All other Geographic fields of studies , Interdisciplinary
Mostafa Karimi; Sousan Heidari; Morteza sharif
Abstract
IntroductionIncrease temperatures and decrease rainfall can lead to the drying up of wetlands, lakes and rivers, the formation of aerosol centers, which directly and indirectly change the structure of society and the ecological conditions of lakes around the world; As a result, it leads to changes in ...
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IntroductionIncrease temperatures and decrease rainfall can lead to the drying up of wetlands, lakes and rivers, the formation of aerosol centers, which directly and indirectly change the structure of society and the ecological conditions of lakes around the world; As a result, it leads to changes in the distribution of animal and plant species, ecological diversity, changes in the plant phonological cycle, factors, growth and organisms, and ecological metabolism. These changes also severely affect vegetation in arid and semi-arid climates. Finally, changes in surface conditions caused by human activities may also affect various hydrological processes. Thus, the twenty-first century is facing many environmental problems, one of the most important of which is the variability of environmental and climatic parameters. Lake Urmia is one of the most important water areas in Iran and one of the largest salt lakes on earth. The lake plays an important role in the climatic, environmental and economic situation and a national and international natural heritage in the northwest of Iran.variability of environmental and climatic parameters is one of the most important challenges for human specific in arid and semiarid environment such as Iran. The purpose of this study is to investigate the changes in environmental and climatic parameters in the catchment of Lake Urmia in the last two decades. The purpose of the above was to answer the question of how the changes in environmental and climatic parameters in the basin and the relationship between these changes in the current conditions of the basin Lake Urmia.Data and methodsResearch data includes six categories: 1) TOPEX and Jason 1 to 3 satellites data to study of changes in altitude level of Lake Urmia, 2) Landsat 7 satellite images of 2000 and Landsat 8 of 2019 for extract lake water area changes and 3) Precipitation data from GPM[1] satellite product (IMERG[2]) 4) Vegetation index products of Modis sensor (Mod13A3 v006) to identify vegetation changes, 5) LST Night and daytime of Modis sensor (MOD11A2 v006) and finally 6) gridded reanalysis data (ERA5) to detect of trend air temperature, were used.First, the changes in the water level of the lake were extracted using the data of TOPEX and Jason 1 to 3 satellites, and in the next step, the trend of changes in its was calculated. Landsat 7 images of 2000 and Landsat 8 of 2019 using the Normalized Differential Water Index (MNDWI) were used to achieve changes in the lake's water area. Then LST (day and night) of MOD11A2 v006 products were converted into monthly data using MATLAB software. Finally, the trend changes in precipitation data, 2 m air temperature, LST (day and night) and vegetation (NDVI) were investigated using Mann-Kendall test (Mann, 1945; Kendall, 1975).ResultsThe highest changes in water level in the last two decades are from 2000 to 2010. The decrease in level is evident from the year 2000, from that year to 2010, the water level of the lake decreased by 4 meters and the highest slope of the decrease in it observed in the same period. The change in the area obtained from the MNDWI index is 2740 km2, which has caused the lake to decrease from 5143km2 to 2400km2 in 2019. The decrease of the lake level in its southern and eastern part has been more than the western and northern part. The trend of monthly precipitation changes shows two different temporal and spatial patterns. It is important to note that there is a monthly decreasing trend every three months in January, August and December in the central and southern parts of the basin. In contrast, in May and July, a marked increasing trend is observed in the eastern and southern half of the basin. Spatial displacement of incremental changes in air temperature indicates a clockwise movement from north to east and then south and west from May to August. The trend of day of the LST changes indicates a spatial contrast between the Lake and around it. This behavioral contradiction is more pronounced with the increase of the lake surface temperature and the decreasing trend in the southern and western regions corresponding to the agricultural areas in August, September and October. Changes in LST at the basin level from November to February, in which scattered and small incremental zones are observed, can also be due to reduced vegetation in the cold period of the year. In contrast to the daytime LST, at night what is most noticeable is large zones of temperature rise, especially from June to September throughout the basin. NDVI in the period 2019-2000 has had an increasing trend in all months, but with varying intensity and extent. Three temporal patterns are understandable in the process of basin vegetation change. Increased from January to May, then start decreasing trend from June to August and again increasing trend that continued until December. The lowest increasing trend is observed during the summer months from June to August.DiscussionLake Urmia has experienced a continuous decrease in water level since 2000, so that during the last twenty years, the water level has decreased by more than seven meters. The results of the present study also showed that there was a significant increasing trend in the NDVI index at the basin, especially with the southern of the basin. However, at the basin level, the trend of rainfall changes in this period (2000-2000) is not generally significant and also due to the occurrence of numerous droughts in the basin, which has also had an increasing trend and the expansion of irrigated lands, Demand for groundwater has increased. Therefore, this issue indicates various reasons other than changes in climatic parameters, especially precipitation in reducing the water level of Lake Urmia. In addition to the above, daytime and nighttime LST have increased during the warm period of the year as well as the air temperature on the lake. This increase increment evaporation, especially during periods when recharge is reduced due to seasonal dry. Although precipitation has increased at the end of spring, but with increasing temperature, precipitation increases with increasing evapotranspiration and water requirement of plants is neutralized. Therefore, the simultaneous change of environmental and atmospheric parameters can be considered as aggravating the conditions of hazardous events in this basin.ConclusionBased on the evaluation done in this study, it can be concluded that the basin of Lake Urmia is vulnerable. Therefore, the three main and significant effects of environmental variability in these areas are increasing ground temperature, vegetation and reducing water resources. The result of these conditions on the one hand and the increase of water needs of plants on the other hand will increase the stress on water resources, especially groundwater. Decreasing the lake surface and increasing consumption and reducing water resources can lead to the spread of bare surfaces and the occurrence of dust.
