Andreas Marios Georgiou
Enalia Physis Environmental Research Center (ENALIA)

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A GIS TOOLKIT FOR AUTOMATING DESCRIPTIVE STATISTIC COMPUTATIONS FOR AIR QUALITY MODELING Andreas Marios Georgiou; Themis Kontos
Geoplanning: Journal of Geomatics and Planning Vol 5, No 1 (2018)
Publisher : Department of Urban and Regional Planning, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1536.391 KB) | DOI: 10.14710/geoplanning.5.1.53-62

Abstract

A GIS toolset was developed to support spatial analysis functions, visualization and extraction of a variety of input variables for air quality assessment. The developed toolset allows the automated processing of large amounts of ASCII data converting to points and raster data and the examination of the correlation among them. A case study was performed in Athens basin in Greece. Using the developed GIS toolset, topographic, climatic characteristics and air pollution conditions as well correlations were derived by processing the input data. In addition, thematic maps illustrating the spatial distribution of each parameter were extracted.  The developed GIS toolset greatly reduced the time and effort needed to process the GIS data, and provided a useful tool for a wide variety of environmental applications. The tool uses ArcObjects as the programming language to incorporate equations for statistical analysis in a monthly and a yearly time step. This versatile programming language allows advanced users to incorporate more complex formulations for more accurate results as detailed data is acquired to develop routines for calibration when reference data exist. Results verified the usefulness and feasibility of the developed platform.
Evaluation of MODIS-Derived LST Products with Air Temperature Measurements in Cyprus Andreas Marios Georgiou; Stefani Theofanis Varnava
Geoplanning: Journal of Geomatics and Planning Vol 6, No 1 (2019)
Publisher : Department of Urban and Regional Planning, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/geoplanning.6.1.1-12

Abstract

Air temperature data is usually obtained from measurements made in meteorological stations, providing only limited information about spatial patterns over wide areas. The use of remote sensing data can help overcome this problem, particularly in areas with low station density, having the potential to improve the estimation of air surface temperature at both regional and global scales. Land Surface (skin) Temperatures (LST) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the Terra and Aqua satellite platforms provide spatial estimates of near-surface temperature values. In this study, LST values from MODIS are compared to ground-based near surface air (Tair) measurements obtained from 4 observational stations during 2011 to 2015, covering coastal, mountainous and urban areas over Cyprus. Combining Terra and Aqua LST-8 Day and Night acquisitions into a mean 8-day value, provide a large number of LST observations and a better overall agreement with Tair. Comparison between mean monthly LSTs and mean monthly Tair for all sites and all seasons pooled together yields a very high correlations (r > 0.96) and biases ranging from 1.9oC to 4.1oC. MODIS capture overall variability with a slightly systematic overestimation of seasonal fluctuations of surface temperature. For the evaluation of intra-seasonal temperature variability, MODIS showed biases up to 6.7oC in summer with a tendency to overestimate the variability while in cold seasons, limited biases were presented (0.10oC ± 0.50oC) with a tendency to underestimate the variability. Finally, there was no indication of tendency for MODIS to systematically under- or overestimate the amplitude of the inter-annual variability analysis. The presented high standard deviation can be explained by the influence of surface heterogeneity within MODIS 1km2 grid cells, the presence of undetected clouds and the inherent difference between LST and Tair. Overall, MODIS LST data proved to be a reliable proxy for surface temperature and mostly for studies requiring temperature reconstruction in areas with lack of observational stations.