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Earth’s Global energy Budget is an article written by Kevin Trenberth, John Fasullo, and Jeffery Kiehi. This article dwells on various issues related to earth’s energy budget. It also focuses on the sources of earth’s energy and various methods used to measure it (Trenberth, Fasullo, and Kiehl 1).
Sources of Earth’s Energy
Earth’s climate is determined by the quantity and distribution of ration from the sun. A stable climate is usually achieved when outgoing longwave radiation (OLR) regulates incoming absorbed solar radiation (ASR). Inward bound radiant energy is usually absorbed by the earth’s atmosphere.
The shortwave energy (radiant solar) is converted into kinetic energy, potential energy and latent energy before is it released as longwave radiant energy (Trenberth, Fasullo, and Kiehl 1). Energy may be transported in different forms, stored for a short period or transformed into the different types, thus creating different types of climate on earth’s surface. In addition, the energy balance can be altered in several ways adjusting earth’s climate and weather (Trenberth, Fasullo, and Kiehl 1).
Modern technology is currently being used to estimate and analyze earth’s energy budget. Some experts have used satellite data to document earth’s energy budget for the annual cycle and inter-annual changeability. Several new measurements have been done, especially from CERES (clouds and the earth’s radiant energy system) devices on a number of platforms.
In addition, there are several new estimates made about earth’s energy budget that are credible. Several examinations on the content of ocean heat have also provided a comprehensive analysis of the global heat balance (Trenberth, Fasullo, and Kiehl 2).
For example, Trenberth, Fasullo, and Kiehl present an evaluation of the earth’s energy budgets at the surface and Top of atmosphere (TOA) for the global ambiance, land surface and ocean on the basis of ocean temperature estimates, land domain simulations and analysis of data retrieved from satellite (2). They limited the TOA budget to correspond to estimates of the global disparity during latest periods of satellite coverage related to adjustments in climate and atmospheric composition (Trenberth, Fasullo, and Kiehl 2).
They also analyze the ocean heat budget in great detail and provide observable estimates of energy deviation and a complete evaluation of uncertainty. By discretely examining the land and ocean spheres, Trenberth, Fasullo, and Kiehl discovered a setback in the previous alteration made to Earth Radiation Budget Experiment data when NOAA-9 fail and found it appropriate to harmonize the record independently over land and ocean rather than on a global basis.
The outcome was a modified and somewhat better value for the global outgoing longwave radiation than in KT97. Nonetheless, even larger adjustments emerged from using CERES data that apparently reveal better precision of CERES retrievals and its accuracies in retrieval method as well as its utilization of Moderate Resolution Imaging Spectroradiometer technology for scene recognition (Trenberth, Fasullo, and Kiehl 2).
The discussions above have outlined some of the key issues and problems associated with determining earth’s energy budget. It is appropriate to inspect the ocean and land spheres independently so as to take advantage of the limitations that arises with them and particularly to the capability of the land and ocean to store energy.
Earth’ Energy Imbalance and Implications
According to the article Earth’ Energy Imbalance and Implications, human beings are potentially susceptible to changes in global temperature. Although climate change is caused by several environmental agents, there is a general concession that the current trend in global warming is as a result of human activities that have altered atmospheric composition (Hansen, Sato and Kharecha 1).
Causes of Global Warming
The greenhouse effect is basically the major cause of global warming. For example, when the level of carbon dioxide rises, the atmosphere becomes denser at infrared wavelengths. A denser atmosphere causes the earth’s heat radiation in space to emerge from high and colder regions of the atmosphere thereby preventing heat energy to escape to space. The short-term imbalance between the heat energy absorbed by the atmosphere and heat energy released to space causes the earth to warm until planetary energy equilibrium is re-established.
A climate forcing is defined by planetary energy discrepancy attributed to an adjustment of atmospheric composition. Climate sensitivity, defined as the ultimate change of global temperature per unit forcing, is a well-known phenomenon. However, there are two key elements that constrain the ability of humans to predict changes in global temperatures on a long-term basis (Hansen, Sato and Kharecha 1).
The first element is climate forcing brought about by man-made aerosol which is virtually immeasurable. Aerosols are fine elements; such as sulfates, dust and black soot, suspended in the air. Aerosol climate forcing is intricate since aerosols both absorb solar radiation (which increases temperatures) and reflect solar radiation to space (causing temperatures to fall).
Moreover, atmospheric aerosol can change cloud properties and cloud cover. Second, the rate at which the temperature of the earth’s surface moves toward stability in reaction to a climatic forcing is determined by the manner in which heat perturbations are efficiently blended into the ocean (Hansen, Sato and Kharecha 2).