GIS&RS
Najma Esmailpoor; fatemah esmaeilpoor; mojtaba yami; hosein amirazodi
Abstract
Introduction
The phenomenon of Thermal Island as one of the urban hazards is the result of the way of activity and physical development of cities as well as extensive changes in the land use pattern around cities. The surface temperature of the earth is not only affected by the amount of energy received ...
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Introduction
The phenomenon of Thermal Island as one of the urban hazards is the result of the way of activity and physical development of cities as well as extensive changes in the land use pattern around cities. The surface temperature of the earth is not only affected by the amount of energy received by the sun, but also by the environmental conditions of the place, especially the reduction of suburban arable land, vegetation degradation and increasing impermeability levels and potentially prone to heat production and pollution. Heated island is a term used to describe the warmer atmosphere and higher temperatures of cities compared to non-urban areas. Determining the geographical distribution and nature of UHI, as well as the factors influencing its occurrence or severity, is something that is now efficient, fast, and inexpensive using satellite imagery and remote sensing techniques. Ahvaz is one of the metropolises with ethnic diversity and mixed subcultures that has experienced a large and rapid increase in population and area over the last three decades and the city has expanded in different directions from south to southwest and north to northeast Has found. One of the prominent consequences of this issue is the emergence and strengthening of the Heated island in this city.
Data and Method
To determine the spatial-place changes of the heated islands of Ahvaz and also to determine its relationship with land use changes, first the Landsat satellite TM sensor images in the last 30 days and Envi software were used and the following main steps were performed:
Stage 1 - Preparation of thermal map of the city: To calculate the temperature of the single channel algorithm (SCA) in order to extract LST, an extended infrared thermal band was used and to calculate it, Equation 1 was used.
Ts = γ {𝜀1- (YLsensor + Ψ2) + Ψ3} + δ
Here are five essential steps you can take to begin the process of preparation for mediation.
To calculate each of the parameters in the equation below 5 consecutive steps as described in the headings
The first step is to calculate the spectral radius
The second step is to calculate the light temperature of the sensor
The third step is to calculate the radiative power
Step 4, calculate the values of γ and δ
Step 5, calculate atmospheric parameters
Stage 2: Prepare a land use map using the decision tree: The function of the model is a branch that consists of three levels of decision making and finally to determine the six layers of land cover (including agricultural land, rangeland, irrigated land, heights (Topography), land with little vegetation and built-up lands.
In the model run, after applying the preprocessors to the Landsat images, the corresponding images were created for classification using NDVI, DEM, NDWI and LST indices. Setting a threshold for the NDNI index (NDVI> 0.26) vegetation is isolated from other data. In the correct branch, the next node was isolated using NDWI index (NDWI≤0.0) and determination of rangeland class threshold, agricultural land and water. In the third decision-making branch, based on the thresholds defined in the image indices (DEM≥40), DEM topography was determined, Were introduced.
Results and Discussion
Statistical study of the trend of change in land surface temperature and construction index and the ratio of change of other carabis to urban land uses showed that the trend of change is the average construction of the ascending course and the average temperature of the ascending course and the trend of changes with the transformation process With the expansion of the city of Ahvaz, their vegetation and land have been destroyed and turned into urban lands, and now the thermal island has been directed from the inside of the city to the outskirts. The temperature increase ratio of the urban area was higher than the whole study area.
Conclusion
Based on the results, the temperature of Ahvaz city increased from 282.96 degrees to 287.02 degrees Kelvin between 1988, which shows a growth of 2% and an increase of 4 degrees. Spatially, the highest temperature increase in the city is related to the east and southeast of the city, where agricultural lands and lands with little vegetation have been converted to industrial town and industrial uses and become a source of heat production in this metropolis. Has been. Also in the western part of the city, due to the further expansion of the city and the implementation of residential preparation projects - the NDBI index confirms the same - there has been an increase in temperature. Other influential factors in the spatial change of temperature in these parts of Ahvaz city are the existence of main roads such as Ahvaz-Abadan highway (southern part of the city), Ahvaz-Bandar Imam Khomeini highway (eastern part). Due to the asphalt cover of these routes and more vehicle traffic, they have caused an increase in the thermal map of the region.
The lowest temperature in 2020 is related to the areas around the Karun River. Among the factors that have caused the low temperature in this place compared to other parts of Ahvaz in 2020, we can see the existence of the government park, Shahid Chamran University with a lot of green space and low-density residential texture and more open and green space than they mentioned other parts of the city as well as the wetlands of the last two years.
