Browsing by Author "Spyridon E. Detsikas"

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A novel deep learning change detection approach for estimating spatiotemporal crop field variations from Sentinel-2 imagery
(Elsevier B.V., 2024) Neelam Dahiya; Gurwinder Singh; Dileep Kumar Gupta; Kleomenis Kalogeropoulos; Spyridon E. Detsikas; George P. Petropoulos; Sartajvir Singh; Vishakha Sood
The analysis of crop variation and the ability to quantify it is a critical and challenging task. Remote sensing (RS) has proven to be an effective tool for monitoring crops and detecting seasonal variations worldwide. This opens new opportunities for developing effective crop monitoring models, with deep learning models showing great promise. This study presents a deep learning-based U-Net v5 Change Detection (UCD) model capable of identifying and monitoring the spatio-temporal variations in crop fields. The application of the model is demonstrated using Sentinel-2 imagery over Patiala district in India to monitor the seasonal crop variation (rabi crop) during 2017–2018. The results have shown that the UCD model has achieved better results (95.6–98.4%) in accuracy for classified maps and more than (91.6%–96.6%) in accuracy for change maps. This study will be useful for crop monitoring, precision agriculture and crop yield prediction and can assist in decision and policy making towards a more sustainable environment. © 2024
Examining the variation of soil moisture from cosmic-ray neutron probes footprint: experimental results from a COSMOS-UK site
(Springer Science and Business Media Deutschland GmbH, 2023) Owen D. Howells; George P. Petropoulos; Dimitris Triantakonstantis; Zacharias Ioannou; Prashant K. Srivastava; Spyridon E. Detsikas; George Stavroulakis
Utilising cosmic-ray neutron probes is a relatively new approach in obtaining larger area soil moisture and various operational monitoring networks have been established worldwide utilising this technology to measure operationally this parameter. One such network located in the United Kingdom (UK) is the Cosmic-ray Soil Moisture Observing System, so-called COSMOS-UK, established in 2013. The present study aims at investigating the true footprint and the variations within the footprint detectable area at the COSMOS-UK sites using as a case study one such site located in Riseholme, UK. At the selected experimental site extensive fieldwork was conducted in July 2017 that allowed examining the agreement among the soil moisture data retrieved by the Time Domain Transmissometer (TDT) sensors and the corresponding estimates from the COSMOS-UK network station probe. The COSMOS-UK site footprint was compared using GPS-aided information from ground instrumentation, assisted by drone imagery acquisition and the implementation of geospatial interpolation methods in a Geographical Information System (GIS) environment. Altogether, this information was used for assessing the soil moisture footprint extent from the COSMOS-UK site. The COSMOS-UK station footprint was representative for an area shorter in size than the alleged footprint of 600 m diameter, as generally proposed in various relevant investigations. The COSMOS network slightly overestimated soil moisture content measured by the TDT sensor probes installed in the area. Our study findings although concern specifically the studied experimental site contribute towards efforts aiming at assessing the COSMOS-UK soil moisture measurement footprint showcasing the added value of geospatial analysis in this direction. © 2022, The Author(s).
Exploring the effect of the first lockdown due to covid-19 to atmospheric NO2 using Sentinel 5P satellite data, Google Earth Engine and Geographic Information Systems
(Elsevier, 2024) Georgios Gkatzios; George P. Petropoulos; Spyridon E. Detsikas; Prashant K. Srivastava
Air pollution is a phenomenon that plagues modern societies, causing serious impacts on both the natural and man-made environment. Air pollution is linked to specific substances which, when their concentration exceeds certain limits, become harmful and are called pollutants. Such pollutants include carbon monoxide (CO) and carbon dioxide (CO2), particulate matter (PM10), nitrogen oxides (NOX), ozone (O3), and sulfur dioxide (SO2). Fluctuations in pollutant emissions are affected by various events. An example is the first lockdown implemented on March 23, 2020 as a result of the Covid-19 disease in an effort to protect citizens. The period of lockdown was characterized by the complete suspension of various types of activities, the reduction in transport means, as well as the decrease in industrial operations, activities that significantly contribute to increased emissions. The aim of the present study is to determine the distribution and changes in the concentration specifically of nitrogen dioxide (NO2) in the prefecture of Thessaloniki, Greece. The study period is defined as the corresponding time period 04 May–04 April 2019/2020, that is, one year before and during the first lockdown. More specifically, the correlation between the lockdown and atmospheric NO2 is investigated. As part of the analysis, area characteristics such as population density and land uses are also correlated with the distribution of NO2 concentrations. To satisfy the study objectives, the technologies of satellite remote sensing and Geographic Information Systems (GIS), which are a major pillar of geoinformatics, are used. More specifically, data recording NO2 concentrations are used, which have been collected via the Sentinel 5P satellite. Based on the results obtained, it is found that the month of 2020 during which the lockdown was applied showed a very small decrease in NO2 values (4.03%) compared to the corresponding month of 2019. © 2024 Elsevier Inc. All rights reserved.
RETRACTED ARTICLE: Examining the variation of soil moisture from cosmic-ray neutron probes footprint: experimental results from a COSMOS-UK site (Environmental Earth Sciences, (2023), 82, 1, (41), 10.1007/s12665-022-10721-1)
(Springer Science and Business Media Deutschland GmbH, 2025) Owen D. Howells; George P. Petropoulos; Dimitrios P. Triantakonstantis; Z. Ioannou; Prashant Kumar Srivastava; Spyridon E. Detsikas; G. G. Stavroulakis
The Editors have retracted this article. Following the Comment by Scheiffele et al. (2023), errors were found in data interpretation concerning the footprint radius of cosmic-ray neutron sensors. The authors have been offered to submit a revised manuscript for further peer review in future. George P. Petropoulos has stated on behalf of the authors that they disagree to this retraction. © The Author(s) 2024.