Active Remote Sensing of Chemical Compounds - Essay Example

Name: Date: Institution Active Remote Sensing The paper will address the remote sensing. It will highlight the various categories of remote sensing which includes; the passive remote sensing and the active remote sensing. The paper highlights the significance of active remote sensing and the current and future threats of active remote sensing. The data is collected through remote sensors. These remote sensors can either be passive or active sensors. The passive sensors will respond to the external stimuli. On the other hand, active stimuli will respond to the internal stimuli and do not depend on the earth’s reflected energy (Fix, Andreas, et al p 818206). The paper also highlights the advantages of the FTIR method. This is a technique which replaced the traditional point sampling detection method. It also outlines the common active remote systems that are used around the globe. They include; RADAR (radio detection and ranging), LIDAR (light detection and ranging), and SONAR (sound navigation ranging). The paper highlights the importance of remote sensing which includes; in understanding the following; terrestrial weather, space weather hazard, climate change, threats that are from the asteroids, and tracking of the space debris. Introduction Remote sensing can be defined as the science of collecting information about a given area or object from a distance e.g. from satellites or from aircraft. Remote sensors are in a position to collect data by perceiving the energy that is reflected from the earth surface. These remote sensors are mounted on satellites or on aircraft. The sensors can be classified into two categories; passive sensors and the active sensors. The passive sensors are designed so that they can respond to the external stimuli. They are meant to collect information and record about the natural energy that the earth surface emits. This natural energy reflected by the earth surface is mostly the reflected sunlight (Bergen, et al p 114). On the other hand, active sensors are designed such that they will use internal stimuli to collect information about the earth surface. A good example of an active remote sensor is the laser-beam remote sensing system. This system works by projecting a laser onto the earth surface, it then counts on the time the laser will take to reflect back to the sensor. Figure: 1a different remote sensing platforms Figure 1b: types of remote sensing systems Active remote sensing can be described as the use of a transmitter and a receiver so that the transmission is measured. One can also be in a position to measure the scattering properties of a given medium at radio frequencies. The measurements obtained are used detect the physical state of the medium passed by the signals. In detecting the remote sensing, the following are the media of interest; oceans, land surfaces, the atmosphere, and other terrestrial objects. There are various ways in which active remote sensing are performed including; satellite platforms, ground-based, airborne or a combination of all these methods (Wulfmeyer, et al. p 220). Figure; 2a: Active remote sensing system Figure 2b: passive remote sensing Importance of Active Remote Sensing Active remote sensing can be seen as a principal tool that can be predicted as well as studying the long-term and short-term changes in the atmosphere, the oceans, and land surfaces. The active remote sensing measurement is very important in understanding the following; climate change, terrestrial weather, space weather hazard, threats that are from the asteroids, and tracking of the space debris. The measurements are also crucial to the global community in the process of technological advancement. This is because it will enable countries to conserve their environments. The following are the importance of active remote sensing: a) Saving of lives and property protection from severe storms. This is achieved through active remote sensing. This will also help scientists to understand the global circulation and the upper-atmospheric winds. b) Unique measurement of the ocean waves, currents, wind direction and speed are provided by the active microwave sensors. This application of these waves will include; storm and hurricane warning, global weather prediction, ship routing, wave forecasting, commercial fishing, coastal storm surge, wave monitoring and monitoring of the coastal currents. c) Vital data on land use, are provided by; airborne, space borne, and the active remote sensing that operates on the surface. This will include; synthetic aperture radars, real-aperture radars, and scatterometers. Knowledge in this field is so useful in defense, urban planning, sea ice mapping, volcano studies, and post-disaster assessment. d) There is a great contribution to the knowledge of the solar system, space planning mission, this has been enabled by planetary radar system. e) Through active remote sensing of ionosphere, scientists are able to get the clear understanding the basic physics of the near-space region. There are a number of threats that are associated with the use of spectrum required for active remote sensing. There is a potential difficulty in establishing a new science in the future, due to the allocation of multiple bands to the earth exploration satellites service active. This is because only some portions of the bands are in use. The ability to collect the required scientific data has been hindered and degraded due to the imposition of transmitting restrictions on the active science sensors. RFI has been noted to grow worse