Lecture 1 : The Computational
and Data Sciences
Connecting Theory and
Experiments
Science: Old style
Theory
Experiment
Science: New style
Theory
Experiment
Computational
Science
Computational Science
a blend of disciplines
Data Science
connecting experiments back to theory
Theory
Experiment
Computational
Science
Data Science
connecting experiments back to theory
Data
Science
Theory
Experiment
Computational
Science
Data Science
connecting experiments back to theory
Data
Science
Theory
Experiment
Computational
Science
Data Science
a blend of disciplines
Simulation movie
What is Science?
In-class problem 1
• On a piece of paper, write down if you
believe in global warming and why.
• Write down something that would change
your mind.
What is Science?
a) A set of facts that tells us how nature
works
b) The product of research and analysis by
professional scientists
c) The underlying Truth about the Universe
d) The collection of data an formation of a
hypothesis
e) None of the above
What is Science?
a) A set of facts?
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We are constantly making new
discoveries and collecting new data
Technology and experiments are
changing
Old Theories are replaced by new
Theories
Scientific ``Facts''
What is Science?
b) The product of research and analysis by
professional scientists?
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What is a scientist?
Do you need a PhD?
Amateur Scientists play an important role
in discovery
Being scientific DOES NOT required a
Union Card
What is Science?
c) The underlying Truth about the Universe?
Truth or no truth. There
is no universe
What is Science?
c) The collection of data an formation of a hypothesis
• Getting closer
What is Science?
a) the state of knowing : knowledge as distinguished from
ignorance or misunderstanding
b) a: a department of systematized knowledge as an object
of study <the science of theology> b: something (as a
sport or technique) that may be studied or learned like
systematized knowledge <have it down to a science>
c) 3 a: knowledge or a system of knowledge covering
general truths or the operation of general laws especially
as obtained and tested through scientific method b: such
knowledge or such a system of knowledge concerned
with the physical world and its phenomena : natural
science
d) 4: a system or method reconciling practical ends with
scientific laws <cooking is both a science and an art>
http://www.merriam-webster.com/dictionary/science
What is Science?
the basics
• Science - A study that uses the Scientific
Method
• Natural Science – “A rational approach to
the study of the universe‘” - Wikipedia
The Scientific Method
a definition
• Scientific method is a body of techniques for
investigating phenomena, acquiring new
knowledge, or correcting and integrating
previous knowledge. It is based on gathering
observable, empirical and measurable evidence
subject to specific principles of reasoning. A
scientific method consists of the collection of
data through observation and experimentation,
and the formulation and testing of hypotheses.
http://en.wikipedia.org/wiki/Scientific_method
The Scientific Method
the process
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characterization of existing data
formulation of a hypothesis
deduction - formulation of a predictive test
experimental testing
error elimination and characterization
validate or revise hypothesis
The Scientific Method
In-class problem 2
• Based on the collective memory of the students
in this class, we will try to reconstruct the
process of the scientific method involving the
issue of whether Earth orbits the Sun. Take a
few minutes to write down everything you
remember about this. Then think about how the
elements you remember relates to the elements
of the scientific process that were mentioned on
the slides.
• After 5-minutes, we will discuss your answers as
a group.
Experimental Error
• What time is it?
• Not everyone's clock is perfectly
synchronized
• Error is an intrinsic part of measurement
• Statistics are need to characterize error
The Scientific Method
climate change – a case study
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characterization of existing data
formulation of a hypothesis
deduction - formulation of a predictive test
experimental testing
error elimination and characterization
validate or revise hypothesis
Existing Data
Qouri Kalis Glacier, Peru 1978-2002
Photo credit: Professor L. Thompson
http://scrippsnews.ucsd.edu/Releases/?releaseID=703
Existing Data
Lyell Glacier, Yosemite National Park 1903-2003
1903 taken by G.K.
Gilbert
2003 taken by
Hassan Basagic.
http://web.pdx.edu/~
basagic/snglac.html
Discuss the following
• Glacier data are strong evidence for global
warming
• Glacier data are strong evidence for
anthropogenic global warming
• Glacier data are strong evidence for Earth
being at its warmest level
Existing Data
Temperature of Lake Superior
http://www.d.umn.edu/~jaustin/ICE.html
Existing Data
Atmospheric CO2
Existing Data
questions based on study
• Is the climate of Earth changing?
• If the climate is changing, what are the
causes?
Climate Change
hypothesis and deduction
• Hypothesis: Global Temperatures are increasing
– Deduction: Historical records of temperatures will show this
increase
• Hypothesis: Increases in CO2 are caused by human
activity
– Long term data from ice cores will show rapid changes in the
CO2 levels over the last few hundred years
• Hypothesis: increases in CO2 caused by human
activities play the dominant role in the global average
temperature
– Deduction: Detailed physical models of the climate will show that
the increases in CO2 will cause increases in the average
temperature on Earth
• Natural effects may reinforce the human factors
Climate Change
how does the climate work?