Analysis of the trend of UHI changes and increase in construction using Landsat time series images showed an increase in urban temperature compared to the surrounding area in 1988. This shift in 2020 was due to an increase in regional temperature compared to the city due to river flooding. , Increase in construction and industrial activities in and around the city.
Due to the environmental dangers of the Heated island, which directly and indirectly affect urban air pollution, greenhouse gas emissions and global warming, disrupt thermal comfort, increase water and electricity consumption, and exacerbate diseases such as asthma They leave, It is necessary to prevent the change of agricultural use to urban areas, and within the city, between dense textures and industrial areas, by creating vegetation in the form of parks and gardens, tried to prevent the rise in surface temperature.
Climatology
Atefeh Shahmohammadi; Ali Bayat; Saeed Mashhadizadeh Maleki
Abstract
Introduction Today, the unfavorable weather conditions are one of the critical problems in the world's major cities, which have many harms to humans and the environment. Nitrogen monoxide and nitrogen dioxide are important air pollutants. Nitrogen dioxide is a reddish-brown gas with a pungent odor. ...
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Introduction Today, the unfavorable weather conditions are one of the critical problems in the world's major cities, which have many harms to humans and the environment. Nitrogen monoxide and nitrogen dioxide are important air pollutants. Nitrogen dioxide is a reddish-brown gas with a pungent odor. The most important human resources producing this pollutant are car exhaust and fixed sources such as fossil fuels, power plants, incinerators, and home heating appliances. In addition to human resources, nitrogen oxides are also produced by bacteria, volcanoes, and lightning. The city of Tabriz is one of the metropolises of Iran, and the increase in the population of the city, motor vehicles, consumption of fossil fuels, industrial activities, and improper use of heating devices and the existence of industrial factories has increased energy consumption in this city and many problems. It has created an environment for the residents of this city. The purpose of this paper is to study the trend of nitrogen dioxide as an indicator of air pollution from OMI data using linear fit after eliminating significant rotation periods on the time series of the average monthly nitrogen dioxide for the city of Tabriz. Methodology In this study, the nitrogen dioxide data measured by the OMI satellite sensor and the wind data, the surface temperature and the horizontal visibility measured with the synoptic station during the years 2004 to 2016, contaminated with airborne nitrogen dioxide emissions in Tabriz city is being investigated. The seasonal mean and nitrogen dioxide, temperature, wind, and horizontal visibility, as well as the correlation between nitrogen dioxide and meteorological data, have been investigated to better understand the changes in air pollution. To understand the properties and behavior of the functions, they can be examined in frequency space. Least square spectral analysis can be used to investigate non-distant time series. Statistical tests can also be performed until the periodic intervals obtained from the spectral analysis are statistically validated. After the formation of the time series, the average monthly nitrogen dioxide level between the 2004 to 2016 intervals was observed using spectral analysis of least squares of periods of four, six, and twelve months, which were also statistically significant. To calculate the nitrogen dioxide trend, significant components are eliminated from the time series. After eliminating the significant components of the four, six, and twelve months of the nitrogen dioxide time series, the trend is calculated using linear fit on the remaining time series. Results and discussion The results showed that the highest amount of nitrogen dioxide occurs in cold season and the lowest amount in hot seasons. The average nitrogen dioxide content in the spring, summer, autumn and winter seasons was equal to 2.13, 1.90 ×, 3.88 × and 5.36 × molecules per cm2 and its mean value was calculated at 2.84 × molecules per centimeter square. Also, the highest amount of standard deviation of nitrogen dioxide occurs in winter, 10.4 and its lowest value in summer, 0.97 The study of temporal, wind, and horizontal visibility of Tabriz city for the measurement period 2004 to 2016 shows that nitrogen dioxide and temperature have a relationship. So that nitrogen dioxide has the highest amount in the early and the late months of the year when it is cold, and vice versa. 96 percent of the winds of the city of Tabriz have a speed of less than 0.5 meters per second, so called quiet winds and the prevailing winds of the eastern and northeastern cities. The correlation coefficient of nitrogen dioxide with wind and temperature was -0.49 and -0.32, respectively, indicating a greater significance of wind in the variation of this pollutant. One of the simplest ways to check the air quality is horizontal visibility. The correlation coefficient of nitrogen dioxide with horizontal visibility for Tabriz city is -0.09 and its value has not been significantly different during the year. The amount of nitrogen dioxide in each year for Tabriz was 1.05 × molecules per cm2. Conclusion Paying attention to the quality of life and environmental issues in the city of Tabriz is very important due to population growth and increasing urban life. Air pollution caused by nitrogen dioxide in the cold seasons of the year was mostly due to temperature inversion. As a result, what plays a significant role in air pollution in this city is the increase in urbanization, the development of factories, and the excessive use of fossil fuels, power plants, and motor vehicles. Therefore, adequate measures must be taken to reduce air pollution in order to maintain the health of citizens and the environment. One of the factors reducing air pollution is green space, and the city of Tabriz does not have a great green space, so the lack of green space in this area is strongly felt and is very small compared to international standards.
