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| Titel |
Monitoring Thermal Activity of Eastern Anatolian Volcanoes Using MODIS Images |
| VerfasserIn |
Caner Diker, İnan Ulusoy |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086730
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| Publikation (Nr.) |
 EGU/EGU2014-651.pdf |
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| Zusammenfassung |
| MODIS (Moderate Resolution Imaging Spectroradiometer) instrument is used for imaging
atmosphere, land and ocean with 36 bands. Both AQUA and TERRA platforms acquire 2
images daily (daytime and nighttime). Low temperature anomalies on volcanoes comprise
important clues. Low temperature anomalies on Holocene volcanoes of Eastern Anatolia
were investigated for these clues using MODIS Land Surface Temperature (LST)
images. A total of 16800 daily LST images dated between 2001 and 2012 have been
processed using a code written in IDL (Interactive Data Language). Factors like
shadow, ice/snow and clouds that are affecting the reflectance data are masked. The
mask is derived from MODIS reflectance data state image. Various LST images are
calculated: Two nested region of interest (ROI) windows (square/rectangular) have
been selected on the images. First is the bigger window, which covers the whole
area of the volcano (Total volcano area). Second one is a smaller window which
circumference the summit (crater and/or caldera) of the volcano (Summit cone)
where thermal output is generally higher when compared to the flanks. Two data
sets have been calculated using the ROI’s for each volcano. The first set contains
daytime and nighttime raw data without any correction. The second set contains
topographically corrected images; daytime images are corrected using Cosine and Minnaert
methods and nighttime images are corrected using three step normalization method.
Calculated surface temperatures (Tmax, Tmin, Tmean) are plotted annually. On Nemrut
Volcano as an example, maximum and minimum temperatures are between 26.31oC
and -44.87oC on nighttime data for twelve years period. Temperature difference
between total volcano area ROI and summit cone ROI are calculated (ΔT). High
ΔT indicates that there is an increase of temperature at the summit cone when
compared to the total volcano area. STA/LTA (Short Term Average/Long Term
Average) filter was applied to maximum temperature and ΔT data. Determination of a
threshold value for STA/LTA curve has a potential for volcano monitoring. This
method could be a useful and low cost tool to detect low temperature anomalies on
volcanoes.
Keywords: Eastern Anatolia, MODIS, thermal, volcano, surface temperature, Turkey |
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