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Research Article
Longitudinal Response of the Low-latitude Ionosphere to 2017 Sudden Stratospheric Warming Event
Issue:
Volume 9, Issue 1, June 2025
Pages:
1-8
Received:
6 January 2025
Accepted:
20 January 2025
Published:
10 February 2025
Abstract: The Earth's ionosphere, a crucial region for communication and navigation systems, is susceptible to disturbances driven by both external (solar and geomagnetic activity) and internal (atmospheric waves) forces. These internal forces are known to be amplified during SSW events, creating significant ionospheric perturbations. This study investigates the longitudinal response of the low-latitude ionosphere, specifically focusing on the EIA, to the 2017 SSW event. Addressing a gap in current understanding, this research analyzes the longitudinal variations in TEC within the African and Asian sectors during the February 2017 SSW, aiming to provide a more comprehensive global perspective on SSW-ionosphere coupling. Previous findings have suggested longitudinal variations in EIA behavior, and this study seeks to provide concrete evidence of the SSW's longitudinal impact on the ionosphere through TEC data analysis. Using TEC data obtained from GPS observations, this study reveals a strong ionospheric response to the 2017 SSW event, characterized by irregular perturbations with large amplitudes, particularly in the African sector. During the peak phase of the SSW, ionospheric TEC perturbations begin just a day after the peak in stratospheric temperature and manifest as a suppression of the EIA for approximately 72 hours (3 days), indicative of a downward vertical drift. This suppression suggests a modulation of the fountain effect, which is further supported by the observed response of the mean zonal wind. The observed longitudinal differences in TEC perturbations, with stronger effects over the African sector compared to the Indian sector, highlight the influence of local effects on the ionospheric response to SSWs. These local effects could encompass variations in the geomagnetic field configuration, differences in the background ionospheric density and composition, and regional differences in atmospheric wave propagation and dissipation. Regional variations in tropospheric weather patterns and land-sea distribution can further affect the generation and propagation of atmospheric waves that couple the lower and upper atmosphere. The day to day TEC variations are discussed in the context of upward/downward E×B drift. Therefore, the observed longitudinal discrepancies underscore the importance of considering these local factors when assessing the impact of SSWs on the ionosphere and related technological systems. This study contributes to a more complete understanding of the complex interactions between the stratosphere and the ionosphere during SSW events and their implications for global communication and navigation infrastructure.
Abstract: The Earth's ionosphere, a crucial region for communication and navigation systems, is susceptible to disturbances driven by both external (solar and geomagnetic activity) and internal (atmospheric waves) forces. These internal forces are known to be amplified during SSW events, creating significant ionospheric perturbations. This study investigates...
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Research Article
Droughts in the High Continental Climate of Central Asia
Issue:
Volume 9, Issue 1, June 2025
Pages:
9-18
Received:
12 January 2025
Accepted:
26 January 2025
Published:
11 February 2025
Abstract: Drought, one of the manifestations of emergencies, is a serious problem for Central Asia. Experts estimate that more than 70 per cent of the region's territory is considered vulnerable to natural disasters. Droughts are less frequent than floods, but affect more people. Over the past decade, 60 per cent of the population exposed to extreme weather events has been affected by drought. The most tangible impact of drought is on agriculture and food security in the region. Droughts are expected to become more frequent in Tajikistan, Turkmenistan and Uzbekistan due to projected temperature increases and longer periods of extreme heat and evaporation in areas with lower precipitation. In establishing drought monitoring and early warning systems in Central Asia and adapting drought prediction models, the monitoring of climate indicators and the availability of a rich and deep database of years is an important link. The purpose of this work is to monitor the probability of drought occurrence depending on the meteorological conditions of the Kafirnigan River basin in Tajikistan. The formation and dispersion zones of the Kafirnigan River differ significantly in their meteorological characteristics. The monitoring of droughts in the area of the river's formation and dispersion and their comparison with meteorological conditions allows establishing the existence of certain regularity between them. The results of such dependencies can form the basis for the development of drought early warning systems. A characteristic feature of the drought indices (SPI and SPEI) in the southern Tajik lowlands is their decreasing nature and the significant difference in the trends of change. Differences between SPEI-6 and SPI-6 are due to potential evapotranspiration (PET), which is determined by the difference between precipitation and evaporation. The similarity between SPEI and SPI in winter is reasonable because this is the period when PET tends to have the lowest ratio to precipitation, resulting in a functional approximation of SPEI to SPI. According to the same principles, the largest difference is observed in November, which covers the period from June to November, when PET is highest in relation to precipitation. It is found that for the period 1950-2023, monthly mean precipitation values are significantly lower and temperatures are higher than the climatic norm of the southern Tajik lowlands, leading to negative values of mean annual SPEI and SPI and favoring the occurrence of drought.
