earth.

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A Geostationary satellite stays in the same place with respect to

earth all the time

A Polar orbiting satellite moves above the earth’s surface

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Picture courtesy of the European Organisation for the Exploitation of Meteorological Satellites and photo

courtesy of Dundee University.

The URL ( Uniform Resource Locator ) www.sat.dundee.ac.uk/tour.html will tell

you more about satellites if you are interested

Meteosat: a geostationary satellite. It sends microwave signals back to earth.

The satellite’s signals are received by antennae.

©Eumetsat 2003

This is a Polar Orbiting Satellite

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The satellite can take readings across the entire earth during the course of one day.

Sea

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Radar systems are used here.

Radar stands for radio detection and ranging. Radio waves are transmitted, when they hit a rain cloud they bounce

back to earth and measurements can be taken.

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There is a network of radar systems covering Britain.

This is a radar

station.

The computer and the forecaster receive data from the radar systems.

Radar measurements let the forecaster and the computer know if the radar has seen rain clouds.

Sea

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There are weather ships out to sea

There are also buoys taking weathermeasurements in the sea

This is a Weather ship.

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Buoys are used at sea more than weather ships these days. They send their data automatically back to the computer.

Thanks to www.gdfcartophily.co.uk

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The Meteorological Office uses supercomputers. These are the largest computers in the world.

There will be a new supercomputer in the Met Office’s new location at Exeter.

The Met Office has re-located (moved) to Exeter from Bracknell.Bracknell is near London. Exeter is in the South Westof England.

• Bracknell

• Exeter

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We store Gigabytes (one thousand million bytes 109) of data on the Hard drives in our school.Supercomputers have stores for Terabytes of data.

A Terabyte isone million, million bytes, 1012 bytes.

A supercomputer is a very large computer, which works very, very fast. It is about 1000 times more powerful than a PC.

It also has an enormous store (memory).

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A supercomputer is a very large computer, which works very, very fast. It is about 1000 times more powerful than a PC

The Met Office supercomputers areMassively Parallel Processor machines.

It usually has many processors working in parallel to achieve the fast processing time.

Massively Parallel Processor machines use Parallel processing

Parallel processing is the simultaneous use of several processors to perform a single job. A job may be split into a number of tasks eachof which may be processed by any availableprocessor.

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Parallel processing splits jobs up and gives different processors tasks. These all have

to be brought together.

When a computer usesseveral processors in parallel

it is known asparallel processing.

Parallel processing is difficult to program

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How does parallel processing work?.

287 14 21

1*7

A

2*7

B

4*7 3*7

C D

Let’s give four processors A, B, C, D a sum each

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If processor A did all four sums it would take longer.

Parallel processing is very complicatedto program but it does make it faster to do loads and loads of sums.

Massively Parallel Processor machines.

MPP systems use a distributed hierarchy of memory. This just means that they have to have a system of accessing the memory available.

MPP systems rely on very high bandwidth communications to move data between memory and between different processors so that they are all kept busy during program execution.

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Software consists of programs, routines and procedures which can be run on a computer system.

There are two types of software, • application • system

Application software is designed to carry out a task(such as keeping accounts, or editing text) which would need to be done even if computers didn’t exist.

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System software is designed to control the operation of a computer. An operating system is an example of systems software.

An operating system is the software that controlsthe overall running of the computer.

Operating systems handle the Input/Output operations, interrupts, user requests.

The Met Office calls their application software they use for weather forecasting the Unified Model.

It is modelling software.

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Application software in Weather Forecasting.

The Unified model is run both for climate and operational weather forecasting. It uses a lot of computer time, even on the very latest supercomputers.

The computers at the Met Office use an operating system called Unicos/mk.

Unicos/mk is an interactive system that can run batch work. It is based on UNIX, a very reliable network operating system.

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Systems software in Weather Forecasting

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The weather forecasts are run in batch mode.

Batch mode is when all the jobs or data to be processed are put together for processing and then run together.

The batches are done by a piece of software produced by the same company CRAY that makes the computers. It is known as the NQS, the Network Queueing System.

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Copyright Helen ap Derwen Yewlett

I would like to thank the Met Office for all their help and for permission to use their photographs throughout this presentation.