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CONTRIBUTION OF UPPER-AIR OBSERVING SYSTEMS AND REMOTE SENSING
TECHNOLOGIES TO THE ACCURACY OF METEOROLOGICAL FORECASTS
Authors; Mssrs: Bataze James and Khalid Muwembe, Department of Meteorology
P . O . BOX 7025 Kampala, Email: [email protected],
Telephone +256 – 782103950/ 414- 251798 / 320910
Abstract:
Observing Systems are key determinant in the preparation of weather forecasts, and supported by
innovations and developments in the field of meteorology. The types of observing systems such as
surface, upper-air and remote -sensing used in the monitoring of meteorological phenomena help
greatly to improve on the accuracy of weather forecasts that are issued by different meteorological
office the world over.
Innovative developments in observation technology has helped to increase on the accuracy of
meteorological bulletins issued to all sectors and provide essential contribution to improving weather,
climate, water services and environmental assessment.
The upper-air observing system and remote-sensing technologies are the most effective systems in
monitoring the atmospheric disturbances such wind flow, pressure, cloud development, temperatures,
humidity, that control the weather system. Upper-air observing system has played a major role in
observation and monitoring the bahaviour of meteorological parameters in the lower levels of the
atmosphere, that are the main determinant of accurate weather forecasts and early warning bulletins.
Remote-sensing observing technology through use of satellites, radar, has greatly contributed to the
understanding of global weather system, as charts and pictures sent down through receivers for
analysis and interpretation enhance the products disseminated to the stakeholders. Also through
remote-sensing it is easy to locate, monitor and track weather and climate disasters such tropical
cyclones, typhoons, hurricanes, tornadoes, storms plus many others.
As a result of using upper-air and remote-sensing observing technology the quality of the weather
forecasts issued to aviation, Agriculture, defense, health, energy, marine, environment, tourism,
construction industries and early warning plus disaster preparedness ranging from daily to seasonal
has greatly improved.
It has been observed from the analysis of the data set of meteorological forecasts that has been issued
for the last fifty years, shows an improvement in the accuracy as new innovations in remote-sensing
observing system have been in use..
Strong relationship exists between the accuracy of the forecasts issued and use of upper-air and
remote-sensing observing technology.
Key words:
Balloon, kite, upper-air, observing systems, remote-sensing, technology, forecast, weather, manned,
meteorograph, radiosonde, radar, satellite,
Introduction:
Observations are the bedrock of weather forecasting as these records help to keep track of the weather
changes, how it is and what it was during previous period. For centuries people have made
observations and forecast the weather using observed patterns of events on both land and sea surfaces
plus signs in the atmosphere such as the colour of clouds, movement of wind, strange birds, position
of stars in the sky and behaviour of the sea (Ancient observation methods)www.en.wikipedia.org)
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This ancient and primitive methods of forecasting weather not only misled the forecasters of those
days but also produced inaccurate forecasts, as none of the weather conditions from the upper levels
of the atmosphere was included in making the forecasts, apart from only observing the signs in the
atmosphere from the ground. Also due to the chaotic nature of the atmosphere in comparison to the
Earth’s surface plus the incomplete understanding of the atmospheric process meant that weather
forecasts made without including upper air observations and remote sensing technology data were
less accurate.
Until the middle of the 17th Century, very little was known about the physical characteristics of the
atmosphere above the surface. People knew that it got colder with height but not until the invention of
the barometer and thermometer was it possible to make any measurements. Even then , measurements
could only be done on the surface and measurements in upper air had to wait until the development of
instrumented kites in the 18th Century. ( Dr. Richard Pettifer, PRIMET A short history of upper air
measurements).
