AYBE- İklim ve Deniz Bilimleri Lisansüstü Programı - Yüksek Lisans
Bu koleksiyon için kalıcı URI
Gözat
Son Başvurular
1 - 5 / 46
-
ÖgeIdentification Of Antarctic Freshwater Diatom Species Using Microscopic And Molecular Techniques(Avrasya Yer Bilimleri Enstitüsü, 2020-07-22)Because of the great morphological similarity of some diatom species, eDNA method has been the method that was particularly intended to be used in this study. DNAs were successfully isolated from all of the samples. However, the RuBisCO large subunit (rbcL) gene part that is specific to diatoms could be reproduced in polymerase chain reacton (PCR) only in 2020 Horseshoe Island samples. The DNA damage in 2017 and 2019 samples pointed out rapid damage of diatom DNA and highligths the importance of addition of nuclease blockers for right storage conditions of the samples. However, the amount of diatom DNA in the 2020 samples were not in the required amounts necessary for the new generation sequencing (NGS) method. Between the two microscope methods, SEM gave more successful results for morphological species determination compared to light microscope since it allowed higher resolution images that was necessary for detailed viewing of diatom structures. On the other hand, the light microscope offered a longer time and detailed study on the samples. All the images were then combined with SEM images and a common species designation was made. In conclusion, freshwater diatom species in fourteen Antarctic lakes in King George and Horseshoe Island were determined. This study also provided a basis for new studies in the future, and by knowing the diatom species distributions in Antarctic lakes, metabolic models can be used to understand the possible species-specific response to climate change in Antarctica.
-
ÖgeRelation of STT-Based Enso Indices With The Euro-Mediterranean Temperature Variability(Avrasya Yer Bilimleri Enstitüsü, 2020-07-21)El Niño-Southern Oscillation (ENSO) is a climate phenomenon that causes large scaleclimate variability. It is a coupled mode of ocean-atmosphere interaction between sealevel pressure and sea surface temperature fluctuations in the equatorial Pacific. Typically, in order to observe the phenomena, an ENSO index is used, which is formed with sea surface temperature anomalies. Positive (El Niño phase) and negative (La Niña phase) temperature anomaly have different effects on a global scale. SST-based indexes are created by taking the average of four different regions. These regions, fromthe Peruvian shores to the center of equatorial Pacific, are listed as follows: NINO1+2, NINO3, NINO3.4 and NINO4. Indexes can create different oscillations during thesame period. In addition, even they differ in some regions the effect of each index issimilar. According to some studies (e.g. Ziv et al., 2006; Lolis & Türkeş, 2016) negative phase Arctic Oscillation affects temperature, sea level pressure and 500 hPa geopotential height anomalies (z500) of the Euro-Mediterranean region. Sen et al. (2019) mentioned that, in negative phases of AO and ENSO, strengthening East Asian trough pushes the Mediterranean trough towards west. Consequently, a dipole pattern forms over Euro-Mediterranean region. Sen et al. (2019) study suggested that, NINO1+2 index is more effective on dipole pattern, although NINO3.4 is commonly used. In this study, we investigated which ENSO index is more related to the dipole pattern in the Euro-Mediterranean region. Analyses were conducted for boreal winters (December-January-February) of 70 years between 1950-2019. Correlation analysis indicated that NINO1+2 index is better correlated with z500, sea level pressure and surface temperature than the other indices over the Euro- Mediterranean region. In addition, in the La Niña phase, it has a significant relationship with the omega blocking system formed over Europe. According to some studies (Pozo-Vazquez et al., 2001, 2005), the negative (cold) phase of ENSO is compared with positive North Atlantic Oscillation pattern which means that the low pressure on Iceland deepens while the Azores high becomes stronger. As a result of composite analysis, NINO3.4 has been found to form a low pressure center over Iceland and a high pressure center over Azores. The NINO1+2 deepens the East Asian and Mediterranean troughs in the La Niña phase. Moreover, these troughs move westward in the cold phase. Shift of the Mediterranean trough to the west is also associated with negative phases of Arctic Oscillation and NINO1+2. In addition, the strength of the East Asian trough is positively associated with the displacement of the Mediterranean trough. Z500 composite analysis between NINO1+2 and NINO3.4 shows that NINO1+2 is more related with the dipole pattern over Euro-Mediterranean region. Therefore, we recommend use of the NINO12 index in Euro-Mediterranean climate variability studies.