in a number of bands. High-value science radar measurement has been established. This will cause a threat as a result of planned expansion of the commercial services on the Earth Exploration-satellite. In the recent years, air pollutants have greatly improved. Therefore scientists have developed an interest in developing sensors which are able to detect the even very low concentration of species. These sensors are useful since they are used to measure atmospheric aerosols, pollutants, and species. They are also used to monitor air pollution and therefore addressing the presence of toxic chemicals in the air. The modern satellite and airborne remote sensing techniques have provided opportunities to the coastal monitoring system. It is important to note that analysts should have a lot of concern on the limitations of remote sensing. Remote sensing has numerous applications, for instance; in ocean they are useful in monitoring the current and ocean circulation system, it also helps in measuring the wave lengths and temperatures of the oceans, they are also useful in tracking the sea ice. They are useful in detecting and assessing hazards. In hazard assessment, the remote sensing is used to track soil erosion, earth quakes, hurricanes and floods. The data collected during such natural calamities can be used to assess the effects of such calamities and therefore helpful in developing of preparedness strategies that can be applied before, during and after the natural disaster (Jensen, & John). The remote sensing is also used in coastal regions, they are useful in tracking the transportation of sediments, monitoring changes in the shorelines, and they are also useful in mapping the coastal features. This data is useful in that it can be used to develop measures of preventing soil erosion. Finally, remote sensing is also applicable in resource management; they are used in mapping the wetlands, charting the areas inhabited by wildlife, it is also used to monitor land use. The data collected is useful in detecting and reducing the effects that urban growth on the environments. It is also useful in decision making on the protection measures against depletion of natural resources. In open environments gas phase pollutants are common. In order to identify these pollutants, scientists have adopted Fourier transform infrared (FITR) remote sensing technique. This technique has replaced a point sampling detection method technique which was traditionally used. The FTIR method has several advantages in relation to the traditional method; It is fast in the analysis of multi-component mixtures, It has little maintenance and simple operation, The technique is universal in the detection of polyatomic molecules, Large sampling area with no sample preparation and handling, By applying this technique in measurement, there is no sensor contamination. In the recent years, an automated FTIR remote sensing system has been developed. This system has been useful in the detection of atmospheric air pollutants and trace gases. This measurement technique can be categorized into two categories; the passive and the active technique. The passive technique has not been widely used like the active technique method (Zhao et al. p 190). In the current world, there are many sources of harmful environmental pollutant chemicals which include; chemical weapons, pipelines, agricultural sites, and industrial processing facilities. However, by application of the modern ground-based remote sensing imaging technology, it has been made easy to detect, identify and to map the movement of the hazardous clouds. This information will be useful in that scientist can easily and quickly identify and track airborne compounds. Active Remote Sensing By FTIR Spectroscopy In this technique, a hot infrared source will emit infrared lights. The infrared lights are received by spectrometer optics. The emitted infrared light will then spread towards the open optical paths. Interferometer will modulate the received infrared lights. The infrared lights are detected by the infrared detectors; the spectrometer electronic will be helpful in converting the detected infrared lights into interferogram a form in which it is stored (Ulaby et al). The system has a connected data system which help provides the interferogram with relevant information for the computation of infrared spectrum by Fourier transformation which is a mathematical operation. In case IR-active is present in the optical path, they will be displayed in the IR-spectrum. It will, therefore, be easy to evaluate the quantity and composition of a species following the data in the transmittance spectrum. An increase in the following factors leads to an increase in sensitivity of the detection technique for a target species; 1. The IR-detector element sensitivity 2. Measurement time 3. the length of the optical path 4. Absorption coefficient of the target molecule 5. Modulation efficiency and transmittance of FTIR spectrometer The active remote sensing system depends on their own electromagnetic energy thus do not depend on the sun’s EMR or the earth’s thermal properties. The system’s energy is transmitted to the terrain from the sensor without any atmospheric interference. A backscatter of energy is also produced when the electromagnetic energy interacts with the terrain (Reutebuch et al 291). Finally, the remote sensor’s receiver will have to record the electromagnetic energy. The following the common active remote system used globally; a) RADAR (radio detection and ranging); active microwave- this is a system which is long-wavelength