• Complex equations–
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radiant heat from the Sun
energy loss to space
advection of material through winds
evaporation and changing reflectivity from clouds and
ice
– ocean and land differences in specific heat
– weather
• Way to complicated to calculate by pencil and
paper!
Moving from Equations to Predictions
computational science!
http://celebrating200years.noaa.gov/breakthroughs/climate_model/welcome.html
Conclusions
IPCC Fourth Working Group
“Warming of the climate system is
unequivocal, as is now evident from
observations of increases in global
average air and ocean
temperatures, widespread melting of
snow and ice, and rising global
average sea level...‘”
Conclusions
IPCC Fourth Working Group
``Global atmospheric concentrations of
CO2, CH4 and N2O have increased
markedly as a result of human activities
since 1750 and now far exceed preindustrial values determined from ice
cores spanning many thousands of
years.
...Global increases in CO2
concentrations are due primarily to
fossil fuel use...''
Conclusions
IPCC Fourth Working Group
Reducing and Characterizing Error
• A single model usually doesn't tell you
enough about the uncertainty of a model
• We need to explore these assumptions of
the model
• Multiple runs are needed
• Sometimes multiple models are needed
• Changes in the outcomes show the
sensitivity of the model
Reducing and Characterizing Error
IPCC 2001, Climate Change, The Scientific Basis
Conclusions
climate forcing through CO2
• ``Most of the observed increase in globallyaveraged temperatures since the mid-20th
century is very likely due to the observed
increase in anthropogenic GHG
concentrations....”
• “The observed widespread warming of the
atmosphere and ocean, together with ice mass
loss, support the conclusion that it is extremely
unlikely that global climate change of the past 50
years can be explained without external forcing,
and very likely that it is not due to known natural
causes alone.''
Conclusion of IPCC Fourth Working Group
Summary of Climate Data
• Hypothesis: Global Temperatures are
increasing
• Hypothesis: Increases in CO2 are caused
by human activity
• Hypothesis: increases in CO2 caused by
human activities are the dominant source
in the global average temperature
increases
Are we certain our results are correct?
• All three of our hypotheses are now
supported by very strong evidence
• With enough evidence, a hypothesis
becomes a theory
• However - NO scientific conclusion is ever
more than a theory, no matter how strong
the evidence is!
• Scientific theories can and should still be
tested and refined.
Revised Hypothesis
computer predictions
• Existing data: Detailed computer models should
that polar regions being more affected by climate
change, especially in the arctic because of
ocean warming
• Hypothesis: Polar regions will experience rapid
changes in climate
• Deduction: We should be able to see changes in
polar ice cover in satellite data
• Experiment: Examine historical satellite data of
polar ice cap data
The Data Sciences
satellite measurements of sea ice
• Collect huge amounts of satellite images of
arctic sea ice using multi-spectral scanners
• Process the raw signals from the detectors into
file records
• Archive the records in a database
• Convert the records into images
• Process the images to determine the area
covered by ice
• Use statistics to determine any trends in the data
Gigabytes or Terabytes are changed into a single plot.
Data is transformed into understanding.
Artic Ice Cap
TERRA satellite
[http://terra.nasa.gov/]
Image from oceanmotion.org
Artic Ice Cap
data sciences
Satellite Data - 1979-2003
SSMI Composite Data
See
http://www.everybodysweather.
com/Static_Media/Polar_Ice_C
ap_Melter/index.htm
More Sea Ice Data
More Sea Ice Data
http://nsidc.org/news/press/2007_seaiceminimum/20071001_pressrelease.html
Conclusions
• ``Arctic sea ice during the 2007 melt season plummeted
to the lowest levels since satellite measurements began
in 1979. The average sea ice extent for the month of
September was 4.28 million square kilometers (1.65
million square miles), the lowest September on record,
shattering the previous record for the month, set in 2005,
by 23 percent (see Figure 1). At the end of the melt
season, September 2007 sea ice was 39 percent below
the long-term average from 1979 to 2000. If ship and
aircraft records from before the satellite era are taken
into account, sea ice may have fallen by as much as 50
percent from the 1950s. The September rate of sea ice
decline since 1979 is now approximately 10 percent per
decade, or 72,000 square kilometers (28,000 square
miles) per year.''
http://nsidc.org/news/press/2007_seaiceminimum/20071001_pressrelease.html
Global Warming
scientific method
• Existing data
– Detailed computer models should that polar regions being more affected
by climate change, especially in the arctic because of ocean warming
• Hypothesis:
– Polar regions will experience rapid changes in climate
• Deduction:
– We should be able to see changes in polar ice cover in satellite data
• Experiment
– Examine historical satellite data of polar ice cap data
• Conclusions:
– Satellite data supports our hypothesis
– This is additional evidence that our models are correct
– The original theory of global warming is to be supported by this data
Climate Change
are we done now?
• NO! Science is a process - NOT a set of
conclusions.
• The process goes on as
• new experiments and new data become
available
• better theories and models develop
• Computing is ESSENTIAL in connecting
Theory to Experimental Data