-
ÖgeSebs Modeli Kullanarak Harran Ovası Üzerinde Buharlaşma –Terleme Tahmini(Eurasia Institute of Earth Sciences, 2019-10-01)In recent years, human activity and climate change greatly threaten water resources. Evapotranspiration (ET) is one of the most important components in the water cycle. Estimation of evapotranspiration has always been faced with many uncertainties. Estimating evaporation based on physical and experimental equations is very common. These methods are based on meteorological data whose shortcomings limit the use of these relations. For instance, this information is point-specific and related to meteorological stations. Another uncertainty problem is regional estimation by using statistical methods. Over the past few decades, many studies have been carried out on estimating evapotranspiration using remote sensing technology. One of the methods which are widely used for estimating ET is SEBS algorithm. The SEBS was proposed for estimating fluxes of heat or energy and estimating evaporation fraction [24]. This study aims to estimate ET over the Harran Plain that has the largest agricultural irrigation systems in the Southern Anatolian Project. Evapotranspiration is estimated for 2015. Cloud-free days in each season of 2015 are selected. Results compared with data obtained from TARBIL and evapotranspiration extracted from GLDAS products. TARBIL project gives reference evapotranspiration. For calculating the actual ET from the TARBIL data crop coefficient (Kc) was required. The assumption for estimating Kc is based on cotton plants. Kc for this study considered from 0.35 to 1.3. SEBS shows very good compatibility results with TARBIL data with a 10% error but ET extracted from GLDAS was not in the expected range (0 to 2.7 mm/day). GLDAS generates ET in 0.25-degree (27.5×27.5 km) resolution that it is not enough for relatively small areas like Harran plain while SEBS estimates ET in high resolution (1×1 km). For studies of water management, water budget, land surface fluxes in the area with low vegetation cover and also in large scales GLDAS can be used but in case of our target that it is the estimation of ET in agricultural lands especially in a relatively small area SEBS gives us more accurate and more trustworthy ET.
-
ÖgeTürkiye'deki Kuş Türleri Çeşitliliği Ve Habitatın Uzaktan Algıma Parametleri(Eurasia Institute of Earth Sciences, 2019-09-13)Ecosystems are large and difficult to access. Therefore, it is difficult to measure the biodiversity. However, The development of various remote sensing technologies makes ecosystem research easier and more accurate than ever before. In this thesis, MODIS was used in the main study of Turkey as a whole, and LiDAR was used in further studies in some parts of the Black Sea. It is inevitable that biodiversity is decreasing worldwide. Various natural and physical influences are changing the living place. This study was geared towards birds living in Turkey. Bird populations and species are also decreasing in Turkey due to environmental and climate changes. (boyla et al, 2019). This study identified the relationship between bird species richness and vegetation, which is considered a major habitat for birds. Several studies have already shown that they are positively correlated.(Liang et al, 2018; Seto et al, 2004) There is a need to identify Turkey as a case. I wanted to see if the relationship could be confirmed with the vegetation index, a single parameter. Analysis of the relationship between all bird species and vegetation observed in Turkey, including species that do not have vegetation as their habitat. Remote sensing data was used to obtain vegetation information. The study used NDVI and EVI via MODIS Terra. First, I mapped three years of changes in NDVI and EVI from 2015 to 2017 throughout Turkey. All of them decreased every year. The trend were similar, but EVI was generally lower than NDVI, as usual. The map shows that the vegetation of the central inland regions of Turkey is further reduced. To check the relationship with the obtained vegetation index, bird species data was extracted from Turkish Breeding bird atlas data during the same 2015-2017 period was identified. Both NDVI and EVI showed a positive correlation with the bird species data. Especially, the maximum value of NDVI correlated strongly with Bir Species Richness. And, the mean values were most correlated in EVI. It is believed that EVI is sensitive to the terrain. (Matsushita et al, 2007) In addition, the correlation with 2017 was highist. Even 2015 EVI was analyzed to be independent of bird species richness. It was found that the Species richness at the same time has changed with the decrease of vegetation. The results of this study provide an overall review of the positive correlation between bird species richness and vegetation in Turkey. Furthermore, the usefulness of NDVI and EVI was confirmed again. After the main research as above, to understand the forest area in some areas a more detailed study was attempted. Further research on forest structure and bird diversity in local areas has been conducted. I used light detection and ranging (LiDAR) to collect more accurate high-resolution data for forest structure analysis. The two forests of each 0.4 km wide and 10 km long are selected from the forests with high bird species richness and relatively low bird species richness and their structural analysis using the LiDAR poind cloud data and the CHMs classification which one of forest metrics greatest influence on birds habitat. In addition, I used forest management plans data to analyze the differences in specific tree types and growth levels in each region. Under the assumption that species observed in the Atlas square (50km x 50km), can live in or stay in all the forests in that square. The results were that CHM was similar in overall trend, but the region with high species richness of bird had a higher proportion of '10 -20m ' than the low species richness region. Through the DEM, I could find many ridgelines, including steep slopes in the region with high specie richness. In addition, The region of high specie richness of bird had more varieties of trees than low specie richness region. DBH proportion was '8-19.9cm' of non-thick trees was high. At the top crown closure level, it was confirmed that both areas were dense forests with a high degree of closure. It results show the effectiveness of LiDAR in assessing forest health and productivity, and assessing habitat quality. Continued research into forests and habitats using various techniques such as LiDAR can lead to the creation of appropriate wildlife habitat models to build ecological forest management. Comprehensive correlation analyzes between habitat and other factors, climate change and forest structure etc, are required. Climate and physical changes at the time of the change in vegetation should also be identified. In order to maintain biodiversity, further research should be conducted to identify what changes are being made to the ecosystem and why these changes have occurred.