Abstract: Drought, one of the manifestations of emergencies, is a serious problem for Central Asia. Experts estimate that more than 70 per cent of the region's territory is considered vulnerable to natural disasters. Droughts are less frequent than floods, but affect more people. Over the past decade, 60 per cent of the population exposed to extreme weather ...
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Research Article
The Frequency of Droughts in the Rasht Valley (Tajikistan) Under Climate Change
Issue:
Volume 9, Issue 1, June 2025
Pages:
19-27
Received:
20 February 2025
Accepted:
28 February 2025
Published:
13 March 2025
DOI:
10.11648/j.ijaos.20250901.13
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Abstract: The geographical location of Central Asia, including the Republic of Tajikistan, makes the region highly vulnerable to various climate-related natural disasters, such as floods, droughts and mudslides, which significantly affect sustainable development and people's living conditions, including their access to adequate food and drinking water. Droughts, especially in their extreme forms, accelerate the development of desertification, the main cause of which is excessive anthropogenic pressure, which increases under conditions of prolonged and intense drought. In this context, the issue of developing and improving modern systems for monitoring and forecasting droughts, as well as preparing for and mitigating their consequences, becomes extremely important. The problems of droughts occurrence in two districts of Tajikistan (Rasht, Lakhsh) with developed agricultural industry depending on meteorological conditions with wide application of standardized drought indices are considered. It was found that the occurrence of drought in a specific area does not have certain regularity, but is determined by a combination of meteorological parameters. The dynamics of the Standardised precipitation index and the Standardised precipitation and evapotranspiration index in Rasht district for the period 1950-2023 is characterised by a constant trend. The results of studies of meteorological conditions of Lakhsh district for the period 1961- 2021 to identify the possibility of drought occurrence are presented. The trend of the drought indices shows an increase in humidity over the period 1961-2021. Despite the positive trend in humidity over the period considered, extreme and severe droughts of varying duration have been observed.
Abstract: The geographical location of Central Asia, including the Republic of Tajikistan, makes the region highly vulnerable to various climate-related natural disasters, such as floods, droughts and mudslides, which significantly affect sustainable development and people's living conditions, including their access to adequate food and drinking water. Droug...
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Research Article
Connectivity and Rotation of Entropicly Defined Clusters as a Measure of Hurricane and Tornado State
Issue:
Volume 9, Issue 1, June 2025
Pages:
28-43
Received:
24 December 2024
Accepted:
26 January 2025
Published:
21 March 2025
Abstract: A statistical physical model of the two basic properties of clusters within a hurricane their convectivity and rotation - reveals a relationship for the time evolution of a hurricane. Non-doppler data from NEXRAD surface radar imagery, of Hurricane Irma transiting over Florida, is decomposed into unique clusters based on an annealing process using entropy and energy differences between pixels. Application of the concept of entropic forces between a cluster’s pixels provides an estimate of the radial velocity of each cluster by application of Stokes’ theorem. The ratio of the characteristic rotation and convectivity, associated with radial flow, integrated over the extent of the hurricane, closely tracks the hurricane’s state, providing more time resolution than aircraft sorties alone allow. It is concluded that monitoring the rotational and convective state, in conjunction with the size of a cluster, is capable of quickly providing forecasters and others with changes in a hurricane’s state. It is also shown that entropic tornado state can be similarly described in terms of convectivity and rotation rate.
Abstract: A statistical physical model of the two basic properties of clusters within a hurricane their convectivity and rotation - reveals a relationship for the time evolution of a hurricane. Non-doppler data from NEXRAD surface radar imagery, of Hurricane Irma transiting over Florida, is decomposed into unique clusters based on an annealing process using ...