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Climate sensitivity is determined by climate feedbacks- which entail numerous physical processes that arise when climate adjusts in reaction to a forcing. Positive (magnifying) feedbacks raise the climate response whereas negative (weakening) feedbacks decrease the response. Climate problem are mainly caused climate feedbacks.
Climate feedbacks are complex phenomena to grasp because a climate forcing can be wrongly interpreted as a climate feedback and vice versa. Climate models- developed on the basis of physical laws that portray the dynamics and structure of the land processes, ocean and atmosphere- are utilized to simulate climate. These models help climate experts to grasp the nature of climate sensitivity since they can alter processes in the climate model and examine their interactions (Hansen, Sato and Kharecha 4).
As noted above, global warming is mainly caused by human activities. However, there are several environmental factors that contribute to changes in global temperature. Greenhouse gases such as carbon dioxide increases the density of the atmosphere which in turn prevents heat radiation from escaping to space. This phenomenon leads to global warming. In addition, humans are unable to analyze the underlying cause of global warming because of the complicated nature of climate feedbacks (Hansen, Sato and Kharecha 4).
Principles of Remote Sensing
According to the article Principles of Remote Sensing written by Aggarwal, remote sensing is a method used to monitor atmosphere or earth’s surface using satellite technology or airplanes (23). Several aspects of electromagnetic field are used in remote sensing. It captures data on electromagnetic energy reflected by the surface of earth. The quantity of radiation from radiance (object) is determined by both radiation striking the radiance and the property of the object (Aggarwal 23).
Remote sensing refers to the indirect process of acquiring information about objects found on earth’s surface. Humans use sensing instruments to measure electromagnetic energy transmitted by an object.
Remote sensing instruments enable humans to capture images of earth’s surface in different wavelength areas of electromagnetic spectrum (EMS). A number of of the pictures symbolize reflected solar radiation in the observable infrared areas of the EMS whereas others measure the amount of energy released by the surface of earth (Aggarwal 24).
Remote sensing is essentially a multifaceted science discipline which entails an amalgamation of several disciplines for example photography, spectroscopy, electronic, telecommunication and computer. These disciplines are combined to form a complete system called Remote Sensing System.
There are several phases in a remote sensing process: discharge of electromagnetic radiation (EMR); transmission of energy from the source to earth’s domain; interface of electromagnetic radiation with the surface of earth; broadcast of energy from earth’s surface to the remote sensor; and output of sensor data (Aggarwal 24).
The radiation from the sun is either reflected by earth’s surface, conveyed into the surface or emitted by earth’s surface. On interaction, the electromagnetic radiation experiences several adjustments in direction, magnitude, polarization, phase and wavelength. These adjustments are registered by the remote sensor and the interpreter is able to retrieve vital data concerning the object under observation. The data retrieved has spectral information (color, spectral mark and tone) and spatial data-direction, shape and size (Aggarwal 30).
As noted above, the main source of radiation and electromagnetic radiation is the sun. Radiation from the sun is usually reflected by earth’s surface and sensed by airplane-borne sensor or satellite. The interaction between the atmosphere and electromagnetic radiation is critical to remote sensing for two key purposes.
First, the interactions of electromagnetic with atmosphere enable interpreters to acquire important information concerning the atmosphere itself. Second, data conveyed by electromagnetic radiation is adjusted while navigating via the atmosphere. The atmospheric elements disperse and soak up the radiation reflected from the object by altering its spatial allotment. Both absorption and scattering differ with respect to their effect from one end of the spectrum to another (Aggarwal 34).
Atmospheric scattering takes place when electromagnetic radiations are redirected by fine particles suspended in the atmosphere. Scattering not only alters the spectral signature of objects but also decreases the contrast of the image.
The quantity of electromagnetic radiation scattered is determined by a number of factors: the wavelength of EMR; the mass of particles; the volume of particles; and the density of the atmosphere. The concentration of these particles fluctuates depending on the season and time. This implies that the outcomes of scattering will be spatially irregular and will differ from one season to another (Aggarwal 35).
As noted above, the sun is the main source of EMR. Remote sensing refers to the indirect process of acquiring information about objects found on earth’s surface. Humans use different sensing instruments to measure electromagnetic energy transmitted by an object. The quantity of radiation from an object is determined by both radiation striking the radiance and the property of the object. Remote sensing is thus a useful technique for identifying and classifying various features of the earth and atmosphere.
Aggarwal, Shefali. Principle of Remote Sensing. Dehra Dun: Indian Institute of Remote Sensing, n.d. Print.
Hansen, James, Sato Makiko, and Kharecha, Pushker. Earth’s energy Imbalance and Implications. New York: Columbia University Earth Institute, 2010. Print.
Trenberth, Kevin, Fasullo John, and Kiehl, Jeffery. Earth’s Global Energy Budget. Boulder, Colorado: National Center for Atmospheric Research, 2008. Print.