-
ÖgeDeğı̇şen İklı̇m Şartları Altında Fırat - Dı̇cle Havzasında Su Kaynaklarının Sürdürülebı̇lı̇rlı̇ğı̇ Sorunu(Eurasia Institute of Earth Sciences, 2019-05-01)The global and regional hydrological cycle can be affected by temperature changes in the coming years. In the regions where the water cycle depends on the snowmelt, these fluctuations can be more than other areas due to the effects of increasing temperature on snow cover and seasonal runoff. There are many studies about the consequences and threats of climate change on water sustainability and hydrological cycle around the world. However, the quantity and quality of the data that can be used in related studies has been affected by the insufficient measurement networks and trouble of upkeep of the accessible hydro-meteorological stations. Moreover, regional conflicts and local disputes can seriously complicate field survey in some of these regions. The Euphrates and Tigris River Basin (ETB) has been affected by climate change, and it suffers from all the aforementioned shortcomings. The ETB is a single transboundary watercourse system located in the Middle East. The basin includes two snow- fed rivers called the Euphrates and Tigris rivers, and its water recourses are used for different aims including domestic use, irrigation, hydroelectric power generation, etc. Turkey, Syria, Iraq and Iran are the main riparian countries in the ETB. These countries have started development projects in the basin since 1960s. In this sense, the Southeastern Anatolian Project (GAP) by Turkey has been started for agricultural and hydropower development in the region. These anthropogenic factors and increasing population, together with negative impacts of climate change, will cause mismatches between water demand and water supply in the basin. This study, by utilizing the outputs of GCM (Global Climate Model) and RCM (Regional Climate Model) simulations, aims to contribute to the understanding of future climate variations and their effects on the future of the water resource sustainability in the ETB. Annual time series of climate data provided by Royal Netherlands Meteorological Institute (KNMI) and Coordinated Regional Climate Downscaling Experiment (CORDEX) were used to determine the impacts of climate change in the ETB. In other words, outputs of GCMs and RCMs were used to understand the effects of the climate change on regional water budget in the future (periods of 2016-2035, 2041-2060 and 2081-2100) with respect to past climate (period of 1986-2005). Analysis of the changes in the hydrometeorological parameters (temperature, precipitation, evapotranspiration and net water flux output) were provided using the the outputs from the global and regional climate models based on the territories of the riparian countries in the ETB (i.e., Iran, Syria, Turkey and Iraq). Moreover, the changes in 10 climate indices based on riparian country territories in the ETB were analyzed using output of CMIP5 models for all three periods. These parameters include maximum length of dry spell (CDD), maximum length of wet spell (CWD), daily temperature range (DTR), number of tropical nights (TR), growing season length (GSL), annual total precipitation when daily precipitation >99th percentile (R99pTOT), maximum consecutive 5-day precipitation (Rx5day), simple precipitation intensity index (SDII), warm nights index (TN90p) and warm days index (TX90p). The most striking point is that increasing temperature which is more pronounced for 2081- 2100 period may have profound implications for the snow cover and runoff in the basin. According to global and regional simulations, temperature in the whole Euphrates - Tigris basin increases. Simulations indicate 1 °C increase in surface temperature for 2016-2035 period whereas it is about 3°C and 6 °C for 2041-2060 and 2081-2100 periods, respectively. The consequence of this increase in temperature in the regional hydrological cycle is the reduction in snow cover and temporal shifts to earlier days in melting of snow in the highlands. In terms of precipitation, there is a wide harmony between the simulations, and it decreases up to 15% in Turkey and Syria for the 21century. Precipitation in Iraq and Iran are projected to increase by 5% for 2016-2035 and 2041-2060 periods, whereas simulations produce a decrease by 15% for 2081-2100 period. Predicted changes in the evapotranspiration indicate generally increases in the basin for the early period in response to the increasing temperatures, however it decreases by the end of the century because of decreasing precipitation. Based on different experiments, the surface runoff is found to decrease about 10-50% in Turkey and Iran by the end of the 21st century. Surface runoff in Syria and Iraq also decreases by140% and 250%, respectively. Investigation of climate indices in the ETB indicates that climate extremes will become more intense in the future. Investigation of climate changes in the ETB based on the riparian country territories indicates that Turkey will undergo the most changes. The changes in the surface runoff is projected to be by 20-50% reduction in Turkey by the end of the present century. But down-stream countries, especially Iraq and Syria which are dependent on the water released by the upstream Turkey will experience more stress for the water crisis in the future. The climate change in the ETB may lead to other natural hazards such as salinization and desertification. The ETB has faced severe droughts in the past years. For instance, the severe drought in the winter of 2007 - 2008 had a big effect on the agricultural production in the region. The initiation of development projects by the riparian countries since 1960s which are uncoordinated with water availability in the ETB and crisis in water demand management and inefficient water policy of the riparian countries within the national framework are the main causes of water mismatch between supply and demand in the ETB. On the other hand, changes in hydroclimatic parameters can exacerbate water disputes in the region due to increased water demand and supply imbalance. Important solutions to this problem include coordinated regional actions and assessment of the factors for water allocation.