D1 Satellite Remote Sensing of the Climate System

Topic

The teledetección satellite consists of one of the piles of the observation of the global climate system. The satellites register the electromagnetic radiation that the Tierra emite or refleja en different spectral bands and, a partir de esas mediciones, permiten inferirir variables such as the temperature, the atmospheric composition, the extension of the sky, the humidity and the activation of the vegetation. Estas propiedades no se observation directamente: se calculan a partir de la relación física existente entre cada variable y la radiación registrada por los sensors. The main method of this method is to provide repeated observations and with practical planetary coverage.

A fundamental application is the medicine for the energy balance of the Tierra. Instruments specializados observe tanto the radiación solar reflejada hacia el space como the radiación térmica de onda larga emitted por el planeta. The comparison between the solar energy absorbed and the thermal energy emitted allows the desequilibrium of the terrestrial energy to be determined. The climate system absorbs more energy from the space that exists in a positive equilibrium, actually guaranteed to be 0.87 W/m². The energy supply is permanent in the climatic system and constitutes the base physics of the heating system.

The satélites also allow you to learn the median temperature of the brightness. The radiómetros miden the radiancia en determinadas bandas spectrales y esta se transforma en la temperatura that tendría a black body that emits the misma radiancia observada. The radiometros de microondas use distinct channels, each with different sensitivity to the capas de la atmósfera. Because the absorption and emission of microns depends on the frequency and the propiedades atmosféricas, it is possible to obtain different information from the superficie, the troposfera and the estratosfera. This manera was constructed by registros de la evolution thermal de distintas regionales verticales de la atmósfera.

Another application is the observation of the marine and continental ice. The radiometros pasivos de microondas aprovechan las differences between the emission of the ice and the agua liquid to identify superficies cubiertas de ice and determine the extension. This technical means that the frequency of observations is included in the low conditions and the visible results are limited. Sin embargo, conocer the presence or extension of the sky is not based on determining the volume. To study the power and the cambios de elevation you use other instruments, like altímetros laser, capaces de medir with precision of the altura de la superficie. The combinación de differentes sensors permite así caracterizar tanto the espacial distribution as the evolution física de las masas de hielo.

The vegetation can also be observed from a median point on the propiedades espectrales. The clorofila absorbs intensively the radiation in the red region of the spectrum, mientras that the internal structure of the hojas refleja fuertemente en el infrared cercano. This difference allows you to construct vegetation indicators as part of the reflection media in ambas bandas. A vegetación más densa y activa suele produce a contraste mayor between the infrared cercano and the red, for lo que estos índices permiten seguir cambios en la cobertura y actividad de la vegetación a grandes escalas spaciales y temporales.

The observation of the energetic balance, the temperature of the atmosphere, the conditions of the environment and the vegetation using instruments and bands of different spectral characteristics, but also have a different principle: medium electromagnetic radiation and conversion, median physical relationships and algorithms for processing, en información sobre el state del climático system. This repetitious observation capacity has enormous extensions of the planet, which has satellite telephoto detection, which complements the superficial medical devices and provides a global vision that is impossible to obtain from a single median terrestrial location.

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