By Timipre Ruth George
University of Port Harcourt, Nigeria
Earth observation is the gathering of information about Earth’s physical, biological and chemical systems. It is used to monitor the status of the natural environment; its changes and built environment, thereby providing environmental information to the world. Environmental information is of crucial importance as it helps man to understand how the planet and its climate are changing, and the role played by human activities in inducing these influences in daily life.
Earth observation offers unprecedented levels of information and a holistic view of the environment and resources, both at home and abroad. There are service-focused Earth observation companies and organizations in countries as diverse as India, Israel, Russia, Canada and France. Earth observation data are controlled to all countries’ Earth environmental programs in order to:
Û¢ Assess the current information of the environment;
Û¢ Inform models;
Û¢ Understand relationships among Earth processes, environmental health and well being;
Û¢ Support decision making e.g. toward sustainability and involve stakeholders more effectively in environment decision-making.
Sustainability aims at optimal use of natural resources, protection and conservation of ecological systems and improvement economic efficiency for the sake of future generations. Earth observation has, so far, made sustainability a reality and it will do more as research is continuously done and technology is improved. The well being and security of future generations is dependent on everyone’s actions, and on the decisions being made today on environmental policies. To make the right choice, businesses and citizens must be provided with reliable and updated information on how our planet and its climate are changing.
Earth observation includes technological solutions including satellite observation, navigation and positioning systems. Satellite observation will be our focal point.
EARTH OBSERVATION SYSTEMS
Earth observation systems consist of models designed to measure, monitor and predict the physical, chemical and biological aspects of Earth systems. They range from buoys floating in the oceans to monitor temperature and salinity, to more than 60 high-tech environmental satellites that scan the planet from space. We also have meteorological stations and balloons that record air quality and rain water trends, solar radar systems which estimate fish and population (biodiversity), seismic and global positioning system (GPS) stations that record movements in the Earth’s crust and interior, powerful computerized models that generate simulations and forecasts, and early warning systems that issue alerts to vulnerable populations.
These various systems have typically operated in isolation from one another. In recent years however, sophisticated new technologies for gathering vast quantities of near-real-time high-resolution Earth observation data have become operational. At the same time, improved forecasting models and decision tools are increasingly allowing decision makers and other users of Earth observation to fully exploit this widening stream of information.
GLOBAL POSITIONING SYSTEM
The global positioning system (GPS) is a space-based global navigation satellite system (GNNS) that provides location and time information, in all weather, anywhere or near the water where there is an unobstructed line of sight to four or more GPS satellites.
APPLICATION OF GPS
1) In disaster relief and emergency services: These services depend upon the GPS for data on time and location. For instance, the GPS provides information on disasters like tsunamis, earthquakes, rockslides and volcanic eruptions, including their nature, time, and place of occurrence. Through this information, the tendency of reoccurrence is examined and possibly even prevented, thereby saving lives and resources.
2) In tectonics: GPS enables direct fault motion measurement in earthquakes. It could be used to predict the intensity of the earthquake and areas that could be affected.
3) In surveying: Surveyors also use absolute locations to make maps and determine property boundary.
All the satellites broadcast at the same frequency 1.57542 GHZ (L1 signal) and 1.2276 GHZ (L2 signal).
Navigation systems, usually electronic systems, which are entirely on board a vehicle or vessel, help provide information on hazards or obstacles. This information is used to prevent hazards from occurring, thereby promoting the sustainability of water resources, as the hazard is prevented.
Earth observation satellites are used specifically to observe the Earth from orbit. While they are similar to reconnaissance, they are intended for non-military uses such as environmental monitoring, map-making and meteorology. The synoptic view provided by satellite imagery offers technologically the most appropriate method for quick and reliable mapping and monitoring of various natural resources both in space and time domain. Remote sensing is an application of satellite observation.
A weather satellite is primarily used to monitor the weather and climate on Earth. These meteorological satellites see more than clouds and cloud systems, including city lights, fires, effects of population, sand and dust storms, boundaries of ocean current, energy flow sets and other types of environmental information. For instance, weather satellites helped in monitoring the volcanic ash cloud from Mount St. Helens, and activities from other volcanoes such as Mount Etna. Smoke from fires in western U.S. states such as Colorado and Utah have also been monitored, ensuring sustainability of resources. Some Earth observation satellites include Land Sat 1, Jason 1, Terra (EOS AM-1), GOESS 9, NOAA-15, Meteor 1 series, TIROS-1, and Niger Sat 1, 2.
Remote sensing is the acquisition of information without making physical contact with the object being observed. It uses propagated signals such as electromagnetic radiation emitted from aircraft or satellites. Its light defection and ranging is used to detect and measure the concentration of various chemicals in the atmosphere. Its hyper spectral imaging is used in mineralogy, biology, defense and environmental measurements as it produces images over a contiguous spectral range. The Doppler radar is used to monitor speed limits in enhanced meteorological collections of wind speed within weather systems. It also uses active and passive sensors.
Remote sensing is used to follow-up on and monitor at-risk areas in the long term to defer desertification factors. It also helps support decision makers in defining relevant measures of environmental management, and to assess their impacts. It makes possible the collection of data from dangerous and inaccessible areas. It monitors deforestation in places like the Amazon Basin, glacial features in Arctic and Antarctic regions and depth sounding of coastal and ocean depths. The process of remote sensing is also useful in city planning, archeological investigations, military observations and geomorphologic surveying. It has many roles in disaster management, from risk management and vulnerability analysis, to early warning to damage assessment. It can be used to forecast drought, monitor floods, detect volcano activity, map fires, and facilitate emergency relief and monitor storms like cyclones.
