遙感的物理基礎(chǔ)(2)(參考版)
2025-01-10 10:05本頁(yè)面
【正文】 5. 氣象條件 。 ? 大氣窗口是選擇遙感工作波段的重要依據(jù) 。 ? 水滴、霧、塵埃、煙等氣溶膠常常產(chǎn)生非選擇性散射。 3. 無(wú)選擇性散射 ：當(dāng)微粒的直徑比輻射波長(zhǎng)大得多時(shí)所發(fā)生的散射。 ? 多波段中不使用藍(lán)紫光的原因： 遙感原理 煙臺(tái)師范學(xué)院地理與資源管理學(xué)院 顏色 紅 橙黃 黃 綠 青蘭 紫 紫外線(xiàn) 波長(zhǎng) 散射率 1 ?無(wú)云的晴天，天空為什么呈現(xiàn)藍(lán)色？ ?朝霞和夕陽(yáng)為什么都偏橘紅色？ 遙感原理 煙臺(tái)師范學(xué)院地理與資源管理學(xué)院 2. 米氏散射 ：當(dāng)微粒的直徑與輻射波長(zhǎng)差不多時(shí)的大氣散射。紫外線(xiàn)是紅光散射的 30倍， 4微米紅外線(xiàn)散射的 1萬(wàn)倍。 Scattering ? Atmospheric scattering is the unpredictable diffusion of radiation by particles in the atmosphere. ? Three types of scattering can be distinguished, depending on the relationship between the diameter of the scattering particle (a) and the wavelength of the radiation (l). Scattering of EM energy by the atmosphere 煙臺(tái)師范學(xué)院地理與資源管理學(xué)院 遙感原理 Rayleigh Scatter a l ? Rayleigh scatter is mon when radiation interacts with atmospheric molecules (gas molecules) and other tiny particles (aerosols) that are much smaller in diameter that the wavelength of the interacting radiation. ? The effect of Rayleigh scatter is inversely proportional to the fourth power of the wavelength. As a result, short wavelengths are more likely to be scattered than long wavelengths. ? Rayleigh scatter is one of the principal causes of haze in imagery. Visually haze diminishes the crispness or contrast of an image. Relationship between path length of EM radiation and the level of atmospheric scatter Mie Scatter a = l ? Mie scatter exists when the atmospheric particle diameter is essentially equal to the energy wavelengths being sensed. ? Water vapour and dust particles are major causes of Mie scatter. This type of scatter tends to influence longer wavelengths than Rayleigh scatter. ? Although Rayleigh scatter tends to dominate under most atmospheric conditions, Mie scatter is significant in slightly overcast ones. Nonselective scatter a l ? Nonselective scatter is more of a problem, and occurs when the diameter of the particles causing scatter are much larger than the wavelengths being sensed. ? Water droplets, that monly have diameters of between 5 and 100mm, can cause such scatter, and can affect all visible and near to midIR wavelengths equally. ? Consequently, this scattering is “nonselective” with respect to wavelength. In the visible wavelengths, equal quantities of blue green and red light
環(huán)評(píng)公示相關(guān)推薦
鄂ICP備17016276號(hào)-1