The atmospheric disturbances are key determinant to an accurate forecast, hence a good knowledge of
the weather conditions in the upper levels of the atmosphere greatly affect what happens at the
surface of the Earth. When upper air observing systems were started and routine upper air
observations of temperatures, winds, pressure and humidity carried it enabled meteorologists to make
a hybrid improved forecast composing of both the weather conditions at the surface and upper levels
of the atmosphere. The quality of meteorological forecasts issued out have been improving since the
beginning of the upper air observing systems using pilot balloons with radiosondes attached, aircrafts,
wind profilers and remote sensing technologies of satellites and radar.
Also the prediction potential of weather forecasters was enhanced by the inception of remote sensing
technologies by use of meteorological satellites and radars that have a wide observation area
capability, making it possible to avail globe data of the atmospheric conditions. Space based remote
sensing observations of the atmosphere – ocean – land systems have evolved substantially since the
first weather satellite were launched almost 50 years ago. Earth observation satellites have proved
their capabilities to accurately monitor multiple aspects on the global basis, unlike ground-based
systems that are limited to land areas and cover only about 30% of the planet’s surface. (EO
Handbook of observations, www.eohandbook.com)
From the observing system experiments carried out at European Centre for Medium Range Weather
Forecasts (ECMWF) to assess the relative contribution from various terrestrial observing systems to
the global Numerical Weather Prediction, it was found out that radiosondes, aircraft observations,
wind profilers, satellites and radars provide vital information used in the making of an accurate
meteorological forecast( Jean-Noelthepaut and Graeme Kelly 2007, )
According to research carried out so far upper air observing system and remote sensing technology
have been found to be the most effective observing systems in the safeguarding of life and property
through accurate forecasting and prediction that enables the detection, tracking, monitoring and
giving warnings of severe weather phenomena such as local storms, tornadoes, tropical cyclones,
typhoons, hurricanes, volcanic eruptions, tsunamis and many others that destroy life and property.(
EO Handbook of observations) www.eohandbook.com)
Problem statement:
Of recent there has been debate among meteorologists and other climate scientists about the
contribution of upper air observing systems and remote sensing technologies in the weather
forecasting.
Objectives of this study:
The main objective of this study was to investigate the contribution of upper air observing systems
and remote sensing technologies in the preparation of an accurate meteorological forecast.
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Study Area:
The study area for this research is the evolution of observing systems and weather forecasting, that
have been used for many centuries to forecast weather. This study looked at the inception of upperair observing systems and the innovations in technology that has led to the improvement in quality
and accuracy of the meteorological forecasts issued out.
Right from ancient times people have been observing and trying to forecast weather informally and
formally, and in 650 BC, the Babylonians predicted the weather from cloud patterns as well as
astrology. In about 340 BC, Aristotle described weather patterns in meteorologica, and later
Theophrastus compiled a book on weather forecasting called the book of signs. At around 300BC the
Chinese and Indian astronomers developed weather prediction methods. Later in 904 AD, Ibn
Wahshiyya’s Nabatean Agriculture discussed the weather forecasting of atmospheric changes and
signs from the planetary astral alterations; signs of rain based on observation of the lunar phases; and
weather forecasts based on the movement of winds. Ancient weather forecasting methods usually
relied on observed patterns of events, termed as pattern recognition, for example it might be observed
that if the sunset was particularly red, the following day often brought fair weather) This experience
accumulated over generations to produce weather lore, however not all these predictions proved
reliable, and many many of them have been found not to stand up for rigorous statistical testing.
.(www.en.wikepedia.org
In Europe upper air observation began as early as 1749 with the use of a kite, the kites carried aloft
meteorological instruments or “meteorographs “ that recorded pressure, temperature, and relative
humidity data on a clock driven chart recorder. How ever the use of kites had several disadvantages
such as the average altitude reached was only about 3 km, data could not be readily available for
weather forecasting, observations could only be taken in good weather with winds neither to light or
too strong and there was danger of the kite breaking away and endangering lives and property. And in
1780`s with the invention of hot air balloon in France, it enabled scientists to ascend aloft taking with
them more weather instruments to investigate the structure and chemistry of upper atmosphere.
