The prime objective of our study was to monitor heat losses by using Landsat 7 thermal infrared data from the active fumarolic region of Kuju volcano in Japan. We estimated the radiative heat flux (RHF) of the Kuju fumaroles from 2002 to 2010, used the Stefan -Boltzmann equation. Then, heat discharge rate (HDR) was calculated by using the relationship coefficient of RHF and HDR, obtained from two previous studies. The highest total RHF was found about 57.7 MW in 2002 and lowest about 21.1 MW in 2010. The total RHF decreased from 2002 to 2007 about 33 MW; then, it slight increased about 5 MW in 2008 from 2007, and finally declined about 9MW from 2008 to 2010 in Kuju fumaroles. We found highest HDR about 384.5 MW in 2002 and lowest about 140.8 MW in 2010.The relationship between land surface temperature above ambient and RHF was an expected strong correlation for each result during our study period. RHF anomalous area showed a declining trend in overall during our study period. Overall, our study was able to delineate the decline trend of heat losses that was supported by the previous study of similar declining trend of HDR using steam maximum diameter method from active fumarolic region of Kuju volcano.
Mia, Md. Bodruddoza
Nishijima, Jun
Fujimitsu, Yasuhiro
The Kuju fumaroles in central Kyushu, Japan began to erupt as phreatic in nature on 11 October 1995. To infer the thermal activity, main objectives were to monitor the radiative heat flux (RHF) before and after eruption of Kuju fumaroles in 1995 using 4 sets of Landsat TM thermal infrared data from 1990 to 1996; and to calculate and monitor the heat discharge rate (HDR) after multiplying RHF using a relationship coefficient between RHF and HDR, derived from two previous studies. The RHF was estimated by using the Stefan–Boltzmann equation for heat flow where we applied satellite image-derived spectral emissivity and land surface temperature. An increasing trend of total radiant heat flux was obtained of about 22–39 MW before the Kuju fumaroles eruption from 1990 to 1994 and a declining trend total RHF of about 37–11 MW after eruption from 1995 to 1996. RHF was strongly correlated with land surface temperature (LST) above ambient in our study. Spatial distribution of RHF also showed a similar trend of total RHF. After using this relationship coefficient, we obtained the HDR from our study area about 144.64, 249.74, 239.67 and 68.54 MW in 1990, 1994, 1995 and 1996, respectively. The HDR was much higher before eruption in October 11, 1995 than that of after the eruption in our study. Fumaroles area also showed an abrupt increase of bared land and no vegetation just after eruption within the thematic map in 1995. Statistics of LST and RHF also showed evidences of heat loss activity before and after eruption in 1995. In conclusion, we infer from this study that Landsat TM thermal infrared images are fully competent to monitor thermal activity from any active volcano fumaroles for future eruption.
To monitor heat losses using Landsat 7 thermal infrared data from 2002 to 2010 within the active fumarolic region of Kuju volcano in Japan, we used the Stefan-Boltzmann equation for radiative heat flux (RHF) estimation. Heat discharge rate (HDR) was calculated by using the relationship coefficient of RHF and HDR, obtained from two previous studies. The highest total RHF was found to be about 57.7 MW in 2002 and the lowest was about 21.1 MW in 2010. We found the highest HDR, of about 384.5 MW, in 2002 and the lowest, of about 140.8 MW, in 2010. The RHF anomalous areas were showing a declining trend during our study period. The relationship between the land surface temperature (LST) above ambient and RHF was, as expected, in a strong correlation for each result during our study period. Overall, our study was able to delineate the declining trend of heat losses that supports a previous study of similar declining trend of HDR using steam maximum diameter method from the active fumarolic region of Kuju volcano.
Mia, Md. Bodruddoza
Bromley, Chris J.
Fujimitsu, Yasuhiro
Thermal infrared (TIR) data from available, daytime, Landsat-TM/ETM + satellite imagery, supported by ground measurements, were used in this study to investigate changes between 1990 and 2011 in the radiative component of the anomalous surface heat flux emitted from the 0.5 km(2) Karapiti thermal area, at Wairakei Geothermal Field, Taupo, New Zealand. The geothermal radiative heat flux (net RHF), of subsurface origin, was then assessed by subtracting the re-radiated heat flux that is of solar origin, as determined using coincident satellite imagery at two external sites. The total net RHF decreased by about 7 MW from 1990 to 2011. Results of a vegetation index study, using ratios of two (visible) spectral bands, implied that the area of healthy vegetation at Karapiti has progressively increased during this period. This supports the evidence for a decrease in geothermal heat flux, because the health of thermally-stressed vegetation is inversely related to shallow ground temperature. Although images of apparent land-surface temperature (LST) show large variations with time, this is attributable to ambient temperature change. Spot ground estimates of heat flux using a calorimeter also showed, on average, a decreasing trend of heat fluxes between 2000 and 2009, although several sites showed stable heat fluxes. Further supporting evidence came from repeated ground-based temperature-depth profiles, which showed that the near-surface boiling point depth lowered in levels at most sites between 2000 and 2011, although several sites located in actively-steaming bare-ground (similar to 98 degrees C at similar to 0.1 m depth) remained relatively stable. In conclusion, satellite imagery and supporting ground-based evidence suggest a pattern of gradual decline (despite some time and spatial variations) in overall heat fluxes over the past decade from the Karapiti thermal area. An analysis of satellite infrared data provides a useful and cost-effective option for monitoring of the total radiative component of surface heat-loss from relatively large areas of steaming ground, such as at Karapiti. (C) 2012 Elsevier B.V. All rights reserved.