microwave transmission based (Zolkos et al p 290). The wavelengths are transmitted via the atmosphere where the backscatter amount of energy from the terrain is recorded. The initial application of this technique involved the use of radio waves. Figure 2a: Radar remote sensing b) LIDAR (light detection and ranging); this is a technique which has its basis on the short wavelength laser light transmission where the amount of backscattered light from the terrain is recorded. c) SONAR (sound navigation ranging); this is a technique which is based on sound wave transmission. The sound waves are transmitted via a water column; the amount of energy backscattered from the object within or at the bottom of the water column is recorded. The process for species measurement It is important to note that each molecule that makes a chemical sample is made up of a distinctive combination of different elements which are held together by a number of bonds of varying strengths. The uniqueness of each chemical species can be noted via the absorption spectra of the infrared. The chemical species can also be identified through examination of the optical radiations. This operates by; forcing the molecules bonds that have a small charge distribution into oscillation. This is only possible with the presence of an oscillatory electronic field. This implies that any photon that could be passing will scatter from the molecule. The photon will then force the many energy modes into oscillation. LIBS (laser inducted breakdown spectrum is also another technique that is used to analyze the chemical species. This technique ruptures the structure of the molecule using the laser beam. In the process of rupturing the element a number of atomic components are created allowing one to identify the mother species. Raman scatters intensity and the infrared optical absorption measurements are able to give a picture of the molecular energy states. Due to this capacity, they, therefore, make it easy for identification of most species. It should be noted that the same energy states will occur as both Raman active or infrared active. At times, a molecule may occur in smeared on other materials or liquid form. In the case of such a situation, the energy states will respond to the radiation by ensuring that the bonds between the atoms are stiffened. The chemical species and their concentration present are identified by recognizing the spectral features. Infrared Absorption Molecular vibration is said to be infrared active if there is a modulation of their normal dipole moment. For the radiation to be absorbed, it is required that the impinging radiation field be almost the same as the frequency of the oscillation resonance of a given electric dipole moment. The resonance will have to occur at an energy that will correspond to; stretching, vibrational, bending, twisting, rotational, wagging, or any other form of the oscillatory energy state of a given energy state. Raman scatter A molecule will be said to be Raman active if the action of a scattering photon’s electronic field will induce a dipole. This induction will force a relative motion that will occur between the nuclei and the electrons. The dipole moment induced has to be proportional to the electric field strength and polarizability of the radiation intensity (Lillesand et al). Scattering process Molecular species will have to provide a number of signals that will help detect the various chemical species their distribution and concentration through the scattering of the optimal radiations. In the process of scattering, there is an interaction of molecules with the optical wavelength. Raman lidar measurement These signals are used in the measurement of species concentration. Most of the atmospheric species are measured using this signal. This method works by forming a given ratio to the nitrogen signal. There is an accurate measurement of the Raman cross section for many species have been provided by laboratory measurements, it is, therefore, easy to know the concentration of various species (Campbell, James & Randolph). This is obtained through comparing the nitrogen ratio to the Raman cross section measurement of given species. Remote sensing has the following advantages on land evaluation; it is a reliable cheap method of acquiring up-to-date over a large geographical area (Andersen et al. p 445). This is a method which is useful in obtaining data from the inaccessible regions. It is also possible to view some of the invisible phenomena from the ground. In conclusion, remote sensing can be defined as the science of collecting information about an object from a distance. The information is collected by sensors are positioned in satellites or aircraft. Such sensors are categorized into passive and active sensors. Land remote sensing has been adopted by several analysts; the data used in a number of applications such as land cover mapping, land use, geological resource exploration, archeological investigation, precision farming, global environmental change detection (Andersen et al. 50). The following are the common active remote system that is used globally by analysts; RADAR (radio detection and ranging), this is a technique which is based on; long-wavelength microwave transmission, SONAR (sound navigation ranging), this technique is based on sound wave transmission and finally; LIDAR (light detection and ranging), this is a technique based on short wavelength laser light transmission (Ehret, G., et al 595). In order to increase the sensitivity of the detecting technique it is important to consider the following factors; The