Detection of Disaster Damage Using Changes of City Lights with DMSP/OLS Data in Asia Pacific Region
3. Detection of disaster using DMSP/OLS
3.1 DMSP/OLS data
The U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) data are received and used at operational centers on a continual basis in USA. The data are sent daily to the National Geophysical Data Center (NGDC), located in Boulder, Colorado, USA for creation of an archive. From Boulder, Colorado, these data are transferred in semi real time to the Computer Center for Agriculture, Forestry and Fisheries Research (AFFR), MAFF, Japan.
DMSP/OLS is designed for cloud imaging with two spectral bands, visible-near infrared (0.47-0.95 um) and thermal infrared, at 2.7 km resolution and swath of 3000 km. This instrument can also detect faint sources of visible-near infrared emission such as city lights, wildfire, fishing boats and so on.
Four satellites (F12, F13, F14 and F15) data are archived in SIDaB system. Here is a exsample of daily composite image(Fig. 2).
Fig.2 Example of DMSP/OLS Daily Composite image
3.2 Mt. Usu eruption
Mt. Usu volcano, located at Hokkaido, north of Japan, explored on 31 March, 2000. ANDES project tried to detect this eruption's damage area using DMSP/OLS data.
Kohiyama (Hayashi,2000) proposed a method to estimate the impacted area of the earthquake using visible-near infrared imagery. In this method, it is assumed that the brightness of the impacted area would decrease when the buildings collapsed or blackout occurred due to the earthquake. Thus, the impacted areas where brightness decreased significantly after the earthquake compared with before the earthquake were estimated.
Using this method, we studied Usu volcanic disaster and confirmed the ability of DMSP/OLS to detect disaster damage. Two DMSP/OLS data were used, one was acquired on 10 October, 1999, as the pre-event imagery and another was acquired on 4 April, 2000, as the post-event imagery (Fig. 3). These data were acquired with high visible band gain settings under new moon nights. The volcanic eruption influenced areas were estimated according to difference of visible-near infrared emissions between of the pre-event imagery and of the post-event imagery. The estimated image (Fig. 4) shows that there are significant reductions in nighttime lights at Toyako Hot Spring and in Date City. Indeed there are severe ash flows after Usu volcanic eruption around there.
Fig.3 DMSP/OLS visible-near infrared images before(a) and after(b) the volcanic eruption
