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Measuring the Impact of Vegetation Greenness on Spatial Changes of Heat Island Intensity in Tehran Metropolitan by Using ASTER and Landsat8 Satellite Images
Mojtaba Rafiean, Hadi Rezai Rad,
Volume 4, Issue 3 (9-2017)
Abstract
The simplest definition of urbanization is that urbanization is the process of becoming urban. Urban climate is defined by specific climate conditions which differ from surrounding rural areas. Urban areas, for example, have higher temperatures than surrounding rural areas and weaker winds. Land Surface Temperature is an important phenomenon in global climate change. As the green house gases in the atmosphere increases, the LST will also increase. Energy and water exchanges at the biosphere–atmosphere interface have major influences on the Earth's weather and climate. Numerical models ranging from local to global scales must represent and predict effects of surface fluxes. The urban thermal environment is influenced by the physical characteristics of the land surface and by human socioeconomic activities. The thermal environment can be considered to be the most important indicator for representing the urban environment. Vegetation is another important component of the urban ecosystem that has been the subject of much basic and applied research. Urban vegetation influences the physical environment of cities through selective absorption and reflection of incident radiation and regulation of latent and sensible heat exchange Satellite-borne instruments can provide quantitative physical data at high spatial or temporal resolutions. Visible and near-infrared remote sensing systems have been used extensively to classify phenomena such as city growth, land use /cover changes, vegetation index and population statistics. Finally, we propose a model applying non-parametric regression to estimate future urban climate patterns using predicted Normalized Difference Vegetation Index and Heat Island Intensity.
I conducted all spatial analysis in the UTM Zone 39 Northern Hemisphere projection. The fundamental procedure I used for evaluating change in land surface temperature was to relative temperature for both images, so that the values are temperature difference between the coldest and hottest areas in Tehran metropolitan. subtracting these images from each other results in relative temperature change from 2003 to 2015. Landsat satellite data were used to extract land use/land cover information and their changes for the abovementioned cities. Land surface temperature was retrieved from Landsat thermal images. The relationship between land surface temperature and landuse /land-cover classes, as well as the normalized vegetation index (NDVI) was analyzed.
In this study, LST for Tehran metropolitan was derived using SW algorithm with the use of Landsat 8 Optical Land Imager (OLI) of 30 m resolution and Thermal Infrared Sensor (TIR) data of 100 m resolution. SW algorithm needs spectral radiance and emissivity of two TIR bands as input for deriving LST. The spectral radiance was estimated using TIR bands 10 and 11. Emissivity was derived with the help of land cover threshold technique for which OLI bands 2, 3, 4 and 5 were used. The output revealed that LST was high in the barren regions whereas it was low in the hilly regions because of vegetative cover. As the SW algorithm uses both the TIR bands (10 and 11) and OLI bands 2, 3, 4 and 5, the LST generated using them were more reliable and accurate. NDVI negatively affected LST and Urban Heat Island in vegetation areas in 2003 and 2015 in Tehran metropolitan. This analysis provides an effective tool in evaluating the environmental influences of zoning in urban ecosystems with remote sensing and geographical information systems. This method exhibits a promising performance in UHI forecast. The predicted LST confirms that urban growth has severely influenced UHI pattern through expanding the hot area. Our study confirmed that LST prediction performance is strongly depended on the resolution.
The results reveal that the urban LST is affected mainly by the land surface characteristics and has a close relation to the abundance of vegetation greenness. The spatial distance from the UHI centre is another important factor influencing the LST in some areas. The methodology presented in this paper can be broadly applied in other metropolitans which exhibit a similar dynamic growth. Our findings can represent a useful tool for policy makers and the community awareness of environmental assessment by providing a scientific basis for sustainable urban planning and management. This provides an effective tool in evaluating the vegetation greenness of different zoning in urban ecosystems with remote sensing and geographical information systems. From the perspective of land use planning and urban management, it is recommend that planners and policy makers should pay serious attention to future land use policies that maintain a relevant proportion of public space, green areas, and land surface physical characteristics.

Analysis of the effect of hot oppressive climate on cardiovascular mortality in Tehran metropolitan: Synoptic climatological approach
Ms Mahsa Sepasian, Dr. Bohloul Alijani, Dr. Mohammad Salighe, Dr. Mehry Akbary,
Volume 8, Issue 4 (1-2021)
Abstract

Tehran metropolitan with its large population, daily migrant workforce and many students, needs to planning and designing watch/warning system to reduce the climatic problems for human health.for this purpose, we need to study the climate accurately and Since the factors affecting the climate of warm and cold periods in Iran are different, in this study , the meteorological variables of Tehran warm period (May to September 2002) turned into 4 components in Temporal Synoptic Index (TSI) using PCA Method and using P-Array and Varimax rotation.By the scores of components for each day, the clustering method (in ward method) were used and, the warm days of the year was divided into two cluster named favorable and oppressive airmasses. The average maximum air temperature that is more effective in mortality, was 36.13 ° C. Days with temperatures above  34 ° C, less pressure, mild winds , dryness and more sunshine resulted in more adverse weather conditions, which resulted in a 34% increasing in mortality compare with favorable weather. The total number of deaths from cardiovascular disease during the study period was 154046 that about  67%of deaths have been simultaneous with oppressive airmass.The epidemiological study of mortality also confirms the results of previous research in this area and shows that the incidence of mortality is higher in older people as well as in men. It is clear that not all mortality can be attributed to the effects of climate, but results show that change in climatic conditions will affect on mortality and also for study the effect of climatic hazards on human health, it is better that we study the effect of all variables together on humans.


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