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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/61176

    Title: 地球同步衛星觀測資料之雲區像素辨識;Discrimination of Cloud Pixels for Geostationary Satellite from MODIS Product
    Authors: 李品儀;Lee,Pin-yi
    Contributors: 遙測科技碩士學位學程
    Keywords: 雲區遮罩;像素;反演;cloud mask;pixel;retrieval
    Date: 2013-07-29
    Issue Date: 2013-08-22 12:14:02 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 雲是指停留大氣層上的水滴或冰晶以及其他空氣分子的集合體,遠看是不透明的,近看則發現它並不是不透明,只是能見度有限,這樣不連續的特性,導致雲的邊界模糊難以判定,然而眼見不為憑,肉眼所能看見僅限於可見光波段、能辨認的顏色僅約60種,因此我們需要更多的資訊來彌補眼睛的缺失,正因為不同波段的特性都不盡相同,因此在波段的選取上也是門學問。
    MODIS ( Moderate-resolution Imaging Spectroradiometer) 是搭載在繞極衛星Terra與Aqua上的重要儀器,其資料已廣泛應用於氣象、環境、林業、漁業、自然災害監測等領域,乃氣象觀測之重要儀器,具有全球性觀測、高空間解析及多頻譜之優點; MTSAT (Multifunctional Transport Satellites)為地球同步衛星,具有高時間解析及視野寬廣的優點,然而目前MTSAT仍未有雲分類的相關產品,因此本文使用MODIS雲區遮罩產品 MOD35與 MTSAT資料搭配相近的時間與地點嘗試反演出MTSAT雲區遮罩產品,並將結果與MOD35較驗。本篇論文著重於晴空區域的辨識,使用kappa值進行一致性的評估並嘗試尋找有意義的邏輯判斷式及有根據的門檻值來完成整個雲區遮罩的架構,其中使用了波段特徵上的辨別與數學式子上的討論,其結果幾乎完全與MODIS雲區遮罩產品吻合。
    Clouds are a visible mass of liquid droplets or frozen crystals made of water or various chemicals suspended in the atmosphere. Seeing from a distance it is opaque, but closely it is discontinuous and can be seen through with certain visibility. When cloud existing, it will cover the earth's surface and weaken the information surface and lead to receive imprecise information. Therefore, before further analysis of the data, we should determine the cloud region first so that it can be filtered or corrected. However as mentioned, cloud is capricious, fuzzy and uncertain. This characteristic made the border of cloud uncertain and uneasy to determine whether the cloud existing or not. Therefore the identification is quite challenging. MODIS (Moderate-resolution Imaging Spectroradiometer) and MTSAT (Multifunctional Transport Satellites) are two major sources for cloud monitoring. MODIS is an important imager onboard the sun-synchronous satellites of Terra and Aqua. The advantages of MODIS are global observations, high spatial resolution and multi spectral. On the other hand, MTSAT is a geostationary satellite covered the Asia area which having a superiority of high temporal resolution. Therefore in order to get better temporal resolution to observe same location sustained, we combine MTSAT data collocates with MODIS cloud mask product-MOD35 to retrieve MTSAT cloud mask. This study focuses on the detection of clear pixels. The performance of the algorithm shows an almost perfect result by using kappa as standard compared to MODIS cloud mask.
    Appears in Collections:[遙測科技碩士學位學程] 博碩士論文

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