IR-detector element sensitivity, Measurement time, the length of the optical path, Absorption coefficient of the target molecule, modulation efficiency and transmittance of FTIR spectrometer. Remote sensing has a number of applications; which include: coastal application- where ocean current and circulation system are monitored. In the coastal application the wave lengths and temperatures of the oceans, are measured. The remote sensing is also used to track the sea ice. Hazard assessment application, here, the remote sensing is used to track several natural calamities that are likely to occur such as earth quakes, soil erosion, hurricanes, and floods (Dalponte et al. 1420). The data collected during such natural calamities can be used to assess the effects of such calamities and therefore helpful in developing of preparedness strategies that can be applied before, during and after the natural disaster. Coastal application, here the remote sensing useful in tracking the transportation of sediments, monitoring changes in the shorelines, and they are also mapping the coastal features. The data collected can be used to come up with strategies that will help to curb and prevent soil erosion and finally, resource management; they are used in mapping the wetlands, charting the areas inhabited by wildlife, also they help individuals to monitor land use (Killinger et al). There are regions that are not easily accessible since they could be dangerous, or inaccessible, by use of the remote sensing it is therefore easy to monitor such natural resources. Active remote sensing has a number of advantages: it is easy to save lives and to protect properties from damage through active remote sensing. This could be out of natural calamities such as severe storms. Through active remote sensing, analysts are able to understand the upper-atmospheric winds as well as the global circulation. It is possible to obtain a unique measurement of wind directions and speed, and ocean waves through microwave sensor. It is also useful in storm and hurricane warning, global weather prediction, ship routing, wave forecasting, commercial fishing, coastal storm surge, wave monitoring and monitoring of the coastal currents (Zheng, Guang, and Monika Moskal p 2720). It is possible to obtain crucial data based on the land use given by; airborne, space borne, and the active remote sensing that operates on the surface. This will include; synthetic aperture radars, real-aperture radars, and scatterometers. The knowledge on active remote sensing will have a great contribution to the understanding the solar system, space planning mission, and this will be enabled by the planetary radar system. Through active remote sensing of the ionosphere, scientists are able to get a clear understanding the basic physics of the near-space region. Work cited Andersen, Hans-Erik, Robert J. McGaughey, and Stephen E. Reutebuch. "Estimating forest canopy fuel parameters using LIDAR data." Remote sensing of Environment 94.4 (2005): 441-449. Andersen, Hans-Erik, Stephen E. Reutebuch, and Robert J. McGaughey. "Active remote sensing." Computer applications in sustainable forest management. Springer Netherlands, 2006. 43-66. Bergen, K. M., et al. "Remote sensing of vegetation 3‐D structure for biodiversity and habitat: Review and implications for lidar and radar spaceborne missions." Journal of Geophysical Research: Biogeosciences114.G2 (2009). Campbell, James B., and Randolph H. Wynne. Introduction to remote sensing. Guilford Press, 2011. Dalponte, Michele, Lorenzo Bruzzone, and Damiano Gianelle. "Fusion of hyperspectral and LIDAR remote sensing data for classification of complex forest areas." IEEE Transactions on Geoscience and Remote Sensing 46.5 (2008): 1416-1427. Ehret, G., et al. "Space-borne remote sensing of CO2, CH4, and N2O by integrated path differential absorption lidar: a sensitivity analysis." Applied Physics B 90.3-4 (2008): 593-608. Fix, Andreas, et al. "Optical parametric oscillators and amplifiers for airborne and spaceborne active remote sensing of CO2 and CH4." Proc. SPIE 8182, 818206 (2011); doi: 10.1117/12.898412 8182 (2011): 818206. Jensen, John R. Remote sensing of the environment: An earth resource perspective 2/e. Pearson Education India, 2009. Killinger, Dennis K., and Aram Mooradian, eds. Optical and laser remote sensing. Vol. 39. Springer, 2013. Lillesand, Thomas, Ralph W. Kiefer, and Jonathan Chipman. Remote sensing and image interpretation. John Wiley & Sons, 2014. Reutebuch, Stephen E., Hans-Erik Andersen, and Robert J. McGaughey. "Light detection and ranging (LIDAR): an emerging tool for multiple resource inventory." Journal of Forestry 103.6 (2005): 286-292. Ulaby, Fawwaz T., Richard K. Moore, and Adrian K. Fung. "Microwave remote sensing active and passive." (2015). Wulfmeyer, V., et al. "Comparison of active and passive water vapor remote sensing from space: an analysis based on the simulated performance of IASI and space borne differential absorption lidar." Remote sensing of environment 95.2 (2005): 211-230. Zhao, Kaiguang, Sorin Popescu, and Ross Nelson. "Lidar remote sensing of forest biomass: A scale-invariant estimation approach using airborne lasers." Remote Sensing of Environment 113.1 (2009): 182-196. Zheng, Guang, and L. Monika Moskal. "Retrieving leaf area index (LAI) using remote sensing: theories, methods and sensors." Sensors 9.4 (2009): 2719-2745. Zolkos, S. G., S. J. Goetz, and R. Dubayah. "A meta-analysis of terrestrial aboveground biomass estimation using lidar remote sensing." Remote Sensing of Environment 128 (2013): 289-298. Read More

