Taiwan lies across the Tropic of Cancer and the climate is influenced
by the East Asian Monsson. However, because of the complex terrain and
regional climates, Taiwan faces the heavy precipitation very often,
especially during the rainy/monsoon season (May ~ June) and typhoon
season (July ~ September). This kind of heavy rainfall seasons sometimes
causes the devastated disasters, such as landslide and debris flows,
especially in the area of the steep mountain. Remote sensing is an
effective technique for widely monitoring these disasters without human
involved site observation. Unfortunately, the remotely sensed images
taken by the conventional optical satellite suffer the cloud coverage,
it is therefore, the optical images are not able to observe and analyze
the region of interest. ESA (European Space Agency) C-Band Sentinel-1A
SAR (Synthetic Aperture Radar) satellite, which is all weather capable
and wide coverage, is able to penetrate through the clouds to
monitoring/observe the land surface changes efficiently, such as the
landslide and debris flow. Moreover, the revisit time of Sentinel-1A is
12 days, which is a great advantage of monitoring Taiwan frequently,
especially after the heavy rainfall and typhoons. Consequently,
Sentinel-1A SAR data is utilized in the research of changes in land
surface monitoring, to promote the abilities of SAR researches and
applications and support the policies of disaster prevention for the
government.
台灣所在位置處於亞熱帶地區，其為亞洲季風系統的一部分。因地理位置，冬季東亞大陸冷高壓和夏季西北太平洋副熱帶高壓對臺灣有最直接的影響。尤其夏季季風變動的熱帶暖濕空氣往北輸送加上區域地形和颱風的影響，往往為臺灣帶來非常劇烈的降雨。處於冬夏轉換期的五、六月，如果梅雨鋒面的位置正好在臺灣附近，也會造成災害性的劇烈降雨，如土石外露崩塌和土石流等。台灣全島或部分地區幾乎全年都被雲層所覆蓋，特別是颱風或是梅雨季節時，以至於影響光學衛星影像的品質而無法有效的掌握、監測土石崩塌或土石流之區域。因此全天候、大範圍觀測之雷達(Synthetic
Aperture Radar,
SAR)可彌補傳統光學影像的缺點，進而可有效觀測、分析強降雨所造成之土石災害。本計劃將利用歐洲太空總署(European Space
Agency, ESA)之C波段Sentinel-1雷達衛星觀測台灣地區強降雨所造成之地質災害，特別是坡度較陡峭之山區。Sentinel-1其大範圍拍攝模式
(Interferometric Wide Swath mode, IW)
以及12天重複拍攝同一地區之特性更可有效的密集觀測整年度降雨或強降雨後，山區是否有土石崩落或土石流之情況。本研究藉由利用SAR具有穿透雲雨、可於夜間作業的優勢用以提升本中心遙測技術之能量以及提高遙測影像應用範圍及資料之適時性與正確性，更可支援政府後續減災、防災策略之制定以及支撐土石、地質災害之科學研究工作。
作者：Meng-Che Wu／Assistant
researcher, National Space Organization,
National Applied
Research Laboratories
Wen-Yen Chang／Professor and Director, College of Environmental
Studies and Industrial Innovation-Incubation Center at
National Dong Hwa University and the Eastern Taiwan
Earthquake Research Center (E-TEC)
Yang-Lang Chang／Professor and Director, NVIDIA-Taipei Tech
Embedded GPU Joint Lab in the Department of
Electrical Engineering, National Taipei University of
Technology
Lena Chang／Associate Professor, Department of Communications,
Navigation and Control Engineering, National Taiwan
Ocean University
