Diofantos G. Hadjimitsis

The importance of accounting for atmospheric effects in satellite remote sensing: a case study from the Lower Thames Valley area, UK

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 and any omission produces erroneous results. The effects of the atmosphere are more severe for dark targets such as water reservoirs. The paper presents two methods of assessing the need for atmospheric correction, and addresses the importance of removing atmospheric effects in the satellite remote sensing of large reservoirs.

On the darkest pixel atmospheric correction algorithm: a revised procedure applied over satellite remotely sensed images intended for environmental applications

Atmospheric correction is an essential part of the pre-processing of satellite remote sensing data. Several atmospheric correction approaches can be found in the literature ranging from simple to sophisticated methods. The sophisticated methods require auxiliary data, however the simple methods are based only on the image itself and are served to be suitable for operational use. One of the most widely used and well-known simple atmospheric correction methods is the darkest pixel (DP). Despite of its simplicity, the user must be aware of several key points in order to avoid any erroneous results. Indeed, this paper addresses a new strategy for selecting the suitable dark object based on the proposed analysis of digital number histograms and image examination. Several case studies, in which satellite remotely sensed image data intended for environmental applications have been atmospherically corrected using the DP method, are presented in this article.

Remote Sensing Applications in Archaeological Research

The spectral capability of early satellite sensors opened new perspectives in the field of archaeological research. The recent availability of hyperspectral and multispectral satellite imageries has established a valid and low cost alternative to aerial imagery in the field of archaeological remote sensing. The high spatial resolution and spectral capability can make the VHR satellite images a valuable data source for archaeological investigation, ranging from synoptic views to small details. Since the beginning of the 20th century, aerial photography has been used in archaeology primarily to view features on the earth’s surface, which are difficult if not impossible to visualize from the ground level (Rowland and Sarris, 2006 ; Vermeulen, F. and Verhoeven, G., 2004). Archaeology is a recent application area of satellite remote sensing and features such as ancient settlements can be detected with remote sensing procedures, provided that the spatial resolution of the sensor is adequate enough to detect the features (Menze et al., 2006). A number of different satellite sensors have been employed in a variety of archaeological applications to the mapping of subsurface remains and the management and protection of archaeological sites (Liu et al., 2003). The advantage of satellite imagery over aerial photography is the greater spectral range, due to the capabilities of the various on-board sensors.

Integrated method for tracking changes in archeo-landscapes using remote and close-range technologies

The importance of visible built heritage and archeolandscapes for preservation of collective memory and identity is widely acknowledged across disciplines regarding heritage protection and valorisation. The complex analysis of archaeolandscape transformations through time needs multilevel geospatial information. To this purpose, it is necessary to consider different domains of technological tools but also an appropriate geospatial framework, applying a multi-scale, multitemporal and multi-sensor approach. In this way, the capabilities of new technologies can be further expanded aiming towards to an effective integration and improvement of preservation strategies and protection methodologies for cultural heritage sites. This paper illustrates the integration of in situ surveying campaigns, close range photogrammetry, aerial and satellite remote sensing imagery for identify change detection at the “Nea Paphos”, a UNESCO protected archaeological site of Cyprus. In particular, this paper examines the evolution of a buried archaeological feature (amphitheatre?) which is already known to experts but has not yet been excavated. Changes of shape and size have been documented, interpreted and mapped using resources covering a temporal arch of circa last 50 years. While soil and vegetation marks of the buried feature are very clear in the historic aerial imagery, these traces are disturbed on the recent images. An integrated method of detecting natural and physical consequences for evolving landscapes, using remote sensing techniques, airborne, and 3D photogrammetric models developed using open-source tools has been applied. Such integration is envisaged to (1) provide new kind of information and possible scenarios for retrieving geospatial knowledge of evolving archeolandscapes and their multiple layers of history and to (2) enable archaeologists, public administration and conservation professionals to pursue specific tailored-made preservation strategies of specific archaeological sites and to support them in more informed decision making.

Satellite and Ground Measurements for Studying the Urban Heat Island Effect in Cyprus

An urban heat island (UHI) is a phenomenon whereby an urban area experiences elevated air temperatures due to anthropogenic modification of the environment and is usually more evident at night. During heat waves the local effect of an UHI is superimposed on the re‐ gional temperature field and as a result heat stress is enhanced. Both the intensity and the spatial structure of the observed thermal contrast of the UHI depend on various parameters, such as the structure of the urban tissue, the population density and its associated heat re‐ lease, the land use patterns, the vegetation cover, the surface topography and relief etc. In general terms, the UHI is becoming more intense as city sizes increase. Traditional measure‐ ments of the near-surface UHI are based on measurements of the air temperature using ur‐ ban and rural weather stations or air temperature transects. Thermal satellite sensors, which primarily measure the radiance at the top of the atmosphere in the thermal infrared, retrieve the so called land surface temperature (LST) which is the temperature measured at the Earth’s surface and is regarded as its skin temperature. Given that LST is different from the surface air temperature, a distinction is made in remote sensing studies between surface ur‐ ban heat island (SUHI) and atmospheric heat island (e.g., Nichol, 1996).

