Argyro Nisantzi

Relationship between MODIS based Aerosol Optical Depth and PM10 over Croatia

This study analyzes the relationship between Aerosol Optical Depth (AOD) obtained from Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and ground-based PM10 mass concentration distribution over a period of 5 years (2008–2012), and investigates the applicability of satellite AOD data for ground PM10 mapping for the Croatian territory. Many studies have shown that satellite AOD data are correlated to ground-based PM mass concentration. However, the relationship between AOD and PM is not explicit and there are unknowns that cause uncertainties in this relationship.The relationship between MODIS AOD and ground-based PM10 has been studied on the basis of a large data set where daily averaged PM10 data from the 12 air quality stations across Croatia over the 5 year period are correlated with AODs retrieved from MODIS Terra and Aqua. A database was developed to associate coincident MODIS AOD (independent) and PM10 data (dependent variable). Additional tested independent variables (predictors, estimators) included season, cloud fraction, and meteorological parameters — including temperature, air pressure, relative humidity, wind speed, wind direction, as well as planetary boundary layer height — using meteorological data from WRF (Weather Research and Forecast) model.It has been found that 1) a univariate linear regression model fails at explaining the data variability well which suggests nonlinearity of the AOD-PM10 relationship, and 2) explanation of data variability can be improved with multivariate linear modeling and a neural network approach, using additional independent variables.

Monitoring air pollution in the vicinity of cultural heritage sites in Cyprus using remote sensing techniques

Cultural Heritage Sites are in danger of being destroyed due to several factors, such as earthquakes, uncontrolled urbanization and air pollution. The latest, whether it is from industrial, transport or domestic sources, can cause significant degradation and corrosion of cultural monuments. The use of satellite images for monitoring air pollution in different areas has received considerable attention and several related techniques have already been developed. In this study, such techniques are extended to examine air pollution monitoring in areas located in the vicinity of cultural heritage sites in Cyprus. Sun-photometers and Lidar have been used to support the results. The authors incorporate also 3D documentation using a laser scanner for monitoring changes over time. The available technologies and methodologies for digital recording of heritage sites and objects are really promising and the whole heritage community is trying to adopt these approaches for quick, effective, detailed and straightforward 3D reproduction.

The GLAM Airborne Campaign across the Mediterranean Basin

AbstractThe Gradient in Longitude of Atmospheric Constituents above the Mediterranean Basin (GLAM) airborne campaign was set up to investigate the summertime variability of gaseous pollutants, greenhouse gases, and aerosols between the western (∼3°E) and eastern (∼35°E) sections of the Mediterranean basin as well as how this connects with the impact of the Asian monsoon anticyclone on the eastern Mediterranean in the mid- to upper troposphere (∼5–10 km). GLAM falls within the framework of the Chemistry–Aerosol Mediterranean Experiment (ChArMEx) program. GLAM used the French Falcon-20 research aircraft to measure aerosols, humidity, and chemical compounds: ozone, carbon monoxide, methane, and carbon dioxide. GLAM took place between 6 and 10 August 2014, following a route from Toulouse (France) to Larnaca (Cyprus) and back again via Minorca (Spain), Lampedusa (Italy), and Heraklion (Crete, Greece). The aircraft flew at an altitude of 5 km on its outbound journey and 10 km on the return leg. GLAM also collec...

The study of atmospheric correction of satellite remotely sensed images intended for air pollution using sun-photometers (AERONET) and lidar system in Lemesos, Cyprus

Solar radiation reflected by the Earths surface to satellite sensors is modified by its interaction with the atmosphere. The objective of atmospheric correction is to determine true surface reflectance values by removing atmospheric effects from satellite images. Atmospheric correction is arguably the most important part of the pre-processing of satellite remotely sensed data. The most important parameter in applying any atmospheric correction is the aerosol optical thickness which is also used for assessing air pollution. This paper explores how the AOT is extracted from atmospheric corrected satellite imagery acquired from Landsat ETM + and how then AOT values are used to assess air pollution. The atmospheric correction algorihm developed by Hadjimitsis and Clayton (2009) is applied to short wavelengths like Landsat TM band 1 and 2 (0.45-0.52μm, 0.52-0.60 μm). The results are also assessed using Lidar system and Cimel Sunphotometer located in the premises of the Cyprus University of Technology in Limassol. The authors run the atmospheric correction developed by Hadjimitsis and Clayton (2009) in MATLAB and sample AOT results for the Landsat ETM+ images acquired on the 15/01/2010, 20/4/2010, 09/06/2010 are shown. For the Landsat ETM+ image acquired on 20/4/2010, the AOT was found 1.4 after the application of the atmospheric correction. Such value complies with the AOT value measured by the Cimel Sun-photometer (AERONET) during the satellite overpass. An example of how Lidar is used to assess the existing atmospheric conditions which is useful for assessing air pollution is also presented.

