BRIEF HISTORICAL FLASHBACK


In 1922, first the mathematician Lewis Frei Richardson had
the idea to describe physical processes that take place in the atmosphere by
using the hydrodynamics of fluid equations. In his work “Weather prediction
with numerical methods” described the mathematical methods which one could use
in order to predict the weather evolution with the time. His idea required a
great number of people who would solve the mathematical equations that describe
the atmosphere motions and so they would predict the weather evolution. In
particular, he estimated that 64000 people were needed in order to make a
prediction with the same speed as the weather develops in real time. He also
claimed that in distant future people would compute faster than the weather
evolution. These words were prophetic although “the distant future” was only 40
years later.

In the followings years until 1960 scientific world paid no
regard to prediction and did not trust computers. Weather forecast was an
empirical work and practical meteorologists predicted the weather for the next
day by using mostly their own experience. That season Lorenz one of the biggest
pioneers in numerical forecast worked at M.I.T (Technological Institute of
Massachusetts) and he had a totally different opinion: “The equations that
describe the procedures which take place in the atmosphere, are already known
from a long time. If numerical theory draws precise roots for spaceships and
rockets and predicts planets trajectories why it cannot be used in weather
forecast ?”

Lorenz run into a lot of difficulties especially he had to
face off the scientific establishment which considered his opinions extremes.
But after continual tries he managed with his primitive computer to create a
simple model of the atmosphere that constituted the ancestor of current
atmospheric models. In the next years the scientific world had a lot of hopes
for the capability of weather prediction. There were several tries until the
numerical weather forecast had been an undeniable reality.

At this period of time the bigger successes for the numerical
weather prediction have happened in Reading, a small town outside London where
sheltered and continue to shelter E.C.M.W.F ( European Center for Medium Range
Weather Forecasts). The Europeans showed their confidence to the numerical
weather prediction by using the supercomputer CRAY for the integrations. They
also engaged the best scientific personnel of the ECMWF states of members. In
the other end of ocean efforts overwhelmed also the Americans. Their
supercomputer one Cyber 205 by Control Data executed millions of calculations
in one second and solved in short time model’s systems with 500.000 equations.
The results were very satisfactory and the messages were continuously more
optimistic.

From then up to today they have passed 20 years of continuous
efforts and has been achieved enormous progress. In this it has contributes the
development of supercomputers which today allocates a big number of processors
of enormous possibilities. The velocity of one only processor measured in
Megaflop (One Megaflop is equal with one million calculations in one second).
The atmosphere simulated continuously with more realistic way after the
numerical methods are improved permanently. The simulation of the atmosphere is
continuously more realistic as the numerical methods are improved, the grid
becomes denser, and the under study atmospheric layers are increased. Also
detail information about orography ,vegetation and type of the ground are
introduced in the models. Thus the results that are received are more reliable
and more analytic.