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Research Article
Spatial Distribution of Air Quality in Rangpur Metropolitan, Bangladesh
Issue:
Volume 9, Issue 1, June 2025
Pages:
44-57
Received:
30 September 2024
Accepted:
16 April 2025
Published:
26 May 2025
DOI:
10.11648/j.ijaos.20250901.15
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Abstract: This study investigates the spatial distribution of air quality in Rangpur metropolitan city, Bangladesh, by analyzing particulate matter (PM) concentrations across various land use categories. Using a portable Air Quality Monitor, Indoor Outdoor Formaldehyde (HCHO) Detector (Model: DM106), and Garmin ETrex 10, data was collected from 40 locations categorized into sensitive, residential, mixed, commercial, road intersection, industrial, and village areas. Furthermore, ArcGIS software (version 10.4.1) was applied for spatial analysis, and a dendrogram plot was developed to classify and interpret pollutant clusters. Descriptive statistics and whisker box plots were employed to analyze and visualize variations in pollutant concentrations across different locations. The average concentrations of PM1, PM2.5, and PM10 were found to be 42.22 µg/m³, 70.13 µg/m³, and 89.66 µg/m³, respectively. The Department of Environment (DoE) established the Bangladesh National Ambient Air Quality Standards (NAAQS) for PM2.5 and PM10, which were 65 µg/m³ and 150 µg/m³, respectively. Notably, the PM2.5 concentration (70.13 µg/m³) across different land uses exceeded the NAAQS by 1.07 times. Furthermore, the average PM2.5 and PM10 concentrations were 2.80 and 1.79 times higher than the World Health Organization's (WHO) 24-hour standard levels of 25 µg/m³ and 50 µg/m³, respectively. Commercial areas exhibited the highest pollution levels, attributed to high traffic volumes, ongoing construction, and limited green spaces. In contrast, the industrial area recorded the lowest PM levels, likely due to stringent regulatory measures and lower population density. The study also highlighted that fine particulate matter constitutes a significant proportion of total particulate pollution. Statistical analysis revealed no significant variation in PM concentrations across different locations, while cluster analysis indicated interconnected pollution sources. These findings emphasize the need for targeted pollution control measures and increased awareness to address air quality concerns in Rangpur metropolitan and similar urban settings.
Abstract: This study investigates the spatial distribution of air quality in Rangpur metropolitan city, Bangladesh, by analyzing particulate matter (PM) concentrations across various land use categories. Using a portable Air Quality Monitor, Indoor Outdoor Formaldehyde (HCHO) Detector (Model: DM106), and Garmin ETrex 10, data was collected from 40 locations ...
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Research Article
Heavy Metal Migration and Sedimentation in Syrdarya River (Tajikistan) and Possibility Accumulation in Kayrakkum Reservoir
Issue:
Volume 9, Issue 1, June 2025
Pages:
58-65
Received:
19 April 2025
Accepted:
29 April 2025
Published:
29 May 2025
DOI:
10.11648/j.ijaos.20250901.16
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Abstract: This work is devoted to monitoring the migration of heavy metals along the Syrdarya River bed in Tajikistan and determining the rate of their sedimentation. The concentrations of heavy elements As, Cd, Cu, Ni, Pb and Zn in water samples collected at points along the river were used to determine the concentrations of elements, their migration and sedimentation rate depending on the acid-base conditions of the aquatic environment. Water samples were collected at five points along the river bed, starting from the section where the river crosses the border of Kyrgyzstan and Tajikistan (“Akjar”). Atomic absorption spectrometer “A Analyst 800” was used to analyze heavy metals. It was found that the main form of formation of complexes of the studied heavy metals in the aquatic environment is their hydroxides and the sedimentation rate increases with an increase in the alkalinity of the environment. In addition to anthropogenic factors, natural factors such as water erosion of rocks play a special role in the formation and change of the chemical composition of water bodies. The mobility of heavy metals in the aquatic environment and their uptake by aquatic components of the biosphere largely depend on their state. The state of heavy metals is determined by the types of complexes of heavy metals with ligands and is reflected in the degree of their binding to active centers. Movement of chemical elements by river runoff along the water-soil-plant chain depends on the biological properties of the flora of a given territory and individual elements and is characterized by the transfer coefficient. In turn, the transfer coefficient depends on the soil condition and agrochemistry, pH, clay minerals, chemical composition of irrigation water Ca2+, K+, amount of organic matter in the soil, plant species and other environmental conditions. Taking into account that water resources of most rivers in Central Asia are widely used for irrigation of agricultural lands planned and regular monitoring of hydrochemical parameters of rivers is of special importance. The results of monitoring the distribution of heavy metals (Cd, Zn, As, Pb, Cu, Cr) in the Syrdarya River are presented. It is noted that the regularity of changes in the concentration of elements from the upper to the lower reaches of the Syrdarya River on the territory of Tajikistan is not traceable. It is assumed that the occurrence of such a situation is largely due to the formation of complex compounds of metals with inorganic and organic substances.
Abstract: This work is devoted to monitoring the migration of heavy metals along the Syrdarya River bed in Tajikistan and determining the rate of their sedimentation. The concentrations of heavy elements As, Cd, Cu, Ni, Pb and Zn in water samples collected at points along the river were used to determine the concentrations of elements, their migration and se...
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,
Joshua Benjamin Wisdom