Establishing a Remote Sensing Science Center in Cyprus:First Year of Activities of ATHENA Project

ATHENA H2020 Twinning project is a three-year duration project and its main objective is to strengthen the Cyprus University of Technology (CUT) Remote Sensing Science and Geo-Environment Research Laboratory in the field of “Remote Sensing Archaeology” by creating a unique link between two internationally-leading research institutions: National Research Council of Italy (CNR) and the German Aerospace Centre (DLR). Through the ATHENA project, CUT’s staff research profile and expertise will be raised while S&T capacity of the linked institutions will be enhanced. In this paper the abovementioned objectives are presented through the various activities accomplished in the first year of the project. These activities include both virtual training by experts in topics such as active remote sensing sensors and sophisticated algorithms, as well as scientific workshops dedicated to specific earth observation and cultural heritage aspects. During this first year, outreached activities have been also performed aiming to promote remote sensing and other non-destructive techniques, including geophysics, for monitoring and safeguarding archaeological heritage of Cyprus. The ATHENA center aims to serve the local community of Cyprus, but at the same time to be established in the wider area of eastern Mediterranean.

Mapping air pollution using Earth observation techniques for cultural heritage sites

Air pollutants, together with climatic parameters, are of major importance for the deterioration of cultural heritage monuments. Atmospheric pollution is widely recognized as one of the major anthropogenic threats to architectural cultural heritage, in particular when associated with water absorption phenomena. Atmospheric particle deposition on surfaces of Monuments (of cultural heritage interest) may cause an aesthetic impact induced by a series of chemical reactions. Therefore there is a need for systematic monitoring and mapping of air pollution for areas where important archaeological sites and monuments are found. observation techniques, such as the use of satellite image for the retrieval of Aerosol Optical Thickness (AOT), are ideal for this purpose. In this paper, all important monuments of the Paphos District, listed by the Department of Antiquities of Cyprus, have been mapped using Geographical Information Systems. Several recent (2012) MODIS satellite images (both Aqua and Terra) have been used to extract the AOT values in this area. Multi-temporal analysis was performed to identify areas of high risk where AOT values are considered to be high. In situ observations have been also carried out to verify the results.

Satellite remote sensing, GIS and sun-photometers for monitoring PM10 in Cyprus: issues on public health

PM10 and PM 2.5 particles are very significant issues for the public health of the community. Such parameters are measured from air-pollution stations that are scarcely distributed in the Cyprus region. Satellite remote sensing can provide synoptic coverage of the Cyprus area either daily from MODIS sensor or every 16 days from Landsat. Sunphotometers are used to measure the aerosol optical thickness (AOT) on ground during the satellite overpass. Several different campaigns have been made both for two urban areas in Paphos and Limassol area. For the period 28/10/09 - 30/12/09, the regression analysis between PM10 and ΡΜ2.5 for the Paphos town (central) gave coefficient of determination of R2=0,78 and R2=0,61 respectively. Coefficient of determination R2 =0.61 was found for the period May-June 2009 for the centre of Limassol when PM10 was regressed against AOT measured from MICROTOPS handheld sun-photometer. The AOT data retrieved from MODIS AOT (at 550 nm) and CIMEL sun-photometer (AERONET) also provided a high correlation (r=0.9, R2 = 0.81) for the centre of Limassol for April to July 2010 measurements. Results obtained by correlating MODIS AOT (at 550 nm) against hand-held MICROTOPS sun-photometer in the centre of Limassol for the period January 2009 to March 2010 gave R2=0,81. Using the PM10 limit of 50μg/m3 as prescribed by the European Union and the regression model found for the Limassol area, a threshold value of AOT for this area of 0.6 was found. Such value can be used as threshold AOT values for alerts either using the MODIS or Landsat satellite imagery. An example of how a GIS can provide temporal variations of AOT over the Cyprus area is shown.