Manned ascents by use of kites and hot air balloons to study the upper atmosphere continued until the
end of 1800`s, when unmanned balloons carrying meteographs were introduced.
These soundings reached the stratosphere that was a much great height than that achieved by manned
balloons and kites. The main drawback to this sounding approach was still that the data was not
readily available for weather forecasting and was lost if the meteograph could not be recovered. (A
brief history of upper – air observation. www.ua.nws.noaa.gov).
It was not until the invention of the electric telegraph in 1835 that the modern age of weather
forecasting began, as the telegraph made it faster to transport information about the current state of
weather condition from one place to another. The two men most accredited with the birth of
forecasting as a science were Francis Beaufort, remembered chiefly for the Beaufort scale and his
friend Robert Fitzroy the developer of the Fitzroy barometer whose work gained scientific credence.
In 1920`s saw the advent of aircrafts being used for upper air observations and carrying of
meteographs. However like the kites and balloons the aircraft could not be flown in poor weather and
data could not be analysed until the plane landed. The inability of the kites, balloons and aircrafts to
operate in all weather and provide data in real time helped foster the development for the radio
transmission of upper air data. And in the early 1930`s the first unmanned balloons carrying radio
mateorographs or radiosondes started being flown in the stratosphere to carry out observations of
upper air atmosphere. The radiosondes attached to the balloons led to a breakthrough in upper air
observations in it was able to transmit data back to the station, hence making it readily available for
weather forecasting. These measurements of temperature, humidity, pressure, and winds above the
surface from near surface to the middle of the stratosphere about 21km (13miles) by launching
radiosondes on weather balloons, aircrafts and wind profilers allowed forecast to be made by knowing
what the weather conditions were like further in the upper atmosphere.
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Fig 1.
Shows a history and evolution of upper air observations from 18th Century up to the present
With more advances in upper-air observing technology saw the development of remote- sensing
observing systems such as satellites, radars, wind profilers plus the placement of temperature and
water vapour sensors on commercial aircrafts plus introduction of the GPS based radiosondes that can
transmit data in real time.( NOAA National Weather Service,www.ua.nws.noaa.gov.)
In the late 1950`s saw the launching of the of the first satellite, but the first satellite completely
dedicated to satellite meteorology called TIROS ( Television and Infrared Observational Satellite)
was launched on 1st April 1960, and this brought a new chapter in upper-air observations because of
their almost global coverage. From 1960 up to today many satellites have been launched among them
being the GEOS (Geostationary Operational Environment Satellite) and Earth Orbiting Satellites that
have helped very much in the provision of upper-air and other climate data globally.(History of
satellite meteorology – www.apollo.isc.vsc.edu)
Fig 2: Shows some of the early satellites launched at the end of 1950s.
.
Satellites also provide data on cloud development, information on temperatures at the surface and
cloud tops, but individual clouds can also be tracked from one time and place to another in order to
provide information on wind direction and strengthen at the cloud steering level.
Currently satellite systems monitor the evolution and impact of El Nino episodes, natural droughts,
vegetations cycles and mappings, the ozone hole, solar fluctuations, changes in mountain snow cover,
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sea ice sheets, sea surface temperatures, floods, forest fires, deforestations, coastal zones, urban
development, volcanic eruptions, plate motions and more(observation of climate by earth orbiting
satellites –(CEOS EO Handbook on Observations. www.eohandbook.com).
A good example of how satellites can help to monitor volcanic eruptions was in April 2010 when it
was possible to track the movement of ash clouds from the Icelandic volcano Eyjafjallajökull, and
meteorological offices were able to give accurate warnings and forecasts to the aviation industry and
most of the European air space was closed for traffic for some time.
Fig: 3 Show a network of satellites carrying out upper air observations on the earth.
Such satellites are able to provide accurate aviation products such as satellite pictures,
significant weather charts, upper level winds and temperatures known as wintems.
Also these satellites provide a vital means of obtaining observations of the climate systems
from a global perspective.