Satellite remote sensing and GIS for sustainable development in Skiathos Island, Greece

Remote sensing technology provides a cost-effective tool for monitoring changes in land-cover. The effective use of satellite remote sensing data and a suitable blend with socio-economic data helps in achieving a local specific prescription to achieve sustainable development of a region. This paper presents the results obtained from using remote sensing and GIS techniques to map land-cover changes in Skiathos Island for a period of 13 years. A set of three multidate Landsat TM images were used for the detection and iventory of disturbance and other changes that occur in land use, cover type, and cover condition in areas of research interest. The burnt areas during the 13-years period were well defined showing the changes in the landscape. It is shown that the use of satellite remote sensing can be used not only to improve the understanding of the significant land-cover changes that have been occurred over the past 13 years but also to enable better management decisions to be made.

Integrated Remote Sensing and GIS Applications for Sustainable Watershed Management: A Case Study from Cyprus

Due to the highly complex nature of both human and physical systems, the ability to com‐ prehend them and model future conditions using a watershed approach has taken a geo‐ graphic dimension. Satellite remote sensing and Geographic Information Systems (GIS) technology have played a critical role in all aspects of watershed management, from assess‐ ing watershed conditions through modeling impacts of human activities to visualizing im‐ pacts of alternative scenarios (Tim & Mallavaram, 2003).

Air Pollution from Space

Diofantos G. Hadjimitsis, Rodanthi-Elisavet Mamouri, Argyro Nisantzi, Natalia Kouremerti, Adrianos Retalis, Dimitris Paronis, Filippos Tymvios, Skevi Perdikou, Souzana Achilleos, Marios A. Hadjicharalambous, Spyros Athanasatos, Kyriacos Themistocleous, Christiana Papoutsa, Andri Christodoulou, Silas Michaelides, John S. Evans, Mohamed M. Abdel Kader, George Zittis, Marilia Panayiotou, Jos Lelieveld and Petros Koutrakis

Air Pollution Monitoring Using Earth Observation & GIS

Air pollution has received considerable attention by local and global communities (Wald et al, 1999). Many major cities have established air quality monitoring stations but these stations tend to be scarcely distributed and do not provide sufficient tools for mapping atmospheric pollution since air quality is highly variable (Wald et al, 1999). Satellite remote sensing is a valuable tool for assessing and mapping air pollution as satellite images are able to provide synoptic views of large areas in one image on a systematic basis due to the temporal resolution of the satellite sensors. Blending together earth observation with ground supporting campaigns enables the users or governmental authorities to validate air pollution measurements from space. New state-of-the-art ground systems are used to undertake field measurements such as Lidar system, automatic and hand held sunphotometers etc. The rise of GIS technology and its use in a wide range of disciplines enables air quality modellers with a powerful tool for developing new analysis capability. Indeed, thematic air pollution maps can be developed. Moreover, the organization of data by location allows data from a variety of sources to be easily combined in a uniform framework. GIS provides the opportunity to fill the technical gap between the need of analysts and decision-makers for easy understanding of the information.

Copernicus Sentinel opportunities using field spectroscopy to support deep man-made infrastructures in Cyprus

Satellite remote sensing is considered as an increasingly important technology for military intelligence. It can be applied to a wide range of military applications, as shown from various researchers. However, there is a great need to integrate information from a variety of sources, rendered available at different times and of different qualities using remote sensing tools. This paper provides a solid methodology to support Sentinel remote sensing detection of deep man made infrastructures in Cyprus using field spectroscopy. A number of vegetation indices such as the Normalized Difference Vegetation Index (NDVI), Simple Ratio (SR), Difference Vegetation Index (DVI) and Optimized Soil Adjusted Vegetation Index (OSAVI), combined with other in-band algorithms were utilized for the development of a vegetation index-based procedure aiming at the detection of underground military structures. The measurements were taken at the following test areas: (a) vegetation area covered with the vegetation (barley), in the presence of an underground military structure (b) vegetation area covered with the vegetation (barley), in the absence of an underground military structure. The test areas were identified, analyzed and modelled under different scenarios. Sentinel-2A is a promising tool for detecting underground structures.