The active remote sensing measurement is very important in understanding the following; climate change, terrestrial weather, space weather hazard, threats that are from the asteroids, and tracking of the space debris. The measurements are also crucial to the global community in the process of technological advancement. This is because it will enable countries to conserve their environments. The following are the importance of active remote sensing: a) Saving of lives and property protection from severe storms.

This is achieved through active remote sensing. This will also help scientists to understand the global circulation and the upper-atmospheric winds. b) Unique measurement of the ocean waves, currents, wind direction and speed are provided by the active microwave sensors. This application of these waves will include; storm and hurricane warning, global weather prediction, ship routing, wave forecasting, commercial fishing, coastal storm surge, wave monitoring and monitoring of the coastal currents. c) Vital data on land use, are provided by; airborne, space borne, and the active remote sensing that operates on the surface.

This will include; synthetic aperture radars, real-aperture radars, and scatterometers. Knowledge in this field is so useful in defense, urban planning, sea ice mapping, volcano studies, and post-disaster assessment. d) There is a great contribution to the knowledge of the solar system, space planning mission, this has been enabled by planetary radar system. e) Through active remote sensing of ionosphere, scientists are able to get the clear understanding the basic physics of the near-space region.

There are a number of threats that are associated with the use of spectrum required for active remote sensing. There is a potential difficulty in establishing a new science in the future, due to the allocation of multiple bands to the earth exploration satellites service active. This is because only some portions of the bands are in use. The ability to collect the required scientific data has been hindered and degraded due to the imposition of transmitting restrictions on the active science sensors.

RFI has been noted to grow worse in a number of bands. High-value science radar measurement has been established. This will cause a threat as a result of planned expansion of the commercial services on the Earth Exploration-satellite. In the recent years, air pollutants have greatly improved. Therefore scientists have developed an interest in developing sensors which are able to detect the even very low concentration of species. These sensors are useful since they are used to measure atmospheric aerosols, pollutants, and species.

They are also used to monitor air pollution and therefore addressing the presence of toxic chemicals in the air. The modern satellite and airborne remote sensing techniques have provided opportunities to the coastal monitoring system. It is important to note that analysts should have a lot of concern on the limitations of remote sensing. Remote sensing has numerous applications, for instance; in ocean they are useful in monitoring the current and ocean circulation system, it also helps in measuring the wave lengths and temperatures of the oceans, they are also useful in tracking the sea ice.

They are useful in detecting and assessing hazards. In hazard assessment, the remote sensing is used to track soil erosion, earth quakes, hurricanes and floods. The data collected during such natural calamities can be used to assess the effects of such calamities and therefore helpful in developing of preparedness strategies that can be applied before, during and after the natural disaster (Jensen, & John). The remote sensing is also used in coastal regions, they are useful in tracking the transportation of sediments, monitoring changes in the shorelines, and they are also useful in mapping the coastal features.

This data is useful in that it can be used to develop measures of preventing soil erosion.

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