Extreme Temperature

Data from three thermal sensors with different spatial resolution were assessed for urban surface temperature retrieval over the Yokohama City, Japan. The sensors are Thermal Airborne Broadband Imager (TABI), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and MODerate resolution Imaging Spectroradiometer (MODIS). Two algorithms were developed for land surface temperature (LST) retrieval from TABI image and ASTER thermal infrared (TIR) channels 13 and 14. In addition, ASTER LST and MODIS LST products were also collected. All the LST images were assessed by analyzing the relationship between LST and normalized difference vegetation index (NDVI) and by spatial distributions of LST profiles, derived from typical transects over the LST images. In this study, a strong negative relationship between LST and NDVI has been demonstrated although the degree of correlation between NDVI and LST varies slightly among the different LST images. Cross-validation…

Satellite images in the thermal infrared can be used for assessing the thermal urban environment as well as for defining heat islands in urban areas. In this paper, the thermal environment of major cities in Greece (Athens, Thessaloniki, Patra, Volos and Heraklion) is examined by using satellite images provided by the Landsat
Enhanced Thematic Mapper (ETM+) sensor on board Landsat 7 platform corresponding to daytime and warm period, when the surface urban heat island (UHI) phenomenon is best observed. The spatial structure of the thermal urban environment is analyzed in each case study and the “hottest” surfaces within the urban settings
are identified and related to the urban surface characteristics and land use. For the needs of the study, the Corine land cover (CLC) database for Greece is used, in an effort to define more effectively the link between emissivities, surface temperatures and urban surface characteristics. Results are examined with…

Surface urban heat island (SUHI) is a phenomenon of both high spatial and temporal variability. In this context, studying and monitoring the SUHIs of urban areas through the satellite remote sensing technology, requires land surface temperature (LST) image data from satellite-borne thermal sensors of high spatial resolution as well as temporal resolution. However, due to technical constrains, satellite-borne thermal sensors yield a trade-off between their spatial and temporal resolution; a high spatial resolution is associated with a low temporal resolution and vice versa. To resolve this drawback, we applied in this study four downscaling techniques using different scaling factors to downscale 1-km LST image data provided by the Advanced Very High Resolution Radiometer (AVHRR) sensor, given that AVHRR can offer the highest temporal resolution currently available. The city of Athens in Greece was used as the application site. Downscaled 120-m AVHRR LSTs simulated by…

Satellite images in the thermal infrared can be used for assessing the thermal urban environment as well as for defining heat islands in urban areas. In this study, the thermal environment of major cities in Greece (Athens, Thessaloniki, Patra, Volos and Heraklion) is examined using satellite images provided by the Landsat Enhanced Thematic Mapper (ETM+) sensor on board Landsat 7 satellite corresponding to the daytime and warm period when the surface urban heat island (SUHI) phenomenon is best observed. The spatial structure of the thermal urban environment is analyzed in each case study and the “hottest” surfaces within the urban settings are identified and related to the urban surface characteristics and land use. For the needs of the study, the Corine land cover (CLC) database for Greece is also used, in an effort to define more effectively the link between surface emissivities, land surface temperatures and urban surface characteristics.

A C++ language-based software tool for retrieving land surface temperature (LST) from the data of Landsat TM/ETM+ band6 is developed. It has two main functional modules: (1) Three methods to compute the ground emissivity based on land use/cover classification image, NDVI image and the ratio values of vegetation and bare ground and (2) Converting digital numbers (DNs) from TM/ETM+ band6 to LST. In the software tool, Qin et al.'s mono-window algorithm and Jiménez-Mu?oz and Sobrino's single channel algorithm are programmed to retrieve LST. It will be a useful software tool to study the thermal environment of ground surface or the energy balance between the ground and the bottom atmosphere by using the thermal band of Landsat TM/ETM+.

Climate change caused by increased anthropogenic emissions of carbon dioxide (CO₂) and other greenhouse gases is a long-term climate hazard with the potential to alter the intensity, temporal pattern, and spatial extent of the urban heat island (UHI) in metropolitan regions. Particular meteorological conditions—including high temperature, low cloud cover, and low average wind speed—tend to intensify the heat island effect. Analyses of existing archived climate data for the vicinities of Newark and Camden, New Jersey indicate urban to suburban/rural temperature differences over the previous half-century. Surface temperatures derived from a Landsat thermal image for each site were also analyzed for spatial patterns of heat islands. Potential interactions between the UHI effect and projected changes in temperature, wind speed, and cloud cover are then examined under a range of climate change scenarios, encompassing different greenhouse gas…

Land surface temperature (LST) is a significant parameter in urban environmental analysis. Current research mainly focuses on the impact of land-use and land-cover (LULC) on LST. Seldom has research examined LST variations based on the integration of biophysical and demographic variables, especially for a rapidly developing city such as Beijing, China. This study combines the techniques of remote sensing and geographic information system (GIS) to detect the spatial variation of LST and determine its quantitative relationship with several biophysical and demographic variables based on statistical modeling for the central area of Beijing. LST and
LULC data were retrieved from a Landsat Thematic Mapper (TM) image. Building heights were delimited from the shadows identified on a panchromatic SPOT image. The integration of LULC and census data was further applied to retrieve gridbased population density. Results indicate that the LST pattern was non-symmetrical and non…

The purpose of this study was to determine the relationship between the absence of trees and the presence of micro-urban heat islands. The objectives were to determine the usefullness of Landsat TM bands 3 and 4 for tree cover mapping, and the uisefullness of TM band 6 in identifying micro-urban heat islands. All 7 bands were utilized in this study to provide the full spectral curve for differentiating all cover types. When micro-urban heat islands were determined and maopped in relation to tree cover, the final objective of this study was to conbine the informationn into a GIS to obtain a map or blueprint of the exact location of micro-urban heat islands in the Dallas area.

Background: Extreme heat events are the number one cause of weather-related fatalities in the United States. The current system of alert for extreme heat events does not take into account intra-urban spatial variation in risk. The purpose of this study is to evaluate a potential method to improve spatial delineation of risk from extreme heat events in urban environments by integrating socio-demographic risk factors with estimates of land surface temperature derived from thermal remote sensing data.

Results: Comparison of logistic regression models indicates that supplementing known socio-demographic risk factors with remote sensing estimates of land surface temperature improves the delineation of intra-urban variations in risk from extreme heat events.

Conclusion: Thermal remote sensing data can be utilized to improve understanding of intra-urban variations in risk from extreme heat. The refinement of current risk assessment systems could increase the…

Part of China has been hit by low-temperature and blizzard since 2 January. The snow disaster lead to the most tremendous snow in Beijing and Tianjin since 1951 and it is bound to move to the south of China during 4-6 January 2010.

Source: www.disasterscharter.org