Since 1990 the Hanoi capital region (or Hanoi metropolitan area) in Vietnam has undergone rapid development, which has gone together with increasing socio-economic growth and prosperity. However, the environmental degradation that has accompanied urban development has raised considerable concern from the public in recent years. This research investigates the effects of urban development on urban sprawl, urban heat island (UHI), and metropolitan weather phenomena that are related to the quality of urban life in the period from 1999–2016. To achieve these objectives, remote sensing technologies were applied to satellite images at three time points (i.e., 1999, 2009, and 2016) that were associated with the meteorological dataset from ground-based stations. The spatial distribution evolution was examined for the land use/land cover changes while using the normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI). The increasing impact of urban sprawl on UHI intensity is determined based on the land surface temperature (LST) in multi-temporal forms. Increasing urbanization with the development of gradual outward and northward expansion from the city centre intensified the correlation analysis shows that the UHI. The potential formation of new UHI areas in the near future is also indicated. Furthermore, more than 30% of the metropolitan area is decaying in ecological quality according to an assessment of the urban thermal field variance index (UTFVI). With respect to metropolitan weather, the urbanization in Hanoi affected the observation of meteorological parameters revealed that the relative humidity, total rainfall, temperature, and wind speed over both urban and rural areas. The overall results imply that urban development and its environmental effects and impacts have imposed pressing issues and new challenges to sustainable development in the Hanoi metropolitan area.
Abstract-Geothermal energy is an increasingly important component of green energy in the globe. A prerequisite for geothermal energy development is to acquire the local and regional geothermal prospects. Existing geophysical methods of estimating the geothermal potential are usually limited to the scope of prospecting because of the operation cost and site reachability in the field. Thus, explorations in a large-scale area such as the surface temperature and the thermal anomaly primarily rely on satellite thermal infrared imagery. This study aims to apply and integrate thermal infrared (TIR) remote sensing technology with existing geophysical methods for the geothermal exploration in Taiwan. Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM?) imagery is used to retrieve the land surface temperature (LST) in Ilan plain. Accuracy assessment of satellite-derived LST is conducted by comparing with the air temperature data from 11 permanent meteorological stations. The correlation coefficient of linear regression between air temperature and LST retrieval is 0.76. The MODIS LST product is used for the cross validation of Landsat derived LSTs. Furthermore, Landsat ETM? multi-temporal brightness temperature imagery for the verification of the LST anomaly results were performed. LST Results indicate that thermal anomaly areas appear correlating with the development of faulted structure. Selected geothermal anomaly areas are validated in detail by field investigation of hot springs and geothermal drillings. It implies that occurrences of hot springs and geothermal drillings are in good spatial agreement with anomaly areas. In addition, the significant low-resistivity zones observed in the resistivity sections are echoed with the LST profiles when compared with in the Chingshui geothermal field. Despite limited to detecting the surficial and the shallow buried geothermal resources, this work suggests that TIR remote sensing is a valuable tool by providing an effective way of mapping and quantifying surface features to facilitate the exploration and assessment of geothermal resources in Taiwan.
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Tatun Volcanic Group (TVG) in the northernmost tip of Taiwan is an active volcano area with the possible magnitude of volcanic explosivity index (VEI) 4 which can devastate the Taipei metropolitan area if eruption occurs. To integrate Thermal Infrared (TIR) remote sensing for exploring geothermal energy and monitoring volcanic activity in TVG, Landsat 7 ETM+ imagery is used to retrieve the Land Surface Temperature (LST) and Radiative Heat Flux (RHF); MODIS 8-day average LST products are adopted for monitoring Jinshan fault zone of TVG. Validated results show that occurrences of hot springs and fumaroles conform to LST anomaly distribution and the overall temperature in E-W ridge is higher than the SW-NE ridge in TVG. Thermal anomaly patterns indicate that distributions of higher LST areas appear correlating with the development of Jinshan fault; for further verification, Hilbert-Huang Transform (HHT) was applied for decomposing MODIS 8-day average LST time series (2002-2016) in Jinshan fault zone. Possible related physical processes underneath Ensemble Empirical Mode Decomposition (EEMD) components based on HHT were also elaborated. The inference that LST component with average period around a month (EEMD component 1, i.e., C1) has irregular spikes which is likely associated with earthquakes in TVG has been investigated in detail. Finally, HHT comparison analysis with three active volcanoes in Philippines and Indonesia is performed for assessing the eruption potential of TVG. Preliminary results show that the regular C4 annual cycle from TVG's LST time series implies the TVG's current status is calm and resting with no sign of eruption for future decades.
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