Searching data for supporting archaeo-landscapes in Cyprus: an overview of aerial, satellite, and cartographic datasets of the island

The landscape of Cyprus is characterized by transformations that occurred during the 20th century, with many of such changes being still active today. Landscapes’ changes are due to a variety of reasons including war conflicts, environmental conditions and modern development that have often caused the alteration or even the total loss of important information that could have assisted the archaeologists to comprehend the archaeo-landscape. The present work aims to provide detailed information regarding the different existing datasets that can be used to support archaeologists in understanding the transformations that the landscape in Cyprus undergone, from a remote sensing perspective. Such datasets may help archaeologists to visualize a lost landscape and try to retrieve valuable information, while they support researchers for future investigations. As such they can further highlight in a predictive manner and consequently assess the impacts of landscape transformation -being of natural or anthropogenic cause- to cultural heritage. Three main datasets are presented here: aerial images, satellite datasets including spy satellite datasets acquired during the Cold War, and cadastral maps. The variety of data is provided in a chronological order (e.g. year of acquisitions), while other important parameters such as the cost and the accuracy are also determined. Individual examples of archaeological sites in Cyprus are also provided for each dataset in order to underline both their importance and performance. Also some pre- and post-processing remote sensing methodologies are briefly described in order to enhance the final results. The paper within the framework of ATHENA project, dedicated to remote sensing archaeology/CH, aims to fill a significant gap in the recent literature of remote sensing archaeology of the island and to assist current and future archaeologists in their quest for remote sensing information to support their research.

Earth observation technologies in service to the cultural landscape of Cyprus: risk identification and assessment

The Cultural landscapes are witnesses of “the creative genius, social development and the imaginative and spiritual vitality of humanity. They are part of our collective identity”, as it is internationally defined and accepted (ICOMOSUNESCO). The need for their protection, management and inclusion in the territorial policies has already been widely accepted and pursued. There is a great number of risks to which the cultural landscapes are exposed, arising mainly from natural (both due to slow geo-physical phenomena as well as hazards) and anthropogenic causes (e.g. urbanisation pressure, agriculture, landscape fragmentation etc.). This paper explores to what extent Earth Observation (EO) technologies can contribute to identify and evaluate the risks to which Cultural Landscapes of Cyprus are exposed, taking into consideration specific phenomena, such as land movements and soil erosion. The research of the paper is illustrated as part of the activities carried out in the CLIMA project - “Cultural Landscape risk Identification, Management and Assessment”. It aims to combine the fields of remote sensing technologies, including Sentinel data, and monitoring of cultural landscape for its improved protection and management. Part of this approach will be based on the use of InSAR techniques in order to monitor the temporal evolution of deformations through the detection and measurement of the effects of surface movements caused by various factors. The case study selected for Cyprus is the Nea Paphos archeological site and historical center of Paphos, which are listed as UNESCO World Heritage sites. The interdisciplinary approach adopted in this research was useful to identify major risks affecting the landscape of Cyprus and to classify the most suitable EO methods to assess and map such risks.

Study of Air Pollution with the Use of MODIS Data, LIDAR and Sun Photometers in Cyprus

In the frame of ‘AIRSPACE’ project, ground-based measurements were conducted in the four main cities of Cyprus. Limassol, comprises the main test site as Lidar and CIMEL sun photometer (NASA/AERONET network) are located at the premises of CUT, while the other cities (Nicosia, Larnaca and Paphos) are used as validation sites. During data collection campaign, measurements from handheld sun-photometers, DustTrak (PM10), Lidar and meteorological stations were used to extract an algorithm for relating satellite MODIS AOD retrievals and ground-based PM10 data for different types of geographical areas. For this purpose, the vertical distribution of atmosphere after the processing of daily lidar signals and meteorological parameters such as relative humidity, wind speed and direction were used.