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Data source:
The source of data for this research has been achieves of meteorological information, papers written
by other researchers, reports, manuals and internet.
Earth Observing Systems and Networks:
Current Earth observing systems include networks of satellite- borne and ground-based sensorsincluding ocean buoys, weather stations and atmospheric radiosondes, that provide important
parameters relating to land, ocean and atmospheric processes. This clearly demonstrates that a single
programme, agency or country cannot satisfy the range of the observations many of which are global,
needed to understand and monitor climate and other earth system process and to assess the impact of
human activity. The main Earth observing networks and international programmes that coordinate the
different observations include:
- World Weather Watch (WWW) is a global system for collection, analysis, monitoring, and
distribution of weather and other environment information. The world weather watch has
three basic components the Global Observing System (GOS), the Global Telecommunication
System (GTS) and the Global Data Processing System.(GDPS).
- The Global Observing System comprising facilities on land, at sea, in the air, and in the outer
space, for observation and measurement of meteorological phenomena.. (GOS) also ensures
that every country carries out weather observations at least every three hours so as to generate
data for weather analysis, forecast and warnings on day today basis.
- The Global Telecommunication System (GTS) is a world-wide telecommunication system for
the rapid exchange of the observational information as well as analysed and processed
information, including forecasts.
- The Global Data Processing System.(GDPS) is a network of world and regional computerised
data processing centres.
- Global Atmosphere Watch (GAW) responsible for observations and information on
on ozone, solar radiation, ultraviolet radiation and other greenhouse gases.
- Global Ocean Observing System (GOOS) is responsible for coordinating all ocean and
marine observing systems and observations, and it is complemented by the Global Sea Level
Observing System (GLOSS) which monitors all sea level observations.
- Global Terrestrial Observing System (GTOS) is responsible for Terrestrial observations in
situ, remotely sensed and from a range of international, regional, and national observing
systems.
- Global Climate Observing System (GCOS) this ensures that observations and information
needed to address climate- related issues are obtained and made available to all potential
users.
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-
Committee on Earth Observation Satellites, (CEOS ) coordinates civil space-borne
observations of the Earth
by
satellites. (Earth Observations Handbook –
www.eohandbook.com)
All the networks above help in the standardization of observing and measuring methods and
techniques, the development of common telecommunication procedures, and presentation of both
observational data and processed information in a manner which is understood by all, regardless of
the language.
Discussion of results:
From this research it shows that right from the period people started making observations
and weather forecasting, the early observing methods were based on pattern recognition
of invents on land, sea and the atmosphere such the lunar phases, position of stars, colour
of the sky, movement of winds and sea surfaces. The evolution of observing systems plus
advancement and innovations in technology have greatly helped to revolutionilised
meteorology in general and the upper air observing systems and remote sensing in
particular. From this study it has been found out that since the inception of upper air
observing system in 18th century and remote sensing technologies in the 20th century the
accuracy of meteorological forecasts have greatly improve.
With the application of satellite meteorology it has become easy to identify and track
severe weather disaster such as storm storms and give warnings that help to protect life
and property.
Conclusion:
From this study it has been found out that the upper air observing system and remote
sensing technology have really contributed greatly to accuracy of meteorological
forecasts given out the world over.
Recommendation:
I recommend that further research need to be done to find out the relative contributions
from various terrestrial observing systems to the Numerical Weather Predictions
.
References:
Ancient observation methods)www.en.wikipedia.org
Dr. Richard Pettifer, (1997) A short history of upper air measurements:
EO Handbook of observations, www.eohandbook.com
Jean-Noelthepaut and Graeme Kelly ( 2007 ) Final report on the relative contributions from various terrestrial
observing systems in the ECMWF system.
A brief history of upper – air observation. www.ua.nws.noaa.gov
NOAA National Weather Service www.ua.nws.noaa.gov
History of satellite meteorology – www.apollo.isc.vsc.edu
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