ROLES OF SATELLITE OBSERVATION IN ENSURING GLOBAL SUSTAINABILITY
The data from Earth observation satellites can contribute to world sustainability by providing information, measurements and quantifications of natural or artificial phenomena. Change detection through repeating satellite observation over various temporal and spatial scales offers the most economical means of assessing environmental impact of developmental processes; monitoring bio-species diversity of an ecosystem and evolution of appropriate action plans for sustainable development. It also helps to ensure appropriate steps are taken to deal with global environmental issues such as climate change and stratospheric ozone destruction. The roles it plays are:
1) Monitoring of oil spillage: Scientists have used the Moderate Resolution Imaging Spectroradiometer to detect the oil slick, which is often hidden in natural color imagery. Scientists can custom tune the 36 spectral bands on the instrument to reveal the extent and trajectory of the slick. After the explosion of an oil rig in the Gulf of Mexico, ESA’S Envisat satellite as well as other SAR satellites was continuously providing Radar imagery of the oil spilling, using its Advanced Synthetic Aperture Radar (ASAR) and medium resolution imaging spectrometer. In general, radar instruments are especially suited for detecting oil spills and can work day and night, see through clouds (unlike optical sensors) and are particularly sensitive to the smaller water surface caused by the oil. Monitoring oil spillage helps to make the world more sustainable as it prevents the destruction of certain ecosystems and the wasting of the resource. The Nigerian Sat-1 can also help monitor the perennial problem of oil pipeline vandalizing, and could assist in combating and managing oil spill incidents.
2) Helps to monitor global warming: Satellite observation systems could be used in monitoring green house gases on global bases. If sustainability is to be attained in our world today, then the issue of global warming must be addressed, and satellite observation is of great use here. It promotes the understanding of current climatic conditions. Green house gases observing satellite Û÷’IBUKI” (GOSAT) is the first satellite used to observe green house gases and changes they cause. The Japan Aerospace Exploration Agency launched the satellite from the island of Tanegashima in southern Japan. Using high precision sensors, IBUKI can measure from outer space the concentration of green house gases throughout almost the entire surface of the Earth. The data obtained is used to determine the emission, transportation and absorption of these gases with a view of contributing to the control of global warming.
3) Tracking Bio-diversity and wildlife trends: The world can be more sustainable when biodiversity and wildlife are conserved. Satellite observations could be used to promote the understanding of biodiversity and also monitor the trends. It monitors the land based flora and marine phytoplankton. Weather satellites measure sea surface, thereby determining what organisms will survive. Alerts on downward trends of wildlife could be given as a result of data obtained from satellite observation, thereby promoting sustainability.
4) Observation of carbon cycle: Using carbon cycle observation stations, stations with carbon flux monitoring towers, an ecosystem observation network can be constructed to learn about the effects of carbon cycles and disruption of ecosystems. Therefore creating awareness and helping promote sustainability.
5) Monitoring of water resources: SAR imagery can be used to map and monitor superficial and underground water resources. It has been used in arid and semi-arid regions in Africa. SAR data are suitable for mapping water bodies, as the signals are sensitive to moisture and to surface moisture. The mapping and monitoring of water bodies and wetlands is based on satellite data. It aims at mapping mares or open water surfaces as areas of ground water recharge and surface water resources, Thereby sustaining water resources.
6) Observation of stratospheric transport: Satellite observation can be used to monitor the distribution of substances. It also identifies the scope of human-induced pollution, the trends in persistent pollutants, aerosols and acidic pollutants transported over large distances. Thereby providing data for constant monitoring of climatic change as the ozone is also observed.
7) Monitoring and responding to disasters: Satellite observation is also used to monitor natural disasters such as forest fires, floods, earthquakes and tsunamis. The Moderate Resolution Imaging spectroradiometer aboard the Terra satellite can detect thermal hot spots associated with wild fires, volcanoes and industrial hot spots. Nigeria Sat-2 monitors disaster prone areas like the Sahara, which experiences severe drought in dry seasons. It also acquired more than 20 images each of Asian Tsunami disaster affected areas as large as 300 kilometers by 150 kilometers. CryoSat-2 measures polar thickness, and reduces the impact of disasters. The data acquired promotes sustainability in our world.
8 ) Managing of natural resources: Resources such as energy, fresh water and agriculture are managed properly as a result of the data acquired from satellite observation. Artificial satellites could also observe levels of precipitation, soil water content and levels of water vapor. Deforestation is monitored, as is crop growth. With the collected information, laws promoting sustainability of agricultural resources can be formed.
If properly used, data acquired from satellite observation can indeed help build a more sustainable world. Improvement on terrestrial observation networks can help improve the technology. Satellite observation is applied in mapping, environmental monitoring and meteorology. The world cannot be sustainable without checking the trends of biodiversity, rate of logging in our forests and level of ozone depletion. This paper has given us some of the areas in which satellite observation can be applied to promote a more sustainable world.
Matt Ball (2010) retrieved from www.vector1media.com on 29/11/2011.
R.R. Nagaland & Satish .C. Jaynanthi, retrieved from www.scidev.net on 25/11/2011
Salami.A.T (ed.)(2006)Imperatives of Space Technology for sustainable forest Management in Nigeria, www.spaceloauife.net.