Recent measurements of broad-band turbidity parameters in the island of Cyprus

In the present analysis broad-band turbidity coefficients, which depend upon the attenuation over the entire solar spectrum, are presented. These coefficients are determined from unfiltered pyrheliometric observations of normal incidence direct solar irradiance. Thus, the Linke turbidity factor T(L) and the Unsworth-Monteith attenuation coefficient T(UM) were calculated from pyrheliometric cloudless-sky observations at Athalassa, Cyprus, for the period 1985 to 1992. It was shown that the minima of turbidity levels occur during the winter (January) and maxima during spring (May). A Linke turbidity factor 'derived' from hourly pyranometric observations is presented. Finally, the rural climate of Athalassa, Cyprus, proved to have lower turbidity levels than several other sites representing semi-rural, urban-polluted and desert climates, respectively

On the diffuse fraction of daily and monthly global radiation for the island of Cyprus

Six years of hourly global and diffuse irradiation measurements on a horizontal surface performed at Athalassa, Cyprus, are used to establish a relationship between the daily diffuse fraction and the daily clearness index. Two types of correlations - yearly and seasonal - have been developed. These correlations, of first and third order in the clearness index are compared to the various correlations established by Collares-Pereira and Rabl (1979), Newland (1989), Erbs et al. (1982), Rao et al. (1984), Page (1961), Liu and Jordan (1960) and Lalas et al. (1987). The comparison has been performed in terms of the widely used statistical indicators (MBE) and (RMSE) errors; an additional statistical indicator, the t-statistic, combining the earlier indicators, is introduced. The results indicate that the proposed yearly correlation matches the earlier correlations quite closely and all correlations examined yield results that are statistically significant. For large K̄(T)>0.60 values, most of the earlier correlations exhibit a slight tendency to systematically overestimate the diffuse fraction. This marginal disagreement between the earlier correlations and the proposed model is probably significantly affected by the clear sky conditions that prevail over Cyprus for most of the time as well as atmospheric humidity content. It is clear that the standard correlations examined in this analysis appear to be location-independent models for diffuse irradiation predictions, at least for the Cyprus case

Recent measurements of broad-band turbidity parameters in the island of Cyprus

In the present analysis broad-band turbidity coefficients, which depend upon the attenuation over the entire solar spectrum, are presented. These coefficients are determined from unfiltered pyrheliometric observations of normal incidence direct solar irradiance. Thus, the Linke turbidity factor T(L) and the Unsworth-Monteith attenuation coefficient T(UM) were calculated from pyrheliometric cloudless-sky observations at Athalassa, Cyprus, for the period 1985 to 1992. It was shown that the minima of turbidity levels occur during the winter (January) and maxima during spring (May). A Linke turbidity factor 'derived' from hourly pyranometric observations is presented. Finally, the rural climate of Athalassa, Cyprus, proved to have lower turbidity levels than several other sites representing semi-rural, urban-polluted and desert climates, respectively

Flood mapping of Yialias river catchment area in Cyprus using Alos Palsar radar images

This study strives to highlight the potential of flood inundation monitoring and mapping in a catchment area in Cyprus (Yialias river) with the use of radar satellite images. Due to the lack of satellite data acquired during dates flood inundation events took place, the research team selected specific images acquired during dates that severe precipitation events were recorded from the rain gauge station network of Cyprus Meteorological Service in the specific study area. The relationship between soil moisture and precipitation was thoroughly studied and linear regression models were developed to predict future flood inundation events. Specifically, the application of fully polarimetric (ALOS PALSAR) and data acquired over different dates for soil moisture mapping is presented. The PALSAR (Phased Array type L-band Synthetic Aperture Radar) sensor carried by the ALOS (Advanced Land Observing Satellite) have quadruple polarizations (HH, VV, HV, VH). The amount of returned radiation (as backscatter echoes) that dictates the brightness of the image depends on factors such as the roughness, size of the target relative to the signal's wavelength, volumetric and diffused scattering. The variation in soil moisture pattern during different precipitation events is presented through soil moisture maps obtained from ALOS PALSAR and data acquired during different dates with different precipitation rates. Soil moisture variation is clearly seen through soil moisture maps and the developed regression models are used to simulate future inundation events. The results indicated the considerable potential of radar satellite images in soil moisture and flood mapping in catchments areas of Mediterranean region. 2012 SPIE

GIS and remote sensing techniques for the assessment of land use change impact on flood hydrology: the case study of Yialias basin in Cyprus

Floods are one of the most common natural disasters worldwide, leading to economic losses and loss of human lives. This paper highlights the hydrological effects of multi-temporal land use changes in flood hazard within the Yialias catchment area, located in central Cyprus. A calibrated hydrological model was firstly developed to describe the hydrological processes and internal basin dynamics of the three major subbasins, in order to study the diachronic effects of land use changes. For the implementation of the hydrological model, land use, soil and hydrometeorological data were incorporated. The climatic and stream flow data were derived from rain and flow gauge stations located in the wider area of the watershed basin. In addition, the land use and soil data were extracted after the application of object-oriented nearest neighbor algorithms of ASTER satellite images. Subsequently, the cellular automata (CA)–Markov chain analysis was implemented to predict the 2020 land use/land cover (LULC) map and incorporate it to the hydrological impact assessment. The results denoted the increase of runoff in the catchment area due to the recorded extensive urban sprawl phenomenon of the last decade